Measuring adherence to oral antidiabetic multi-drug treatment: Comparative validity of prescription claims-based adherence measures against hospitalization

Adherence Definitions, Measurement Modalities, and Psychometric Properties in HIV, Diabetes, and Nutritional Supplementation Studies: A Scoping Review

Measuring adherence has been a priority for researchers to help inform effective care for patients regularly consuming medications for chronic conditions. As a widely accepted "gold standard" adherence measure or operational definition does not exist, studies measure adherence using different modalities, which may lead to different conclusions about adherence patterns. The purpose of the scoping review was to identify modalities used to measure adherence to HIV medication, diabetes medication, and nutritional supplementation and explore the variation in adherence definitions, measurement modalities, and psychometric properties being reported across studies. Comprehensive searches were performed in PubMed, Scopus, and PsycINFO from January 2012 to January 2022. We included studies reporting psychometric properties of adherence/compliance to HIV medication, diabetes medication, or nutritional supplements. In total, we included 88 studies in the review. The 8-item Morisky Medication Adherence Scale (MMAS-8) was the most frequently used self-reported measure. We found almost no relationship between country income level and triangulation levels. The operational definition of adherence fell into four categories: numerical, dichotomous, ranked ordinal, and undefined. The amount of variation in an adherence definition category within a modality depended on whether the measures within the modality could be assessed numerically and whether widely accepted cutoffs existed for the measure. Across studies, 46 (52%) reported both validity and reliability, 28 (31%) reported validity only, and 14 (16%) reported reliability only. Fourteen types of validity and six types of reliability were identified across the studies. Measuring adherence accurately and reliably continues to be a challenge for research in HIV, diabetes, and nutritional supplementations. When reporting adherence measurements, we suggest including adherence results from multiple measures and modalities, presenting adherence results numerically, and reporting multiple types of validity and reliability.

Gender differences in the association between adherence to healthy diet principles and adherence to cardiopreventive medication among adults from Québec (Canada)

Adherence to healthy diet principles and to cardiopreventive medication, both key behaviours in CVD prevention, is known to differ between women and men. Whether these adherence behaviours are differentially related among women and men has never been thoroughly assessed. The objective was to assess gender differences in the association between adherence to healthy diet principles and to cardiopreventive medication in adults free of CVD. This cross-sectional study included 268 women and 204 men from the CARTaGENE cohort (Québec, Canada) who were using antihypertensive and/or cholesterol-lowering medication. Adherence to healthy diet principles was assessed using the Alternate Healthy Eating Index (AHEI, %), calculated from a validated FFQ assessing diet in the 12-month preceding its completion. Medication adherence was assessed using the daily pharmacotherapy possession rate (DPPR, %), calculated from prescription claim data over the same 12-month period. In multivariable-adjusted analyses, an inverse association between AHEI and DPPR was observed among men (βAHEI for 10 % increment in DPPR = -0·65 %; 95 % CI -1·28 %, -0·03 %; P = 0·04), while it tended to be positive among women (β = 0·44 %; 95 % CI -0·11 %, 1·00 %; P = 0·12; Pgender×DPPR = 0·01). The negative association between AHEI and DPPR was stronger among men who never smoked or used cholesterol-lowering medication only. Among women, the positive association was stronger and statistically significant among those with obesity or using ≥ 3 medications simultaneously. Association between adherence to healthy diet principles and to cardiopreventive medication differs between women and men, with men potentially facing greater challenges in achieving optimal complementarity between these two behaviours.

Medication adherence to inflammatory bowel disease medications in Aotearoa New Zealand and correlation with health outcomes: A nationwide database analysis

AIMS

Inflammatory bowel disease (IBD) management entails long-term medication therapy. Worse disease outcomes and reduced quality of life might arise from poor medication adherence (MA). This study is the first to investigate patients with IBD's adherence across Aotearoa New Zealand and its relationship with disease outcomes.

METHODS

Dispensing claims data (Pharmaceutical Collection) were used to calculate (3- and 5-year) adherence, using daily polypharmacy possession ratio. Using hospitalization data (National Minimum Dataset), the relationship between adherence and the numbers of hospitalizations and corticosteroid dispensings was investigated.

