Advice - Epidemiology Research

  1. A well-defined research question (causal or descriptive) states: 1) the target population, characterized by person and place, and anchored in time; 2) the outcome, event, or health state or characteristic; and 3) the measure of occurrence that will be used to summarize the outcome (e.g., incidence, prevalence, average time to event, etc.). A causal question requires specifying additional components, such as exposures and covariates that are thought to be confounders, effect modifiers, or mediators. For descriptive questions, consideration of additional variables is optional, but if auxiliary variables will be considered, a well-defined descriptive question will 4) prespecify any other variables of interest and how they will be considered (e.g., to characterize the population, as a stratification factor to characterize the outcome distribution, or as a “nuisance” variable that we would like to adjust for or standardize over). For a descriptive question, indiscriminate adjustment for these other variables can lead to uninterpretable results that may mislead (9); as such, researchers should be clear as to the purpose of adjustment in descriptive studies, understand the implications of such adjustments, and be cautious in interpreting adjusted statistics (10).

Example: We illustrate application of this framework to description of one portion of the human immunodeficiency virus (HIV) care continuum (11): What was the prevalence of viral suppression on December 31, 2019, among adults living with HIV who had been linked to HIV care (i.e., saw a clinician who was aware of their HIV status and had the ability to prescribe antiretroviral therapy) in the United States? We will explore specific components of this question to make it more well-defined (and tie those components to analytical decisions) below.

References

  1. Catherine R Lesko, Matthew P Fox, Jessie K Edwards, A Framework for Descriptive Epidemiology, American Journal of Epidemiology, Volume 191, Issue 12, December 2022, Pages 2063–2070, https://doi.org/10.1093/aje/kwac115