Fundamento y generalidades de la construcción de modelos estadísticos multinivel en el ámbito de la investigación en salud

Este trabajo tiene como objetivo presentar una mirada global de la aplicabilidad de los modelos de análisis multinivel en el ámbito de la investigación sanitaria. Ofrece información sobre los fundamentos teóricos, metodológicos y estadísticos y, además, menciona los pasos básicos para la construcción de estos modelos, y da ejemplos de su uso, según la estructura jerárquica de los datos. Cabe resaltar que, antes de utilizar estos modelos, se requiere contar con un soporte teórico sobre la necesidad de uso y una valoración estadística que dé cuenta del porcentaje de varianza explicada por el efecto de agrupación de las observaciones. Los requisitos para llevar a cabo este tipo de análisis dependen de condiciones especiales como el tipo de variables, la cantidad de unidades por nivel o el tipo de estructura jerárquica. Se concluye que los modelos de análisis multinivel son una herramienta útil para lograr la integración de información, dadas la complejidad de las relaciones y las interacciones que determinan la mayoría de las condiciones de salud, incluida la pérdida de independencia entre las unidades de observación.

This topic review aims to present a global vision of multilevel analysis models' applicability to health research, explaining its theoretical, methodological, and statistical foundations. We describe the basic steps to build these models and examples of their application according to the data hierarchical structure. It ir worth noticing that before using these models, researchers must have a rationale for needing them, and a statistical evaluation accounting for the variance percentage explained by the observations grouping effect. The requirements to conduct this type of analysis depends on special conditions such as the type of variables, the number of units per level, or the type of hierarchical structure. We conclude that multilevel analysis models are a useful tool to integrate information, considering the complexity of the relationships and interactions involved in most health conditions, including the loss of independence between observation units.

Construction of multilevel statistical models in health research: Foundations and generalities / Fundamento y generalidades de la construcción de modelos estadísticos multinivel en el ámbito de la investigación en salud

This topic review aims to present a global vision of multilevel analysis models' applicability to health research, explaining its theoretical, methodological, and statistical foundations. We describe the basic steps to build these models and examples of their application according to the data hierarchical structure. It ir worth noticing that before using these models, researchers must have a rationale for needing them, and a statistical evaluation accounting for the variance percentage explained by the observations grouping effect. The requirements to conduct this type of analysis depends on special conditions such as the type of variables, the number of units per level, or the type of hierarchical structure. We conclude that multilevel analysis models are a useful tool to integrate information, considering the complexity of the relationships and interactions involved in most health conditions, including the loss of independence between observation units.

Este trabajo tiene como objetivo presentar una mirada global de la aplicabilidad de los modelos de análisis multinivel en el ámbito de la investigación sanitaria. Ofrece información sobre los fundamentos teóricos, metodológicos y estadísticos y, además, menciona los pasos básicos para la construcción de estos modelos, y da ejemplos de su uso, según la estructura jerárquica de los datos. Cabe resaltar que, antes de utilizar estos modelos, se requiere contar con un soporte teórico sobre la necesidad de uso y una valoración estadística que dé cuenta del porcentaje de varianza explicada por el efecto de agrupación de las observaciones. Los requisitos para llevar a cabo este tipo de análisis dependen de condiciones especiales como el tipo de variables, la cantidad de unidades por nivel o el tipo de estructura jerárquica. Se concluye que los modelos de análisis multinivel son una herramienta útil para lograr la integración de información, dadas la complejidad de las relaciones y las interacciones que determinan la mayoría de las condiciones de salud, incluida la pérdida de independencia entre las unidades de observación.

Clinical Outcomes of Medical Management Options for Chronic Anal Fissures in a Long-Term Follow-up: Systematic Review and Meta-Analysis.