RESULTS

In total, 4654 patients (53% female; 55% Crohn's disease [CD], 45% ulcerative colitis [UC]; median age-at-first-dispensing, 43 years) and 3148 patients (54% female; 55% CD, 44% UC; median age-at-first-dispensing, 44 years) were in the 3- and 5-year cohorts, respectively. The 3- and 5-year cohorts had mean 4.6 and 4.2 IBD-related hospitalizations and 6.9 and 9.2 corticosteroid dispensings, respectively. Average adherence estimates were 77.4% (95% confidence interval: 76.9-78.0%) and 74.9% (95% confidence interval: 74.1-75.6%; 3 and 5 years), while 54% and 51% of patients, respectively, had good adherence (MA ≥ 80%). There was no correlation between adherence and the numbers of hospitalizations (Pearson's R = -.0007; P = .65 and R = -.04; P = .02 [3 and 5 years]) and corticosteroid dispensings (R = .08; P = <.0001 and R = .08; P = <.0001, respectively).

CONCLUSION

MA of Aotearoa New Zealand patients with IBD is moderately high but just over half of patients meet the adherent threshold. There was no correlation between adherence and hospitalizations or corticosteroid dispensings; hence, research into longitudinal adherence patterns and associated factors is needed.

A comparison of methods for the measurement of adherence to antihypertensive multidrug therapy and the clinical consequences: a retrospective cohort study using the Korean nationwide claims database

OBJECTIVES

In observational studies, the methods used to measure medication adherence may affect assessments of the clinical outcomes of drug therapy. This study estimated medication adherence to multidrug therapy in patients with hypertension using different measurement methods and compared their impacts on clinical outcomes.

METHODS

This was a retrospective cohort study using the Korean National Health Insurance Service-National Sample Cohort database (2006-2015). Adults diagnosed with hypertension who initiated multidrug antihypertensive therapy in the index year 2007 were included. Adherence was defined as over 80% compliance. Adherence to multidrug antihypertensive therapy was measured in 3 ways using the proportion of days covered (PDC) with 2 approaches to the end-date of the study observations: PDC with at least one drug (PDCwith≥1), PDC with a duration weighted mean (PDCwm), and the daily polypharmacy possession ratio (DPPR). The primary clinical outcome was a composite of cardiovascular and cerebrovascular disease-specific hospitalizations or all-cause mortality.

RESULTS

In total, 4,226 patients who initiated multidrug therapy for hypertension were identified. The mean adherence according to the predefined measurements varied from 72.7% to 79.8%. Non-adherence was associated with an increased risk of a primary outcome. The hazard ratios (95% confidence intervals, CIs) primary outcomes varied from 1.38 (95% CI, 1.19 to 1.59) to 1.44 (95% CI, 1.25 to 1.67).

CONCLUSIONS

Non-adherence to multidrug antihypertensive therapy was significantly associated with an increased risk of a primary clinical outcome. Across the varying estimates based on different methods, medication adherence levels were similar. These findings may provide evidence to support decision-making when assessing medication adherence.

Adherence to antidiabetic treatment among patients managed in primary care centres in Spain: the INTENSE study

AIMS

To determine the degree and factors related to non-insulin antidiabetic drug (NIAD) adherence in people with type 2 diabetes mellitus (DM2) treated in primary carecentres in Spain.

METHODS

We did a cross-sectional study. During the study visit, variables related todifferent clinical characteristics, Adherence to Refills and Medications Scale Spanishversion (ARMS-e) and usage of NIAD were collected. We estimated the adherence toNIADs using the proportion of days covered (PDC) equation.

RESULTS

In total, 515 participants were included in the study. The mean PDC ratio was70.6 ( ± 28.9), and 50.5% (260) were classified as good adherent (PDC ≥80). Good adherence was highest among users of metformin (67.3%) and lowest among the participants using thiazolidinedione (0.8%). The score for ARMS-e was higher in the poor adherence group. In the multivariable analysis, HbA1c and the use of GLP1-RA or SGLT-2i were negatively associated with good adherence (odds ratio [OR]: 0.67, 95% confidence interval [CI]: 0.54, 0.82, OR: 0.20, 95%CI: 0.08, 0.46; OR: 0.56, 95%CI: 0.35, 0.89, respectively).

