Proposal of Standardization to Assess Adherence With Medication Records: Methodology Matters

The evaluation of an osteoporosis medication management service in community pharmacy, a cohort study

Background: Effective treatment of osteoporosis is hindered by poor adherence and lack of persistence with medical therapy. Interventions can be designed to elicit and address patients' concerns about side effects and promote self-management. Objective(s): The aim was to develop and evaluate the impact of a community pharmacy-based medication management intervention on patients' adherence to osteoporosis medicines using both objective and subjective measures of adherence. Secondary aims were to report the proportion of patients that had been referred to their General Practitioner (GP) for assistance with osteoporosis management, and to measure patients' experiences with the service. Methods: This study used a cohort design. Community pharmacy dispensing data were obtained as an objective measure of adherence. Self-reported beliefs about medicines (Beliefs about Medicines Questionnaire) and self-reported adherence (Medication Adherence Reporting Scale 5) were also collected. Data were collected and compared between baseline, 4 weeks after intervention, and endpoint (approximately a year after intervention). Analysis of correlations between measures was also conducted. GP referral percentage and perceived service quality scale (pSQS-SF6) was obtained. Results: Pharmacists and support staff from 26 Australian community pharmacies were recruited and trained to implement the service, and 107 patients were recruited. Of these, 71 were available for follow-up interviews by research team at 4 weeks, and 54 at the endpoint. No changes were found in pre-post analysis for the objective or self-reported measures of adherence. Patients' concerns about osteoporosis medicines were lower at 4 weeks and at the study endpoint compared to baseline. Uptake of pharmacists' referrals to patients' GPs was 48.1% by 4 weeks. Patient experience was rated highly (median pSQS-SF6 = 6.5/7). Conclusions: This study demonstrates the potential of community pharmacy interventions designed to optimize medication adherence by eliciting patients' thoughts and feelings about using osteoporosis medicines and addressing them using motivational interview techniques.

Concordance between pharmacy dispensing and electronic monitoring data of direct oral anticoagulants - A secondary analysis of the MAAESTRO study

BACKGROUND

Direct oral anticoagulants are the preferred treatment for stroke patients with atrial fibrillation. Pharmacy dispensing data represent a practical method to identify suboptimal medication adherence.

OBJECTIVE

This study investigates whether pharmacy dispensing data are indicative of real-life adherence behavior, using data from 130 patients in the MAAESTRO study (2018-2022) in Basel, Switzerland.

METHODS

This secondary data analysis of the MAAESTRO study (Dietrich, 2024) included patients with electronic monitoring (EM) and dispensing data for 12 months. Patients with at least two refills were included in the analysis. We categorized refill series into three adherence patterns using the Delta T method (Baumgartner, 2022): all refills on time, erratic refills, end-gaps ≥10 days. EM-adherence was assessed through "taking adherence" and "missing days" (24h without intake). We analyzed: i) all dispensing data ("all refills"); ii) all data independently of the MAAESTRO phase ("all phases"); iii) the last two dispensing data ("last"), and iv) EM data from the MAAESTRO phase that match the date of the last refill ("matched"). Associations between refill patterns and adherence were examined using Spearman correlation and Fisher's exact test.

RESULTS

Data analyzed from 50 patients (mean age 76.4 ± 9.1 years, 56.0 % male) included 252 refills with a median of 4 refills per patient. Refill patterns were: all refills on time (40.0 %), erratic refills (36.0 %), and end-gaps >10 days (24.0 %). Mean taking adherence was 89.3 ± 13.7 %. EM data revealed missing days in 82.0 % of patients, with 61.0 % having irregular refill patterns. Matched taking adherence was moderately associated with Delta T over all refills (p = 0.034) and the last refill (p = 0.013).

CONCLUSIONS

Dispensing data processed with the Delta T method correlate moderately with EM data. The Delta T value for the last two refills shows promise for estimating irregular adherence, suggesting potential for targeted interventions in pharmacy practice.

The impact of frailty on initiation, continuation and discontinuation of secondary prevention medications following myocardial infarction

AIM

To evaluate the association between frailty and initiating, continuing, or discontinuing secondary prevention medications following myocardial infarction (MI).