BACKGROUND: Topical treatments and botulinum toxin injections are valid options for the management of patients with chronic anal fissures (CAF), but little is known about the efficacy of these techniques in long-term follow-up. The aim of this meta-analysis was to evaluate the effectiveness, given to clinical outcomes, of medical treatments with calcium antagonists, nitroglycerin, and botulinum toxin on CAF treatment in adults. METHOD: A systemic review and meta-analysis developed according to PRISMA [PLoS Med. 2009 Jul 21;6(7):e1000100; BMJ. 2010 Mar 23;340:c332] and registered in PROSPERO (Registration number: CRD42020120386). A systematic literature search was conducted through MEDLINE, EMBASE, Web of Science, and Cochrane Library databases. Randomized control trials that compared medical treatment were identified; publications had to have a clinical definition of CAF with at least one of the following signs or symptoms: visible sphincter fibers at the base of the fissure, anal papillae, sentinel piles, and indurated margins. The symptoms had to be chronic for at least 4 weeks. Data were independently extracted for each study, and a meta-analysis was drawn using fixed- and random-effects models. RESULTS: 17 randomized trials met the inclusion criteria. Diltiazem showed a superior effect compared with glycerin (RR = 1.16 [95% CI = 1.05-1.30]; I2 = 18%) and with fewer adverse effects (RR = 0.13 [95% CI = 0.04-0.042]; I2 = 87%). Similar results were evidenced with the use of nifedipine compared with lidocaine (RR = 4.53 [95% CI = 2.99-6.86]; I2 = 28%). Botulinum toxin did not show statistically significant differences compared to glycerin (RR = 0.81 [95% CI = 0.02-29.36]; I2 = 93%) or isosorbide dinitrate (RR = 1.45 [95% CI = 0.32-6.54]; I2 = 85%). Regarding recurrence, nifedipine was superior to lidocaine (RR = 0.18 [95% CI = 0.08-0.44]; I2 = 31%). CONCLUSIONS: Calcium channel blockers performed well regarding the healing of CAF when compared to others in long-term follow-up. The superiority of botulinum toxin was not evidenced compared to topical treatments. More studies are needed to better assess recurrence rates.

Health conditions of Hitnü indigenous people potentially exposed to crude oil in Arauca, Colombia / Condiciones de salud de los indígenas hitnü potencialmente expuestos a petróleo crudo (Arauca, Colombia)

Introduction: The Hitnü indigenous people live in precarious sanitary conditions, with food insecurity and being victims of sociopolitical violence in Arauca, Colombia. In addition, it is possible that they may be affected by exposure to hydrocarbons found in oil. Objective: To identify the health outcomes of morbidity and mortality profiles of the Hitnü people that could be associated with the exposure to crude oil. Materials and methods: A cross-sectional study was carried out with Hitnü indigenous people, during February and March, 2021, time of drought. A household questionnaire was applied, and one individual to collect data from the environment around the house, occupations and other activities, as well as data from sociodemographic, signs, symptoms, and findings of a medical examination. The potential association with hydrocarbons was explored considering three groups: inhabitants in Arauca city, Aspejaná reserve (not exposed), and San José del Lipa and La Vorágine reserves (exposed by the Ele river and tributaries). With free listings, causes of death were explored. The study incorporated a rigorous intercultural management in all its components. Results: A total of 576 indigenous people from 16 settlements participated. The water consumed could serve as means of exposure to hydrocarbons. Health problems were very varied, including infectious and chronic diseases, malnutrition, and trauma. The masses on the neck were associated with residing in the ancestral reserves (PR = 3.86; CI95% 1.77-8.39), territories with potential exposure to crude-oil. The most relevant causes of death were homicide, tumors, and tuberculosis. Conclusion: For its possible association with exposure to hydrocarbons, it is a priority to start the intercultural study of lymphadenopathies in indigenous communities potentially exposed to crude oil.

