[Numerical expression of the clinical course of the disease. Data management]. / Expresión numérica del curso clínico de la enfermedad. Manejo de datos.

Data management "behind the scenes" refers to collection, cleaning, imputation, and demarcation; and despite of being indispensable processes, they are usually neglected and thus, generate erroneous information. During the collection are errors: omission of covariates, deviation from the objective, and insufficient quality. The omission of covariates distorts the result attributed to the main manoeuvre. Deviation from the primary objective commonly occurs when the outcome is rare, delayed, or subjective and promotes substitution by non-equivalent surrogate variables. Moreover, insufficient quality occurs due to inadequate instruments, omission of the measurement procedure, or measurements out of context, such as attribution at the wrong time or equivalent. Furthermore, cleaning implies identifying erroneous, extreme, and missing values, which may or may not be imputed, depending on the percentage. The values of the manoeuvre or the outcome are never imputed, nor are patients eliminated due to a lack of values. Finally, the demarcation of each variable seeks to give it a clinical meaning about the outcome, for which a hierarchical sequence of criteria is followed: 1) previous clinical study, 2) expert agreement, 3) clinical judgment of the investigator/investigators, and 4) statistics. Acting without quality controls in data management frequently causes involuntary lies and confuses instead of clarifying.

El manejo de datos "tras bambalinas" se refiere a los procesos de recopilación, limpieza, imputación y demarcación; los cuales, aun siendo indispensables, usualmente suelen ser descuidados, por lo que generan información errónea. Durante la recopilación son errores: omisión de covariables, desvío del objetivo, y calidad insuficiente. La omisión de covariables distorsiona el resultado atribuido a la maniobra principal. El desvío del objetivo primario es común cuando el desenlace es raro, tardado o subjetivo y promueve la sustitución por variables subrogadas no equivalentes. Además, la calidad insuficiente, sucede por instrumentos inadecuados, omisión del procedimiento de medición, o medición fuera de contexto -como atribución a destiempo o equivalente-. Por otro lado, la limpieza implica identificar valores erróneos, extremos y faltantes, que podrán ser o no imputados, dependiendo del porcentaje se imputará comúnmente por la medida de resumen. Nunca se imputan los valores de la maniobra ni del desenlace, ni se eliminan pacientes por falta de valores. Finalmente, la demarcación de cada variable busca un significado clínico en referencia al desenlace, para ello se sigue una secuencia jerárquica de criterios: 1) estudio clínico previo, 2) acuerdo de expertos, 3) juicio clínico del investigador/investigadores y 4) estadística. Actuar sin controles de calidad en el manejo de datos provoca frecuentemente mentiras involuntarias y confunde en lugar de esclarecer.

Age and sex differences in the impact of the COVID-19 pandemic on mental health and coping mechanisms in Latin American youth.

BACKGROUND: The COVID-19 pandemic has had negative effects on mental health. Understanding sex and age differences in the perception of stressors, the use of coping strategies, and the prevalence of depression and anxiety can lead to detecting at-risk groups. METHODS: A cross-sectional online study surveyed perceived stressors, coping strategies, and the PHQ-9 and GAD-7 rating scales for symptoms of depression and anxiety. The study was open from Spring 2020 to Spring 2021 and was aimed at children, adolescents and young adults of Latin America. RESULTS: The survey was completed by 3965 participants (63.8% females). The sample was divided into children (N = 621, 15.7%), adolescents (N = 1123, 28.3%) and young adults (N = 2021, 56%). Moderate to severe symptoms of depression and anxiety were found in 43.53% and 27%, respectively, being more frequent in females. Children of both sexes showed the lowest scores in rating scales. Adult females reported a higher level of stress in regards to pandemic news, having someone close diagnosed with COVID-19,the possibility of getting sick, academic delays, economic impact, and depression, while female adolescents reported a higher level of stress regarding the lockdown, losing contact with peers and anxiety. In juxtaposition, females also reported a higher frequency of positive coping strategies. A multivariate analysis confirmed the association of several variables with the presence of depression and anxiety. CONCLUSION: A high prevalence of depression and anxiety was found among young people. Specific intervention programs must be created taking into account age and sex differences.

Association between CLOCK gene polymorphisms and ADHD in Mexican teenagers: A comprehensive assessment.

This study aimed to evaluate markers of the CLOCK gene rs1801260 and rs4864548 in Mexican adolescents, addressing clinical and biological aspects previously associated with ADHD. 347 Mexican adolescents were assessed for mental disorders, metabolic disruption and related conditions, circadian preference, as well as genotyping for the CLOCK. We found a significant association between ADHD and the AA and AG genotypes of rs1801260. Also, we identified in the ADHD group that the total Triiodothyronine and total Thyroxine values were respectively 10 ng/dl units and 0.58 ug/dl units lower in females than in males. Previously reported common variations of the CLOCK gene have been associated with ADHD like the Rs1801260 polymorphism hereby we could consider it as risk factor, but genetic, biochemical and clinical studies in the Mexican population are entailed.

