Skip to main content

Table 2 How summary results can obscure situations where the typical patient receives no benefit or risks net harm

From: Assessing and reporting heterogeneity in treatment effects in clinical trials: a proposal

Assumption: Treatment reduces baseline risk by 25% but with a cost of 2 serious treatment-related adverse events per 1,000 patients per year
  Control Event Rate
(CER, %)
Experimental Event Rate
(EER, %)
Relative Risk Reduction (RRR) Absolute Risk Reduction
(ARR)
Number Needed to Treat (NNT)
   (% of study population) Results over 5 years
Scenario #1      
Overall result (100%) 8 7 0.125 0.01 100
   Average risk subjects (75%) 4 4 0 0
   High risk subjects (25%) 20 16 0.2 0.04 20
Scenario #2      
Overall result (100%) 9 7.75 0.14 0.0125 80
   Average risk subjects (75%) 2 2.5 -0.25† -0.005† -200
   High risk subjects (25%) 30 23.5 0.22 0.065 15
  1. † The minus sign denotes that treatment had net harm, rather than benefit.