METHODS

We conducted a cohort study using linked health data, including all adults aged ≥65 years who discharged from hospital following MI from January 2013 to April 2018 in Victoria, Australia (N = 29,771). The Hospital Frailty Risk Score (HFRS) was used to assess frailty. Logistic regression was used to investigate associations of frailty with initiation, continuation, and discontinuation of secondary prevention medications (P2Y12 inhibitor antiplatelets, beta-blockers, renin-angiotensin-aldosterone system (RAAS) inhibitors, and lipid-lowering therapies) in the 90 days from discharge post-MI, by HFRS, adjusted for age, sex, and Charlson Comorbidity Index.

RESULTS

Increasing frailty was associated with lower probability of initiating and continuing P2Y12 inhibitors, RAAS inhibitors, and lipid-lowering therapies, but not beta-blockers. At at an HFRS of 0, the predicted probabiliy of having all four medications initiated or continued was 0.59 (95 %CI 0.57-0.62) for STEMI and 0.35 (0.34-0.36) for non-STEMI, compared to 0.38 (0.33-0.42) and 0.16 (0.14-0.18) at an HFRS of 15. Increasing frailty was associated with higher probability of discontinuing these medications post-MI. The predicted probability of discontinuing at least one secondary prevention medication post-MI at an HFRS of 0 was 0.10 (0.08-0.11) for STEMI and 0.14 (0.13-0.15) for non-STEMI, compared to 0.27 (0.22-0.32) and 0.34 (0.32-0.36) at an HFRS of 15.

CONCLUSION

People with higher levels of frailty were managed more conservatively following MI than people with lower levels of frailty. Whether this conservative treatment is justified warrants further study.

Rhinitis Control and Medication Use in a Real-World Sample of Patients With Persistent Rhinitis or Rhinosinusitis: A Community Pharmacy Study

BACKGROUND

Little is known about rhinitis control in real-life, nor about the contribution of treatment-related and patient-related factors.

OBJECTIVE

This study aimed to examine the level of rhinitis control and rhinitis medication utilization in patients with persistent rhinitis and to identify predictors of rhinitis control.

METHODS

A cross-sectional observational study was conducted in patients with persistent rhinitis recruited in community pharmacies. Participants completed the Rhinitis Control Assessment Test, a questionnaire on patient/rhinitis characteristics, and rhinitis medication use. A visual analog scale for nasal symptoms was also completed. Pharmacy dispensing data were used to calculate adherence to intranasal glucocorticoids. Nasal spray technique was evaluated using a standardized checklist. Predictors of rhinitis control were explored using a linear regression model.

RESULTS

A total of 1,514 patients, recruited in 215 pharmacies, participated in the study (mean age 48.7 y, 62% female). Almost 60% exhibited suboptimal rhinitis control (Rhinitis Control Assessment Test ≤ 21 of 30). A 50-mm cut-off on the visual analog scale yielded 78.1% sensitivity to identify suboptimal rhinitis control. Participants most frequently used intranasal glucocorticoids (55.6%) and intranasal decongestants (47.4%). Only 10.3% of current nasal spray users demonstrated perfect technique. More than half (54.8%) of glucocorticoid users were identified as underadherent. Female sex, self-reported nasal hyperreactivity, active asthma, and use of oral/intranasal decongestants or nasal saline were identified as predictors of worse rhinitis control.

CONCLUSIONS

Suboptimal rhinitis control was common in this real-life sample of persistent rhinitis patients. Improving use of rhinitis medication may be key to increase disease control.

Estimation of adherence to urate-lowering therapy in people living with gout using Australia's Pharmaceutical Benefits Scheme and patient-reported dosing

AIMS

The aim of this study was to estimate adherence to urate-lowering therapy (ULT), predominately allopurinol, from Australia's Pharmaceutical Benefits Scheme (PBS) claims database in association with (1) patient-reported doses and (2) World Health Organization's (WHO) defined daily doses (DDD), namely, allopurinol (400 mg/day) or febuxostat (80 mg/day).

