Table 1 Six-month ACR50 responders in key RCT comparing methotrexate with methotrexate/TNF inhibitor combinations
Biological agentTrialGroupRecruitedACR50 respondersPercentage of responders (%)NNT
InfliximabMaini et al (1999)113 mg/kg per 8 weeks8622275 (4–9)
3 mg/kg per 4 weeks8625294 (3–7)
EtanerceptKlareskog et al (2004)122 × 25 mg/week231136593 (3–4)
AdalimumabKeystone et al (2004)1340 mg/2 weeks20781393 (3–5)
GolimumabKeystone et al (2009)250 mg/4 weeks8933374 (3–8)
100 mg/4 weeks8929335 (3–13)
Certolizumab pegolSmolen et al (2009)1200 mg/4 weeks24680333 (3–4)
400 mg/4 weeks24681333 (3–4)
Keystone et al (2009)9200 mg/4 weeks393146373 (3–4)
400 mg/4 weeks390156403 (3–4)
  • These trials differed in the type of patients enrolled, their initial disease activities and the clinical situation from which they were drawn (treatment in the 1990s was different to the 2005–8 era). These differences explain variations in the absolute numbers of active and placebo responders. However, the relationship between active and placebo treatments shown by the number needed to treat (NNT) should not be affected by these variations. ACR50, American College of Rheumatology 50% improvement; RCT, randomised controlled trial; TNF, tumour necrosis factor.