Examining factors associated with nonadherence and identifying providers caring for nonadherent subgroups

Abstract

Objectives To examine racial/ethnic and regional differences in medication adherence in patients with diabetes taking oral anti-diabetic, anti-hypertensive, and cholesterol lowering medications and to identify the pharmacies and prescribers who serve these communities. Methods Administrative claims data was analyzed for members enrolled in a large health plan in Hawaii (2008-2010) with diabetes mellitus who were taking three types of medications: 1) oral anti-diabetic medications; 2) anti-hypertensive medications; 3) cholesterol lowering medications (n=5136). The primary outcome was medication adherence based on medication possession ratios. Multivariable logistic regression models were estimated to examine the association between race/ethnicity and region to adherence to each drug class separately, followed by non-adherence to all three. Covariates included age, gender, education level, chronic conditions, copayment level, and number of prescribers and pharmacies from which the patients received their medications. Key Findings After adjustment for other factors, Filipinos [OR=0.58, 95%CI(0.45,0.74)], Native Hawaiians [OR=0.74, 95%CI(0.56,0.98)], and people of other race [OR=0.67, 95%CI(0.55,0.82)] were significantly less adherent to anti-diabetic and anti-hypertensive medications than Japanese. For cholesterol-lowering medications, all racial and ethnic groups were significantly less adherent than Japanese, except mixed race. We also found that different racial/ethnic groups tended to use different pharmacies and prescribers, particularly in rural areas Conclusion Adherence differed by race/ethnicity as well as age and region. Qualitative research involving subgroups (e.g. Filipinos, Native Hawaiians, people under age 50) is needed to identify how to adapt and enhance the effects of interventions shown to be efficacious in prior studies.

Ethnic disparities in medication adherence? A systematic review examining the association between ethnicity and antidiabetic medication adherence

“…All articles were published between 2005 and 2020 and were conducted in nine countries: United States (n=25)[25-49], New Zealand (n=3) [50-52], United Kingdom (n=2)[53, 54], Canada (n=1)[55], Malaysia (n=3)[56-58], Singapore(n=2)[59, 60], Brazil (n=1)[61], Qatar (n=1)[62] and United Arab Emirates (n=1)[63]. The majority of included studies were retrospective database studies [ 26-29, 31-55, 57, 59, 60, 64], while the remaining were cross-sectional studies [ 28, 56, 58, 61-63]. The sample sizes ranged from 57[57] to 1,888,682 patients [ 37], and the mean age of patients ranged from 14 to 71 years.…”

“…The data sources were clearly defined in all studies; however, three papers did not state the time frame for data [26, 47, 59]. Of the 33 studies, 29 clearly stated the eligibility criteria, but 16 did not explain the rationale for these criteria [ 26, 28, 34, 39, 45, 47-49, 51, 52, 54, 55, 57, 60, 64]. The method of medication adherence measurement was clearly described in the majority of studies, but, for some studies, the method of handling the switching of drugs within and between therapeutic classes was not appropriately explained [26, 27, 34, 38, 42-46, 48, 49, 52, 54, 55, 59, 60].…”

“…A variety of measures using pharmacy refill data were used to assess adherence to antidiabetic medications among different ethnic groups, including the MPR[28, 34, 40, 43, 44, 46, 48-51, 54, 57, 60, 64], proportion of days covered[29, 35-38, 41, 42, 45, 52, 55, 59], and other measures, such as medication refill adherence and continuous single-or multiple-interval measures of medication gaps[26, 27, 31, 33, 53].…”

“…Fourteen studies used the MPR to evaluate medication adherence for people with diabetes from different ethnic groups. Three studies assessed adherence to antidiabetic medications among the following ethnic groups: Japanese, Hawaiians, Whites, Filipinos, Chinese, mixed races, and other races [ 28, 40, 60]. The reported adherence rates varied by ethnicity with people of Japanese ethnicity most likely to be adherent to antidiabetic medications, followed by Whites, Chinese, Hawaiians, Filipinos, and other ethnic groups; this difference was statistically significant in two studies [ 28, 60].…”

“…Three studies assessed adherence to antidiabetic medications among the following ethnic groups: Japanese, Hawaiians, Whites, Filipinos, Chinese, mixed races, and other races [ 28, 40, 60]. The reported adherence rates varied by ethnicity with people of Japanese ethnicity most likely to be adherent to antidiabetic medications, followed by Whites, Chinese, Hawaiians, Filipinos, and other ethnic groups; this difference was statistically significant in two studies [ 28, 60]. The difference between people from the following ethnicities: Whites, African Americans, Hispanics, Asians, American Indians, and others in adherence to antidiabetic medications was also reported in seven studies [ 34, 43, 44, 46, 48, 49, 64].…”