METHODS

Proportion of days covered (PDC) was calculated in 108 Gout App (Gout APP) trial participants with at least two recorded ULT dispensings in an approximately 12-month period before provision of intervention or control apps. Adherence was defined as PDC ≥80%. We measured the correlation between the two methods of calculating PDC using a Wilcoxon signed rank test. Agreement between ULT-taking status (self-reports) and ULT-dispensed status (PBS records) was tested with Cohen's kappa (κ), and positive and negative percent agreement.

RESULTS

Allopurinol was prescribed in 93.5% of participants taking ULT. Their self-reported mean daily dose (SD) was 291 (167) mg/day. Mean PDC (SD) for allopurinol was 83% (21%) calculated using self-reported dose, and 63% (24%) using WHO's DDD. Sixty-three percent of allopurinol users were identified as adherent (PDC ≥80%) using self-reported dose. There was good agreement between self-reported ULT use and PBS dispensing claims (κ = 0.708, P < .001; positive percent agreement = 90%, negative percent agreement = 82%).

CONCLUSIONS

Participant-reported allopurinol daily doses, in addition to PBS dispensing claims, may enhance confidence in estimating PDC and adherence compared to using DDD. This approach improves adherence estimations from pharmaceutical claims datasets for medications where daily doses vary between individuals or where there is a wide therapeutic dose range.

Prescription Sequence Symmetry Analysis (PSSA) to assess prescribing cascades: a step-by-step guide

Prescribing cascades occur when patients are prescribed medication to treat the adverse drug reaction of previously prescribed medication. Prescription sequence symmetry analysis (PSSA) can be used to assess the association between two medications in prescription or dispensing databases and thus the potential occurrence of prescribing cascades. In this article, a step-by-step guide is presented for conducting PSSA to assess prescribing cascades. We describe considerations for medication data collection and setting time periods for relevant parameters, including washout window, exposure window, continued exposure interval and blackout period. With two examples, we illustrate the impact of changes in these parameters on the strengths of associations observed. Given the impact seen, we recommend that researchers clearly specify and explain all considerations regarding medication included and time windows set when studying prescribing cascades with PSSA, and conduct subgroup and sensitivity analyses.

Use of secondary prevention medications in metropolitan and non-metropolitan areas: an analysis of 41,925 myocardial infarctions in Australia

BACKGROUND

People in remote areas may have more difficulty accessing healthcare following myocardial infarction (MI) than people in metropolitan areas. We determined whether remoteness was associated with initial and 12-month use of secondary prevention medications following MI in Victoria, Australia.

METHOD

We included all people alive at least 90 days post-discharge following MI between July 2012 and June 2017 in Victoria, Australia (n=41,925). We investigated dispensing of P2Y12 inhibitors (P2Y12i), statins, ACE-inhibitors or angiotensin receptor blockers (ACEI/ARBs), and beta-blockers within 90 days post-discharge. We estimated 12-month medication use using proportion of days covered (PDC). Remoteness was determined using the Accessibility/Remoteness Index of Australia (ARIA). Data were analyzed using adjusted parametric regression models stratified by STEMI and NSTEMI.

RESULTS

There were 10,819 STEMI admissions and 31,106 NSTEMI admissions. Following adjustment across NSTEMI and STEMI, there were no medication classes dispensed in the 90-days post-discharge that differed in a clinically significant way from the least remote (ARIA=0) to the most remote (ARIA=4.8) areas. The largest difference for NSTEMI were ACEi/ARB, with 71%(95%CI 70-72%) versus 80%(76%-83%). For STEMI, it was statins with 89%(88-90%) versus 95%(91-97%). Predicted PDC for STEMI and NSTEMI were not clinically significant across remoteness, with the largest difference in NSTEMI being P2Y12i with 48%(47-50%) versus 55%(51-59%), and in STEMI it was ACEi/ARB with 68%(67-69%) versus 76%(70-80%).

CONCLUSION

Remoteness does not appear to be a clinically significant driver for medication use following MI. Possible differences in cardiovascular outcomes in metropolitan and non-metropolitan areas are not likely to be explained by access to secondary prevention medications.

