Miguel A Hernán
Dados Biográficos
| ID | 1742522 |
|---|---|
| NOME | Miguel A Hernán |
| PRENOMES | Miguel A |
| SOBRENOME | Hernán |
| ASSINATURA | HERNÁN M A |
| AFILIAÇÕES | Harvard University |
| ORCID | 0000-0003-1619-8456 |
| VERIFICADO | Sim |
| TOTAL DE OBRAS | 25 |
| TOTAL DE CITAÇÕES | 89 |
| TOTAL COMO AUTOR | 25 |
| TOTAL COMO EDITOR | 0 |
| PRIMEIRO ANO DE PUBLICAÇÃO | 1999 |
| ANO MAIS RECENTE DE PUBLICAÇÃO | 2026 |
| ÍNDICE H | 3 |
Evolution of outdoor sports during the Covid-19 post-lockdown in Spain
Participation in outdoor sports, abruptly interrupted during the strict home-confinement, was not resumed immediately but remained severely reduced early after the lockdown. Seven months later, baseline levels had been recovered in general, although differences were observed depending on sociodemographic and health-status factors. This highlights the importance of considering personal and contextual characteristics to plan physical activity and s…
Sars-CoV-2 Infection During the First and Second Pandemic Waves in Spain
Objectives. To describe participant characteristics associated with severe acute respiratory syndrome coronavirus 2 infection in Spain’s first 2 COVID-19 waves per the Spanish National Seroepidemiological Survey of SARS-CoV-2 Infection (ENE–COVID). Methods. A representative cohort of the noninstitutionalized Spanish population, selected through stratified 2-stage sampling, answered a questionnaire and received point-of-care testing April to June …
Design and Implementation of a Nationwide Population-Based Longitudinal Survey of Sars-CoV-2 Infection in Spain
Data System. The Spanish National Seroepidemiological Survey of SARS-CoV-2 (or ENE-COVID; SARS-CoV-2 [severe acute respiratory syndrome coronavirus 2] is the causative agent of COVID-19) was funded by the Spanish Ministry of Health, the Instituto de Salud Carlos III, and the Spanish National Health System. Data Collection/Processing. A stratified 2-stage probability sampling was used to select a representative cohort of the noninstitutionalized p…
BNT162b2 mRNA Covid-19 Vaccine in a Nationwide Mass Vaccination Setting
BACKGROUND: As mass vaccination campaigns against coronavirus disease 2019 (Covid-19) commence worldwide, vaccine effectiveness needs to be assessed for a range of outcomes across diverse populations in a noncontrolled setting. In this study, data from Israel's largest health care organization were used to evaluate the effectiveness of the BNT162b2 mRNA vaccine. METHODS: All persons who were newly vaccinated during the period from December 20, 20…
Two Pandemics, Two Surveys in the United States and in Spain
For ENE-COVID, the first wave of data collection was completed in two weeks by mobilizing and training 4400 health professionals in more than 1400 primary care centers, as well as creating an information system capable of hosting up to 2000 concurrent users The preexistence of a health care system with clinical laboratories around the country, with coordination from the National Centre for Microbiology at the Instituto de Salud Carlos III, allowe…
Critical Care Requirements Under Uncontrolled Transmission of Sars-CoV-2
Objectives. To estimate the critical care bed capacity that would be required to admit all critical COVID-19 cases in a setting of unchecked SARS-CoV-2 transmission, both with and without elderly-specific protection measures. Methods. Using electronic health records of all 2432 COVID-19 patients hospitalized in a large hospital in Madrid, Spain, between February 28 and April 23, 2020, we estimated the number of critical care beds needed to admit …
Prevalence of Sars-CoV-2 in Spain (ENE-Covid)
RoB 2
Assessment of risk of bias is regarded as an essential component of a systematic review on the effects of an intervention. The most commonly used tool for randomised trials is the Cochrane risk-of-bias tool. We updated the tool to respond to developments in understanding how bias arises in randomised trials, and to address user feedback on and limitations of the original tool.
