Objective: Research on adherence has emphasized the need to consider patient ethnicity when developing adherence plans. The objective of this study is to identify predictors of adherence for specific groups, particularly Asian Americans and Pacific Islanders.
Methods: We examined the factors, including drug class, associated with antihypertensive adherence for 28,395 adults in Hawaii (July 1999-June 2003) using health plan administrative data. The population included Japanese (n=13,836), Filipino (n=3,812), Chinese (n=2,280), Korean (n=450), part-Hawaiian (n=3,746) and white (n=3,920) patients. Members with antihypertensive medication in their possession >or=80% of the time were considered adherent. Multivariable logistic regression models were used to identify factors associated with adherence.
Results: Overall adherence rates were less than 65% among all racial/ethnic groups. After adjustment for patient age, gender, morbidity level, health plan type, isle of residence, comorbidities and year of treatment, Japanese were more likely than whites to adhere to antihypertensive therapy [OR=1.21 (1.14-1.29)], whereas Filipino [OR=0.69 (0.64-0.74)], Korean [OR=0.79 (0.67-0.93)] and Hawaiian [OR=0.84 (0.78-0.91)] patients were less likely to adhere. These results were consistent across therapeutic class. Other patient factors associated with lower adherence included younger age, higher morbidity and history of heart disease. Patient factors were also significantly related to adherence, including gender and seeing a sub-specialist. Seeing a physician of the same ethnicity did not appear to improve adherence.
Conclusions: Our findings of substantial disparities among Asian Pacific American subgroups highlight the need to examine subgroups separately. Future qualitative research is needed to determine appropriate interventions, particularly for Filipino, Korean and Hawaiian patients.