Nonadherence in Patients with Resistant Hypertension

Resistant hypertension is a common comorbidity among patients with kidney disease and is a risk factor for adverse cardiovascular outcomes. Patients with resistant hypertension also undergo increased screening for secondary hypertension. According to Gabrielle Emma Marie Bourque, MD, and colleagues, not all patients with apparent resistant hypertension have true resistant hypertension.

Reports of nonadherence among patients with resistant hypertension range from 3% to 86%; however, those data do not differentiate between intentional and nonintentional nonadherence. Nonintentional nonadherence is characterized by occasional forgetfulness and can be identified with pill counts or data on pharmacy refills. Accurate diagnosis of intentional nonadherence requires more precise methods such as therapeutic drug monitoring or directly observed therapy.

Dr. Bourque et al. conducted a systematic review to assess the overall prevalence of nonadherence in patients with resistant hypertension; the secondary outcome of interest was a differentiation between nonintentional and intentional adherence subtypes. Results of the review were reported during a poster session at Kidney Week 2019 in a poster titled The Prevalence of Nonadherence in Patients with Resistant Hypertension: A Systematic Review.

The review included searches of MEDLINE, EMBASE, and the Cochrane library for observational studies and randomized controlled trials that reported on the prevalence of nonadherence in resistant hypertension. The secondary outcome was examined using the pooled prevalence of nonadherence based on indirect and direct measures of nonadherence. The random effects model was used to estimate the weighted summary prevalence for the outcomes.

A total of 1415 nonduplicate citations were retrieved during the literature search. Following application of eligibility criteria, the researchers retrieved 197 full citations; of those, 27 were included in the review. Most of the included studies were retrospective database studies or cross-sectional studies; 63% used indirect measured of assessment, including medication possession ratio or the Morisky scale. The most common cutoff used for a diagnosis of nonadherence was 80%.

The pooled prevalence of nonadherence was 31%, with high statistical heterogeneity (I-squared 99). The pooled prevalence was higher with direct measures than with indirect measures (45% vs 19%, respectively).

“The prevalence of nonadherence varied based on the severity of hypertension, but also based on the method of measurement of adherence. Indirect measures underestimate the extent of true nonadherence. Incorporation of direct measures such as drug assays or direct observed therapy should be considered for more widespread adoption,” the researchers said.

Source: Bourque GEM, Ilin JV, Ruzicka M, Hiremath S. The prevalence of nonadherence in patients with resistant hypertension: A systematic review. Abstract of a poster presented at the American Society of Nephrology Kidney Week 2019 (Abstract TH-PO685), November 7, 2019, Washington, DC.