[Thyroid dysfunction due to 131I-metaiodobenzylguanidine in patients with neuroblastoma]. / Disfunción tiroidea por I131-Metayodo Benzilguanidina en pacientes con neuroblastoma.

INTRODUCTION: The treatment of advanced neuroblastoma includes chemotherapy, surgery, and radiotherapy with 131-I-Metaiodobenzylguanidine (131-I-MIBG). Despite strategies to protect thyroid function, its dysfunction is reported between 12 and 85%. OBJECTIVE: To identify the frequency of thyroid dys function in cases of neuroblastoma treated with 131-I-MIBG. PATIENTS AND METHOD: Cross-sectional study. We included all the cases with neuroblastoma treated with 131-I-MIBG between 2002 and 2015, with complete somatometry, and complete thyroid profile (TSH, free and total T3 and T4, and anti-thyroglobulin and antiperoxidase antibodies). RESULTS: 27 patients were identified out of which eleven died (40%). Out of the 16 surviving cases, 9 (56%) presented thyroid dysfunction: 2 (13%) cases with subclinical hypothyroidism and 7 (44%) cases with clinical hypothyroidism (3 cases due to psychomotor developmental delay and 4 due to growth deceleration). The patients presented cli nical manifestations at 16.1 months (1.2-66.3 months) after receiving the radiopharmaceutical at a cumulative dose of 142 mCi (96-391.5 mCi). No differences were found in the age at diagnosis, age at the start of treatment with 131-I-MIBG, the cumulative dose of 131-I-MIBG, and the time elapsed between the dose and the thyroid profile among the cases with or without thyroid dysfunction. Con clusions: 56% of patients with neuroblastoma had thyroid dysfunction. Most of the cases with hy pothyroidism were referred when thyroid dysfunction was clinically evident. A thyroid profile should be performed every 6 months, along with an annual endocrinological evaluation during the next 5 years in these patients.

Association of leptin with cardiometabolic factors in schoolchildren and adolescents with congenital adrenal hyperplasia. / Asociación de leptina con factores cardiometabólicos en escolares y adolescentes con hiperplasia suprarrenal congénita.

Introduction: In congenital adrenal hyperplasia (CAH), obesity, hyperinsulinemia and leptin levels are increased. Objective: To identify the frequency of cardiometabolic risk factors (CRF) in children and adolescents with CAH and to explore the relationship with leptin levels. Method: Cross-sectional study of 40 patients who underwent anthropometric measurements and had fasting glucose, insulin, triglycerides, 17-hidroxyprogesterone, leptin, HDL and LDL-cholesterol assessed. The patients were classified according to the number of CRFs, and leptin levels were analyzed with the Kruskal-Wallis test. Pearson's correlation was applied between leptin, body mass index (BMI) z-score and body fat percentage. Results: Fifty percent of the patients had obesity and overweight, 59% had hypertriglyceridemia, 40%, hypoalphalipoproteinemia, 27.5%, high LDL-cholesterol and 22.5% insulin resistance. There was positive correlation between leptin and body fat percentage (r = 0.64), BMI z-score (r = 0.55) and the number of CRFs (r = 0.65). In the obesity-adjusted multivariate analysis, leptin levels were associated with the number of CRFs. Conclusion: CAH had a high frequency of CRFs and leptin appeared to be associated with a more adverse cardiometabolic profile in subjects with obesity and overweight.

Introducción: En la hiperplasia suprarrenal congénita (HSC), la obesidad, la hiperinsulinemia y los niveles de leptina se encuentran incrementados. Objetivo: Identificar la frecuencia de los factores de riesgo cardiometabólico (FRC) en niños y adolescentes con HSC y explorar la relación con los niveles de leptina. Método: Estudio transversal de 40 pacientes a quienes se realizó somatometría y evaluación de glucosa, insulina, triglicéridos, 17-hidroxiprogesterona, leptina, colesterol HDL y LDL en ayuno. Los pacientes fueron clasificados por el número de FRC y se analizaron los niveles de leptina con Kruskal-Wallis. Se aplicó correlación de Pearson entre la leptina, puntuación Z del índice de masa corporal (zIMC) y porcentaje de grasa corporal. Resultados: 50 % de los pacientes presentó obesidad y sobrepeso, 59 % hipertrigliceridemia, 40 % hipoalfalipoproteinemia, 27.5 % colesterol LDL alto y 22.5 % resistencia a la insulina. Hubo correlación positiva entre leptina y porcentaje de grasa corporal (r = 0.64), el zIMC (r = 0.55) y el número de FRC (r = 0.65). En el análisis multivariado ajustado por obesidad, los niveles de leptina se asociaron con el número de FRC. Conclusión: La HSC tuvo alta frecuencia de FRC y al parecer la leptina se asoció con perfil cardiometabólico más adverso en sujetos con obesidad y sobrepeso.

[Comparison of serum uric acid and liver enzyme levels in adolescents with obesity and with metabolic syndrome]. / Comparación de los niveles séricos de ácido úrico y enzimas hepáticas entre adolescentes con obesidad y con síndrome metabólico.