Looking for factors affecting functioning in euthymic patients with bipolar I disorder: the importance of cognitive complaints and BDNF's Val66Met polymorphism.

INTRODUCTION: Functioning in Bipolar Disorder (BD) is affected in a substantial proportion of patients. The impact of demographic, clinical, cognitive, and genetic factors on functioning has been shown individually; however, as a complex phenomenon, a global approach to identify the most relevant as well as possible interactions is needed. METHODS: 102 patients with type I BD in euthymia were invited for evaluation of demographic, clinical, and cognitive characteristics as well as genotype for Val66Met polymorphism of BDNF gene to determine those associated with poor functioning according to the FAST scale cut-off score. Clinical evaluation included assessment of residual affective symptoms and anxiety. Cognitive evaluation included the COBRA scale, verbal memory, and executive functions testing. RESULTS: Residual depressive symptoms, anxiety, cognitive complaints and being a Met carrier were more frequent in the poor functioning group and were entered in a logistic regression model. Being a Met carrier (OR=4.46, CI=1.19-16.67) and cognitive complaints (OR=1.29, CI= 1.13-1.46) were the most important predictors of poor functioning in type I BD. LIMITATIONS: Cross-sectional study, with select population limiting generalizability of findings. CONCLUSIONS: A better understanding of underlying factors affecting cognition, including the possible involvement of BDNF Val66Met polymorphism, its systematic evaluation and a continued search for targeted treatment, along with recognition and attention of residual affective and anxious symptoms might improve psychosocial outcomes such as functioning in this population.

Executive Functioning in Children and Adolescents with ADHD and Disruptive Behavior Disorders.

Objective: The goal was to compare the impairment on executive functions in children and adolescents with attention deficit hyperactivity disorder (ADHD) alone and with comorbid oppositional defiant disorder (ODD), conduct disorder (CD), or both (ADHD+ODD+CD). Design: A total of 162 patients were diagnosed with the Mini International Neuropsychiatric Interview for Children and Adolescents (MINI-KID), and the results of their performances in Behavior Rating Inventory of Executive Function (BRIEF) and the Tower of London (ToLo) were compared. Results: Patients with only ADHD showed less impairment in the BRIEF domains and were younger than those with ADHD+CD; the latter group showed a better performance in the time-related domains of ToLo. Patients with ADHD+ODD+CD did not present a consistently worse cognitive performance. Conclusion: The cognitive performance of patients with ADHD and externalizing disorders seems to vary according to the types of specific comorbid diagnoses, rather than the number of externalizing comorbidities.

Limited Prosocial Emotions in a Clinical Population of Children and Adolescents: Proposal for Core and Ancillary Characteristics.

OBJECTIVE: Limited prosocial emotions (LPE) has been recently incorporated into international classifications as a specifier for conduct disorder in the DSM-5 and for all disruptive behavioural disorders in the ICD-11. The aims of the current work were to determine (a) the accuracy of each of the characteristics used to assess the LPE specifier and (b) whether the manner in which symptoms group together supports the idea of LPE having core characteristics. METHOD: Trained clinicians conducted interviews and determined LPE characteristics using responses from 74 parent/guardian and child/adolescent participants. RESULTS: The distribution of LPE characteristics among those participants with LPE (n = 13) was compared to those with only one LPE characteristic (n = 11). The proposal of callous lack of empathy (CLE) and shallow deficient affect (SDA) as core characteristics was supported by strong associations with the presence of the LPE specifier, larger specificity, and sensitivity indices than those for unconcerned about performance and lack of remorse or guilt, as well as by a robust aggregation in a latent class analysis. CONCLUSIONS: CLE and SDA could be considered as core characteristics of LPE in children and adolescents.

Ten-year course of treated bipolar I disorder: The role of polarity at onset.

INTRODUCTION: Early-stage predictors of illness course are needed in bipolar disorder (BD). Differences among patients with a first depressive versus maniac/hypomanic episode have been stated, although in most studies, memory bias and time from onset to start of specialized treatment might interfere. The aim was to compare the first 10 years of illness course according to polarity at onset. METHODS: 49 type I BD patients admitted for treatment for a first-time affective episode and a following 10-year attendance to the institution were included. A retrospective year by year comparison according to polarity at onset (depressive (DPO) or maniac (MPO)) was performed. Cramer's V and Cohen d were computed to determine effect size. RESULTS: 59.2% (n = 29) started with MPO. Both groups were similar in demographic and social outcome characteristics, clinical features, and treatment variables. Patients with DPO reported more depressive episodes than MPO patients (U = 149.0 p < .001, Cohen's d = 0.87); both groups had a similar number of manic episodes. Only during the first year of follow-up, suicide attempts (SA) were more frequent in patients with DPO while the presence of a psychotic episode and psychiatric hospitalizations were more frequent in the MPO group. CONCLUSION: According to these findings, it can be concluded that illness onset is only indicative of depressive predominant polarity but is not related to other poor prognostic variables after the first year of illness onset, in treated BD. SA in the first year of an affective disorder could represent a marker of BD.