CONCLUSIONS

Adherence to NIADs observed in our study is far from optimal. HbA1c and ARMS-e items could be used as adherence indicators to encourage treatment changes to improve T2DM control.

Anti-Hyperglycemic Medication Adherence and Health Services Utilization in People with Diabetes: A Longitudinal Study of Alberta's Tomorrow Project

BACKGROUND

Little is known about the long-term (>2 years) relationship between the time-varying drug adherence and healthcare utilization for patients with diabetes.

OBJECTIVE

To characterize the relationship between time-varying anti-hyperglycemic medication adherence and healthcare utilization in patients with diabetes, using data from Alberta's Tomorrow Project, a population-based cohort study in Alberta, Canada.

METHODS

Incident cases of diabetes with at least 24 months of follow-up were included in the study. Anti-hyperglycemic drug adherence was measured by proportion of days covered (PDC) in the past 12 months for each year after diagnosis. The rate of healthcare utilization was assessed for the subsequent 12 months, 36 months and 60 months. A time-varying, negative binomial generalized estimating equation model was used to examine the association between medication adherence and healthcare utilization.

RESULTS

Among 2155 incident cases of diabetes, average age at diagnosis was 59.6±9.3, 51.0% were female and average duration of follow-up was 7.3±3.7 (range, 2.0-16.2) years. The proportion of patients taking anti-hyperglycemic medications was 47.6% during the first year of diagnosis, which increased to 77.3% by the end of follow-up. Compared to adherent patients (PDC≥0.8), non-adherent patients (PDC<0.8) had substantially higher rate of all-cause hospitalization [incident rate ratio, IRR=1.48 (1.22-1.79), ED visits [1.30 (1.15-1.47)] and GP visits [1.17 (1.08-1.27)] in the subsequent 12 months. However, these associations became weaker with longer follow-up [eg, IRR=1.18 (0.98-1.39) and 1.05 (0.94-1.18) for all-cause hospitalization in the subsequent 36 and 60 months, respectively].

CONCLUSION

Poor adherence among diabetic patients was associated with substantially higher rate of healthcare utilization in the short term (eg, 12 months); however, this association weakened over a longer period (eg, 36-60 months).

Comparing the Sensitivities of Measures of Adherence to Antihypertensive Drugs Using Korean National Health Insurance Claims Data

PURPOSE

Numerous studies have utilized various forms of adherence measures. However, methods for measuring adherence are inconsistent. Moreover, few studies are available that have compared sensitivities of the effects of several criteria on medication adherence. This study aims to compare measures of adherence using varied analytical decisions.

MATERIALS AND METHODS

We included three measures for adherence: proportion of days covered with one or more medications (PDC_with≥1), duration weighted mean PDC (PDC_wm), and daily polypharmacy possession ratio (DPPR). We compared the sensitivities of the measures by changing parameters in the Korean nationwide claims database. First, we used PDC_with≥1 as our base model. Then, we divided an adherence measure algorithm into three categories: (1) definition of data cleaning, (2) inclusion criteria and observation period, and (3) calculation methods of medication adherence. The categories included eight decision nodes that incorporated 25 alternative options. Finally, we assessed the medication adherence for the base-case with commonly used values and then varied to measure with each alternative option.

RESULTS

The base-case included 14,288 beneficiaries with antihypertensives. Among eight decisions, both handling an end-date-of-study and overlaps had the strongest impacts on measuring PDC_with≥1, PDC_wm, and DPPR, with small differences in sample size. Instead of the estimates of adherence from PDC_wm, those of PDC_with≥1 and DPPR were similar. Furthermore, a tendency toward a higher medication adherence was observed with a smaller study population.

CONCLUSION

The decisions regarding identifying an end-date-of-study and overlaps showed meaningful impacts of all three measures including PDC_with≥1, PDCwm, and DPPR on measuring medication adherence.