Introducción. El pueblo hitnü vive en condiciones sanitarias precarias, con inseguridad alimentaria y víctima de la violencia sociopolítica en Arauca (Colombia). Además, se sospecha que pueden estar afectados por la exposición a los hidrocarburos del petróleo. Objetivo. Identificar los eventos de salud del perfil de morbilidad y mortalidad de los indígenas hitnü que podrían asociarse con la exposición a petróleo crudo. Materiales y métodos. Se realizó un estudio transversal con indígenas hitnü, durante febrero y marzo de 2021, época de sequía. Se aplicó un cuestionario de hogares y uno individual para recolectar datos del ambiente peridomiciliario, ocupaciones y otras actividades, así como datos sociodemográficos, signos, síntomas y hallazgos de un examen médico. La potencial asociación con los hidrocarburos se exploró considerando tres grupos, según su localización: cabecera de Arauca, resguardo Aspejená (no expuestos) y resguardos de San José del Lipa y La Vorágine (expuestos por su cercanía al río Ele y afluentes). Con listados libres, se exploraron las causas de muerte. El estudio incorporó un riguroso manejo intercultural en todos sus componentes. Resultados. Participaron 576 indígenas de 16 asentamientos. El agua consumida pudo servir como medio de exposición a los hidrocarburos. Los problemas de salud fueron muy variados e incluían enfermedades infecciosas y crónicas, malnutrición y trauma. Las masas en el cuello se asociaron con residir en los resguardos ancestrales (RP=3,86; IC95% 1,77-8,39), territorios potencialmente expuestos al petróleo. Las causas de muerte más relevantes fueron el homicidio, los tumores y la tuberculosis. Conclusión: Por su posible asociación con los hidrocarburos, es prioritario el estudio intercultural de linfoadenopatías entre indígenas potencialmente expuestos al petróleo.

Condiciones de salud de los indígenas hitnü potencialmente expuestos a petróleo crudo (Arauca, Colombia) / Health conditions of Hitnü indigenous people potentially exposed to crude oil in Arauca, Colombia

Introducción. El pueblo hitnü vive en condiciones sanitarias precarias, con inseguridad alimentaria y víctima de la violencia sociopolítica en Arauca (Colombia). Además, se sospecha que pueden estar afectados por la exposición a los hidrocarburos del petróleo. Objetivo. Identificar los eventos de salud del perfil de morbilidad y mortalidad de los indígenas hitnü que podrían asociarse con la exposición a petróleo crudo. Materiales y métodos. Se realizó un estudio transversal con indígenas hitnü, durante febrero y marzo de 2021, época de sequía. Se aplicó un cuestionario de hogares y uno individual para recolectar datos del ambiente peridomiciliario, ocupaciones y otras actividades, así como datos sociodemográficos, signos, síntomas y hallazgos de un examen médico. La potencial asociación con los hidrocarburos se exploró considerando tres grupos, según su localización: cabecera de Arauca, resguardo Aspejená (no expuestos) y resguardos de San José del Lipa y La Vorágine (expuestos por su cercanía al río Ele y afluentes). Con listados libres, se exploraron las causas de muerte. El estudio incorporó un riguroso manejo intercultural en todos sus componentes. Resultados. Participaron 576 indígenas de 16 asentamientos. El agua consumida pudo servir como medio de exposición a los hidrocarburos. Los problemas de salud fueron muy variados e incluían enfermedades infecciosas y crónicas, malnutrición y trauma. Las masas en el cuello se asociaron con residir en los resguardos ancestrales (RP=3,86; IC95% 1,77-8,39), territorios potencialmente expuestos al petróleo. Las causas de muerte más relevantes fueron el homicidio, los tumores y la tuberculosis. Conclusión. Por su posible asociación con los hidrocarburos, es prioritario el estudio intercultural de linfoadenopatías entre indígenas potencialmente expuestos al petróleo.

