Health inequities and societal costs for patients with fibromyalgia and their spouses: a Danish cohort study

Objective: To assess the burden of illness of people with fibromyalgia (FM) and their spouses compared with selected match populations in Denmark.

Methods: Population-based, cohort case-control study using data from Danish registries from 1994 to 2021. Individuals with an FM diagnosis were identified from the National Patient Register (2008-2019) and randomly matched to a 1:4 general population comparator. Spouses or persons co-living with subjects with FM at the time of diagnosis were compared with matched comparator spouses. Healthcare and societal costs, socioeconomic status and occurrence of comorbidities were evaluated for subjects with FM, spouses and controls.

Results: 9712 subjects with FM (94.9% females, mean age 50 years) and 5946 spouses were included. At year of diagnosis, subjects with FM had significantly more comorbidities compared with controls, including significantly more comorbid rheumatic disorders. The highest risk at the time of FM diagnosis was a comorbid diagnosis of ankylosing spondylitis (OR 7.0, 95% CI 4.9 to 10.0). Significantly more comorbidities were also observed in spouses. Subjects with FM and spouses had higher healthcare and public transfer costs and lower income from employment at all timepoints. Loss of income from employment in subjects with FM occurred years before establishment of the FM diagnosis. The employment rate after diagnosis was 22%. 10 years after the FM diagnosis, 50% received disability pension as compared with 11% of matched controls. The observed net average increased societal cost for subjects with FM amounted to €27 193 per patient-year after diagnosis.

Conclusion: FM has major health and socioeconomic consequences for patients, their partners and society and call for improved healthcare strategies matching patients' needs.