The C-Word
A response is provided to several articles within the issue on the theory of causation for diseases, including in regard to statistical association and observational studies data. An overview of the risk of research bias, including bias's relationship with mismeasurement and research selection, is provided
The C-Word
Causal inference is a core task of science. However, authors and editors often refrain from explicitly acknowledging the causal goal of research projects; they refer to causal effect estimates as associational estimates. This commentary argues that using the term “causal” is necessary to improve the quality of observational research. Specifically, being explicit about the causal objective of a study reduces ambiguity in the scientific question, e…
Robins-I
Non-randomised studies of the effects of interventions are critical to many areas of healthcare evaluation, but their results may be biased. It is therefore important to understand and appraise their strengths and weaknesses. We developed ROBINS-I (“Risk Of Bias In Non-randomised Studies - of Interventions”), a new tool for evaluating risk of bias in estimates of the comparative effectiveness (harm or benefit) of interventions from studies that d…
Longitudinal Causal Inference
Evaluation of the Duplication of Staging CT Scans for Localized Colon Cancer in a Medicare Population
BACKGROUND: To quantify and characterize duplicated tests performed during the staging of localized colon cancer in the Medicare population. METHODS: We used the SEER-Medicare linked database to select patients diagnosed with localized colon cancer between the years 1996 and 2009. We considered a patient as adequately staged after having received a colonoscopy, an abdominal computed tomography (CT) scan, and a pelvic CT scan. Abdominal and pelvic…
Comparative Effectiveness of Two Anemia Management Strategies for Complex Elderly Dialysis Patients
BACKGROUND: Randomized trials found that use of erythropoiesis-stimulating agents to target normal hematocrit (Hct) levels (>39%) compared with 27%-34.5% increases cardiovascular risk and mortality among chronic kidney disease patients. However, the effects of the most widely used Hct target in the past 2 decades, 34.5%-39%, have never been examined. OBJECTIVE: To compare the effects of 2 Hct target strategies-30.0%-34.5% (low) and 34.5%-39.0% (m…
Constructing Inverse Probability Weights for Marginal Structural Models
The method of inverse probability weighting (henceforth, weighting) can be used to adjust for measured confounding and selection bias under the four assumptions of consistency, exchangeability, positivity, and no misspecification of the model used to estimate weights. In recent years, several published estimates of the effect of time-varying exposures have been based on weighted estimation of the parameters of marginal structural models because, …
Malnutrition Among Children Younger Than 5 Years-Old in Conflict Zones of Chiapas, Mexico
We performed a cross-sectional, community-based survey, supplemented by interviews with community leaders in Chiapas, Mexico, to examine the prevalence and predictors of child malnutrition in regions affected by the Zapatista conflict. The prevalence rates of stunting, wasting, and underweight were 54.1%, 2.9%, and 20.3%, respectively, in 2666 children aged younger than 5 years. Stunting was associated with indigenous ethnicity, poverty, region o…
Estimating causal effects from epidemiological data
In ideal randomised experiments, association is causation: association measures can be interpreted as effect measures because randomisation ensures that the exposed and the unexposed are exchangeable. On the other hand, in observational studies, association is not generally causation: association measures cannot be interpreted as effect measures because the exposed and the unexposed are not generally exchangeable. However, observational research …
Pregnancy outcomes, site of delivery, and community schisms in regions affected by the armed conflict in Chiapas, Mexico
A Structural Approach to Selection Bias
The term "selection bias" encompasses various biases in epidemiology. We describe examples of selection bias in case-control studies (eg, inappropriate selection of controls) and cohort studies (eg, informative censoring). We argue that the causal structure underlying the bias in each example is essentially the same: conditioning on a common effect of 2 variables, one of which is either exposure or a cause of exposure and the other is either the …
A definition of causal effect for epidemiological research
Estimating the causal effect of some exposure on some outcome is the goal of many epidemiological studies. This article reviews a formal definition of causal effect for such studies. For simplicity, the main description is restricted to dichotomous variables and assumes that no random error attributable to sampling variability exists. The appendix provides a discussion of sampling variability and a generalisation of this causal theory. The differ…
