Illness Perceptions and Costs in Patients with Fibromyalgia

BACKGROUND Patients with Fibromyalgia (FM) experience a high disease burden, leading to substantial economic costs (1). These costs may be due to the chronic nature of FM, dissatisfaction with the diagnosis, lack of a uniform and effective treatment, and perhaps also beliefs of individuals. Investigating potential determinants of costs is pivotal for reducing the economic burden of FM. Several clinical and demographic factors are associated with costs in FM, but the influence of illness perceptions on costs is unknown. Illness perceptions refer to beliefs about timeline and course, consequences, control, illness coherence and emotional representation of a disease (2). As illness perceptions can be targeted in treatment, investigating whether illness perceptions may influence costs in FM is warranted. OBJECTIVES To examine the relationship between illness perceptions and costs in patients with FM, taking clinical factors into account. METHODS Baseline data from a cohort of patients with FM were used. Clinical data, severity of FM (FIQ), and illness perceptions (IPQ-R-FM) were gathered. Cost data were based on self-reported questionnaires assessing health care use (e.g. consultation, medication use), work absenteeism and presenteeism, and productivity losses (SF-HLQ). Cost data were dichotomized by median split (high versus low costs). Descriptive statistics were computed. Two hierarchic logistic regression models were used to examine the unique association of illness perceptions with 1) health care costs and 2) costs of work absenteeism, presenteeism and productivity losses. Severity of FM and comorbidities were potential covariates for costs. In both hierarchic models step 1 included the potential covariates and step 2 included the seven illness perception dimensions. RESULTS 280 patients participated in this study. Mean age of the study sample was 42 years (SD=11.8), the majority was female (95%), mean severity of FM was 58.6 (SD=14.9), and 78% had ≥1 comorbidities. A high score on severity of FM (P=.04), a high score on IPQ-dimension consequences (P=.03) and a low score on IPQ-dimension emotional representation (P<.01) were associated with high health care costs. Comorbidities was not associated with health care costs (P=.12). This model explained 7% of the variance. None of the variables were significantly associated with costs of work absenteeism, presenteeism and productivity losses. CONCLUSIONS Most illness perceptions are not related to costs in FM. Only patients perceiving more negative consequences of FM on daily life and perceiving less distress of FM have higher health care costs, when correcting for the severity of FM. Our results do not indicate that targeting illness perceptions will result in a reduction of costs.