Introduction. The Hitnü indigenous people live in precarious sanitary conditions, with food insecurity and being victims of sociopolitical violence in Arauca, Colombia. In addition, it is possible that they may be affected by exposure to hydrocarbons found in oil. Objective. To identify the health outcomes of morbidity and mortality profiles of the Hitnü people that could be associated with the exposure to crude oil. Materials and methods. A cross-sectional study was carried out with Hitnü indigenous people, during February and March, 2021, time of drought. A household questionnaire was applied, and one individual to collect data from the environment around the house, occupations and other activities, as well as data from sociodemographic, signs, symptoms, and findings of a medical examination. The potential association with hydrocarbons was explored considering three groups: inhabitants in Arauca city, Aspejaná reserve (not exposed), and San José del Lipa and La Vorágine reserves (exposed by the Ele river and tributaries). With free listings, causes of death were explored. The study incorporated a rigorous intercultural management in all its components. Results. A total of 576 indigenous people from 16 settlements participated. The water consumed could serve as means of exposure to hydrocarbons. Health problems were very varied, including infectious and chronic diseases, malnutrition, and trauma. The masses on the neck were associated with residing in the ancestral reserves (PR = 3.86; CI95% 1.77-8.39), territories with potential exposure to crude-oil. The most relevant causes of death were homicide, tumors, and tuberculosis. Conclusion. For its possible association with exposure to hydrocarbons, it is a priority to start the intercultural study of lymphadenopathies in indigenous communities potentially exposed to crude oil.

Incidence of acute respiratory symptoms and COVID-19 infection in children in public schools in Bogotá, Colombia, from July to November, 2020 / Incidencia de síntomas respiratorios agudos y COVID-19 en niños de escuelas públicas de Bogotá, Colombia, entre julio y noviembre de 2020

Introduction: More than 90% of children infected with COVID-19 worldwide developed mild to moderate disease. In Colombia, during 2020, COVID-19 infections in children stayed below 9.2% of the total cases, with no trends for age group or sex. Objective: To estimate the incidence of acute respiratory symptoms and COVID-19 in children from public schools in Bogotá, Colombia during the second semester of 2020. Material and methods: A telephone survey was conducted in over 5,000 scholar children. Antecedents and use of health services were informed. Descriptive statistics were used. Results: A total of 151.470 persons per day accounting for an IR of 157,8 per 100,000 people; almost three times the rate reported by the official surveillance system in the city. Conclusion: A lack of diagnosis and consultation in children was found compared to the general population. Further research is needed to elucidate the true burden of the disease in children.

Introducción. Más del 90% de los niños infectados con COVID-19 en el mundo, desarrollaron enfermedad leve a moderada. En Colombia, durante el 2020, la infección del COVID-19 en niños se mantuvo por debajo de 9,2 % del total de los casos sin tendencias por grupo de edad o sexo. Objetivo. Estimar la incidencia de síntomas respiratorios agudos y COVID19 en niños de escuelas públicas en Bogotá (Colombia) durante el segundo semestre de 2020. Materiales y métodos. Se hizo una encuesta telefónica en más de 5.000 escolares. Se recolectó información de antecedentes médicos y uso de servicios de salud. La información obtenida se describió mediante estadística descriptiva. Resultados. Se contabilizó un total de 151.470 personas al día para una tasa de incidencia de 157,8 en 100.000 personas, casi tres veces la tasa reportada por el sistema de vigilancia oficial de la ciudad. Conclusión. Se encontraron deficiencias en el diagnóstico y consulta de los niños, al compararlos con la población general. Se necesita más investigación para dilucidar la verdadera carga de la enfermedad en la población infantil.

Impact of the COVID-19 pandemic on routine childhood immunisation in Colombia.

OBJECTIVE: To assess the impact of the COVID-19 pandemic on routine childhood vaccination coverage in Colombia by age group, rural/urban residence, state and vaccine type. DESIGN: Ecological study of official monthly vaccination records. SETTING: Vaccination records from the Colombian Ministry of Health (March-October 2019 and 2020). PARTICIPANTS: Aggregated data for Colombian children (<12 months, n=676 153; 12-23 months, n=700 319; and 5 years, n=734 295) participating in the Expanded Program on Immunization. MAIN OUTCOME MEASURES: Proportion of eligible population receiving vaccination. RESULTS: Vaccination coverage showed an overall decline of approximately 14.4% from 2019 to 2020 (2019 coverage=76.0, 2020 coverage=61.6%). The greatest reduction in proportion vaccinated was observed in children <12 months of age for pneumococcal vaccine (second dose) (2019 coverage=81.4%; 2020 coverage=62.2%; 2019-2020 absolute difference, 19.2%; 95% CI 14.8% to 23.7%). For children aged 12-23 months, the proportion vaccinated for yellow fever declined by 16.4% (12.4% to 20.9%) from 78.3% in 2019 to 61.8% in 2020. Among children 5 years of age, the biggest decrease occurred for the oral polio vaccine (second dose), with a difference of 11.4% (7.1% to 15.7%) between 2019 and 2020 (73.1% and 61.7% for 2019 and 2020). We observed a statistically significant effect on vaccine coverage in rural versus urban areas for children <12 months and 5 years of age. CONCLUSIONS: Reduced uptake of immunisations during the COVID-19 pandemic poses a serious risk of vaccine-preventable disease outbreaks. Colombia and other middle-income countries need to continue to monitor immunisation programme coverage and disease outbreaks at the national and subnational levels and undertake catch-up vaccination activities.

