QUESTIONS TO ASK IN PROGNOSTIC STUDIES Onofre Morán MD, MSc. Professor, Faculty of Medicine, Universidad Autónoma de San Luis Potosí, S.L.P. México. PhD Candidate University of British Columbia, Vancouver, Canada.

Questions to ask in Prognostic studies WHY: Justified? Hypothesis/purpose of the study? HOW: Was an inception cohort assembled? Were objective outcome criteria used? Was the outcome assessment “blind”? Were DIAGNOSTIC SUSPICION BIAS and EXPECTATION BIAS avoided?

Questions to ask in Prognostic studies WHO: Is the studied sample CLEARLY described? Is the referral pattern described? Is there evidence of REFERRAL FILTER BIAS or DIAGNOSTIC ACCESS BIAS? Do the authors account for every patient who was eligible for the study but did NOT enter it? Was complete follow-up achieved?

Questions to ask in Prognostic studies WHAT: Was adjustment for known prognostic factors carried out (THERAPEUTIC ACCESS BIAS)? Was there LEAD TIME BIAS considered? Were losses to follow-up handled appropriately and was their clinical status determined? Were all clinically relevant outcomes reported?

Questions to ask in Prognostic studies HOW MANY? Was statistical significance considered? Were statistical test applied appropriately? Was any measurement of risk provided? Was the study large enough to detect important outcomes? If no increased risk was found, was there any consideration of the power of the study?

Questions to ask in Prognostic studies SO WHAT? Are the results clinically significant? Are the results (and patients) sufficiently described to be generalized to the clinical practice? Is the therapeutic intervention feasible in your practice?