INTRODUCTION: a relationship has been observed between elevated levels of liver enzymes and uric acid with the presence of metabolic syndrome (MS) in the pediatric population. OBJECTIVE: to compare serum liver enzyme and uric acid levels between adolescents with and without MS. METHODS: a cross-sectional study was carried out in adolescents with obesity between 10 and 18 years old. Somatometric data, serum insulin, lipid profile, uric acid levels and liver enzymes (aspartate aminotransferase [AST], alanine aminotransferase [ALT] and gamma-glutamyl transferase [GGT]) were analyzed. STATISTICAL ANALYSIS: Student's t test or the Chi-square test was used to evaluate differences between groups. RESULTS: a total of 1095 adolescents with obesity were included (444 with MS and 651 without MS). The group with MS had a higher BMI (with MS 2.28 vs without MS 2.11 p < 0.001), with no difference in body fat (42.9 % vs 42.9 %, p = 0.978). The MS group had significantly higher levels of AST (34.4 vs. 29.5, p = 0.013), ALT (42.2 vs. 34.6, p = 0.003), and uric acid (6.17 vs. 5.74, p = 0.002). comparison to the group without MS. The proportion of ALT (40.5 % vs 29.5 %, p = 0.029) and altered uric acid (58.1 % vs. 45.6 %, p = 0.019) was higher in the MS group. CONCLUSIONS: serum levels of ALT, AST and uric acid in adolescents with obesity and MS were higher compared to those without MS. Altered ALT was a risk factor for SM.

Factors associated with vitamin D deficiency in health care workers exposed to SARS-CoV-2: a cross-sectional study.

Introduction: Globally, up to 76.6% of the population may be affected by vitamin D (VD) deficiency, which has been linked to increased morbidity and mortality from COVID-19. This underscores the importance of further research into VD supplementation, particularly for health care workers, who are at higher risk due to indoor work environments and dietary challenges associated with shift schedules. Objective: This study aimed to identify factors associated with VD deficiency in Mexican health care workers exposed to SARS-CoV-2. Materials and methods: We conducted a cross-sectional study from June 2020 to January 2021 among frontline health care workers treating hospitalized COVID-19 patients. Blood samples were collected to measure 25-hydroxy VD levels via radioimmunoassay. We also assessed previous COVID-19 infection and comorbidities that could influence VD levels. Results: The study included 468 health care workers. The median serum VD concentration was 16.6 ng/mL. VD deficiency was found in 69.4% (n = 325) of participants, while only 5.1% (n = 24) had normal levels. Those with type 2 diabetes (13.3 ng/mL vs. 17.1 ng/mL) or obesity (15.7 ng/mL vs. 17.1 ng/mL) had significantly lower VD levels than their counterparts (p < 0.001 and p = 0.049, respectively). No significant differences were found among participants with high blood pressure. Multivariate analysis revealed that type 2 diabetes was independently associated with VD deficiency. Conclusion: There is a high prevalence of VD deficiency among health care workers, which is potentially linked to both personal health factors and occupational conditions.

Impact of an educational intervention on the knowledge of testicular self-examination and attitudes toward it.

INTRODUCTION: There is evidence that the percentage of adolescents that practice testicular self-examination is low. OBJECTIVE: To assess the short-term and long-term (6 months) impact in male adolescents of an educational intervention on the knowledge of testicular self-examination and attitude toward it. METHODS: We conducted a quasi-experimental pre-test post-test study in male adolescents. A questionnaire was validated to assess knowledge on testicular self-examination and attitudes towards it (awareness, intentions, and behaviour). The educational intervention was group-based and consisted in an instructional talk with the aid of diagrams and brochures. The questionnaire was administered before and after the intervention. A follow-up was scheduled 6 months later, and the talk was delivered again, with administration of the questionnaire before and after. RESULTS: The study included 139 adolescents with a median age of 14 years. We found an improvement in knowledge (18.3% vs 78.9%; P = 0.02) and attitude (5.6% vs 53.5%; P = 0.02) after the initial intervention. At the 6-month follow-up (n=98), there was no change in knowledge (87.0% vs 93.0%; P = 0.671), but attitude improved after the second intervention (58.0% vs 78.0%; P = 0.009). CONCLUSION: An educational intervention on testicular self-examination improved the proportion of adolescents with an adequate attitude (5.6% vs 53.5%) and adequate knowledge (18.3% vs 78.9%). The repetition of the intervention at 6 months increased the proportion of adolescents with an adequate attitude (53.5% vs 86.4%).

Leptin/adiponectin ratio as a prognostic factor for increased weight gain in girls with central precocious puberty.

Objective: To determine if the leptin, adiponectin, and leptin/adiponectin ratio (LAR) can predict weight gain at the end of GnRH analogs (GnRHa) treatment in girls with central precocious puberty (CPP). Material and methods: Study design: prospective cohort. Serum levels of leptin and adiponectin were determined at diagnosis of CPP. Anthropometry was performed at diagnosis of CPP and every six-months, until treatment with GnRHa was discontinued and they presented menarche. Patients were divided according to BMI<94 and BMI>95 percentile at diagnosis of CPP. The outcome was the increased in weight gain (e.g., from normal weight to overweight) at the end of follow-up. Statistical analysis: repeated measures ANOVA test and Student's t-test were used to compare groups. Logistic regression analysis was used to evaluate the association of leptin and adiponectin levels, as well as LAR values with increased weight gain. Results: Fifty-six CPP patients were studied, 18 had BMI >95 percentile and 38 BMI <94 percentile. Of the 18 patients who initially had BMI >95th, two patients went from obesity to overweight, while among the 38 patients who started with BMI <94th, 21 (55.2%) increased their weight gain at the end of follow-up. This last group had higher leptin levels (8.99 ± 0.6 vs 6.14 ± 0.8, p=0.005) and higher LAR values compared to those who remained in the same weight (1.3 ± 0.5 vs 0.96 ± 0.56, p=0.01). In the logistic regression analysis, it was found that higher leptin levels and higher LAR values were associated with increased weight gain (RR 1.31, 95%CI 1.03-1.66, RR 4.86, 95%CI 1.10-21.51, respectively), regardless of birth weight, pubertal stage, age, and bone/chronological age ratio. Conclusions: In patients with CPP, leptin levels and higher LAR values appear to be associated with significantly greater weight gain during GhRHa treatment, particularly in girls starting with BMI < 94 percentile.