COVID-19 distribution in Bogotá, Colombia: effect of poverty during the first 2 months of pandemic.

BACKGROUND: The current SARS-CoV-2 pandemic has especially affected individuals living in conglomerate settings having poverty as common characteristic. However, evidence of the association between COVID-19 severity and social determinants is still scarce, particularly, for Latin American countries. The objective was to assess the effect of socioeconomic deprivation in the clinical severity of COVID-19 infection among different localities of Bogotá, Colombia. METHODS: Secondary analyses using data of SARS-CoV-2 infected cases in Bogotá from 6 March 2020 to 19 April 2020 were carried out. Direct and indirect indicators of deprivation at area level and individual demographic characteristics (age, sex and type of case) were included in the analyses. FINDINGS: 1684 COVID-19 cases were included in the study. There were 217 (12.9%; 95% CI 11.3 to 14.5) serious cases, of which 32.6% (95% CI 26.4 to 38.8) cases were deceased. In the multilevel logistic regression, age, sex (female), type of case (different of imported case), number of serious cases recorded the previous day and multidimensional poverty were associated with serious cases (median OR: 1.72, 95% CI 1.56 to 1.87). INTERPRETATION: This paper explored the association between COVID-19 severity and social determinants. Expressions of poverty were associated with more severe cases during first 2 months of pandemic. It is a clear syndemic for the joint presentation of COVID-19 and other comorbidities among more serious cases.

Socioeconomic variation of multimorbidity in Colombian older adults.

Multimorbidity (MM) prevalence among older adults is increasing worldwide. Variations regarding the socioeconomic characteristics of the individuals and their context have been described, mostly in high-income settings. However, further research is needed to understand the effect of the coexistence of infectious diseases along with socioeconomic factors regarding MM. This study aims to examine the variation of MM regarding infectious diseases mortality after adjusting for socioeconomic factors. A cross-sectional multilevel study with a nationally representative sample of 17,571 Colombian adults of 60 years of age or older was conducted. Individual socioeconomic, demographic, childhood and health related characteristics, as well as group level variables (multidimensional poverty index and infectious diseases mortality rate) were analyzed. A two-level stepwise structural equation model was used to simultaneously adjust for the individual and contextual effects. Multimorbidity prevalence was 62.3% (95% CI 61.7-62.9). In the multilevel adjusted models, age, female sex, having functional limitations, non-white ethnicity, high body mass index, higher income, physical inactivity and living in urban areas were associated with multimorbidity among the sample for this study. The median odds ratio for multidimensional poverty was 1.18 (1.16-1.19; p = 0.008) and for infectious diseases was 1.25 (1.22-1.28; p = 0.014). This paper demonstrates that MM varies regarding the mortality of infectious diseases and shows a strong association between MM and poverty in a low-middle income country. Differences in the factors involved in the etiology of multimorbidity are expected among wealthy and poor countries regarding availability and prioritization of health services.

Are we using the right method to estimate the number of COVID-19 cases?

The great concern stemming from the current COVID-19 pandemic has been a challenge for governments and international organizations around the world. Likewise, the diagnosis has played an important role in the prioritization processes, in particular, for the identification and follow-up of cases. In this context, PCR and serological tests have become the international standard; however, some limitations, as well as the scope of these techniques, must be understood in terms of population numbers. This comment seeks to clarify the interpretation of the results of these tests from a public health perspective.

