Risk Factors and the Usual Source of Care on Non-Adherence to Antihypertensive Drugs in Immigrants with Hypertension

Abstract

Background

Immigrants are vulnerable to suboptimal health care utilization including non-adherence of medication use. Thus, we aimed to identify the potential risk factors of non-adherence and evaluate whether utilizing a usual source of care was associated with medication adherence in immigrants.

Methods

We utilized the Korea National Health Insurance Claims Database between 2012 and 2015. Cases were immigrants who had antihypertensive prescriptions at the time of hypertension diagnosis in 2012. Controls were native-born Koreans with hypertension who were 1:1 matched to immigrants by age, sex, and Charlson comorbidity index. We used the medication possession ratio for three years to assess the adherence to antihypertensive drugs. The likelihood of non-adherence was evaluated between cases and controls by multivariate linear regression models stratified by age, sex, and number of clinic visits. We assessed the potential risk factors of non-adherence in immigrants by multivariate linear regression and logistic regression models, respectively.

Results

In total, 4114 immigrants and 4114 matched native-born Koreans with hypertension were included. The mean MPR was significantly lower in immigrants (56% vs 70%, p<0.0001). Immigrants showed almost two times the level of non-adherence as native-born Koreans (odds ratio [OR], 2.01; 95% confidence interval [CI], 1.83–2.21). Stratified analyses on non-adherence presented the highest non-adherence (2.28 times) in immigrants in the younger group (30–49 years old) and the lowest non-adherence in immigrants in 65 and old group where the risk was 1.69 times higher than native Korean with the same age. The absence of a usual source of care significantly increased medication non-adherence by 1.31 to 1.58 times among immigrants.

Conclusion

When the number of visited clinics increased, the degree of non-adherence increased consistently. Therefore, the systematization of registering with primary care (a usual source of care) might be a modifiable health care strategy to improve health care outcomes in immigrants.

Keywords:

• usual source of care
• hypertension
• immigrants
• health care strategy

Acknowledgment

This study used NHIS-NHID data (NHIS-2018-1-042) made available by the National Health Insurance Service (NHIS). The authors declare no conflicts of interest with the NHIS. We would like to thank the NHIS for its cooperation.

Disclosure

The authors report no conflicts of interest for this work.

Hyemin Cho and Sohyun Jeong equally contributed as first authors.

Additional information

Funding

This research was funded by the Basic Science Research Program through the National Research Foundation of Korea (NRF) (2017R1D1A1B03034121). However, the funding body had no influence on conducting the research or writing the manuscript.