Number needed to treat (NNT) to prevent cardiovascular event with treatment of lipids in type 2 diabetes

Primary prevention (6 RCTs) with lipid lowering therapy in Type 2 diabetes

• there was a significant reduction in the risk of cardiovascular events (cardiovascular mortality, myocardial infarction and stroke) with lipid-lowering drugs (RR 0.78, 95% CI: 0.67, 0.89; ARR 0.03, 95% CI: 0.01, 0.04)
  
  
• pooled estimate of NNT to prevent an event was 34.5 for a weighted trial average of 4.3 years. There was no significant heterogeneity between the studies. The sensitivity analysis changed the estimates of effect only slightly

Secondary prevention (8 RCTs) with lipid lowering therapy in Type 2 diabetes patients with cardiovascular disease

• was a significant reduction in the risk of cardiovascular events (cardiovascular mortality, myocardial infarction and stroke) with lipid-lowering drugs (RR 0.76, 95% CI: 0.59, 0.93; ARR 0.07, 95% CI: 0.03, 0.12)
  
  
• pooled estimate of NNT to prevent an event was 13.8 for a weighted trial average of 4.9 years. There was significant heterogeneity between the studies. The sensitivity analysis found that the removal of one study eliminated the heterogeneity and slightly reduced the estimates of effectiveness

Reference:

• Vijan S,Hayward RA. Pharmacologic lipid-lowering therapy in type 2 diabetes mellitus: background paper for the American College of Physicians.Ann Intern Med. 2004 Apr 20;140(8):650-8.