The role of circadian rhythms in individuals with attention deficit hyperactivity disorder and obesity: A narrative review / El papel de los ritmos circadianos en personas con trastorno por déficit de atención con hiperactividad y obesidad: Una revisión narrativa

Abstract Background A relationship between attention deficit hyperactivity disorder (ADHD) and obesity has been consistently documented. Obesity and metabolic syndrome have been associated with misalignment between daily activities and circadian rhythm. ADHD patients have a high prevalence of delayed sleep phase syndrome, which is a circadian rhythm disorder. Understanding this relationship is important for the evaluation of obese population at risk. Objective The aim of this narrative review was to summarize the information updated until 2019 about the role of circadian rhythms in obese ADHD individuals. Method A search was performed in MEDLINE, EMBASE, and Google Scholar database. The terms ADHD, obesity, circadian rhythm, sleep disorders, adolescent, adult, Adolesc, circadian, attention deficit hyperactivity disorder, and child were combined with logical functions. Results A total of 132 articles were reviewed. Evidence showed that ADHD subjects have an increased risk to present obesity and circadian rhythms disorders. Some possible pathways for this relationship have been hypothesized including obesity as a risk factor, an underpinned common biological dysfunction, and behavioral and cognitive features of individuals with ADHD. As most of the articles are methodologically cross-sectional, it is not possible to establish causative associations. Discussion and conclusion This review points out the importance of early recognizing and treating circadian rhythms disorders and obesity in ADHD patients. Future studies must be carried out with a longitudinal design to establish the effect of each comorbidity in the treatment of individuals with ADHD.

Resumen Antecedentes La relación entre el trastorno por déficit de atención con hiperactividad (TDAH) y la obesidad se ha documentado consistentemente. Por otro lado, el síndrome metabólico y la obesidad se han asociado con un desfase del ritmo circadiano. En poblaciones clínicas con TDAH se han encontrado una alta prevalencia del trastorno de fase de sueño retrasada, el cual es un trastorno del ritmo circadiano. Entender la relación entre estos padecimientos es importante para evaluar la población en riesgo de obesidad. Objetivo Resumir la información actualizada hasta 2019 sobre el rol del ritmo circadiano en individuos obesos con TDAH. Método Se realizó una búsqueda de artículos en las bases de datos MEDLINE, EMBASE y Google Scholar. Los términos TDAH, obesidad, ritmos circadianos, trastornos del sueño, adolescentes, adultos y niños se combinaron con operadores lógicos. Resultados Se revisaron un total de 132 artículos. La evidencia demostró que los sujetos con TDAH tienen un alto riesgo de sufrir obesidad y ritmos circadianos alterados. Existen algunas hipótesis para establecer esta relación, incluyendo la obesidad como factor de riesgo para TDAH, la disfunción biológica común entre estos trastornos y las características conductuales y cognitivas de los individuos con TDAH. Sin embargo, como la mayoría de los artículos son transversales, no es posible establecer una asociación causal. Discusión y conclusión Esta revisión señala la importancia del reconocimiento temprano y tratamiento de los trastornos del ritmo circadiano y obesidad en pacientes con TDAH. Estudios futuros deben realizarse de manera longitudinal para establecer el efecto de estas comorbilidades en el tratamiento de los individuos con TDAH.

Back to the clinic. Methods II. The Architecture of Clinical Research. Subject interaction, maneuvers and disease throughout time.

Medicine is characterized by the application of the scientific method through clinical judgment, by correct interpretation and use of the clinical course and/or natural history of the disease; its best description is observed in the architecture of clinical research. Through a temporal sequence, this model explains the phenomenon of causality with three sections: baseline status, maneuver, and outcome. The baseline status assesses who the patient is, where does he come from, his general conditions, the diagnosis, stage and aggressiveness of the pathology, complications, previous therapies, socioeconomic-cultural level, habits, therapeutic indications or contraindications, and the expected evolution is anticipated. In the maneuver, risk or prognostic factors, specific or symptomatic treatment, and general measures can be evaluated. In the outcome, early and late evolution are monitored. The model also allows the causes of follow-up loss to be determined. Anticipating patient evolution by recognizing his condition, disease, and expected effect of medical decisions allows acting in advance, since waiting for the manifestations of the evolutionary process of disease results in detriment to the patient.