Incidence of acute respiratory symptoms and COVID-19 infection in children in public schools in Bogotá, Colombia, from July to November, 2020 / Incidence of acute respiratory symptoms and COVID-19 infection in children in public schools in Bogotá, Colombia, from July to November, 2020

INTRODUCTION: More than 90% of children infected with COVID-19 worldwide developed mild to moderate disease. In Colombia, during 2020, COVID-19 infections in children stayed below 9.2% of the total cases, with no trends for age group or sex. OBJECTIVE: To estimate the incidence of acute respiratory symptoms and COVID-19 in children from public schools in Bogotá, Colombia during the second semester of 2020. MATERIAL AND METHODS: A telephone survey was conducted in over 5,000 scholar children. Antecedents and use of health services were informed. Descriptive statistics were used. RESULTS: A total of 151.470 persons per day accounting for an IR of 157,8 per 100,000 people; almost three times the rate reported by the official surveillance system in the city. CONCLUSION: A lack of diagnosis and consultation in children was found compared to the general population. Further research is needed to elucidate the true burden of the disease in children.

Introducción. Más del 90% de los niños infectados con COVID-19 en el mundo, desarrollaron enfermedad leve a moderada. En Colombia, durante el 2020, la infección del COVID-19 en niños se mantuvo por debajo de 9,2 % del total de los casos sin tendencias por grupo de edad o sexo. Objetivo. Estimar la incidencia de síntomas respiratorios agudos y COVID19 en niños de escuelas públicas en Bogotá (Colombia) durante el segundo semestre de 2020. Materiales y métodos. Se hizo una encuesta telefónica en más de 5.000 escolares. Se recolectó información de antecedentes médicos y uso de servicios de salud. La información obtenida se describió mediante estadística descriptiva. Resultados. Se contabilizó un total de 151.470 personas al día para una tasa de incidencia de 157,8 en 100.000 personas, casi tres veces la tasa reportada por el sistema de vigilancia oficial de la ciudad. Conclusión. Se encontraron deficiencias en el diagnóstico y consulta de los niños, al compararlos con la población general. Se necesita más investigación para dilucidar la verdadera carga de la enfermedad en la población infantil.

Coinfection of other respiratory pathogens and HIV in COVID-19 patients: Is there a pattern?

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) has led to the elaboration of multiple studies to increase knowledge and understanding, hence, having the ability to accomplish an adequate and timely diagnosis and give an optimal treatment according to the patient's condition. The clinical manifestations of COVID-19 pose a series of challenges both in understanding and delimiting the disease secondary to the SARS-CoV-2 infection. This is due to the fact that the main axis of this disease is the endothelial compromise and the production of a "cytokine storm," triggering multiple organ failure and death. Given that a complete understanding of its pathophysiology and clinical behavior has not yet been achieved, we wondered if coinfection with other respiratory viruses modifies its performance and outcomes described so far. A literature search was performed, obtaining 68 articles, of which 25 were analyzed. The analysis showed us that there is a high variety both in the types of associated infections and in the clinical behavior of patients and their outcomes. Therefore, we consider that the search for other infections should be performed exhaustively, especially in those cases that may be susceptible to treatment such as Influenza A, human immunodeficiency virus, or bacterial infections. As well as optimize the analysis of these cases and establish if there are characteristics that allow establishing the possibility of carrying an additional infection to that of SARS-CoV-2 and the implications for the management and prognosis of the patient.

Epidemiology of self-care beyond the individual and the sanitary spheres / [Epidemiología del autocuidado más allá de lo individual y lo sanitario].

Amid the global pandemic crisis, international concern has centered on the control and prevention measures aimed at reducing the speed of the virus transmission while a more radical sanitary measure, such as vaccines, is achieved. Governmental and social efforts have had great impact on various sectors of society and their consequences have exceeded the sphere of health. This essay discusses the scope of specific measures in the sense of the appropriation of risk control measures and proposes the epidemiological method as an alternative that goes beyond the quantification of risks and the attribution of responsibilities. To conclude, the emphasis is placed on the need to promote information about socialization processes to better understand the consequences of individual acts favoring alternatives other than pandemic control based on the use of coercive measures.