Vitamin D levels in the pre- and post-COVID-19 pandemic periods in pediatric patients with chronic kidney disease.

Introduction: Vitamin D (VD) deficiency is common in children with chronic kidney disease (CKD) because of multiple factors. During the coronavirus disease 2019 (COVID-19) pandemic, it increased because of medicine shortage and no enough medical service for patients with non-COVID-19 diseases. Objective: To analyze the effects of the COVID-19 pandemic-related lockdown on the serum levels and status of 25-hydroxyvitamin D3 (25-[OH]D) in children with CKD. Materials and methods: This retrospective study included patients (6-18 years old) who were diagnosed with CKD stage 2-5 and routinely measured for serum VD levels between May 2019 and December 2022. Serum 25-(OH)D levels were measured before, during, and after the pandemic (2019, 2020-2021, and 2022, respectively). The daily dose of cholecalciferol supplementation and the readjustment (if required) were recorded. Results: This study included 171 patients (median age: 12 years). Before the pandemic, the median serum VD level was 25.0 ng/mL (19.3% VD deficiency). Then, VD supplementation was adjusted to 400-1,200 UI daily in 98.8% (n = 169) of patients. During the pandemic, the median VD level decreased to 22.5 ng/mL (43.3% VD deficiency). Hence, the supplementation was readjusted, and after the pandemic, the level was 28.7 ng/mL (18.7% VD deficiency), indicating a statistically significant increase in serum VD levels from the prepandemic period (p = 0.007). Conclusion: Decreased serum VD levels and increased VD deficiency frequency were observed in patients with CKD during the COVID-19 but improved after readjustment of supplementation.

[Correlation of uric acid with carotid intima media thickness in obese adolescents]. / Correlación del ácido úrico con el grosor de la íntima media de la carótida en adolescentes con obesidad.

Introduction: Introduction: obesity in the pediatric population is a public health problem. The correlation of uric acid and carotid intima media thickness in adults has been demonstrated. Objective: to identify the correlation of uric acid and carotid intima media thickness in adolescents with obesity. Material and methods: an observational, cross-sectional study was carried out. Patients aged ten to 16 years with a diagnosis of obesity were included. Uric acid, lipid profile and carotid intima media thickness were determined. In relation to the statistical analysis, carotid intima media thickness was correlated with uric acid levels through Spearman's correlation coefficient. Results: one hundred and sixty-nine adolescents were included with a median age of 13 years, without predominance of sex. A positive correlation of uric acid with carotid intima media thickness was identified (r = 0.242, p = 0.001). When stratified according to sex, there was no correlation in women (r = -0.187, p = 0.074), while in men it increased (r = 0.36, p = 0.001) and by pubertal stage, pubertal male adolescents had a positive correlation (p = 0.384, p = 0.002). Conclusion: a weak positive correlation was identified between carotid intimal thickness and uric acid in obese adolescents.

Introducción: Introducción: la obesidad en la población pediátrica es un problema de salud pública. Se ha demostrado la correlación del ácido úrico y el grosor de la íntima media de la carótida en adultos. Objetivo: identificar la correlación del ácido úrico y el grosor de la íntima media de la carótida en adolescentes con obesidad. Material y métodos: se realizó un estudio observacional, transversal. Se incluyeron pacientes de diez a 16 años con diagnóstico de obesidad. Se determinó ácido úrico, perfil de lípidos y grosor de la íntima media carotidea. En el análisis estadístico, se correlacionó el grosor de la íntima media carotídea con los niveles de ácido úrico a través del coeficiente de correlación de Spearman. Resultados: se incluyeron 169 adolescentes con una mediana para la edad de 13 años, sin predominio de sexo. Se identificó una correlación positiva del ácido úrico con el grosor de la íntima media carotídea (r = 0,242, p = 0,001). Al estratificarse de acuerdo con el sexo, no hubo correlación en las mujeres (r = -0,187, p = 0,074), mientras que en los hombres aumentó (r = 0,36, p = 0,001) y por estadio puberal, los adolescentes varones púberes tuvieron una correlación positiva (p = 0,384, p = 0,002). Conclusión: se identificó una correlación positiva débil entre el grosor de la íntima de la carótida y el ácido úrico en adolescentes con obesidad.

Adipokines as predictive factor of cardiac function in pediatric patients with chronic kidney disease.