Causal Knowledge as a Prerequisite for Confounding Evaluation
Common strategies to decide whether a variable is a confounder that should be adjusted for in the analysis rely mostly on statistical criteria. The authors present findings from the Slone Epidemiology Unit Birth Defects Study, 1992-1997, a case-control study on folic acid supplementation and risk of neural tube defects. When statistical strategies for confounding evaluation are used, the adjusted odds ratio is 0.80 (95% confidence interval: 0.62,…
Marginal Structural Models and Causal Inference in Epidemiology
In observational studies with exposures or treatments that vary over time, standard approaches for adjustment of confounding are biased when there exist time-dependent confounders that are also affected by previous treatment. This paper introduces marginal structural models, a new class of causal models that allow for improved adjustment of confounding in those situations. The parameters of a marginal structural model can be consistently estimate…
Marginal Structural Models to Estimate the Causal Effect of Zidovudine on the Survival of HIV-Positive Men
Standard methods for survival analysis, such as the time-dependent Cox model, may produce biased effect estimates when there exist time-dependent confounders that are themselves affected by previous treatment or exposure. Marginal structural models are a new class of causal models the parameters of which are estimated through inverse-probability-of-treatment weighting; these models allow for appropriate adjustment for confounding. We describe the…
Food frequency consumption and lipoproteins serum levels in the population of an urban area, Brazil
OBJECTIVE: To identify the association between food group consumption frequency and serum lipoprotein levels among adults. METHODS: The observations were made during a cross-sectional survey of a representative sample of men and women over 20 years old living in Cotia county, S. Paulo, Brazil. Data on food frequency consumption, serum lipids, and other covariates were available for 1,045 adults. Multivariate analyses adjusted by age, gender, body…
Desnutrición infantil y tenencia de la tierra en Cuscatlán seis años después de los acuerdos de paz
El programa de reconstrucción de las zonas devastadas por la guerra civil salvadoreña debería, a estas alturas, haber reducido los niveles de pobreza y de desnutrición infantil. Sin embargo, seis años después de la firma de los acuerdos de paz, ha sido evidente que la ejecución del plan nacional de reconstrucción no ha sido uniforme. La prevalencia elevada de desnutrición infantil está relacionada con las demoras en la implementación de los acuer…
Estimating causal effects from epidemiological data
In ideal randomised experiments, association is causation: association measures can be interpreted as effect measures because randomisation ensures that the exposed and the unexposed are exchangeable. On the other hand, in observational studies, association is not generally causation: association measures cannot be interpreted as effect measures because the exposed and the unexposed are not generally exchangeable. However, observational research …
The C-Word
Causal inference is a core task of science. However, authors and editors often refrain from explicitly acknowledging the causal goal of research projects; they refer to causal effect estimates as associational estimates. This commentary argues that using the term “causal” is necessary to improve the quality of observational research. Specifically, being explicit about the causal objective of a study reduces ambiguity in the scientific question, e…
A definition of causal effect for epidemiological research
Estimating the causal effect of some exposure on some outcome is the goal of many epidemiological studies. This article reviews a formal definition of causal effect for such studies. For simplicity, the main description is restricted to dichotomous variables and assumes that no random error attributable to sampling variability exists. The appendix provides a discussion of sampling variability and a generalisation of this causal theory. The differ…
Food frequency consumption and lipoproteins serum levels in the population of an urban area, Brazil
OBJECTIVE: To identify the association between food group consumption frequency and serum lipoprotein levels among adults. METHODS: The observations were made during a cross-sectional survey of a representative sample of men and women over 20 years old living in Cotia county, S. Paulo, Brazil. Data on food frequency consumption, serum lipids, and other covariates were available for 1,045 adults. Multivariate analyses adjusted by age, gender, body…
Two Pandemics, Two Surveys in the United States and in Spain
