A double-blind, randomized, controlled study of amitriptyline, nortriptyline and placebo in patients with fibromyalgia. An analysis of outcome measures.

OBJECTIVE: To study the efficacy and tolerability of amitriptyline and nortriptyline in a Brazilian population with fibromyalgia and to evaluate the instruments used to measure the efficacy of the treatment. METHODS: A total of 118 fibromyalgia patients were randomly assigned to 3 groups: amitriptyline (AM, n = 40), nortriptyline (NOR, n =38) and placebo (PL, n = 40), and were blindly given 25 mg at bedtime of the assigned treatment for 8 weeks. Clinical evaluation before and at the end of the study included the number of tender points (NTP), FIQ score (FIQ), and global improvement as reported by the patients on a verbal scale (VSGI). RESULTS: The 3 groups were comparable at baseline for all the parameters studied. After 8 weeks, the 3 groups improved in all parameters: (36.5% AM, 26.7% NOR and 24% PL patients improved on FIQ; 13.9% AM, 19.5% NOR and 8.57% PL patients improved on NTP; 86.5% AM, 72.2% NOR and 57.6% PL patients improved on VSGI). Only the AM group differed from the PL group on VSGI. Side effects were noted among the groups, but none were serious (16 in the AM group, 31 in the NOR group, and 25 in the PL group). CONCLUSION: All three groups improved after treatment. Only the patient's subjective global assessment of improvement differed between the AM patients and the PL group (p < or = 0.03). In fibromyalgia, placebo groups are important in drug trials. Different measures of therapeutic effect are not better than the patient's self assessment.