Medication Nonadherence Among US Immigrants: Complex Roles of Insurance, Citizenship, and Length of Time in the United States.

Objective: Medication accessibility and adherence are essential factors in healthcare as they ensure patients can follow their doctor's guidance, enhance treatment success, and lower healthcare costs. Yet, immigrants-a population facing structural disadvantages-remain underrepresented in adherence research. Drawing upon the assimilation theory, this study aims to identify independent and combined effects of cost-related medication nonadherence among immigrants. Study design: This is a secondary data analysis using the 2019-2022 National Health Interview Survey. The data included individuals who self-reported that they were born outside of the U.S. and were aged 18 years and older. Methods: Over four years, the total weighted sample is 53,739,380, and 52.7% had taken any medication within 12 months before the survey. Chi-squared tests were conducted to examine the differences in characteristics between people currently with and without medications and whether insurance, citizenship, and time in the U.S. affected their medication accessibility and adherence. Any p-value less than 0.05 is considered statistically significant. Results: Compared to immigrants without medications, immigrants with medications were more likely to have U.S. citizenship (53.4% > 36.8%, p < 0.001). Those who entered the U.S. less than five years ago are more likely to delay getting medical care due to cost (15.1% > 8.5%, p = 0.0022). Conclusions: Certain aspects of healthcare become more accessible for those living in the U.S. for more than five years. There are various possible explanations for these findings, including the 5-year policy required for permanent residents to access Medicaid. Insurance alone does not eliminate cost-related barriers. Targeted policy interventions for recently arrived and uninsured immigrants are needed to close these structural gaps.