For ENE-COVID, the first wave of data collection was completed in two weeks by mobilizing and training 4400 health professionals in more than 1400 primary care centers, as well as creating an information system capable of hosting up to 2000 concurrent users The preexistence of a health care system with clinical laboratories around the country, with coordination from the National Centre for Microbiology at the Instituto de Salud Carlos III, allowe…
Sars-CoV-2 Infection During the First and Second Pandemic Waves in Spain
Objectives. To describe participant characteristics associated with severe acute respiratory syndrome coronavirus 2 infection in Spain’s first 2 COVID-19 waves per the Spanish National Seroepidemiological Survey of SARS-CoV-2 Infection (ENE–COVID). Methods. A representative cohort of the noninstitutionalized Spanish population, selected through stratified 2-stage sampling, answered a questionnaire and received point-of-care testing April to June …
Critical Care Requirements Under Uncontrolled Transmission of Sars-CoV-2
Objectives. To estimate the critical care bed capacity that would be required to admit all critical COVID-19 cases in a setting of unchecked SARS-CoV-2 transmission, both with and without elderly-specific protection measures. Methods. Using electronic health records of all 2432 COVID-19 patients hospitalized in a large hospital in Madrid, Spain, between February 28 and April 23, 2020, we estimated the number of critical care beds needed to admit …
Malnutrition Among Children Younger Than 5 Years-Old in Conflict Zones of Chiapas, Mexico
We performed a cross-sectional, community-based survey, supplemented by interviews with community leaders in Chiapas, Mexico, to examine the prevalence and predictors of child malnutrition in regions affected by the Zapatista conflict. The prevalence rates of stunting, wasting, and underweight were 54.1%, 2.9%, and 20.3%, respectively, in 2666 children aged younger than 5 years. Stunting was associated with indigenous ethnicity, poverty, region o…
Desnutrición infantil y tenencia de la tierra en Cuscatlán seis años después de los acuerdos de paz
El programa de reconstrucción de las zonas devastadas por la guerra civil salvadoreña debería, a estas alturas, haber reducido los niveles de pobreza y de desnutrición infantil. Sin embargo, seis años después de la firma de los acuerdos de paz, ha sido evidente que la ejecución del plan nacional de reconstrucción no ha sido uniforme. La prevalencia elevada de desnutrición infantil está relacionada con las demoras en la implementación de los acuer…
Marginal Structural Models and Causal Inference in Epidemiology
In observational studies with exposures or treatments that vary over time, standard approaches for adjustment of confounding are biased when there exist time-dependent confounders that are also affected by previous treatment. This paper introduces marginal structural models, a new class of causal models that allow for improved adjustment of confounding in those situations. The parameters of a marginal structural model can be consistently estimate…
Marginal Structural Models to Estimate the Causal Effect of Zidovudine on the Survival of HIV-Positive Men
Standard methods for survival analysis, such as the time-dependent Cox model, may produce biased effect estimates when there exist time-dependent confounders that are themselves affected by previous treatment or exposure. Marginal structural models are a new class of causal models the parameters of which are estimated through inverse-probability-of-treatment weighting; these models allow for appropriate adjustment for confounding. We describe the…
Food frequency consumption and lipoproteins serum levels in the population of an urban area, Brazil
OBJECTIVE: To identify the association between food group consumption frequency and serum lipoprotein levels among adults. METHODS: The observations were made during a cross-sectional survey of a representative sample of men and women over 20 years old living in Cotia county, S. Paulo, Brazil. Data on food frequency consumption, serum lipids, and other covariates were available for 1,045 adults. Multivariate analyses adjusted by age, gender, body…
Causal Knowledge as a Prerequisite for Confounding Evaluation
Common strategies to decide whether a variable is a confounder that should be adjusted for in the analysis rely mostly on statistical criteria. The authors present findings from the Slone Epidemiology Unit Birth Defects Study, 1992-1997, a case-control study on folic acid supplementation and risk of neural tube defects. When statistical strategies for confounding evaluation are used, the adjusted odds ratio is 0.80 (95% confidence interval: 0.62,…
A Structural Approach to Selection Bias
The term "selection bias" encompasses various biases in epidemiology. We describe examples of selection bias in case-control studies (eg, inappropriate selection of controls) and cohort studies (eg, informative censoring). We argue that the causal structure underlying the bias in each example is essentially the same: conditioning on a common effect of 2 variables, one of which is either exposure or a cause of exposure and the other is either the …