La medicina se caracteriza por la aplicación del método científico a través del juicio clínico, por la correcta interpretación y el uso del curso clínico o historia natural de la enfermedad; su descripción más lograda la observamos en la arquitectura de la investigación clínica. A través de una secuencia temporal, este modelo explica el fenómeno de causalidad con tres apartados: estado basal, maniobra y desenlace. En el estado basal se evalúa quién es el paciente, de donde proviene, sus condiciones generales, el diagnóstico, el estadio y la agresividad de la patología, las complicaciones, terapias previas, nivel socioeconómi­co-cultural, hábitos, indicaciones o contraindicaciones terapéuticas y se prevé la evolución esperada. De la maniobra se pueden evaluar los factores de riesgo o pronóstico, tratamiento específico, sintomático y medidas generales. En el desenlace se vigila la evolución temprana y tardía. El modelo también permite determinar las causas de pérdida de seguimiento. Anticipar la evo­lución del paciente al reconocer su condición, enfermedad y efecto esperado de la decisiones médicas permite actuar antici­padamente, ya que esperar las manifestaciones del proceso evolutivo de la enfermedad resulta en detrimento del paciente.

De vuelta a la clínica. Métodos II. Arquitectura de la investigación clínica. Interacción sujeto, maniobras y enfermedad a través del tiempo / Back to the clinic. Methods II. Architecture of clinical research. Subject interaction, maneuvers and disease throughout time

Resumen La medicina se caracteriza por la aplicación del método científico a través del juicio clínico, por la correcta interpretación y el uso del curso clínico o historia natural de la enfermedad; su descripción más lograda la observamos en la arquitectura de la investigación clínica. A través de una secuencia temporal, este modelo explica el fenómeno de causalidad con tres apartados: estado basal, maniobra y desenlace. En el estado basal se evalúa quién es el paciente, de donde proviene, sus condiciones generales, el diagnóstico, el estadio y la agresividad de la patología, las complicaciones, terapias previas, nivel socioeconómico-cultural, hábitos, indicaciones o contraindicaciones terapéuticas y se prevé la evolución esperada. De la maniobra se pueden evaluar los factores de riesgo o pronóstico, tratamiento específico, sintomático y medidas generales. En el desenlace se vigila la evolución temprana y tardía. El modelo también permite determinar las causas de pérdida de seguimiento. Anticipar la evolución del paciente al reconocer su condición, enfermedad y efecto esperado de la decisiones médicas permite actuar anticipadamente, ya que esperar las manifestaciones del proceso evolutivo de la enfermedad resulta en detrimento del paciente.

Abstract Medicine is characterized by the application of the scientific method through clinical judgment, by correct interpretation and use of the clinical course and/or natural history of the disease; its best description is observed in the architecture of clinical research. Through a temporal sequence, this model explains the phenomenon of causality with three sections: baseline status, maneuver, and outcome. The baseline status assesses who the patient is, where does he come from, his general conditions, the diagnosis, stage and aggressiveness of the pathology, complications, previous therapies, socioeconomic-cultural level, habits, therapeutic indications or contraindications and the expected evolution is anticipated. In the maneuver, risk or prognostic factors, specific or symptom treatment, and general measures could be evaluated. In the outcome, early and late evolution are monitored. The model also allows the causes of follow-up loss to be determined. Anticipating patient evolution by recognizing his condition, disease, and expected effect of medical decisions allows acting in advance, since waiting for the manifestations of the evolutionary process of disease results in detriment to the patient.

The ball search field task in the evaluation of methylphenidate treatment of children with attention deficit / hyperactivity disorder.

Assessing behavioral change in psychiatric contexts requires retesting patients where, however, ecologically relevant tasks are rarely used. We employed the Ball Search Field Task (BSFT) to evaluate the performance of attention deficit/hyperactivity disorder (ADHD) outpatients before and after administration of methylphenidate (MPH) and compared their performance with that of non-medicated ADHD outpatients and age-matched controls. The outpatient groups showed poorer performance at initial testing, improved performance at re-test although not to the level of the controls, and no clear effect of MPH treatment. The BSFT is thus sufficiently motivating and discriminating for the behavioral evaluation of treatments in psychiatric contexts.

Lesiones autoinfligidas con fines no suicidas según el DSM-5 en una muestra clínica de adolescentes mexicanos con autolesiones / DSM-5 Non-Suicidal Self-Injury Criteria in a Clinical Sample of Self-Harming Mexican Adolescents

