Affiliation:
1. Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, BC, Canada
2. Arthritis Research Canada, Richmond, BC, Canada
3. School of Pharmacy, University of Otago, Dunedin, New Zealand
4. Division of Rheumatology, Department of Medicine, The University of British Columbia, Vancouver, BC, Canada
Abstract
Objective We estimated the incremental (extra) direct medical costs of a population-based cohort of newly diagnosed systemic lupus erythematosus (SLE) for five years before and after diagnosis, and the impact of sex and socioeconomic status (SES) on pre-index costs for SLE. Methods We identified all adults newly diagnosed with SLE over 2001–2010 in British Columbia, Canada, and obtained a sample of non-SLE individuals from the general population, matched on sex, age, and calendar-year of study entry. We captured costs for all outpatient encounters, hospitalisations, and dispensed medications each year. Using generalised linear models, we estimated incremental costs of SLE each year before/after diagnosis (difference in costs between SLE and non-SLE, controlling for covariates). Similar models were used to examine the impact of sex and SES on costs within SLE. Results We included 3632 newly diagnosed SLE (86% female, mean age 49.6 ± 15.9) and 18,060 non-SLE individuals. Over the five years leading up to diagnosis, per-person healthcare costs for SLE patients increased year-over-year by 35%, on average, with the biggest increases in the final two years by 39% and 97%, respectively. Per-person all-cause medical costs for SLE the year after diagnosis (Year + 1) averaged C$12,019 (2013 Canadian) with 58% from hospitalisations, 24% outpatient, and 18% from prescription medications; Year + 1 costs for non-SLE averaged C$2412. Following adjustment for age, sex, urban/rural residence, socioeconomic status, and prior year's comorbidity score, SLE was associated with significantly greater hospitalisation, outpatient, and medication costs than non-SLE in each year of study. Altogether, adjusted incremental costs of SLE rose from C$1131 per person in Year –5 (fifth year before diagnosis) to C$2015 (Year –2), C$3473 (Year –1) and C$6474 (Year + 1). In Years –2, –1 and +1, SLE patients in the lowest SES group had significantly greater costs than the highest SES. Unlike the non-SLE cohort, male patients with SLE had higher costs than females. Annual incremental costs of SLE males (vs. SLE females) rose from C$540 per person in Year –2, to C$1385 in Year –1, and C$2288 in Year + 1. Conclusion Even years before diagnosis, SLE patients incur significantly elevated direct medical costs compared with the age- and sex-matched general population, for hospitalisations, outpatient care, and medications.
Funder
British Columbia Lupus Society
Canadian Institutes of Health Research
Michael Smith Foundation for Health Research
Canadian Arthritis Network