Methods to assess COPD medications adherence in healthcare databases: a systematic review

BACKGROUND

The Global Initiative for Chronic Obstructive Lung Disease 2023 report recommends medication adherence assessment in COPD as an action item. Healthcare databases provide opportunities for objective assessments; however, multiple methods exist. We aimed to systematically review the literature to describe existing methods to assess adherence in COPD in healthcare databases and to evaluate the reporting of influencing variables.

METHOD

We searched MEDLINE, Web of Science and Embase for peer-reviewed articles evaluating adherence to COPD medication in electronic databases, written in English, published up to 11 October 2022 (PROSPERO identifier CRD42022363449). Two reviewers independently conducted screening for inclusion and performed data extraction. Methods to assess initiation (dispensing of medication after prescribing), implementation (extent of use over a specific time period) and/or persistence (time from initiation to discontinuation) were listed descriptively. Each included study was evaluated for reporting variables with an impact on adherence assessment: inpatient stays, drug substitution, dose switching and early refills.

RESULTS

160 studies were included, of which four assessed initiation, 135 implementation and 45 persistence. Overall, one method was used to measure initiation, 43 methods for implementation and seven methods for persistence. Most of the included implementation studies reported medication possession ratio, proportion of days covered and/or an alteration of these methods. Only 11% of the included studies mentioned the potential impact of the evaluated variables.

CONCLUSION

Variations in adherence assessment methods are common. Attention to transparency, reporting of variables with an impact on adherence assessment and rationale for choosing an adherence cut-off or treatment gap is recommended.

Minimal Adherence Threshold to Non-Vitamin K Antagonist Oral Anticoagulants in Patients with Atrial Fibrillation to Reduce the Risk of Thromboembolism and Death: A Nationwide Cohort Study

PURPOSE

Poor adherence to non-vitamin K antagonist oral anticoagulants (NOACs) may raise thromboembolic risks in patients with atrial fibrillation (AF). However, the minimal adherence to maintain the protective effect of NOACs is currently unknown. Therefore, we investigated thresholds of NOAC adherence in association with thromboembolic and mortality risks.

METHODS

Patients with AF initiating NOACs between 2013 and 2019 were identified in Belgian nationwide data. Adherence was measured using the proportion of days covered (PDC) after one year of treatment. Inverse probability of treatment weighted Cox regression was used to investigate outcomes.

RESULTS

92,111 persons were included (250,750 person-years). Compared to NOAC users with a one-year PDC of 100%, significantly higher risks of stroke or systemic embolism were observed among NOAC users with PDCs of 85-89% (adjusted hazard ratio (aHR) 1.35, 95% confidence interval (CI) (1.19-1.54)), 80-84% (aHR 1.31, 95%CI (1.08-1.58)) and < 80% (aHR 1.64, 95%CI (1.34-2.01)), while no significant differences were observed among NOAC users with one-year PDCs of 95-99% (aHR 1.02, 95%CI (0.94-1.12)) or 90-94% (aHR 1.06, 95%CI (0.95-1.18)). Significantly higher risks of all-cause mortality were observed with decreasing levels of NOAC adherence, which were already higher among NOAC users with a one-year PDC of 90-94% versus 100% (aHR 1.09, 95%CI (1.01-1.17)). Findings were similar with once-daily and twice-daily dosed NOACs.

CONCLUSION

Poor adherence to NOACs is associated with increased risks of thromboembolism and all-cause mortality. The minimal adherence threshold should be ≥ 90%, preferably even ≥ 95%.

Investigating Levothyroxine Use and Its Association with Thyroid Health in Patients with Hypothyroidism: A Community Pharmacy Study