Background: Adipokines are associated with cardiovascular disease; in chronic kidney disease (CKD) patients adipokines could be useful prognostic factors. Objectives: To explore whether leptin and adiponectin in kidney replacement therapy (KRT) children could have a role on their cardiac function, in the long-term. Design: Prospective cohort study was performed with pediatric KRT patients, aged 8 to 17 years who were undergoing hemodialysis or peritoneal dialysis. At enrollment, lipid profile, adipokines (leptin, leptin receptor, free leptin, and adiponectin), anthropometric measurements and cardiological evaluation were determined. At two-year follow-up, a new cardiological evaluation was performed. Statistical analysis: Quantitative data are presented as median and interquartile range (IQR). Mann-Whitney U test and Chi-squared were used for the between-group comparison. Multivariate analyzes were performed to determine the association of adipokines levels with ventricular ejection fraction (LEVF). Results: We included 56 patients, with a median age of 12.5 years. In the first cardiological evaluation, median LVEF was 70.0% (IQR 61%, 76%), 20 patients (35.7%) had some cardiovascular condition, and 10 (17.8%) altered LVEF. At 24-month follow-up, the median LVEF was 70.5% (IQR 65.1%, 77%), while the delta-LVEF values was 3% (IQR -6.5%, 7%). Delta-LVEF were correlated with baseline adipokines serum levels, and the only positive correlation found was with free leptin (r=0.303, p=0.025). In multivariate analysis, levels of free leptin (Coef. 0.12, p<0.036) and leptin (coef. 1.72, p=0.049), as well as baseline LVEF (Coef. -0.65, p<0.001) were associated with delta-LVEF. Conclusions: Free leptin, leptin and LVEF at the beginning of follow-up were associated with the LVEF decrease at the 24-month follow-up in KRT children.

[Usefulness of a nutritional strategy on dyslipidemia in pediatric patients with terminal chronic kidney disease]. / Utilidad de una estrategia nutricional sobre la dislipidemia en pacientes pediátricos con enfermedad renal crónica terminal.

Introduction: Background and objective: in chronic kidney disease (CKD) there are several factors that increase the presence of dyslipidemia. The aim of this study was to identify the usefulness of a nutritional intervention, in children with terminal CKD, on dyslipidemia 6 months after intervention start. Materials and methods: a quasi-experiment study (before and after) was performed. End-stage CKD patients on peritoneal dialysis and hemodialysis were included. Each child underwent a determination somatometry, and lipid profile at the beginning and at 6 months of follow-up. A nutritional guide was made with food traffic lights, turning the food that should be consumed in the least amount possible in red. In addition to including life-size food using educational models. To compare the quantitative variables before and after the intervention, the variables were transformed to their logarithm and a paired Student's t-test was applied. Results: a total of 41 patients were analyzed. After the intervention, the parameters in the lipid profile were modified; meanwhile HDL concentrations increased (41.0 mg/dL vs 44.4 mg/dL, p = 0.048), triglyceride concentrations decreased (227.1 mg/dL vs 185.9 mg/dL, p = 0.007), and these changes persist even after excluding patients who were under lipid-lowering treatment (195 mg/dL vs 171.6, p = 0.049). Regarding the state of dyslipidemia, hypertriglyceridemia decreased, without reaching significance (80.5 % vs 62.5 %, p = 0.073). Conclusions: the nutritional intervention improved HDL and triglyceride concentrations 6 months afterwards in children with terminal CKD.

Introducción: Antecedentes y objetivo: en la enfermedad renal crónica (ERC) existen múltiples factores que incrementan la presencia de la dislipidemia. El objetivo fue identificar la utilidad de una intervención nutricional sobre la dislipidemia, en niños con ERC terminal, a los 6 meses del inicio de la intervención. Materiales y métodos: estudio cuasiexperimental (antes y después). Se incluyeron pacientes con ERC terminal en diálisis peritoneal y hemodiálisis. A cada niño se le realizaron una somatometría y un perfil de lípidos al inicio y a los 6 meses de seguimiento. Se realizó un manual de alimentación con semaforización de los alimentos, poniendo de color rojo los alimentos que se deben consumir en la menor cantidad posible, además de incluir alimentos a tamaño real utilizando modelos educativos. Para comparar las variables cuantitativas antes y después de la intervención se transformaron las variables a su logaritmo y se aplicó la "t" de Student pareada. Resultados: se analizaron 41 pacientes. Posteriormente a la intervención se modificaron los parámetros del perfil lipídico; las concentraciones de HDL se incrementaron (41,0 mg/dL vs. 44,4 mg/dL, p = 0,048), mientras que las concentraciones de triglicéridos disminuyeron (227,1 mg/dL vs. 185.9 mg/dL, p = 0,007), lo cual persiste incluso una vez excluidos aquellos pacientes que se encontraban bajo tratamiento hipolipemiante (195 mg/dL vs. 171,6, p = 0,049). En cuanto al estado de dislipidemia, la hipertrigliceridemia disminuyó sin alcanzar la significancia (80,5 % vs. 62,5 %, p = 0,073). Conclusiones: la intervención nutricional mejoró las concentraciones de HDL y triglicéridos pasados 6 meses de la intervención en niños con ERC terminal.

The leptin/adiponectin ratio as prognostic marker for dyslipidemia during 1 year of follow-up in pediatric patients receiving kidney replacement therapy.

Introduction: Background: leptin and adiponectin are associated with cardiovascular disease in chronic kidney disease (CKD) patients and could be useful prognostic factors. Objectives. to explore the usefulness of the leptin/adiponectin ratio (LAR) to predict the presence or worsening of dyslipidemia during 1 year of follow-up in children receiving kidney replacement therapy (KRT). Material and methods: a prospective cohort study was performed. Pediatric KRT patients aged between 8 and 17 years who were undergoing hemodialysis or peritoneal dialysis were included. At enrollment, the lipid profile, adiponectin and leptin levels, and somatometric measurements, including body fat percentage, were determined. At the one-year follow-up, the lipid profile was reassessed. Results: of the 70 patients included, the median age was 13 years, and there was no sex predominance (52.8 % males). At the end of follow-up, the patients were divided into three groups: those without dyslipidemia (WOD), those who developed or experienced worsening of their dyslipidemia (DWD) and those with persistent dyslipidemia (PD). A LAR > 0.85 (OR, 16.7) and body fat percentage (OR, 1.46) were associated with an increased risk of PD and DWD at 12 months, independently of urea level, BMI Z-score, benzafibrate treatment, CKD progression time, and replacement treatment. Conclusions: a LAR > 0.85 and fat body percentage at the beginning of follow-up were strongly associated with the presence, persistence or worsening of dyslipidemia at the 12-month follow-up in children with KRT.

