Table 2.

Checklist: Guidance and key considerations for study design for an observational CER protocol^*

Guidance	Key Considerations	Check
Provide a rationale for study design choice and describe key design features.	-Cohort study proposals should clearly define cohort entry date (baseline date), employ a new user design (or provide rationale for including prevalent users), and include plans for reporting losses to followup. -Case-control study proposals should clearly describe the control sampling method, employ a new user design (or provide a rationale for assessing confounders at index date), and assess potential for recall bias (if applicable). -Case-cohort study proposals should include how the sampling scheme will be accounted for during analysis. -Case-crossover study proposals should discuss the potential for confounding by time-varying factors and clearly state how the resulting effect estimate can be interpreted. -Case-time controlled study proposals should clearly weigh the pros and cons of accounting for calendar trends in the prevalence of exposure.	□
Define start of followup (baseline).	-The time point for start of followup should be clearly defined and meaningful, ideally anchored to the time of a medical intervention (e.g., initiation of drug use). -If alternative approaches are proposed, the rationale should be provided and implications discussed.	□
Define inclusion and exclusion criteria at start of followup. (baseline).	-Exclusion and inclusion criteria should be defined at the start of followup (baseline) and should be based solely on information available at this point in time (i.e., ignoring potentially known events after baseline). -The definition should include the time window for assessment (usually the same for all cohort members).	□
Define exposure (treatments) of interest at start of followup.		□
Define outcome(s) of interest.	-Information should be provided on measures of accuracy if possible.	□
Define potential confounders.	-Potential confounders known to be associated with treatment and outcome should be prespecified when possible. -Confounders should be assessed prior to exposure or treatment initiation to ensure they are not affected by the exposure. -Approaches to empirical identification of confounders should be described if planned.	□

^*Reprinted with permission from: Velentgas P, Dreyer NA, Nourjah P, et al. (eds.) Developing a Protocol for Observational Comparative Effectiveness Research: A User’s Guide. AHRQ Publication No. 12(13)-EHC099. Rockville, MD: Agency for Healthcare Research and Quality; January 2013. P. 31. [Available at http://www.effectivehealthcare.ahrq.gov/ehc/products/440/1166/User-Guide-to-Observational-CER-1-10-13.pdf].