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Health Services Research & Development

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2007 HSR&D National Meeting Abstract

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National Meeting 2007

3037 — When More is Not Better: Treatment Intensification among Hypertensive VA Patients with Poor Medication Adherence

Heisler M (Center for Practice Management and Outcomes) , Hogan MM (Center for Practice Management and Outcomes), Hofer TP (Center for Practice Management and Outcomes), Kerr EA (Center for Practice Management and Outcomes Research)

In spite of the clinical importance of achieving good blood pressure (BP) control, many VA patients, including those with cardiovascular disease and diabetes, continue to have high BP. The relative contribution toward poor BP control of patient medication nonadherence versus failure of providers to intensify medications is poorly understood. In a sample of 41,756 VA patients on at least one BP medication with recorded outpatient BPs>=140/90, we examined the prevalence of and relationship between poor medication adherence and provider treatment intensification.

We identified all patients in VISN 11 who received two or more outpatient BP medication fills during 2004 and who had at least one outpatient visit and one elevated BP during 2005 (n=41756). For each episode of elevated blood pressure during 2005 (73,597 events), we examined patients’ medication adherence over a 12-month period prior to the elevated BP and occurrence of medication intensification in response to the elevated BP. We then examined bivariate and multivariate relationships between adherence level and whether or not intensification occurred. We calculated gaps in medication fills using the Continuous, Multiple interval measure of Gaps in therapy (CMG) measure for each hypertension medication class. Intensification included any of the following actions within 14 days of the elevated BP: a) adding a new class; b) switching to a new class; c) switching to a different medication within the same class; or d) increasing the dosage category of an ongoing medication.

For forty one percent of elevated BP events we found prior medication refill gaps 20 percent or greater in one or more BP medication classes. Intensification took place after 30 percent of elevated BP events, including 31 percent of events with refill gaps 20 percent or greater. Accounting for the clustering of elevated BP events within patients, those aged 75 or older were less likely to undergo intensification than patients younger than 65 (AOR: 0.91, 95% CI: 0.88-0.96) and patients with cardiovascular disease were less likely to undergo intensification than patients with neither cardiovascular disease or diabetes (AOR: 0.81, 95% CI: 0.76-0.86). In these models, when patients’ worst adherence gap was modeled as a continuous variable, worse adherence was associated with significantly higher odds of undergoing medication intensification than better adherence (AOR: 1.21, 95% CI: 1.10-1.34). The odds of intensification were elevated in the face of adherence problems until there were gaps representing 60% of prescribed days.

Poor adherence and/or lack of intensification were present in the majority of cases of high blood pressures. Significant medication refill gaps (20 percent or greater) in the prior year were present in over 40 percent of elevated BP events. Patients with poor medication refill adherence were significantly more likely than patients with good adherence to undergo medication intensification.

Providers need to systematically assess patients’ medication adherence before intensifying medications. Intensification of medications in the face of poor adherence is likely to be costly and ineffective.

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