Mini Review calls for transparency in AFO population assumptions to support valid causal interpretation

Research on community health effects of Animal Feeding Operations (AFOs) frequently relies on prevalence-based effect measures, particularly for chronic respiratory outcomes. Interpreting these measures as indicators of comparative disease occurrence requires specific structural population assumptions, yet it remains unclear whether such assumptions are reported in this literature. We conducted a Mini Review of observational studies identified through a previously published systematic review and an ongoing living systematic review to assess whether prevalence studies of AFO exposures and community health explicitly reported the assumptions required to interpret prevalence ratios or prevalence odds ratios as approximations of comparative incidence. Eligible studies used prevalent disease status and reported comparative prevalence-based effect measures. We assessed whether authors discussed assumptions related to population stability, outcome duration, temporal ordering, reverse causality, and disease rarity. Across 15 included studies, none explicitly reported or discussed these structural population assumptions, despite routinely presenting covariate-controlled effect estimates. Greater transparency in reporting population-level assumptions is needed to support valid causal interpretation of prevalence-based effect measures in AFO research and to better inform public health decision-making.