Introducción: Antecedentes: la leptina y la adiponectina se asocian con enfermedad cardiovascular en los pacientes con enfermedad renal crónica (ERC) y podrían ser factores pronósticos útiles. Objetivos: explorar la utilidad del cociente leptina/adiponectina (LAR) para predecir la presencia o empeoramiento de la dislipidemia durante 1 año de seguimiento en niños que reciben terapia de reemplazo renal (TRR). Material y métodos: se realizó un estudio de cohortes prospectivo. Se incluyeron pacientes pediátricos con TRR de entre 8 y 17 años que estaban en hemodiálisis o diálisis peritoneal. Al inicio del estudio se determinaron el perfil lipídico, los niveles de adiponectina y leptina, y las mediciones somatométricas, incluido el porcentaje de grasa corporal. En el seguimiento de un año, se reevaluó el perfil de lípidos. Resultados: de los 70 pacientes incluidos, la mediana de edad fue de 13 años y no hubo predominio de sexo (52,8 % de varones). Al final del seguimiento, los pacientes se dividieron en tres grupos: aquellos sin dislipidemia (SD), aquellos que desarrollaron o experimentaron un empeoramiento de su dislipidemia (ED) y aquellos con dislipidemia persistente (PD). Un LAR > 0,85 (OR: 16,7) y el porcentaje de grasa corporal (OR: 1,46) se asociaron con un mayor riesgo de ED y PD a los 12 meses, independientemente del nivel de urea, la puntuación Z del IMC, el tratamiento con benzafibrato, el tiempo de progresión de la ERC y el tratamiento de reemplazo. Conclusiones: un LAR > 0,85 y el porcentaje de grasa corporal al inicio del seguimiento se asociaron fuertemente con la presencia, persistencia o empeoramiento de la dislipidemia a los 12 meses de seguimiento en niños con TRR.

Screening for COVID-19 in Children Undergoing Elective Invasive Procedures.

OBJECTIVE: To report the frequency of asymptomatic infection with SARS-CoV-2 in pediatric patients undergoing invasive medical procedures in a tertiary pediatric hospital. METHODS: From June to October 2020, a SARS-CoV-2 real-time reverse-transcription polymerase chain reaction (rRT-PCR) test was performed for all pediatric patients scheduled to undergo an elective invasive procedure. None of the patients was symptomatic. The cycle threshold (Ct) values of the ORF1ab gene were recorded for all patients. RESULTS: A total of 700 patients were screened for SARS-CoV-2 infection. The median age was 5.7 y old. In total, 46.6% (n = 326) of the patients were male, and 53.4% (n = 374) were female. The most common underlying diseases were hemato-oncological (25.3%), gastrointestinal (24.9%), and genitourinary (10.3%). The main scheduled surgical-medical procedures were surgical treatment for acquired congenital diseases, biopsy sampling, local therapy administration, organ transplantation, and the placement of central venous catheters, among others. The SARS-CoV-2 rRT-PCR test was positive in 9.4% (66), and the median Ct value was 35.8. None of the patients developed COVID-19. CONCLUSIONS: The frequency of asymptomatic SARS-CoV-2 infection was detected in less than 10% of pediatric patients scheduled to undergo an elective invasive procedure in a tertiary hospital. This frequency is higher than those in reports from different countries.

[Main biases in clinical research]. / Principales sesgos en la investigación clínica.

In developing a research protocol, authors must consider the possible errors that may occur throughout the study. In clinical research, two types of biases are recognized: random errors and systematic errors; the latter are called biases. To date, dozens of biases have been described, which is why the purpose of this article is to describe the main biases that can occur in clinical research studies, as well as strategies to avoid them or to minimize their effects. Since there are several classifications, in order to provide a more practical overview in this review, the biases are grouped into three types: selection biases, information (or performance) biases, and confounding biases. In addition, to make it even more specific, we describe the biases considering the purpose of the research: prognosis, therapeutics, causality, and diagnostic test studies.

En la elaboración de un protocolo de investigación, los autores deben tomar en cuenta los posibles errores que puedan ocurrir a lo largo del estudio. En la investigación clínica se reconocen dos tipos: los errores aleatorios y los errores sistemáticos, estos últimos se denominan sesgos. A la fecha se han descrito decenas de sesgos, por lo que este artículo tiene como objetivo describir los principales sesgos que pueden ocurrir en los estudios de investigación clínica, así como la forma para evitarlos o minimizar sus efectos. En virtud de que existen varias clasificaciones, en la presente revisión y, a fin de disponer un panorama más práctico, los sesgos se agrupan en tres: sesgos de selección, sesgos de información (o ejecución) y sesgos de confusión. Además, para una descripción más específica, se toma en cuenta el propósito del estudio: pronóstico, terapéutica, causalidad y la evaluación de una prueba diagnóstica.

25-Hydroxyvitamin D level is associated with mortality in patients with critical COVID-19: a prospective observational study in Mexico City.

