Evolution of direct costs in the first years of rheumatoid arthritis: impact of early versus late biologic initiation--an economic analysis based on the ESPOIR cohort

Abstract

Objectives: To estimate annual direct costs of early RA by resource component in an inception cohort, with reference to four distinct treatment strategies: no disease modifying antirheumatic drugs (DMARDs), synthetic DMARDs only, biologic DMARDs in the first year ('first-year biologic', FYB), and biologic DMARDs from the second year after inclusion ('later-year biologic', LYB); to determine predictors of total and non-DMARD related costs.

Methods: The ESPOIR cohort is a French multicentric, prospective study of 813 patients with early arthritis. Data assessing RA-related resource utilisation and disease characteristics were collected at baseline, biannually during the first two years and annually thereafter. Costs predictors were determined by generalised linear mixed analyses.

Results: Over the 4-year follow-up, mean annual direct total costs per treatment strategy group were €3,612 for all patients and €998, €1,922, €14,791, €8,477 respectively for no DMARDs, synthetic DMARDs only, FYB and LYB users. The main predictors of higher costs were biologic use and higher Health Assessment Questionnaire (HAQ) scores at baseline. Being a biologic user led to a higher total cost (FYB Rate Ratio (RR) 7.22, [95% CI 5.59-9.31]; LYB RR 4.39, [95% CI 3.58-5.39]) compared to non-biologic users. Only LYB increased non-DMARD related costs compared to all other patients by 60%.

Conclusions: FYB users incurred the highest levels of total costs, while their non-DMARD related costs remained similar to non-biologic users, possibly reflecting better RA control.

Figure 1. Disease activity per period among matched groups of FYB and LYB users.

* 37 FYB users and 37 LYB users were matched for clinical and sociodemographic baseline characteristics using a logistic regression propensity score. ** Low disease activity is defined as DAS-28≤3.2.

Figure 2. Mean costs per period according to treatment strategy.

(A) Mean total costs according to treatment strategy; (B) Mean other health resource use costs according to treatment strategy.