Sensitivity Analyses: No or very small differences between results from Proc Genmod and when multiple imputation used for missing BMI, systolic, HHincome, medvisits and copay for either model.
Disparities in Antihypertensive Medication Adherence ADAMS
Antihypertensive Medication Adherenceamong Newly Treated Patients:Opportunities for Disparities Reduction?Alyce S. Adams, PhDConnie Uratsu, RN 18th Annual HMOWendy Dyer, MS Research NetworkDavid Magid, MD, MPH ConferencePatrick O’Connor, MD, MA, MPH April 29-May 2, 2012Arne Beck, PhD Seattle, WAMelissa Butler, PhDP. Michael Ho, MD, PhDJulie A. Schmittdiel, PhD
AcknowledgementsINSTITUTIONSKaiser Permanente Division of Research, Oakland, CA; Institute for Research,Kaiser Permanente, Denver, CO; Kaiser Permanente Center for HealthResearch Southeast, Atlanta, GA; HealthPartners Research Foundation,Minneapolis, MN; Denver VA Medical Center, Denver, COFUNDERSNational Heart, Lung, and Blood Institute and the National Institute forMental Health as a supplement to the HMO Research Network CardiovascularDisease Network [3U19HL091179-04S1].National Institute for Diabetes, Digestive and Kidney Diseases Health DeliverySystems Center for Diabetes Translational Research [P30DK092924](Adams, Schmittdiel, O’Connor)OTHERDr. Alan Go (critical edits), Ms. Karen R. Hansen (manuscript preparation)
Conceptual Framework Predisposing Factors •Beliefs about risks and Mediators benefits of medicines Primary Health Status Income •Medication Coverage Non-Adherence •Patient-Provider RelationshipRace/Ethnicity Education Geography •Perceived affordability Whites •Blacks Rural/Urbanicity Social Support Enabling Factors •Hispanics Early Culture •Health Literacy/Education •Asians Preferences •Patient self-care skills Non-Persistence Racism •Medication Affordability Stress •Medication Tolerability Perceived Barriers •Affordability/Ease of Access •Competing Demands Non-Adherence •Cognitive Issues/Complexity
Research Questions 1. Are racial and ethnic differences in antihypertensive medication taking behavior consistent over time? 2. What factors contribute to differences in mediation taking Behavior at different stage of adherence by race and Ethnicity?
MethodsSetting: Kaiser Permanente Northern CaliforniaPatients: Adults (≥18 years) with hypertension who were new users ofantihypertensive therapy in 2008Outcome MeasuresPrimary non-adherence: failing to fill a prescribed antihypertensive agent within60 days after it was ordered by physicianEarly non-persistence: failing to refill within 90 days of running out of thefirst prescriptionNon-adherence: not having medication available for 20% or more of daysduring the 12 months following initiation of therapyModeling: Multivariate logistic regression analysis, with sensitivity analysesusing proc genmod and multiple imputation
Logistic Regression Model Estimating Non-Adherence with Antihypertensive Agents Black (non- Asian (non- Hispanic Hispanic) Hispanic)Model 1: Age, Gender 1.73 (1.53-1.96) 1.20 (1.07-1.35) 1.68 (1.51-1.87)+ smoking status, BMI, SBP 1.71 (1.51-1.94) 1.22 (1.08-1.37) 1.67 (1.51-1.86)+ household income 1.67 (1.47-1.89) 1.22 (1.09-1.38) 1.65 (1.48-1.83)+physical comorbidity 1.67 (1.47-1.90) 1.23 (1.09-1.38) 1.65 (1.48-1.84)+mental health comorbidity 1.67 (1.47-1.90) 1.23 (1.09-1.39) 1.65 (1.48-1.84)+ physician visits 1.68 (1.48-1.90) 1.23 (1.09-1.39) 1.65 (1.48-1.84)+medication copay & mail order 1.54 (1.35-1.75) 1.13 (1.00-1.28) 1.48 (1.33-1.65)pharmacy use
Key Findings • In this setting where patients have more or less equal access to care, non-white race was associated with both early non-persistence & non-adherence • These relationships were robust to the inclusion of sociodemographic and clinical factors. • However, the relationship between race/ethnicity and non-adherence was appreciably attenuated by the inclusion of medication copay and mail order pharmacy use.
Limitations • Unmeasured confounders • beliefs and preferences unlikely to change over time • limits our understanding of differences and why they occur • Logistic regression • OR may overestimate effects, additional sensitivity analyses planned • Missing Data • Results robust to multiple imputation • Racial/Ethnic misclassification • may bias results if the misclassification is correlated with both race/ethnicity and adherence
Conclusions • Racial and ethnic differences in medication taking behavior occur early in the course of treatment. • System level changes that ease access to medications may have the potential to attenuate persistent gaps in the use of these and other clinically effective therapies.