Background: To gain maximum therapeutic effect while minimizing side effects, it is imperative for patients with hypothyroidism to use their levothyroxine (LT4) correctly, such as adhering to the prescribed regimen. Little is currently known about how patients actually use LT4 in real life. We investigated the use of LT4, as well as the thyroid health (thyrotropin [TSH] and health-related quality of life [HR-QoL]), and evaluated if proper LT4 use is associated with better thyroid health. Methods: A cross-sectional observational study was conducted in a Belgian community sample of adults using LT4 for hypothyroidism since ≥2 years. Participants completed a self-administered questionnaire on patient characteristics, self-reported adherence to LT4, timing of intake, and co-medication. They also completed the thyroid-specific patient-reported outcome (ThyPRO-39) questionnaire, measuring the HR-QoL. Pharmacy dispensing data were used to calculate the medication possession ratio (MPR). Results: We included 856 participants (mean age 61.4 ± 14.3 years, 86% [740/856] females). Approximately one in four participants (138/563) had out-of-range TSH levels. Generally, ThyPRO-39 scores were in the lower part of the range (indicating better HR-QoL), with the scales "emotional susceptibility" and "tiredness" showing the worst scores. Approximately 28% (178/632) of the participants were classified as non-adherent (MPR <80%), corresponding to at least 73 cumulative days per year without LT4 intake. Twenty-five percent (212/854) of participants self-reported non-adherence, with unintentional non-adherence (forgetfulness) most frequently reported (21.9%, 187/854). Only 39% (329/836) of participants complied with the recommendation of ingesting LT4 ≥ 30 minutes before eating. Additionally, 7% (58/856) of participants concurrently used molecules that bind to LT4, without applying the recommended dosing interval. There was no significant correlation between LT4 usage (adherence, timing of intake, and interaction with complex forming drugs) and TSH or HR-QoL. Conclusions: We found that many participants with hypothyroidism did not use their LT4 as effectively as possible, particularly with respect to timing of administration. However, the participants' HR-QoL seemed largely satisfactory, and there was no significant correlation between correctly using LT4 and thyroid health.

Patterns of statin adherence in primary cardiovascular disease prevention during the pandemic

Background: Study of medication adherence patterns can help identify patients who would benefit from effective interventions to improve adherence. Objectives: To identify and compare groups of statin users based on their adherence patterns before and during the COVID-19 pandemic, to characterize the profile of users in each group, and to analyze predictors of distinct adherence patterns. Methods: Participants of the CARhES (CArdiovascular Risk factors for HEalth Services research) cohort, comprising individuals aged >16 years, residing in Aragón (Spain), with hypertension, diabetes mellitus and/or dyslipidemia, took part in this observational longitudinal study. Individuals who began statin therapy during January-June 2019 were selected and followed up until June 2021. Those with a cardiovascular event before or during follow-up were excluded. Data were obtained from healthcare system data sources. Statin treatment adherence during the implementation phase was estimated bimonthly using the Continuous Medication Availability (CMA9) function in the AdhereR package. Group-based trajectory models were developed to group statin users according to their adherence pattern during July 2019-June 2021. Group characteristics were compared and predictors of each adherence pattern were analyzed using multinomial logistic regression. Results: Of 15,332 new statin users, 30.8% had a mean CMA9 ≥80% for the entire study period. Four distinct adherence patterns were identified: high adherence (37.2% of the study population); poor adherence (35.6%); occasional use (14.9%); and gradual decline (12.3%). The latter two groups included users who showed a change in adherence (increase or decrease) during the pandemic emergence. Users with suboptimal adherence were likely to be younger, not pensioners, not institutionalized, with low morbidity burden and a low number of comorbidities. Female sex and switching between statins of different intensity increased the likelihood of belonging to the occasional use group, in which improved adherence coincided with the pandemic. Conclusion: We identified four distinct adherence patterns in a population of new statin users; two of them modified their adherence during the pandemic. Characterization of these groups could enable more effective distribution of resources in future similar crisis and the routine implementation of patient-centered interventions to improve medication adherence.

Gaps and discontinuation of statin treatment in Norway: potential for optimizing management of lipid lowering drugs

Aims

In clinical practice, many patients do not reach the recommended treatment targets for LDL-cholesterol levels. We aimed to examine treatment patterns and adherence for patients on lipid lowering drugs in Norway to inform future strategies to improve therapies.