A definition of causal effect for epidemiological research
Estimating the causal effect of some exposure on some outcome is the goal of many epidemiological studies. This article reviews a formal definition of causal effect for such studies. For simplicity, the main description is restricted to dichotomous variables and assumes that no random error attributable to sampling variability exists. The appendix provides a discussion of sampling variability and a generalisation of this causal theory. The differ…
Pregnancy outcomes, site of delivery, and community schisms in regions affected by the armed conflict in Chiapas, Mexico
Estimating causal effects from epidemiological data
In ideal randomised experiments, association is causation: association measures can be interpreted as effect measures because randomisation ensures that the exposed and the unexposed are exchangeable. On the other hand, in observational studies, association is not generally causation: association measures cannot be interpreted as effect measures because the exposed and the unexposed are not generally exchangeable. However, observational research …
Malnutrition Among Children Younger Than 5 Years-Old in Conflict Zones of Chiapas, Mexico
We performed a cross-sectional, community-based survey, supplemented by interviews with community leaders in Chiapas, Mexico, to examine the prevalence and predictors of child malnutrition in regions affected by the Zapatista conflict. The prevalence rates of stunting, wasting, and underweight were 54.1%, 2.9%, and 20.3%, respectively, in 2666 children aged younger than 5 years. Stunting was associated with indigenous ethnicity, poverty, region o…
Constructing Inverse Probability Weights for Marginal Structural Models
The method of inverse probability weighting (henceforth, weighting) can be used to adjust for measured confounding and selection bias under the four assumptions of consistency, exchangeability, positivity, and no misspecification of the model used to estimate weights. In recent years, several published estimates of the effect of time-varying exposures have been based on weighted estimation of the parameters of marginal structural models because, …
Evaluation of the Duplication of Staging CT Scans for Localized Colon Cancer in a Medicare Population
BACKGROUND: To quantify and characterize duplicated tests performed during the staging of localized colon cancer in the Medicare population. METHODS: We used the SEER-Medicare linked database to select patients diagnosed with localized colon cancer between the years 1996 and 2009. We considered a patient as adequately staged after having received a colonoscopy, an abdominal computed tomography (CT) scan, and a pelvic CT scan. Abdominal and pelvic…
Comparative Effectiveness of Two Anemia Management Strategies for Complex Elderly Dialysis Patients
BACKGROUND: Randomized trials found that use of erythropoiesis-stimulating agents to target normal hematocrit (Hct) levels (>39%) compared with 27%-34.5% increases cardiovascular risk and mortality among chronic kidney disease patients. However, the effects of the most widely used Hct target in the past 2 decades, 34.5%-39%, have never been examined. OBJECTIVE: To compare the effects of 2 Hct target strategies-30.0%-34.5% (low) and 34.5%-39.0% (m…
Longitudinal Causal Inference
Robins-I
Non-randomised studies of the effects of interventions are critical to many areas of healthcare evaluation, but their results may be biased. It is therefore important to understand and appraise their strengths and weaknesses. We developed ROBINS-I (“Risk Of Bias In Non-randomised Studies - of Interventions”), a new tool for evaluating risk of bias in estimates of the comparative effectiveness (harm or benefit) of interventions from studies that d…
The C-Word
A response is provided to several articles within the issue on the theory of causation for diseases, including in regard to statistical association and observational studies data. An overview of the risk of research bias, including bias's relationship with mismeasurement and research selection, is provided
The C-Word
Causal inference is a core task of science. However, authors and editors often refrain from explicitly acknowledging the causal goal of research projects; they refer to causal effect estimates as associational estimates. This commentary argues that using the term “causal” is necessary to improve the quality of observational research. Specifically, being explicit about the causal objective of a study reduces ambiguity in the scientific question, e…
RoB 2
Assessment of risk of bias is regarded as an essential component of a systematic review on the effects of an intervention. The most commonly used tool for randomised trials is the Cochrane risk-of-bias tool. We updated the tool to respond to developments in understanding how bias arises in randomised trials, and to address user feedback on and limitations of the original tool.
