Background Published findings on natural history of fibromyalgia (FM) are limited.
Objectives The multisite US prospective observational cohort study followed FM subjects to assess disease burden and natural history.
Methods At enrollment, consented subjects completed an online questionnaire to screen for chronic widespread pain (CWP, pain on both sides and above and below waist for ≥1 week); a physician site visit to determine FM diagnosis; and another online questionnaire to capture demographics, clinical characteristics, medications, healthcare resource use (HRU), pain (Brief Pain Inventory-Short Form [BPI-SF]), FM (modified [self-report] American College of Rheumatology [ACR] 2010 criteria, Revised Fibromyalgia Impact Questionnaire [FIQ-R]), sleep (Medical Outcomes Study-Sleep Scale [MOS-SS]), and health status (Short Form 12-item Health Survey [SF-12]). At follow-up, approximately 2 years later, subjects and physicians completed the same assessments. Statistical significance of changes was tested (p<0.05) using analysis of covariance and generalized McNemar's test.
Results A total of 76 FM subjects participated at both time points (at enrollment: 89.5% female, mean age 50.9 years, mean duration of FM 4.1 years, 86.8% white). Mean number of tender points at each physician visit was 14.1 and 13.5, respectively. Distribution of FM severity based on physician evaluation at enrollment was 19.7% mild/very mild, 48.7% moderate, 31.6% severe/very severe, and at follow-up was 15.6% mild/very mild, 43.8% moderate, 40.6% severe/very severe. At follow-up, 20.3% of subjects reported their overall health status had improved since enrollment, while 47.5% reported a decline. Comorbidities reported by ≥20% of subjects at follow-up: arthritis, lower back pain, depression, high cholesterol, hypertension, headache/migraine, anxiety, and sleep apnea. Medication use for pain was reported by 59.2% and 62.0% of subjects at each time point, respectively. Most common medication classes were opioids (32.4%), SSRIs (16.9%), and tramadol (14.1%) at follow-up. Mean number of healthcare provider visits for pain over the past 3 months (among those with ≥1) was 5.4 and 4.9 at each time point, respectively. There were no statistically significant changes in pain-related HRU. Significant mean changes (p-value <0.05) over time were observed for mean modified ACR 2010 criteria score (18.4 to 16.9, p=0.004), BPI-SF pain interference index (5.9 to 5.3, p=0.013), and MOS-SS overall sleep problems index (58.3 to 52.7, p=0.004). No statistically significant differences were observed for BPI-SF pain severity index (5.2 to 5.1), FIQ-R overall score (53.2 to 53.2), SF-12 physical (32.8 to 34.1) and mental (41.9 to 42.4) component summary scores.
Conclusions FM patients continued to report high levels of disease burden at follow-up. There was variability among patients in outcomes, with few significant differences over time. Data suggest improvement in symptoms, sleep and pain interference with function due potentially to active management (pharmacologic, nonpharmacologic) of the condition.
Disclosure of Interest C. Schaefer Consultant for: Pfizer Inc (paid consulting services provided by Covance Market Access Services), E. Adams Consultant for: Pfizer Inc (paid consulting services provided by Covance Market Access Services), M. Udall Shareholder of: Pfizer Inc., Employee of: Pfizer Inc., E. Masters Shareholder of: Pfizer Inc., Employee of: Pfizer Inc., R. Mann Consultant for: Pfizer Inc (paid consulting services provided by Covance Market Access Services), S. Daniel Consultant for: Pfizer Inc (paid consulting services provided by Covance Market Access Services), H. McElroy Consultant for: Pfizer Inc (paid consulting services provided by Covance Market Access Services), J. Cappelleri Shareholder of: Pfizer Inc., Employee of: Pfizer Inc., A. Clair Shareholder of: Pfizer Inc., Employee of: Pfizer Inc., M. Hopps Employee of: Pfizer Inc., R. Staud Grant/research support from: Investigator initiated grant from Pfizer Inc., P. Mease Grant/research support from: Pfizer Inc., Consultant for: Pfizer Inc., Speakers bureau: Pfizer Inc., S. Silverman Grant/research support from: Pfizer Inc., Consultant for: Pfizer Inc. and Lilly, Speakers bureau: Pfizer Inc. and Lilly