Controlled trials of therapy in fibromyalgia (FM) syndrome
November 3, 1994
Many different interventions have been studied in the therapy of
fibromyalgia syndrome (Tables 1 and 2). While most have been
effective, in general these trials have been short term.
Furthermore, important or substantial improvement, when it has
been assessed, occurs in only small proportions of patients.
Long-term, comparative trials of both efficacy and toxicity
are necessary. Trials such as these require large numbers of
patients (compared with placebo-controlled trials, which are
generally impractical in long-duration trials due to the large
numbers of dropouts in the placebo arm) and therefore are
expensive and difficult to accomplish. Two other approaches
offer potential solutions to the problem of adequate long-term
comparative trials: (a) N-of-1 trials and (b) meta-analysis.
N-of-1 trials have the advantage of random assignment,
double-blinding and multiple potential comparisons in the same
patient. Meta-analysis involves combining the results of
studies, which individually may have conflicting results and
lack adequate statistical power, to reach an overall result
with sufficient statistical power to make meaningful
conclusions, especially with respect to comparative efficacy.
Peluso and colleagues (1993) have performed a recent
meta-analysis of available therapies in fibromyalgia syndrome
and found that the effect-size (a standardized measure of the
efficacy of a given therapy) of several non-medication
therapies such as electroacupuncture exceeded that of
traditional medication therapies. Unfortunately, lack of
uniformity in the use of outcome measures across included
trials and the small numbers of comparable non-medication
trials makes definitive conclusions regarding relative
efficacy of therapies difficult. Nevertheless, application of
meta-analytic methods such as these should facilitate future
comparisons of different interventions. Ideally, future
clinical trials in fibromyalgia syndrome should employ the
same outcome measures to permit application of these methods.
Few trials have assessed improvement in functional status.
Functional status measures such as the HAQ (Fries et al.,
1980), the Fibromyalgia Impact Questionnaire (Burckhardt et
al, 1991) or similar instruments should be employed in future
studies of therapy in fibromyalgia. Given that individual
modalities appear to confer relatively modest benefit on
average. Combination approaches are reasonable, although
randomized, blinded trials to assess these approaches are
methodologically complex. Several preliminary studies which
have addressed this approach appear promising (see Chapter 12;
Goldenberg et al, 1993). Finally, no studies have yet assessed
the comparative cost-efficacy of available treatments.
Controlled trials which address the cost-efficacy of commonly
employed, but unproven treatments such as physiotherapy
chiropractic manipulation and injection techniques are
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