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2015 HSR&D/QUERI National Conference Abstract

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3116 — Racial Differences in the Control of Hypertension: Examining Medication Adherence and Treatment Intensification

Petersen LA, VA HSR&D Center for Innovations in Quality, Effectiveness & Safety (IQuESt) and Baylor College of Medicine; Woodard LD, VA HSR&D Center for Innovations in Quality, Effectiveness & Safety (IQuESt) and Baylor College of Medicine; Urech TH, VA HSR&D Center for Innovations in Quality, Effectiveness & Safety (IQuESt); Pietz K, VA HSR&D Center for Innovations in Quality, Effectiveness & Safety (IQuESt); Virani SS, VA HSR&D Center for Innovations in Quality, Effectiveness & Safety (IQuESt) and Baylor College of Medicine;

Objectives:
We examined racial disparities in antihypertensive medication adherence and whether lack of adherence drives the disparities documented for blood pressure (BP) control. We also sought to determine if there were differences by race for the receipt of treatment intensification among patients with uncontrolled blood pressure.

Methods:
We identified Veterans with hypertension receiving primary care at 1 VA Network between April 2011 and March 2012. We used the patient's last BP reading (index) to evaluate BP status (controlled BP defined as < 140/90 mmHg). We calculated adherence using the proportion of days covered (PDC) ratio, examining medication use in the 365 days prior to index. We examined racial differences in adherence by medication class. We evaluated the effects of race and adherence on BP control using logistic regression. We assessed a 90-day follow-up period to determine receipt of intensification.

Results:
69,450 Veterans met our study inclusion criteria (17% black; 83% non-black). Overall, 74.4% of blacks compared to 82.4% of non-blacks had controlled BP at index (P < .0001). For each of the 8 medication classes examined, non-blacks had a higher proportion of adherent patients compared to blacks (P < .0001 for each class). After adjusting for significant patient and provider characteristics, adherent black patients remained less likely to have controlled blood pressure compared to adherent non-black patients (OR = 0.81, 95% CI, 0.75-0.87). Of the 3,062 blacks and 10,098 non-blacks with uncontrolled BP, 40.8% of blacks versus 34.2% of non-blacks received treatment intensification (P < .0001).

Implications:
Compared to non-blacks, blacks had lower rates of medication adherence and lower odds of controlled BP at index. Adjusting for medication adherence and the interaction of race and adherence did not fully explain the disparity in BP control between blacks and non-blacks. Blacks had higher rates of treatment intensification in response to uncontrolled BP. It seems unlikely that racial differences in BP control are due to lack of provider response during follow-up.

Impacts:
Neither lack of adherence nor lack of treatment intensification explains race disparities. Further work should elucidate the underlying drivers of racial disparities in BP control and outcome, including differences in tolerability and side effects of medications.