Pain assessment in patients with fibromyalgia syndrome: a consideration of methods for clinical trials.

Objective: This study was designed to compare 3 commonly used methodologies for assessing clinical pain during trials involving patients diagnosed with fibromyalgia syndrome. Baseline characteristics, characteristics over time, and compliance were evaluated for each of the methods.

Methods: Fourteen patients diagnosed with fibromyalgia syndrome were asked to monitor their symptoms of pain using 3 different strategies over a 12-week period: 1) real-time pain reports were collected on an electronic diary using randomly-scheduled audible prompts; 2) end-of-week reports asked patients to rate their mean pain over the past week on the electronic diary; and 3) monthly in-clinic reports asked patients to rate their mean pain for the week using a traditional paper and pencil diary.

Results: Significantly different baseline values were obtained for the 3 methods. Paper and pencil produced the highest values, and real-time pain reports produced the lowest baseline values. Pain ratings were more likely to reflect decreases in the 2 methods relying on recall than the real-time strategy. The average adherence with pain monitoring using the electronic diary was 85%, which was superior to the adherence for the recall measures completed during the clinic visits.

Conclusion: Pain assessment methods relying on recall might contribute to an apparent improvement in clinical trials in the absence of an intervention; such an effect has been considered a "placebo response." Future clinical trials might consider using a real-time approach to pain assessment, which in this study appeared to mitigate against seeing improvement in the absence of an intervention and demonstrated higher levels of patient adherence.