BACKGROUND/OBJECTIVES: Considering the high number of deaths from coronavirus disease 2019 (COVID-19) in Latin American countries, together with multiple factors that increase the prevalence of vitamin D deficiency, we aimed to determine 25-hydroxyvitamin D (25[OH]D) levels and its association with mortality in patients with critical COVID-19. SUBJECTS/METHODS: This was a prospective observational study including adult patients with critical COVID-19. Data, including clinical characteristics and 25(OH)D levels measured at the time of intensive care unit admission, were collected. All patients were followed until hospital discharge or in-hospital death. The patients were divided into those surviving and deceased patient groups, and univariate and multivariate logistic regression analyses were performed to determine independent predictors of in hospital mortality. RESULTS: The entire cohort comprised 94 patients with critical COVID-19 (males, 59.6%; median age, 61.5 years). The median 25(OH)D level was 12.7 ng/mL, and 15 (16%) and 79 (84%) patients had vitamin D insufficiency and vitamin D deficiency, respectively. The median serum 25(OH)D level was significantly lower in deceased patients compared with surviving (12.1 vs. 18.7 ng/mL, P < 0.001). Vitamin D deficiency was present in 100% of the deceased patients. Multivariate logistic regression analysis revealed that age, body mass index, other risk factors, and 25(OH)D level were independent predictors of mortality. CONCLUSIONS: Vitamin D deficiency was present in 84% of critical COVID-19 patients. Serum 25(OH)D was independently associated with mortality in critical patients with COVID-19.

[From research to practice: clinical phases for drug development]. / De la investigación a la práctica: fases clínicas para el desarrollo de fármacos.

Clinical trials become very relevant in the development of new drugs when their pharmacokinetics, pharmacodynamics, efficiency, safety and possible adverse effects are being assessed. So new drugs are available for their daily use in patients, a model has been proposed for more than four decades; This model consists in the realization of sequential research studies, which were called clinical phases I, II, III and IV, which begin once the drugs' effects have been verified in cellular and animal models (preclinical phase). In this article, the general characteristics of each of the clinical phases are synthesized but, apart from that, the modifications that have been done over the years are described with the purpose of making new drugs available in a quicker way.

Los ensayos clínicos toman gran relevancia en el desarrollo de nuevos fármacos al evaluar la farmacocinética, farmacodinamia, eficacia, seguridad y sus posibles efectos adversos. Para que un nuevo fármaco esté disponible para su uso cotidiano en pacientes, desde hace más de cuatro décadas se propuso un modelo que consiste en la realización de estudios de investigación secuenciales que se denominaron fases clínicas I, II, III y IV, las cuales se inician una vez que se han comprobado los efectos del fármaco en modelos celulares y animales (fase preclínica). En este artículo se sintetizan las características generales de cada una de las fases clínicas, pero además se describen las modificaciones que se han realizado en el trascurso de los años, a fin de disponer rápidamente de nuevos fármacos.

[Factors related to the presence of hospital malnutrition in patients under five years old in a third level unit]. / Factores relacionados con la presencia de desnutrición hospitalaria en pacientes menores de cinco años en una unidad de tercer nivel.

INTRODUCTION: Objective: to identify the factors related to the presence of hospital malnutrition (HM) in patients under five years of age hospitalized in a third level care unit. Material and methods: cohort study. Patients under five years of age hospitalized were included. The record identified age, sex, pathological history, reason for admission and nutritional status by calculating weight/age (W/A), height/age (H/A) and weight/height (W/H). The entire somatometry intake process was performed upon admission, and was repeated on days 2, 4 and 7 of follow-up. The HM was defined as a decrease of more than 0.25 standard deviations in the W/H after seven days of hospitalization. Results: eighty-three patients were identified. The reason for admission was non-surgical pathology in 77% (n = 64). Seventy per cent (n = 58) had underlying disease. At the time of admission, 66% (n = 55) presented malnutrition. A progressive decrease in the Z score of W/H was observed as hospitalization progressed (p < 0.001). An incidence of 67.5% of HM was identified. It was shown that the presence of malnutrition at admission of hospitalization increased the risk of HM (OR 2.9, 95% CI 1.05 to 8.10, p = 0.03). In patients with malnutrition from admission, an age younger than two years decreased the risk of HM (OR 0.093, 95% CI 0.009 to 0.959, p = 0.046), while the underlying disease increased the risk (OR 6.34, 95% CI 1.009 to 39.89, p = 0.049). Conclusions: the presence of malnutrition and underlying disease prior to admission were risk factors to present HM.

INTRODUCCIÓN: Objetivo: identificar los factores relacionados con la presencia de desnutrición hospitalaria (DH) en pacientes menores de cinco años hospitalizados en una unidad de tercer nivel de atención. Material y métodos: estudio de cohorte. Se incluyeron pacientes menores de cinco años de edad hospitalizados. Del expediente se identificaron la edad, el sexo, los antecedentes patológicos, el motivo de ingreso y el estado nutricional mediante el cálculo de los índices peso/edad (P/E), talla/edad (T/E) y peso/talla (P/T). El proceso de toma de somatometría completa se realizó al ingreso y se repitió en los días 2, 4 y 7 de seguimiento. La DH se definió como disminución de más de 0,25 desviaciones estándar en el índice de P/T después de siete días de hospitalización. Resultados: se identificaron 83 pacientes. El motivo de ingreso fue patología no quirúrgica en un 77% (n = 64). El 70% (n = 58) presentaba alguna enfermedad subyacente. Al momento del ingreso, el 66% (n = 55) tenía desnutrición. Se observó una disminución progresiva del score Z de P/T conforme avanzó el tiempo de hospitalización (p < 0,001). Se identificó una incidencia del 67,5% de DH. Se demostró que la presencia de desnutrición al ingreso de la hospitalización aumentaba el riesgo de DH (OR 2,9, IC 95% 1,05 a 8,10, p = 0,03) y en los pacientes con desnutrición desde el ingreso una edad menor a dos años disminuía el riesgo de DH (OR 0,093, IC 95% 0,009 a 0,959, p = 0,046), mientras que alguna enfermedad subyacente aumentaba el riesgo (OR 6,34, IC 95% 1,009 a 39,89, p = 0,049). Conclusiones: la presencia de desnutrición y antecedentes patológicos previo al ingreso fueron factores de riesgo para presentar DH.

