The assessment of functional impairment in fibromyalgia (FM): Rasch analyses of 5 functional scales and the development of the FM Health Assessment Questionnaire.

OBJECTIVE: Functional assessment by self-report questionnaire plays an important role in most rheumatic conditions, but psychometric properties of questionnaires have not been studied in fibromyalgia (FM), particularly by Rasch analysis, which allows for examining adequacy of the questionnaire scale. To assess currently used instruments, we examined the Fibromyalgia Impact Scale (FIQ), 4 versions of the Health Assessment Questionnaire (HAQ), and the Medical Outcome Survey Short Form (SF-36). METHODS: More than 2,500 patients from 4 sites (3 US, 1 Israel) completed the FIQ. The HAQ questionnaires were completed by 1438 patients participating in the US National Data Bank for Rheumatic Diseases. Seven hundred sixty patients from Wichita, Kansas, completed the SF-36. Rasch analysis was applied separately to each of these data sets. RESULTS: The FIQ systematically underestimated functional impairment by its handling of activities not usually performed. All questionnaires had problems with non-unidimensionality and ambiguous items when applied to patients with FM. In addition, scales were found to be non-linear. Because of these findings we used the 20 item HAQ questionnaire as an item bank to develop a new questionnaire more suitable for use in FM, the fibromyalgia HAQ (FHAQ). This questionnaire fits the Rasch model well, is relevant, is linear, and has a long, well spaced scale. CONCLUSION: No available functional assessment questionnaire works well in FM. A new questionnaire, the FHAQ, was developed. It has appropriate metric properties and should function well in this condition. Since the FHAQ is a subset of the larger HAQ questionnaire, a new questionnaire is not required; only a different method of scoring is needed. Additional studies regarding sensitivity to change are required to fully validate the FHAQ.

A prospective, longitudinal, multicenter study of service utilization and costs in fibromyalgia.

OBJECTIVE: To study, for the first time, service utilization and costs in fibromyalgia, a prevalent syndrome associated with high levels of pain, functional disability, and emotional distress. METHODS: Five hundred thirty-eight fibromyalgia patients from 6 rheumatology centers were enrolled in a 7-year prospective study of fibromyalgia outcome. Patients were assessed every 6 months with validated, mailed questionnaires which included questions regarding fibromyalgia symptoms and severity, utilization of services, and work disability. RESULTS: Fibromyalgia patients averaged almost 10 outpatient medical visits per year, and when nontraditional treatments were considered, this number increased to approximately 1 visit per month. Patients were hospitalized at a rate of 1 hospitalization every 3 years. In each 6-month study period, patients used a mean of 2.7 fibromyalgia-related drugs. Costs increased over the course of the study. The mean yearly per-patient cost in 1996 dollars was $2,274. However, results were skewed by high utilizers, and many patients used few services and had limited costs. Total costs and utilization were independently associated with the number of self-reported comorbid or associated conditions, functional disability, and global disease severity. Compared with patients with other rheumatic disorders, those with fibromyalgia were more likely to have lifetime surgical interventions, including back or neck surgery, appendectomy, carpal tunnel surgery, gynecologic surgery, abdominal surgery, and tonsillectomy, and were more likely than other rheumatic disease patients to report comorbid or associated conditions. Almost 50% of hospitalizations occurring during the study were related to fibromyalgia-associated symptoms. CONCLUSION: The average yearly cost for service utilization among fibromyalgia patients is $2,274. Fibromyalgia patients have high lifetime and current rates of utilization of all types of medical services. They report more symptoms and comorbid or associated conditions than patients with other rheumatic conditions, and symptom reporting is linked to service utilization and, to a lesser extent, functional disability and global disease severity.

Work and disability status of persons with fibromyalgia.

OBJECTIVE: To determine the prevalence and determinants of self-reported work disability in persons with fibromyalgia (FM). METHODS: A longitudinal, multicenter survey of 1604 patients with FM from 6 centers with diverse socioeconomic characteristics was begun in 1988. Assessments were by self-report questionnaire and telephone contact, and included work and disability events that occurred before and after 1988. Comparative analyses were performed on the entire data set and, separately, on the Wichita data set. RESULTS: More than 16% of patients reported receiving US Social Security disability (SSD) payments (highest center rate 35.7%; lowest center rate 6.3%) compared to 2.2% of the US population (US Social Security Administration data) and 28.9% of patients with rheumatoid arthritis seen at the Wichita outpatient rheumatology clinic. Overall, 26.5% reported receiving at least one form of disability payment when SSD and other sources of disability payments were considered. In Wichita, less than 25% of SSD awards were made specifically for FM, but after 1988 that figure increased to 46.4%. Work disability was greatest at the San Antonio and Los Angeles centers. Multivariate predictors (correlates) included pain, Health Assessment Questionnaire disability, and unmarried status. In addition, more than 70% of patients reporting being disabled did receive disability payments. On the other hand, 64% reported being able to work all or most days, and more than 70% were employed or were homemakers. CONCLUSION: Although most patients (64%) report being able to work, we found high rates of self-reported work disability awards among persons with FM followed in 6 rheumatology centers. But we also found great variability among centers as to awards and as to self-reported work ability. Center differences in work disability might reflect clinic referral patterns, physician beliefs, or socioeconomic status.