Methods and results

We obtained information on all dispensed statins, ezetimibe, and proprotein convertase subtilisin/-kexin 9 (PCSK9) inhibitors 2010-2019 from the Norwegian Prescription Database. Treatment gaps were assessed assuming patients take one tablet per day and were defined to occur if a patient did not refill a prescription when the previous one should have been depleted. Treatment was defined as discontinued when the preceding prescription would have been used and no new subsequent prescription was filled. The mean proportion of days covered (PDC) was calculated by aggregating the total number of tablets dispensed during each calendar year and dividing by 365. Patients 80 years were excluded. A considerable proportion of statin users in Norway had long treatment gaps or discontinuation in treatment. The 19.6% of the patients had treatment gaps of 180 days or more, and 10.8% had gaps or greater than 365 days. Similar results were found for patients on antidiabetics and hypertensives. PDC ranged from 84.9% for simvastatin to 72.2% for ezetimibe (2019). The most common lipid lowering drugs in 2019 were atorvastatin, simvastatin, and ezetimibe.

Conclusion

There is a great potential for improving drug adherence and optimizing lipid lowering therapy by switching to more effective statins in greater doses, and more often add ezetimibe and PCSK9 inhibitors to treatment.

Linkage between electronic prescribing data and pharmacy claims records to determine primary adherence: the case of antihypertensive therapy in the Lisbon and Tagus Valley Region, Portugal

BACKGROUND

Hypertension (HT) is highly prevalent and a major risk factor for cardiovascular disease. Over 42% of Portuguese adults have HT. Even though the benefits of antihypertensive (AHT) drugs have been demonstrated, HT control remains inadequate. One major reason is that patients often fail to take their medications as prescribed. This paper aims to determine primary adherence to AHT therapy in newly diagnosed and treated hypertensive patients in Primary Health Care (PHC) units of Lisbon and Tagus Valley Health Region.

METHODS

This study reports data from a population-based, retrospective, cohort study from patients diagnosed with HT in PHC units of Lisbon and Tagus Valley Region from 1 January to 31 March 2011, with no prior use of AHT drugs. Primary adherence rate was expressed as number of claims records/total number of prescriptions records. Data were collected from SIARS for each patient during a 2-year period.

RESULTS

Overall primary adherence rate was 58.5%, increasing with age. Rates were higher for men, living in the Lisbon Metropolitan Area and diagnosed with uncomplicated HT. Drugs acting on the renin-angiotensin system had the highest rates, increasing for fixed-dose combinations and diminishing with the increase of cost for the patient.

CONCLUSIONS

Overall, almost 1 out of 2 prescribed AHT drugs were not dispensed. Until this study, little was known in Portugal about primary adherence. Our findings imply that the potential benefits of AHT therapy cannot be fully realized in this population.

Adherence and persistence to oral anticoagulants in patients with atrial fibrillation: A Belgian nationwide cohort study

Background

Since non-vitamin K antagonist oral anticoagulants (NOACs) do not require coagulation monitoring, concerns of lower adherence and persistence to NOACs than vitamin K antagonists (VKAs) have been raised. Moreover, little is known on the frequency of permanent cessation and switching between anticoagulants in patients with atrial fibrillation (AF). Therefore, persistence, reinitiation, switching and adherence to oral anticoagulants (OACs) were investigated.

Materials and methods

AF patients with a first OAC prescription claim between 2013 and 2019 were identified in Belgian nationwide data. Persistence, reinitiation and switching were estimated using Kaplan-Meier analyses. Adherence was investigated using the proportion of days covered (PDC). Predictors for non-adherence and non-persistence were identified by multivariable logistic regression.

Results

Among 277,782 AF patients, 69.6% NOAC and 37.2% VKA users were persistent after 1 year, whereas 44.3% and 18.9% after 5 years, respectively. After one year, 67.1% rivaroxaban, 68.1% dabigatran, 69.8% apixaban, and 76.9% edoxaban users were persistent. Among subjects having discontinued NOAC or VKA treatment, 75.4% and 46.1% reinitiated any OAC within 5 years, respectively. VKAs were more frequently switched to NOACs than vice versa (17.6% versus 2.5% after 1 year). After 1 year, a high PDC (≥ 90%) was observed in 87.8% apixaban, 88.6% dabigatran, 91.3% rivaroxaban, and 94.7% edoxaban users (90.2% NOAC users). Adherence and persistence were higher in older, female subjects, while lower in subjects with dementia or hyperpolypharmacy.

