Large differences in cost of illness and wellbeing between patients with fibromyalgia, chronic low back pain, or ankylosing spondylitis

Abstract

Objective: To compare the cost of illness of three musculoskeletal conditions in relation to general wellbeing.

Methods: Patients with fibromyalgia, chronic low back pain (CLBP), and ankylosing spondylitis who were referred to a specialist and participated in three randomised trials completed a cost diary for the duration of the study, comprising direct medical and non-medical resource utilisation and inability to perform paid and unpaid work. Patients rated perceived wellbeing (0-100) at baseline. Univariate differences in costs between the groups were estimated by bootstrapping. Regression analyses assessed which variables, in addition to the condition, contributed to costs and wellbeing.

Results: 70 patients with fibromyalgia, 110 with chronic low back pain, and 111 with ankylosing spondylitis provided data for the cost analyses. Average annual disease related total societal costs per patient were 7813 euro for fibromyalgia, 8533 euro for CLBP, and 3205 euro for ankylosing spondylitis. Total costs were higher for fibromyalgia and CLBP than for ankylosing spondylitis, mainly because of cost of formal and informal care, aids and adaptations, and work days lost. Wellbeing was lower in fibromyalgia (mean, 48) and low back pain (mean, 42) than in ankylosing spondylitis (mean, 67). No variables other than diagnostic group contributed to differences in costs or wellbeing.

Conclusions: In patients under the care of a specialist, there were marked differences in costs and wellbeing between those with fibromyalgia or CLBP and those with ankylosing spondylitis. In particular, direct non-medical costs and productivity costs were higher in fibromyalgia and CLBP.

Figure 1

Cox probability curve illustrating the proportion of patients incurring more than a specific amount of costs in €/patient per year for each of the three chronic back conditions. AS, ankylosing spondylitis; CLBP, chronic low back pain; FM, fibromyalgia.