RESUMEN Introducción: El diagnóstico de lesiones autoinfligidas con fines no suicidas (NSSI) propuesto por el DSM-5 requiere estudios de validez en poblaciones diferentes de las europeas. Los objetivos del presente estudio fueron determinar la frecuencia de este diagnóstico en una muestra de adolescentes mexicanos con autolesiones y examinar las variables asociadas. Métodos: Se revisaron 585 expedientes clínicos de adolescentes con historia de autolesiones que acudieron a un hospital público en la Ciudad de México entre los arios 2005 y 2012. Un grupo de expertos estableció el diagnóstico según el DSM-5. Se compararon las características clínicas y demográficas de los pacientes con y sin NSSI. Resultados: Se diagnosticó NSSI en 351 pacientes con autolesiones (60%). Las razones principales de que no se diagnosticaran fueron haber realizado un intento suicida -criterio A, 158 sujetos (26,87%)- o que otro diagnóstico explicara las autolesiones -criterio F, 60 sujetos (10,25%)-. El grupo con NSSI incluyó una mayor proporción de varones (el 26,5 frente al 16,2%) y de pacientes con trastornos de conducta (el 28,5 frente al 13,7%); también se observó que estos pacientes solicitaban atención psiquiátrica debido a las autolesiones con mayor frecuencia (el 31,9 frente al 14,1%). Las características clínicas asociadas incluyeron trastorno de conducta (OR = 2,51; IC95%, 1,62-3,90), trastorno de personalidad (OR = 0,56; IC95%, 0,33-0,97), hospitalización (OR = 0,23; IC95%, 0,16-0,33), síntomas depresivos (OR = 0,60; IC95%, 0,42-0,85), síntomas de ansiedad (OR = 2,08; IC95%, 1,31-3,31) y autolesionarse para influir en otros (OR = 2,19; IC95%, 1,54-3,11). Conclusiones: Más de la mitad de los adolescentes con autolesiones de la población clínica cumplen los criterios diagnósticos de NSSI del DSM-5. Existen características clínicas y demográficas que pueden asociarse con este diagnóstico.

ABSTRACT Introduction: The DSM-5 diagnostic criteria for non-suicidal self-injury (NSSI) needs to be validated in non-European populations. The aims of this study were to determine how common NSSI was in a sample of self-harming Mexican adolescents and examine the associated variables. Methods: We examined the medical records of 585 adolescents with a history of self-injurious behaviour who attended a public hospital in Mexico City from 2005 to 2012. A group of experts established the diagnosis according to the DSM-5. The clinical and demographic characteristics of patients with and without NSSI were compared. Results: NSSI was diagnosed in 351 patients (60%) with evidence of self-harm. The main reasons for not being diagnosed were a previous suicide attempt (criterion A, 158 subjects [26.87%]) and another diagnosis that better explained the self-injurious behaviour (criterion F, 60 subjects [10.25%]). The NSSI group had a higher proportion of males (26.5% vs 16.2%) and patients with behavioural disorders (28.5% vs 13.7%). These patients were also found to seek psychiatric support in relation to their self-harm more frequently (31.9% vs 14.1%). The associated clinical characteristics included behavioural disorder (OR=2.51; 95% CI, 1.62-3.90), personality disorders (OR=0.56; 95% CI, 0.33-0.97), hospital admission (OR=0.23; 95% CI, 0.16-0.33), depressive symptoms (OR=0.60; 95% CI, 0.42-0.85), anxiety symptoms (OR=2.08; 95% CI, 1.31-3.31) and self-harming to influence others (OR=2.19; 95% CI, 1.54-3.11). Conclusions: More than half of the adolescents in the clinical sample with self-injury met DSM-5 criteria for NSSI. There are clinical and demographic characteristics which may be associated with this diagnosis.

DSM-5 Non-Suicidal Self-Injury Criteria in a Clinical Sample of Self-Harming Mexican Adolescents. / Lesiones autoinfligidas con fines no suicidas según el DSM-5 en una muestra clínica de adolescentes mexicanos con autolesiones.

INTRODUCTION: The DSM-5 diagnostic criteria for non-suicidal self-injury (NSSI) needs to be validated in non-European populations. The aims of this study were to determine how common NSSI was in a sample of self-harming Mexican adolescents and examine the associated variables. METHODS: We examined the medical records of 585 adolescents with a history of self-injurious behaviour who attended a public hospital in Mexico City from 2005 to 2012. A group of experts established the diagnosis according to the DSM-5. The clinical and demographic characteristics of patients with and without NSSI were compared. RESULTS: NSSI was diagnosed in 351 patients (60%) with evidence of self-harm. The main reasons for not being diagnosed were a previous suicide attempt (criterion A, 158 subjects [26.87%]) and another diagnosis that better explained the self-injurious behaviour (criterion F, 60 subjects [10.25%]). The NSSI group had a higher proportion of males (26.5% vs 16.2%) and patients with behavioural disorders (28.5% vs 13.7%). These patients were also found to seek psychiatric support in relation to their self-harm more frequently (31.9% vs 14.1%). The associated clinical characteristics included behavioural disorder (OR=2.51; 95% CI, 1.62-3.90), personality disorders (OR=0.56; 95% CI, 0.33-0.97), hospital admission (OR=0.23; 95% CI, 0.16-0.33), depressive symptoms (OR=0.60; 95% CI, 0.42-0.85), anxiety symptoms (OR=2.08; 95% CI, 1.31-3.31) and self-harming to influence others (OR=2.19; 95% CI, 1.54-3.11). CONCLUSIONS: More than half of the adolescents in the clinical sample with self-injury met DSM-5 criteria for NSSI. There are clinical and demographic characteristics which may be associated with this diagnosis.