[Android/gynecoid ratio as a prognostic factor for dyslipidemia in pediatric patients with chronic kidney disease]. / Cociente androide/ginecoide como factor pronóstico para dislipidemia en pacientes pediátricos con enfermedad renal crónica.

INTRODUCTION: Background: there are multiple factors that increase the presence of dyslipidemia in chronic kidney disease (CKD). Objective: to determine if the android/gynecoid ratio (A/GR) has utility as a cardiometabolic factor for dyslipidemia in pediatric patients with chronic renal failure. Materials and methods: cohort study. Patients with terminal CKD in peritoneal dialysis and hemodialysis were included. Determinations of body composition, body mass index (BMI), and lipid profile were assessed for each patient. Subsequently, somatometry and lipid profile were performed at 6 and 12 months of follow-up. Statistical analysis: to identify the difference between the initial somatic and biochemical variables, and at 6 and 12 months, the Friedman test was applied. The Spearman coefficient determined the correlation of bodily and biochemical variables. Results: twenty-one patients were analyzed. Tryglycerides (TGL) serum at 12 months of follow-up increased significantly (6 vs 12 months, p = 0.05), without evidence of an increase in the Z score of the BMI (p = 0.98) or total cholesterol (p = 0.49). Body fat, fat percentage and Z score BMI did not correlate with changes in cholesterol and triglyceride levels at 6 and 12 months; however, the A/GI presented a statistically significant association with the change in serum concentrations of TGL at 6 (r = 0.65, p = 0.003) and 12 months of follow-up (r = 0.54, p = 0.02). Conclusions: the A/GI showed an association with the increase in the serum concentration of TGL at 12 months of follow-up.

INTRODUCCIÓN: Introducción: los pacientes con enfermedad renal crónica (ERC) deben ser considerados como un grupo de alto riesgo cardiovascular, ya que existen múltiples factores que incrementan la presencia de dislipidemia. Objetivo: determinar si el cociente androide/ginecoide (CA/G) tiene utilidad como factor cardiometabólico para dislipidemia en pacientes pediátricos con insuficiencia renal crónica Materiales y métodos: estudio de una cohorte. Se incluyeron pacientes con ERC terminal en diálisis peritoneal y hemodiálisis. A cada paciente se le realizó determinación de la composición corporal, índice de masa corporal (IMC) y perfil de lípidos. Posteriormente, se realizó somatometría y perfil de lípidos a los 6 y 12 meses de seguimiento. Análisis estadístico: para identificar la diferencia entre las variables somatométricas y bioquímicas iniciales, a los 6 y 12 meses se aplicó la prueba de Friedman. El coeficiente de Spearman determinó la correlación de variables corporales y bioquímicas. Resultados: se analizaron 21 pacientes. Las concentraciones séricas de los triglicéridos a 12 meses de seguimiento aumentaron significativamente (6 vs. 12 meses; p = 0,05), sin evidencia de un incremento en el score Z del IMC (p = 0,98) o colesterol total (p = 0,49). La grasa corporal, su porcentaje y score Z del IMC no se correlacionaron con los cambios en los niveles del colesterol y triglicéridos a los 6 y 12 meses; sin embargo, el CA/G presentó una asociación estadísticamente significativa con la modificación en las concentraciones séricas de los triglicéridos a los 6 (r = 0,65, p = 0,003) y 12 meses de seguimiento (r = 0,54, p = 0,02). Conclusiones: el CA/G mostró asociación al incremento en la concentración sérica de triglicéridos a 12 meses de seguimiento.

Impacto de una maniobra educativa sobre el conocimiento y actitud de la autoexploración testicular / Impact of an educational intervention on the knowledge of testicular self-examination and attitudes toward it

Introducción: Se ha descrito que la autoexploración testicular se realiza en un bajo porcentaje de los adolescentes. Objetivo: Evaluar el impacto de una maniobra educativa a corto y largo plazo (6 meses) sobre el conocimiento y la actitud de los adolescentes varones en la autoexploración testicular. Métodos: Se realizó un cuasiexperimento, antes y después en adolescentes varones. Se validó un cuestionario para evaluar el conocimiento y la actitud (conciencia, intenciones y comportamiento) sobre la autoexploración testicular. La maniobra educativa consistió en una charla informativa de manera grupal que incluía esquemas y folletos. Se les aplicó el cuestionario antes y después de la maniobra educativa. Se citaron a los 6 meses posteriores y se les dio nuevamente la charla aplicándose un cuestionario antes y después de la misma. Resultados: Se incluyeron 139 adolescentes con una mediana para la edad de 14 años. El conocimiento (18,3% vs. 78,9% p=0,02) y la actitud (5,6% vs. 53,5% p=0,02) mejoraron posteriormente a la primera charla informativa. A los 6 meses de seguimiento (n=98) el conocimiento no se modificó (87,0% vs. 93,0% p=0,671); sin embargo, la actitud mejoró tras la segunda charla (58,0% vs. 78,0% p=0,009). Conclusión: Una maniobra educativa sobre la autoexploración testicular mejoró la proporción de una adecuada actitud (5,6% vs. 53,5%) y conocimiento (18,3% vs. 78,9%) en los adolescentes. El reforzamiento de la maniobra a los 6 meses mejora la proporción de adolescentes con una adecuada actitud (53,5% vs. 86,4%). (AU)

