Session 1: Randomized Trials

Facilitator: Bob Goodman 

Objectives

 Residents will be able to: 

·      Read randomized trials systematically to evaluate for bias.

·      Interpret and use measures of effect such as relative risk, relative risk reduction, absolute risk reduction, and number needed to treat.

·      Interpret “negative” results.

·      Interpret “subgroup” analyses.

·      Interpret 95% confidence intervals and p-values.

Case

      You are in clinic and seeing a 72 year old woman with hypertension and heart failure with preserved ejection fraction (“HF-PEF”), the latter diagnosed 1-1/2 years ago when she was hospitalized for a “CHF exacerbation.” She is feeling well, is able to walk several blocks, as well as up two flights of stairs, without dyspnea. Her current medications are HCTZ, 25 mg daily, metoprolol, 100 mg daily, and ASA, 81 mg daily. Her blood pressure today is 134/82. A recent echo revealed an EF = 60%, with moderate LVH. Your preceptor suggests you start her on spironolactone, citing a recent study published in the New England Journal of Medicine. You proudly report that you read that study, and that it was “negative.” Your preceptor points out, however, showing you the supplementary appendix, which he happens to have in the pocket of his lab coat, that in the subgroup of subjects not hospitalized within the past year, there was in fact a statistically significant, 35% reduction in the primary endpoint. “The supplementary appendix,” you think to yourself. “Drat!” You ask to borrow his copy and plan to take a closer look at it on the subway ride home.

 

Reading:

Pitt B, et al. Spironolactone for Heart Failure with Preserved EjectionFraction. N Engl J Med 2014; 370:1383-1392.

Supplementary Appendix

Randomized Trial Primer 2016