[The relevance and irrelevance of charts in clinical research]. / Pertinencia e impertinencia de los gráficos en la investigación clíni-ca.

Charts are a visual aid that is used in articles in order to highlight the results of an investigation. They allow illustrating the results with the purpose of making them clearer. Charts, just like statistical tests, are selected based on the objective of the study, the types of variable, and the statistical analyzes to be illustrated. Some of the most commonly used charts in clinical practice are frequency histograms, which illustrate qualitative variables or frequencies; also error charts, that are used for normally distributed quantitative variables; box plots or violin plots are used for distribution-free quantitative variables, and survival curves are for variables that include the person-time variable. The aforementioned charts can be used to illustrate the comparisons between maneuvers and outcome depending on the type of variable that is being analyzed. When two groups are compared and the dependent variable is dichotomous, forest plots are used; for multivariate models, the chart depends on the type of analysis. As for logistic regression and linear regression, tree diagrams are used; and scatter plots are used for linear regression. Survival plots are used for Cox proportional hazards. Although charts can be very useful, if they are misused, they can show differences where there are none, which leads to a misinterpretation of the studies. In this article, we will use examples to complement the topics that were previously addressed in the articles of this series.

Los gráficos constituyen una ayuda visual que usan los artículos para resaltar los resultados de una investigación. Estos permiten ilustrar los resultados con el fin de hacerlos más claros. Los gráficos, al igual que las pruebas estadísticas, se seleccionan a partir del objetivo del estudio, de los tipos de variable y de los análisis estadísticos que se desee ilustrar. Algunos de los gráficos más usados en la práctica clínica son los histogramas de frecuencia que ilustran las variables cualitativas o frecuencias, los gráficos de error se usan para variables cuantitativas con distribución normal, el gráfico de cajas o gráfico de violín para variables cuantitativas de libre distribución y las curvas de supervivencia para las variables que incluyen la variable tiempo/persona. Estos mismos gráficos pueden ser usados para ilustrar las comparaciones entre maniobras y desenlace dependiendo del tipo de variable que se analice. Cuando se comparan dos grupos y la variable dependiente es dicotómica se usan gráficos de bosque. Para los modelos multivariados los gráficos dependen del tipo de análisis, en el caso de la regresión logística se utilizan gráficos de árbol y para la regresión lineal, de dispersión; y para los riesgos proporcionales de Cox, gráficos de supervivencia. Si bien los gráficos son de gran utilidad, mal utilizados pueden mostrar diferencias donde no las hay, provocando una errónea interpretación de los estudios. En este artículo complementaremos con ejemplos los temas abordados con anterioridad en los artículos de esta misma serie.

[Correlation: not all correlation entails causality]. / Correlación: no toda correlación implica causalidad.

The concept of correlation entails having a couple of observations (X and Y), that is to say, the value that Y acquires for a determined value of X; the correlation makes it possible to examine the trend of two variables to be grouped together. We know that, with increasing age, blood pressure figures also increase, therefore, if we want to answer a research question like "what is the connection between age and blood pressure?" the relevant statistical test is a correlation test. This test makes it possible to quantify the magnitude of the correlation between two variables, but it is also helpful for predicting values. If these variables had a perfect correlation, the value of the variable Y could be deduced by knowing the value of X. Because of these advantages, the correlation is one of the most frequently used tests in the clinical setting since, in addition to measuring the direction and magnitude of the association of two variables, it is one of the foundations for prediction models, such as linear regression model, logistic regression model and Cox proportional hazards model.

El concepto de correlación implica contar con un par de observaciones (X y Y), es decir, el valor que toma Y para determinado valor de X; la correlación permite examinar la tendencia de dos variables a ir juntas, por ejemplo, sabemos que al incrementar la edad también aumentan las cifras de presión arterial, por lo tanto, si queremos responder una pregunta de investigación como ¿cuál es la relación entre edad y presión arterial?, la prueba estadística pertinente es una prueba de correlación. Esta prueba permite cuantificar la magnitud de la correlación entre dos variables y ayuda a predecir valores. Si estas variables tuvieran una correlación perfecta se podría inferir el valor de la variable Y conociendo el valor de X. Debido a estas ventajas, la correlación es una de las pruebas más usadas en el ámbito clínico, ya que además de medir la dirección y magnitud de la asociación de dos variables, es uno de los fundamentos de los modelos de predicción, como los modelos de regresión lineal, logística y riesgos proporcionales de Cox.

De vuelta a la clínica. Métodos I. Diseños de investigación. Mayor calidad de información, mayor certeza a la respuesta.