Conclusion

Adherence and persistence to NOACs were high. However, 10% of subjects were non-adherent after 1 year and one-fourth did not reinitiate anticoagulation within 5 years after NOAC discontinuation.

Adherence to vitamin and mineral supplementation after bariatric surgery - A two-year cohort study

BACKGROUND

Lifelong vitamin and mineral supplementation is recommended after bariatric surgery to prevent nutritional deficiencies, but it is not clear to which extent patients adhere to the recommended medication. The aim of this study was to assess adherence to supplementation. Additionally, we assessed predictors of low adherence and biochemical deficiencies.

METHODS

263 adults were followed two years post bariatric surgery (89.4 % Roux-en-Y gastric bypass, 10.6 % sleeve gastrectomy) regarding adherence to calcium-vitamin D, vitamin B₁₂ and iron. Pharmacy refill data was used to objectively capture adherence-rate. Predictors of low adherence were assessed via questionnaires and medical records. Blood sampling was performed preoperatively, and 1- and 2-years post-surgery.

RESULTS

About 60 % of the study participants had high adherence-rate (≥ 80 %) two years post-surgery, but a significant proportion had discontinued the intended lifelong supplementation: 15 % for calcium-vitamin D and 12 % for B₁₂. Biochemical deficiencies were uncommon two years after surgery, both in adherent and non-persistent subjects, except for a 10 % prevalence of anemia. Younger age, experience of side effects, mental health problems and no regular use of medication before surgery, were factors associated with low adherence.

CONCLUSION

Substantial variation existed in adherence to supplementation regimens after bariatric surgery during the first two years after bariatric surgery, but biochemical deficiencies were rare. The results indicate need for tailored follow-up and strategies to support long-term persistence.

Core Concepts in Pharmacoepidemiology: Measures of drug utilization based on individual-level drug dispensing data

Background

Drug utilization studies are essential to facilitate rational drug use in the society.

Aim

In this review, we provide an overview of drug utilization measures that can be used with individual‐level drug dispensing data, referencing additional reading on the individual analysis. This is intended to serve as a primer for those new to drug utilization research and a shortlist from which researchers can identify useful analytical approaches when designing their drug utilization study.

Results and Discussion

We provide an overview of: (1) basic measures of drug utilization which are used to describe changes in drug use over time or compare drug use in different populations; (2) treatment adherence measures with specific focus on persistence and implementation; (3) how to measure drug combinations which is useful when assessing drug–drug interactions, concomitant treatment, and polypharmacy; (4) prescribing quality indicators and measures to assess variations in drug use which are useful tools to assess appropriate use of drugs; (5) proxies of prescription drug misuse and skewness in drug use; and (6) considerations when describing the characteristics of drug users or prescribers.

A Pharmacy-Based eHealth Intervention Promoting Correct Use of Medication in Patients With Asthma and COPD: Nonrandomized Pre-Post Study

BACKGROUND

Asthma and chronic obstructive pulmonary disease (COPD) affect millions of people worldwide. While medication can control and improve disease symptoms, incorrect use of medication is a common problem. The eHealth intervention SARA (Service Apothecary Respiratory Advice) aims to improve participants' correct use of inhalation medication by providing information and as-needed tailored follow-up support by a pharmacist.

OBJECTIVE

The primary aim of this study was to investigate the effect of SARA on exacerbation rates in participants with asthma and COPD. Secondary aims were to investigate its effects in terms of adherence to maintenance medication and antimycotic treatment.

METHODS

In this nonrandomized pre-post study, medication dispensing data from 382 Dutch community pharmacies were included. Exacerbation rates were assessed with dispensed short-course oral corticosteroids. Medication adherence between new and chronic users was assessed by calculating the proportion of days covered from dispensed inhalation maintenance medication. Antimycotic treatment was investigated from dispensed oral antimycotics in participants who were also dispensed inhaled corticosteroids (ICS). Outcomes were assessed 1 year before and 1 year after implementation of SARA and were compared between SARA participants and control participants. More specifically, for exacerbation rates and medication adherence, a difference score was calculated (ie, 1 year after SARA minus 1 year before SARA) and was subsequently compared between the study groups with independent-samples t tests. For antimycotics, the relative number of participants who were dispensed antimycotics was calculated and subsequently analyzed with a mixed-effects logistic regression.

