Estimation of health care costs as a function of disease severity in people with psoriatic arthritis in the UK

Abstract

Objectives. The primary aim of this study was to estimate annual health care costs for biologic-naïve patients with PsA in the UK. The relationship between disease severity, defined by physical limitations, and costs was also explored. Methods. This study utilized data from the British Society of Rheumatology Biologics Register (BSRBR) to develop a multivariate model estimating disease severity from parameters available in routine primary care data. The HAQ Disability Index was used to determine disease severity. This algorithm was then applied to routine data from The Health Improvement Network (THIN). Annual costs were estimated for drugs, contacts with a general practitioner and other health care professionals, tests, hospital outpatient attendances and inpatient admissions from a National Health Service perspective using official tariffs. The relationship between disease severity and health care costs was estimated using a generalized linear model. Results. Three hundred and fifty-six cases with PsA were identified in the BSRBR and 4492 in THIN. Total mean annual health care costs ranged from £11 to £20 782 with a mean of £1446 (s.d. £1756). When costs were sub-grouped by the predicted HAQ score, the mean annual observed costs ranged from £548 per person for the least severely affected (HAQ ≤1.2) to £4832 for the most severely affected (HAQ >2.6). Prescription costs and secondary care episodes accounted for more than a third of total care costs each (38 and 34%, respectively). When the relationship between disease severity and costs was examined, estimated HAQ was found to be a significant predictor of total health care costs. Conclusions. Treatment of people with PsA resulted in considerable financial costs and these costs varied markedly by disease severity.