Research designs refer to the way information is obtained and are limited by ethical, economic and temporal viability. Research designs are standardized strategies to reduce biases, which in the architectural model of research are identified in the baseline state, the maneuver and the outcome; hence, there are no specific designs for each question. The design with the lowest probability of bias is the clinical trial, followed by cohort and case-control studies and, finally, by cross-sectional surveys. Among the main characteristics that give merit to research designs are the following: population inquiry, which refers to the situation of the population in relation to the clinical course/natural history of the disease; the maneuver, or action that is expected to modify the baseline state, which can be observational or experimental; follow-up, or documented monitoring that is given to each subject, which can be longitudinal or cross-sectional; and directionality, which can prolective or retrolective and refers to the timing of data collection for research purposes. It will always be better having a valuable question, even when answered with a design with higher risk of bias, than a question that is irrelevant or has no applicability.

Los diseños de investigación se refieren a la forma como se obtiene la información y están limitados por viabilidad ética, económica y temporal. Son estrategias estandarizadas para disminuir los sesgos que en el modelo arquitectónico de la investigación se identifican en el estado basal, maniobra y desenlace; de ahí que no hay diseños específicos para cada pregunta. El diseño con menor probabilidad de sesgos es el ensayo clínico, seguido de la cohorte, el estudio de casos y controles y, finalmente, la encuesta transversal. Entre las principales características que dan mérito a los diseños están las siguientes: la pesquisa de la población, que se refiere a la ubicación de la población en relación con el curso clínico o historia natural de la enfermedad; la maniobra, o acción que se espera modifique la condición basal, que puede ser observacional o experimental; el seguimiento, o monitoreo documentado que se le da a cada sujeto, que puede ser longitudinal o transversal; y la direccionalidad, prolectiva o retrolectiva, que alude al tiempo de recopilación de la información con fines de investigación. Siempre será mejor tener una pregunta valiosa, incluso cuando se responda con un diseño con mayor riesgo de sesgos, que una pregunta irrelevante o sin aplicabilidad.

De vuelta a la clínica. Métodos I. Diseños de investigación. Mayor calidad de información, mayor certeza a la respuesta / Back to the clinic. Methods I. Research designs. Higher quality of information, greater certainty to the answer

Resumen Los diseños de investigación se refieren a la forma como se obtiene la información y están limitados por viabilidad ética, económica y temporal. Son estrategias estandarizadas para disminuir los sesgos que en el modelo arquitectónico de la investigación se identifican en el estado basal, maniobra y desenlace; de ahí que no hay diseños específicos para cada pregunta. El diseño con menor probabilidad de sesgos es el ensayo clínico, seguido de la cohorte, el estudio de casos y controles y, finalmente, la encuesta transversal. Entre las principales características que dan mérito a los diseños están las siguientes: la pesquisa de la población, que se refiere a la ubicación de la población en relación con el curso clínico o historia natural de la enfermedad; la maniobra, o acción que se espera modifique la condición basal, que puede ser observacional o experimental; el seguimiento, o monitoreo documentado que se le da a cada sujeto, que puede ser longitudinal o transversal; y la direccionalidad, prolectiva o retrolectiva, que alude al tiempo de recopilación de la información con fines de investigación. Siempre será mejor tener una pregunta valiosa, incluso cuando se responda con un diseño con mayor riesgo de sesgos, que una pregunta irrelevante o sin aplicabilidad.

Abstract Research designs refer to the way information is obtained and are limited by ethical, economic and temporal viability. Research designs are standardized strategies to reduce biases, which in the architectural model of research are identified in the baseline state, the maneuver and the outcome; hence, there are no specific designs for each question. The design with the lowest probability of bias is the clinical trial, followed by cohort and case-control studies and, finally, by cross-sectional surveys. Among the main characteristics that give merit to research designs are the following: population inquiry, which refers to the situation of the population in relation to the clinical course/natural history of the disease; the maneuver, or action that is expected to modify the baseline state, which can be observational or experimental; follow-up, or documented monitoring that is given to each subject, which can be longitudinal or cross-sectional; and directionality, which can prolective or retrolective and refers to the timing of data collection for research purposes. It will always be better having a valuable question, even when answered with a design with higher risk of bias, than a question that is irrelevant or has no applicability.

De vuelta a la clínica: sin justificación no existe pregunta de investigación que valga.

A clinical research question requires the concurrence of clinical experience and knowledge on methodology and statistics in that who formulates it. Initially, a research question should have a structure that clearly establishes what is that which is being sought (consequence or outcome), in whom (baseline status), and by action of what (maneuver). Subsequently, its reasoning must explore four aspects: feasibility and reasonableness of the questioning, lack of a prior answer, relevance of the answer to be obtained, and applicability. Once these aspects are satisfactorily covered, the question can be regarded as being "clinically relevant", which is different from being statistically significant, which refers to the probability of the result being driven by chance, which does not reflect the relevance of the question or the outcome. One should never forget that every maneuver entails adverse events that, when serious, discredit good results. It is imperative to have the possible answer estimated from within the structure of the question. The function of clinical research is to corroborate or reject a hypothesis, rather than to empirically test to find out what the outcome is.

