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Abstract: TH-PO685

The Prevalence of Nonadherence in Patients with Resistant Hypertension: A Systematic Review

Session Information

Category: Hypertension and CVD

  • 1401 Hypertension and CVD: Epidemiology, Risk Factors, and Prevention


  • Bourque, Gabrielle Emma marie, The Ottawa Hospital, Ottawa, Ontario, Canada
  • Ilin, Julius Vladimir, University of Ottawa, Ottawa, Ontario, Canada
  • Ruzicka, Marcel, University of Ottawa, Ottawa, Ontario, Canada
  • Hiremath, Swapnil, University of Ottawa, Ottawa, Ontario, Canada

Resistant hypertension (RH) is common and is a risk factor for higher cardiovascular outcomes. These patients also undergo more screening intensity for secondary hypertension. Not all patients with apparent resistant hypertension have true RH. Reports of the prevalence of non-adherence vary widely from 3 to 86%. However intentional and non-intentional non-adherence are not differentiated in this data. Non-intentional non-adherence refers to occasional forgetfulness and can be diagnosed with pill counts or pharmacy refill data.Intentional non-adherence requires more intensive measures (such as therapeutic drug monitoring or directly observed therapy) to diagnose. The objective of this systematic review is to establish the overall prevalence of non-adherence in the RH population and differentiate the contribution of non-intentional and intentional non-adherence subtypes.


The databases MEDLINE, EMBASE, and the Cochrane library were searched for observational studies and randomized controlled trials reporting the prevalence of non-adherence in RH. The primary outcome studied is the pooled prevalence of non-adherence in RH. The secondary outcome examined will be the pooled prevalence of non-adherence based on indirect and direct measures of non-adherence. Weighted summary prevalence for the outcomes was estimated using the random effects model.


The literature search retrieved 1415 non-duplicate citations. After applying eligibility criteria, 197 full text citations were retrieved, and 27 studies were included in the review. Most studies were retrospective database studies or cross-sectional in nature and (63%) used indirect measures of assessment such as medication possession ratio or the Morisky scale with 80% adherence being the most common cutoff used for diagnosis of non-adherence. The pooled prevalence of non-adherence was 31%, with high statistical heterogeneity (I-squared 99). The pooled prevalence was higher with direct measures (45%) than indirect measures (19%).


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