En medio de la crisis pandémica a nivel global, la preocupación internacional ha girado en torno a la adopción de medidas de control y prevención orientadas a la reducción de la velocidad de propagación del virus en espera de que se disponga de una medida sanitaria radical como la vacuna. El esfuerzo gubernamental y social ha tenido un gran impacto en diversos sectores de la sociedad y las consecuencias han superado el ámbito sanitario. En este ensayo se discute su alcance en el sentido de la apropiación de las medidas de control del riesgo y se propone el método epidemiológico como una alternativa que va más allá de la cuantificación de los riesgos y la atribución de responsabilidades. Por último, se plantea la necesidad de fomentar procesos de socialización de la información que ayuden a la comprensión de las consecuencias de los actos individuales y favorezcan la superación de la expectativa de control pandémico únicamente basada en el uso de medidas coercitivas.

Performance of the Colombian surveillance system during the COVID-19 pandemic: A rapid evaluation of the first 50 days / [Desempeño del sistema de vigilancia colombiano durante la pandemia de COVID-19: evaluación rápida de los primeros 50 días].

Introduction: The COVID pandemic is a challenge for public health surveillance and an opportunity to assess its strengths and weaknesses to improve the response. Objective: To evaluate the performance of the Colombian public health surveillance system during the first 50 days of the COVID-19 pandemic in the country. Materials and methods: We analyzed the data published between March 6 and April 24, 2020, by the Instituto Nacional de Salud and the World Health Organization (WHO). We evaluated: i) the quality of the data according to the fulfillment of Benford's law, and ii) the timeliness of the information measured as the difference in dates between the data generated by the Instituto Nacional de Salud and WHO's situational reports. We assessed the fulfillment of Benford's law using the p values of the log-likelihood ratio, the chi square or Moreno's exact tests. Results: Until April 24 there were 4,881 cases of COVID-19 in Colombia. During most of the first 50 days of the pandemic, Benford's law was fulfilled except the first days of the epidemic. The difference between Instituto Nacional de Salud and WHO reports largely depends on the different reporting times. Conclusion: In general, the Colombian public health surveillance system fulfilled Benford's law suggesting that there was quality in the data. Future studies comparing the performance of the departments and districts will improve the diagnosis of the Colombian surveillance system.

Introducción. La pandemia de COVID es un desafío para la vigilancia en salud pública y una oportunidad para evaluar sus fortalezas y debilidades en aras de mejorar la respuesta. Objetivo. Evaluar el desempeño del sistema de vigilancia en salud pública colombiano durante los primeros 50 días de la pandemia de COVID-19 en el país. Materiales y métodos. Se analizaron los datos publicados entre el 6 de marzo y el 24 de abril de 2020 por el Instituto Nacional de Salud y la Organización Mundial de Salud (OMS). Se consideraron en la evaluación: i) la calidad de los datos según la ley de Benford y ii) la oportunidad de la información, medida como la diferencia en fechas entre los datos generados en el Instituto Nacional de Salud y los recogidos en el informe situacional de la OMS. La variabilidad en el cumplimiento de la ley de Benford se evaluó con los valores de p en las pruebas de razón del logaritmo de la verosimilitud, ji al cuadrado o exacta de Moreno. Resultados. Hasta el 24 de abril hubo 4.881 casos de COVID-19 en Colombia. En la mayoría de los primeros 50 días se cumplió la ley de Benford, excepto en los primeros días de la epidemia. La diferencia entre los informes del Instituto Nacional de Salud y la OMS ha dependido, en gran medida, de la diferencia en los horarios de cierre de la información. Conclusión. En general, el sistema de vigilancia en salud pública colombiano cumplió con la ley de Benford, lo cual sugiere que hubo calidad en los datos. En futuros estudios que comparen el desempeño de los departamentos y distritos se podrá mejorar el diagnóstico de la vigilancia en salud pública del país.