UBC Faculty Research and Publications

Incremental Direct Medical Costs of Systemic Lupus Erythematosus Patients in the Years Preceding Diagnosis : A General Population-Based Study McCormick, Natalie; Marra, Carlo A.; Sadatsafavi, Mohsen; Aviña-Zubieta, J. Antonio


Objective We estimated the incremental (extra) direct medical costs of a population-based cohort of newlydiagnosed 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 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 3,632 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 $12,019 (2013 Canadian) with 58% from hospitalisations, 24% outpatient, and 18% from prescription medications; Year +1 costs for non-SLE averaged $2,412. 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 $1,131 per-person in Year -5 (fifth year before diagnosis) to $2,015 (Year -2), $3,473 (Year -1), and $6,474 (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 (versus SLE females) rose from $540 perperson in Year -2, to $1,385 in Year -1, and $2,288 in Year +1. Conclusion Even years before diagnosis, SLE patients incur significantly-elevated direct medical costs than the age- and sex-matched general population, for hospitalisations, outpatient care, and medications.

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