Prevalence of Sars-CoV-2 in Spain (ENE-Covid)
BNT162b2 mRNA Covid-19 Vaccine in a Nationwide Mass Vaccination Setting
BACKGROUND: As mass vaccination campaigns against coronavirus disease 2019 (Covid-19) commence worldwide, vaccine effectiveness needs to be assessed for a range of outcomes across diverse populations in a noncontrolled setting. In this study, data from Israel's largest health care organization were used to evaluate the effectiveness of the BNT162b2 mRNA vaccine. METHODS: All persons who were newly vaccinated during the period from December 20, 20…
Two Pandemics, Two Surveys in the United States and in Spain
For ENE-COVID, the first wave of data collection was completed in two weeks by mobilizing and training 4400 health professionals in more than 1400 primary care centers, as well as creating an information system capable of hosting up to 2000 concurrent users The preexistence of a health care system with clinical laboratories around the country, with coordination from the National Centre for Microbiology at the Instituto de Salud Carlos III, allowe…
Critical Care Requirements Under Uncontrolled Transmission of Sars-CoV-2
Objectives. To estimate the critical care bed capacity that would be required to admit all critical COVID-19 cases in a setting of unchecked SARS-CoV-2 transmission, both with and without elderly-specific protection measures. Methods. Using electronic health records of all 2432 COVID-19 patients hospitalized in a large hospital in Madrid, Spain, between February 28 and April 23, 2020, we estimated the number of critical care beds needed to admit …
Sars-CoV-2 Infection During the First and Second Pandemic Waves in Spain
Objectives. To describe participant characteristics associated with severe acute respiratory syndrome coronavirus 2 infection in Spain’s first 2 COVID-19 waves per the Spanish National Seroepidemiological Survey of SARS-CoV-2 Infection (ENE–COVID). Methods. A representative cohort of the noninstitutionalized Spanish population, selected through stratified 2-stage sampling, answered a questionnaire and received point-of-care testing April to June …
Design and Implementation of a Nationwide Population-Based Longitudinal Survey of Sars-CoV-2 Infection in Spain
Data System. The Spanish National Seroepidemiological Survey of SARS-CoV-2 (or ENE-COVID; SARS-CoV-2 [severe acute respiratory syndrome coronavirus 2] is the causative agent of COVID-19) was funded by the Spanish Ministry of Health, the Instituto de Salud Carlos III, and the Spanish National Health System. Data Collection/Processing. A stratified 2-stage probability sampling was used to select a representative cohort of the noninstitutionalized p…
Evolution of outdoor sports during the Covid-19 post-lockdown in Spain
Participation in outdoor sports, abruptly interrupted during the strict home-confinement, was not resumed immediately but remained severely reduced early after the lockdown. Seven months later, baseline levels had been recovered in general, although differences were observed depending on sociodemographic and health-status factors. This highlights the importance of considering personal and contextual characteristics to plan physical activity and s…
Medicine (19 obras) · Advanced Causal Inference Techniques (10 obras) · Internal Medicine (9 obras) · Environmental health (8 obras) · Mathematics (8 obras) · Computer Science (7 obras) · Population (7 obras) · Statistics (7 obras) · Artificial Intelligence (6 obras) · Coronavirus disease 2019 (COVID-19) (6 obras)