Objective:

Patients with Sjogren’s syndrome (SjS) who develop interstitial lung disease (ILD) suffer from poorer quality of life and risk higher mortality. As innovative treatments for ILD have been developed, evidence demonstrating the economic burden of ILD is needed. This study aims to estimate the direct healthcare costs associated with ILD among patients with SjS in a national sample of the commercially insured population in the United States.

Methods:

Individuals with a diagnosis of SjS between January 1, 2006, and September 30, 2015, with or without a diagnosis of ILD, were identified from the PharMetrics Plus for Academics database. A 5:1 propensity score (PS) matching was applied to control for baseline variables (i.e., age, sex, region, insurance type). The cost ratio and average marginal cost for total direct medical costs comparing SjS patients with and without ILD were estimated using a generalized linear model. All costs were represented from a health plan payer perspective and inflated to 2020 U.S. dollars.

Results:

A total of 815 SjS-ILD cases were identified and fully matched to 4,075 SjS-only controls. The 180-day total cost of SjS-ILD cases was about two times higher than that of SjS-only controls (adjusted cost ratio=1.94, 95% CI=1.76-2.15). The average cost difference between patients with and without ILD was $8,814 (95% CI=$7,149-$10,479). Costs were mainly contributed from outpatient services other than physician office visits (such as radiological and pathological tests), inpatient services, and outpatient pharmacy for both groups (39.4%, 38.8%, and 16.3% for SjS-ILD cases; 43.7%, 22.6%, and 22.9% for SjS-only controls, respectively).

Conclusions:

Total direct healthcare cost was substantially higher in patients with SjS and ILD compared to patients with SjS without ILD. Our findings provide the foundation for further economic evaluation on innovative treatments to reduce the clinical and economic burden imposed by ILD among patients with SjS.