A backward-looking review of outcomes in a group of patients who already received the same treatment or diagnosis.
A retrospective case series describes a cohort of patients identified after the fact—typically via chart review or registry data—who share a condition, exposure, or intervention, with outcomes reported descriptively and without a comparison group. It sits low on the evidence hierarchy: useful for hypothesis generation and documenting rare presentations or complications, but vulnerable to selection bias, recall/documentation gaps, and confounding, so causal claims should not be drawn from it. Sample sizes are usually small, and there is no randomization or blinding.
This guide was auto-drafted and is pending editorial review.