Cost of illness and illness perceptions in patients with fibromyalgia.

Objectives: The disease impact and economic burden of fibromyalgia (FM) are high for patients and society at large. Knowing potential determinants of economic costs may help in reducing this burden. Cognitive appraisals (perceptions) of the illness could affect costs. The present study estimated costs of illness in FM and examined the association between these costs and illness perceptions.

Methods: Questionnaire data of FM severity (FIQ), illness perceptions (IPQ-R-FM), productivity losses (SF-HLQ) and health care use were collected in a cohort of patients with FM. Costs were calculated and dichotomised (median split). Univariate and hierarchic logistic regression models examined the unique association of each illness perception with 1) health care costs and 2) costs of productivity losses. Covariates were FM severity, comorbidity and other illness perceptions.

Results: 280 patients participated: 95% female, mean age 42 (SD=12) years. Annualised costs of FM per patient were €2944 for health care, and €5731 for productivity losses. In multivariate analyses, a higher disease impact (FIQ) and two of seven illness perceptions (IPQ-R-FM) were associated with high health care costs: 1) high scores on 'cyclical timeline' reflecting a fluctuating, unpredictable course and 2) low scores on 'emotional representations', thus not perceiving a connection between fibromyalgia and emotions. None of the variables was associated with productivity losses.

Conclusions: Our study indicates that perceiving a fluctuating course and low emotional representation, which perhaps reflects somatic fixation, are associated with health care costs in FM. Future studies should examine whether targeting these illness perceptions results in reduction of costs.