The functional index for hand osteoarthritis (FIHOA), a 10-item investigator-administered questionnaire, was validated in 1995. It is relevant, reliable and has good external and internal validities.To assess the sensitivity to change over time of the FIHOA.symptomatic [visual analog scale (VAS) > or = 30 mm, FIHOA > or = 5] hand OA patients [American College of Rheumatology (ACR) criteria, > or = 2 radiologically affected joints] were included in a 6-month randomized, double-blind, placebo-controlled trial. Recorded parameters: Pain on VAS, FIHOA score, morning stiffness duration, grip strength.mean standardized response (MSR = delta DO-M6/S.D. of delta) was calculated for each parameter in an intention-to-treat (ITT) population before breaking the randomization code.239 women, 22 men, mean age 61 +/- 7.5 years were recruited. Characteristics of HOA: 88% of patients were right-handed, 48% had a family history of hand OA. The location of OA was the first trapezo-metacarpal (TMC) joint (62%), proximal interphalangeal (PIP) joint (47.5%), distal interphalangeal (DIP) joint (67.6%). The mean number of painful flares (previous 12 months) was 4.4, that of painful joints was 3.7, that of nodal joints in the right hand 3.1, and that of radiologically affected joints was 4.4. Baseline symptomatic severity assessment gave pain on VAS=54.4 +/- 14 mm, FIHOA score=10.4 +/- 3.7, morning stiffness duration=20 +/- 27.6 min and grip strength=59.3 +/- 21.2 mm Hg. The MSR value was 0.58 for the FIHOA and 0.87 for pain on VAS.The sensitivity to change of the FIHOA over 6 months is high, but inferior to that of pain on VAS in this trial.