Evaluation of Access Disparities to Biologic Disease-Modifying Antirheumatic Drugs in Rural and Urban Communities

Abstract

The American College of Rheumatology guidelines provides a strong recommendation for the use of biologic disease-modifying antirheumatic drugs (bDMARDs) when conventional rheumatoid arthritis treatments fail to meet treatment targets. Although bDMARDs are an effective and important treatment component, access inequalities remain a challenge in many communities worldwide. The purpose of this analysis is to assess nationwide trends in bDMARD access in the United States, with a specific focus on rural and urban access gaps. This study combined multiple county-level databases to assess bDMARD prescriptions from 2015 to 2019. Using geospatial analysis and the Moran's I statistic, counties were classified according to prescription levels to assess for hotspots and coldspots. Analysis of variance (ANOVA) was used to compare significant counties across 49 socioeconomic variables of interest. The analysis identified statistically significant hotspot and coldspot prescription clusters within the United States. Coldspot (Low-Low) clusters with low access to bDMARDs are located predominantly in the rural west North Central region, extending down to Oklahoma and Arkansas. Hotspot (High-High) clusters are seen in urban and metro areas of Wisconsin, Minnesota, Pennsylvania, North Carolina, Georgia, Oregon, and the southern tip of Texas. Comparing coldspot to hotspot areas of bDMARD access revealed that the Medicare populations were older, more rural, less educated, less impoverished, and less likely to get their bDMARDs from a rheumatologist.

Keywords: disease-modifying antirheumatic drugs; geospatial analysis; healthcare inequality; medicare data; rural vs metropolitan.

Figure 1. Prescribed days of bDMARDs per 10,000 Medicare members

Visual representation of counties with Moran's I spatial outlier categories (p < 0.05) for average yearly prescribed days of bDMARDs per 10,000 Medicare Part D members. Gray areas signal non-significance in the geographic designation. bDMARDs: Biologic disease-modifying antirheumatic drugs

Figure 2. Prescribed days of individual bDMARDs per 10,000 Medicare members

Visual representation of counties with Moran's I spatial outlier categories (p < 0.05) for individual bDMARDs — A: Rituximab, B: Abatacept, C: Adalimumab, D: Etanercept. Gray areas signal non-significance in the geographic designation. bDMARDs: Biologic disease-modifying antirheumatic drugs

Figure 3. Prescribed days of individual bDMARDs per 10,000 Medicare members

Visual representation of counties with Moran's I spatial outlier categories (p < 0.05) for individual bDMARDs — A: Infliximab, B: Certolizumab, C: Tocilizumab, D: Golimumab. Gray areas signal non-significance in the geographic designation. bDMARDs: Biologic disease-modifying antirheumatic drugs

Figure 4. Log of prescribed days of bDMARDs per 10,000 Medicare members

Paired histograms of the number of counties in (A) urban, (B) metro, and (C) rural areas. Gray bars indicate the number of counties in each classification with zero bDMARD prescriptions. bDMARDs: Biologic disease-modifying antirheumatic drugs

Figure 5. Geospatial analysis of bDMARD prescriptions in the United States (2015 to 2019)

A: Number of days of bDMARDs prescribed per provider per 10,000 Medicare members per year on average. B: Percentage of bDMARDs prescribed by rheumatologists as a percentage of total bDMARD prescriptions. C: Number of prescribers of bDMARDs per 10,000 Medicare members for all specialties. D: Percentage of bDMARD prescribers who are rheumatologists. bDMARDs: Biologic disease-modifying antirheumatic drugs