La formulación de una pregunta de investigación clínica requiere la concurrencia de experiencia clínica y conocimiento en metodología y estadística. Inicialmente, la pregunta de investigación debe contar con una estructura que deje claro qué se busca (consecuencia o desenlace), en quién (estado basal) y por acción de qué (maniobra). Posteriormente, su argumentación debe explorar cuatro aspectos: factibilidad y sensatez del cuestionamiento, ausencia de respuesta previa, relevancia de la respuesta a obtener y aplicabilidad. Una vez que estos aspectos han sido cubiertos en forma satisfactoria puede considerarse que la pregunta es "clínicamente relevante", que es diferente a significancia estadística (la probabilidad de que el resultado se deba al azar y que no refleja la relevancia de la pregunta ni de los resultados). Nunca se debe olvidar que toda maniobra conlleva eventos adversos, que cuando son graves demeritan los buenos resultados. Es imperativo estimar la posible respuesta desde la estructura de la pregunta; la función de la investigación clínica es corroborar o rechazar una hipótesis, no probar empíricamente para ver qué resulta.

De vuelta a la clínica: sin justificación no existe pregunta de investigación que valga / Back to the clinic: without justification there is no worthwhile research question

Resumen La formulación de una pregunta de investigación clínica requiere la concurrencia de experiencia clínica y conocimiento en metodología y estadística. Inicialmente, la pregunta de investigación debe contar con una estructura que deje claro qué se busca (consecuencia o desenlace), en quién (estado basal) y por acción de qué (maniobra). Posteriormente, su argumentación debe explorar cuatro aspectos: factibilidad y sensatez del cuestionamiento, ausencia de respuesta previa, relevancia de la respuesta a obtener y aplicabilidad. Una vez que estos aspectos han sido cubiertos en forma satisfactoria puede considerarse que la pregunta es "clínicamente relevante", que es diferente a significancia estadística (la probabilidad de que el resultado se deba al azar y que no refleja la relevancia de la pregunta ni de los resultados). Nunca se debe olvidar que toda maniobra conlleva eventos adversos, que cuando son graves demeritan los buenos resultados. Es imperativo estimar la posible respuesta desde la estructura de la pregunta; la función de la investigación clínica es corroborar o rechazar una hipótesis, no probar empíricamente para ver qué resulta.

Abstract A clinical research question requires the concurrence of clinical experience and knowledge on methodology and statistics in that who formulates it. Initially, a research question should have a structure that clearly establishes what is that which is being sought (consequence or outcome), in whom (baseline status), and by action of what (maneuver). Subsequently, its reasoning must explore four aspects: feasibility and reasonableness of the questioning, lack of a prior answer, relevance of the answer to be obtained, and applicability. Once these aspects are satisfactorily covered, the question can be regarded as being "clinically relevant", which is different from being statistically significant, which refers to the probability of the result being driven by chance, which does not reflect the relevance of the question or the outcome. One should never forget that every maneuver entails adverse events that, when serious, discredit good results. It is imperative to have the possible answer estimated from within the structure of the question. The function of clinical research is to corroborate or reject a hypothesis, rather than to empirically test to find out what the outcome is.

[List of Ethical Principles for Medical Research Involving Human Subjects]. / Lista para Aspectos Éticos de Investigaciones en Humanos.

The ethical principles of a research proposal are not contained only in a paragraph or in the informed consent form; actually, they are an essential part of the whole protocol from the beginning to the end. In a complementary manner to the regulatory and educative documents, our objective in this article is to propose a checklist of questions so researches can ensure they have included the necessary information and precautions to meet the ethical considerations that are required for every research with human beings, which shall be called List of Ethical Principles for Medical Research Involving Human Subjects. We propose questions that researchers must ask themselves when they compose the background, justification, objectives, research question, hypothesis, selection criteria, sample size calculation, sampling, research design, statistical analysis plan, ethical aspects, publication plan, and references.

Los aspectos éticos de una propuesta de investigación no están contenidos solamente en un apartado y en el formulario de consentimiento informado, en realidad forman parte esencial de todo el protocolo desde el inicio hasta el final. De manera complementaria a los documentos regulatorios y educativos, el objetivo en este artículo es proponer una lista de cotejo de preguntas para que el investigador pueda asegurarse de haber incluido la información y elementos necesarios para cumplir con los aspectos éticos que toda investigación con seres humanos demanda, a la cual llamaremos LAEIH (Lista para Aspectos Éticos de Investigaciones en Humanos). Proponemos preguntas que deben hacerse los investigadores al redactar los antecedentes, la justificación, objetivos, pregunta de investigación, hipótesis, criterios se selección, cálculo de tamaño de muestra, muestreo, diseño de investigación, plan de análisis estadístico, aspectos éticos, plan de publicación y referencias.