Table 1. A tool for evaluating the methodological quality of case series.

Domains	Leading explanatory questions
Selection	1. Were all the potentially eligible patients included or is the selection method unclear to the extent that other patients with similar presentations may not have been reported?
Definition of exposure and outcomes	2. Was the exposure adequately and clearly defined?
	3. Was the outcome adequately and clearly defined?
Causality	4. Were other alternative causes that may explain the observation ruled out?
	5. Was there a challenge/rechallenge phenomenon?
	6. Was there a dose-response effect?
	7. Was follow-up long enough for outcomes to occur?
Reporting	8. Are the cases described with sufficient details to allow other investigators to replicate the research or to allow practitioners to make inferences related to their own practice?

Adapted from Murad et al. ² Questions 4, 5 and 6 are more relevant for adverse drug events.