Measuring Medication Adherence in a Population-Based Asthma Administrative Pharmacy Database: A Systematic Review and Meta-Analysis

Abstract

Background Limited studies have systematically reviewed the literature to identify and compare the various database methods and optimal thresholds for measuring medication adherence specific to adolescents and adults with asthma. In the present study, we aim to identify the methods and optimal thresholds for measuring medication adherence in population-based pharmacy databases. Methods We searched PubMed, Embase, International Pharmaceutical Abstracts (IPA), Web of Science, Google Scholar, and grey literature from January 1, 1998, to March 16, 2021. Two independent reviewers screened the studies, extracted the data, and assessed the quality of the studies. A quantitative knowledge synthesis was employed. Results Thirty-eight (38) retrospective cohort studies were eligible. This review identified 20 methods for measuring medication adherence in adolescent and adult asthma administrative health records. Two measures namely the medication possession ratio (MPR) and proportion of days covered (PDC) were commonly reported in 87% of the literature included in this study. From the meta-analysis, asthma patients who achieved adherence threshold of “0.75–1.00” [OR: 0.56, 95% CI: 0.41 to 0.77] and “>0.5” [OR: 0.71, 95% CI: 0.54 to 0.94] were less likely to experience asthma exacerbation. Conclusion Despite their limitations, the PDC and the MPR still remain the most common measures for assessing adherence in asthma pharmacy claim databases. The evidence synthesis showed that an adherence threshold of at least 0.75 is optimal for classifying adherent and non-adherent asthma patients.

Measuring adherence to inhaled control medication in patients with asthma: Comparison among an asthma app, patient self‐report and physician assessment

“…Adherence scores were categorised using the clinically significant cut‐off of 75% (≤75%: non‐adherent; >75% adherent), as patients with asthma whose adherence was >75% have previously shown a significant decrease of exacerbations. 35 , 36 Weighted Cohen's kappa and percentage of agreement were used to determine the agreement of the adherence categories. 37 Cohen's kappa values were interpreted as: <0, no agreement; 0–0.20, slight; 0.21–0.40, fair; 0.41–0.60, moderate; 0.61–0.80, substantial and 0.81–1.0, almost perfect agreement.…”

“…Spearman's rho was interpreted as negligible (0–0.3), low (≥0.3–0.5), moderate (≥0.5–0.7), high (≥0.7–0.9) and very high (≥0.9–1) (26). Adherence scores were categorised using the clinically significant cut‐off of 75% (≤75%: non‐adherent; >75% adherent), as patients with asthma whose adherence was >75% have previously shown a significant decrease of exacerbations 35,36 . Weighted Cohen's kappa and percentage of agreement were used to determine the agreement of the adherence categories 37 .…”

Association Between Medication Adherence and Risk of COPD in Adult Asthma Patients: A Retrospective Cohort Study in Canada

“…We used the 0.80 cut-off value for assessing the optimal adherence, as it has been documented as the optimal threshold for achieving important clinical outcomes in adult asthma patients. 11 , 13 , 34 , 35 …”

“…We used the 0.80 cut-off value for assessing the optimal adherence, as it has been documented as the optimal threshold for achieving important clinical outcomes in adult asthma patients. 11,13,34,35 Secondary Exposure -Asthma Severity Asthma severity level was defined based on the criteria specified in the Canadian Asthma Consensus Guidelines for assessing the severity and control of patients with asthma. Based on the algorithm developed by Firoozi et al, 36 we defined asthma severity levels based on the intensity of prescribed ICS/other controller medications, prescription of short-acting-beta 2 agonist, and whether there is an indication of markers of moderate-to-severe asthma exacerbations (asthma-related hospitalization or emergency department visits due to asthma) or not.…”

Pediatric Drug Adherence and Parental Attention: Evidence from Comprehensive Claims Data

“…by drug for a given patient within each month. Our measure is similar to other continuous measures such as the Proportion of Days Covered (PDC), which is a common method to measure for assessing adherence in asthma pharmacy claims databases (Lam and Fresco, 2015;Asamoah-Boaheng et al, 2021).…”