Treatment with quetiapine may be considered for a limited duration (4–12 weeks) to reduce pain, sleep problems, depression, and anxiety in fibromyalgia patients with major depression, data from a Cochrane review has shown.

Many patients with fibromyalgia (up to 70%) meet the criteria for a depressive or anxiety disorder, Brian Walitt, National Institutes of Health, Bethesda, MD, explained. Patients report high disability and poor health-related quality of life. Treatment with antipsychotics are thought to possibly reduce fibromyalgia and related psychiatric symptoms. Walitt and coauthors conducted a review to assess the efficacy, tolerability, and safety of antipsychotics for fibromyalgia in adults. A search was performed in CENTRAL, MEDLINE, and EMBASE up to May 20, 2016, for controlled trials of at least 4 weeks duration of any formulation of antipsychotic used for the treatment of fibromyalgia in adults. 

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The analysis was done using three tiers of evidence: the first tier was derived from data meeting current best standards and subject to minimal risk of bias; second tier was derived from data that failed to meet one or more of these criteria and that was considered some risk of bias but with adequate numbers in the comparison; third tier was derived from data involving small numbers of participants that were considered very likely to be biased or used outcomes of limited clinical utility. The quality of evidence was rated based on the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.

Four studies that evaluated 296 patients were included for the analysis. Three of the studies compared quetiapine, a 2nd generation atypical antipsychotic, vs. placebo. Quetiapine was studied with a bedtime dose between 50–300mg daily. The primary outcomes for this review were participant-reported pain relief of ≥50%, Patient Global Impression of Change (PGIC) “much improved” or “very much improved,” withdrawal due to adverse events and serious adverse events. 

Quetiapine was not shown to be statistically superior to placebo in the number of patients with ≥50% pain reduction (very low quality evidence). There was no study that reported data on PGIC. 

More patients taking quetiapine reported a ≥30% pain reduction (risk difference [RD] 0.12, 95% CI: 0.00–0.23); this was deemed very low quality evidence. Also, a greater proportion of patients on quetiapine reported a clinically relevant improvement of health-related quality of life vs. placebo (RD 0.18, 95% CI: 0.05–0.31); this was also deemed very low quality evidence. 

Compared to placebo, quetiapine was statistically superior in reducing sleep problems (standardized mean difference [SMD] –0.67 95% CI: –1.10 to –0.23), depression (SMD –0.39, 95% CI: –0.74 to –0.04) and anxiety (SMD –0.40, 95% CI: –0.69 to –0.11). Quetiapine was also statistically superior vs. placebo in decreasing the risk of study withdrawal due to lack of efficacy (RD –0.14, 95% CI: –0.23 to –0.05). This was all rated as very low quality evidence. 

The study authors did not observe a statistically significant difference between quetiapine and placebo in the proportion of patients withdrawing due to adverse events, in the frequency of serious adverse events, and in the proportion of participants reporting dizziness and somnolence as an adverse event; all were very low quality evidence. Substantial weight gain was seen more in patients in the quetiapine arm (RD 0.08, 95% CI: 0.02 to 0.15). 

One study with 90 patients evaluated quetiapine to amitriptyline. The data was rated as low quality due to indirectness and imprecision. No statistically significant difference between the two drugs was seen. Neither drug statistically significantly differed in the reduction of average scores for the following: pain, fatigue, sleep problems, depression, anxiety, and for limitations of health-related quality of life and in the proportion of patients reporting dizziness, somnolence, and weight gain as an adverse event. More patients exited the study due to adverse events in the quetiapine group compared to amitriptyline. 

Researchers concluded that possible adverse effects (eg, weight gain) “should be balanced against the potential benefits in shared decision making with the patient.”

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