Introduction: There is evidence that the percentage of adolescents that practice testicular self-examination is low. Objective: To assess the short-term and long-term (6 months) impact in male adolescents of an educational intervention on the knowledge of testicular self-examination and attitude toward it. Methods: We conducted a quasi-experimental pre-test post-test study in male adolescents. A questionnaire was validated to assess knowledge on testicular self-examination and attitudes towards it (awareness, intentions, and behaviour). The educational intervention was group-based and consisted in an instructional talk with the aid of diagrams and brochures. The questionnaire was administered before and after the intervention. A follow-up was scheduled 6 months later, and the talk was delivered again, with administration of the questionnaire before and after. Results: The study included 139 adolescents with a median age of 14 years. We found an improvement in knowledge (18.3% vs. 78.9%; P=.02) and attitude (5.6% vs. 53.5%; P=.02) after the initial intervention. At the 6-month follow-up (n=98), there was no change in knowledge (87.0% vs. 93.0%; P=.671), but attitude improved after the second intervention (58.0% vs. 78.0%; P=.009). Conclusion: An educational intervention on testicular self-examination improved the proportion of adolescents with an adequate attitude (5.6% vs. 53.5%) and adequate knowledge (18.3% vs. 78.9%). The repetition of the intervention at 6 months increased the proportion of adolescents with an adequate attitude (53.5% vs. 86.4%). (AU)

[Experimental studies: research designs for the evaluation of interventions in clinical settings]. / Estudios experimentales: diseños de investigación para la evaluación de intervenciones en la clínica.

Experimental studies are used to assess the efficacy and effectiveness of therapeutic (pharmacological or surgical), preventive (such as vaccination or lifestyle changes) or educational interventions (e.g., workshops to improve quality and healthcare). There are different experimental studies but, currently, randomized controlled trial (RCT) is recognized as the type of study that provides the highest level of evidence. When this type of research cannot be carried out, there are quasi-experimental studies, where there may be no randomization or a control group; however, this type of studies has a lower degree of validity. This article describes the way different types of RCT and quasi-experimental studies are performed; their advantages and disadvantages are also explained.

Los estudios experimentales se utilizan para evaluar la eficacia y efectividad de una intervención terapéutica (farmacológica o quirúrgica), preventiva (como la vacunación o los cambios estilo de vida) o educativa (por ejemplo, taller para mejorar la calidad y la atención a la salud). Existen diferentes estudios experimentales, pero en la actualidad se reconoce que el ensayo clínico controlado y aleatorizado es el que brinda el mayor grado de evidencia. Cuando no se puede llevar a cabo este tipo de investigación se tienen disponibles los estudios cuasiexperimentales, en los cuales puede ser que no se realice aleatorización o no exista un grupo control, sin embargo, tienen un menor grado de validez. En este artículo se describe la forma de realizar los diferentes tipos de ensayo clínico controlado y aleatorizado y estudios cuasiexperimentales; también se exponen sus ventajas y desventajas.

[Research protocol VII. Validity and reliability of the measurements]. / El protocolo de investigación VII. Validez y confiabilidad de las mediciones.

The concept of validity in research refers to what is true or what is close to the truth. It is considered that the results of an investigation will be valid when the study is free of errors. The errors or biases appear in the development of research, are due to methodological problems and, in general, can be grouped into three: selection bias, measurement bias and confusion bias. In this article, measurement biases will be addressed; this type of error has three axes: 1) the research subject, 2) the instrument for the measurement of the variable (s), and 3) those who make the evaluation of the measurement (s). To improve the obtaining of data and to prevent errors, some strategies can be followed: in every study protocol, it is necessary to include the operational definition of the variables; the subjects that will carry out the measurements or surveys must be trained. If measuring instruments are used, their proper functioning must be verified; when questionnaires are included, they must be validated in the language in which they will be applied, they have had a process of adaptation to the language of the participants in the study, and self-applicable ones are preferred. It is necessary to quantify the variability of the measurements from the statistical point of view to increase the validity of a study.

El concepto de validez en investigación se refiere a lo que es verdadero o se acerca a la verdad. Se considera que los resultados de una investigación son válidos cuando el estudio está libre de errores. Los errores o sesgos que se presentan en el desarrollo de una investigación se deben a problemas metodológicos y pueden agruparse en tres categorías: sesgos de selección, sesgo en la medición y sesgo de confusión. En este artículo se abordan los sesgos de medición, tipo de error que tienen tres ejes: el sujeto de investigación, el instrumento para la medición de las variables y el evaluador de las mediciones. Para mejorar la obtención de los datos y prevenir los errores se pueden seguir algunas estrategias: incluir la definición operacional de las variables, la capacitación de los sujetos que van a realizar las mediciones o encuestas, la verificación del adecuado funcionamiento de los instrumentos de medición, la validación de los cuestionarios en el idioma en el que se van a aplicar, su adecuación al idioma de los participantes en el estudio y que de preferencia sean autoaplicables. Es necesario cuantificar la variabilidad de las mediciones desde el punto de vista estadístico, para aumentar la validez de un estudio.