RESULTS

The study population comprised 9452 participants, of whom 2400 (25.39%) were SARA participants. The mean age of the population was 60.8 (15.0) years, and approximately two-thirds (n=5677, 60.06%) were female. The results showed an increase in mean exacerbation rates over time for both study groups (SARA: 0.05; control: 0.15). However, this increase in exacerbation rates was significantly lower for SARA participants (t₉₄₅₀=3.10, 95% CI 0.04-0.16; P=.002; Cohen d=0.06). Chronic users of inhalation medication in both study groups showed an increase in mean medication adherence over time (SARA: 6.73; control: 4.48); however, this increase was significantly higher for SARA participants (t₅₈₈₆=-2.74, 95% CI -3.86 to -0.84; P=.01; Cohen d=-0.07). Among new users of inhalation medication, results showed no significant difference in medication adherence between SARA and control participants in the year after implementation of SARA (t₁₄₃₄=-1.85, 95% CI -5.60 to 0.16; P=.06; Cohen d=-0.10). Among ICS users, no significant differences between the study groups were found over time in terms of the proportion of participants who were dispensed antimycotics (t₅₆₅₄=0.29, 95% CI -0.40 to 0.54; P=.76; Cohen d=0).

CONCLUSIONS

This study provides preliminary evidence that the SARA eHealth intervention might have the potential to decrease exacerbation rates and improve medication adherence among patients with asthma and COPD.

Association of income and educational levels with adherence to direct oral anticoagulant therapy in patients with incident atrial fibrillation: A Finnish nationwide cohort study

Low socioeconomic status has been associated with poor outcomes in patients with atrial fibrillation (AF). However, little is known about socioeconomic disparities in adherence to stroke prevention with direct oral anticoagulants (DOACs). We assessed the hypothesis that AF patients with higher income or educational levels have better adherence to DOACs in terms of treatment implementation and persistence. The used nationwide registry‐based FinACAF cohort covers all patients with incident AF starting DOACs in Finland during 2011–2018. The implementation analyses included 74 222 (mean age 72.7 ± 10.5 years, 50.8% female) patients, and persistence analyses included 67 503 (mean age 75.3 ± 8.9 years, 53.6% female) patients with indication for permanent anticoagulation (CHA₂DS₂‐VASc score >1 in men and >2 in women). Patients were divided into income quartiles and into three categories based on their educational attainment. Therapy implementation was measured using the medication possession ratio (MPR), and patients with MPR ≥0.90 were defined adherent. Persistence was measured as the incidence of therapy discontinuation, defined as the first 135‐day period without DOAC purchases after drug initiation. Patients with higher income or education were consistently more likely adherent to DOACs in the implementation phase (comparing the highest income or educational category to the lowest: adjusted odds ratios 1.18 (1.12–1.25) and 1.21 (1.15–1.27), respectively). No association with income or educational levels was observed on the incidence of therapy discontinuation. In conclusion, we observed that income and educational levels both have independent positive association on the implementation of DOAC therapy but no association on therapy persistence in patients with AF.

Towards better reporting of the Proportion of Days Covered method in cardiovascular medication adherence: A scoping review and new tool TEN-SPIDERS

Although medication adherence is commonly measured in electronic datasets using the proportion of days covered (PDC), no standardized approach is used to calculate and report this measure. We conducted a scoping review to understand the approaches taken to calculate and report the PDC for cardiovascular medicines to develop improved guidance for researchers using this measure. After prespecifying methods in a registered protocol, we searched Ovid Medline, Embase, Scopus, CINAHL Plus and grey literature (1 July 2012 to 14 December 2020) for articles containing the terms “proportion of days covered” and “cardiovascular medicine”, or synonyms and subject headings. Of the 523 articles identified, 316 were reviewed in full and 76 were included (93% observational studies; 47% from the USA; 2 grey literature articles). In 45 articles (59%), the PDC was measured from the first dispensing/claim date. Good adherence was defined as 80% PDC in 61 articles, 56% of which contained a rationale for selecting this threshold. The following parameters, important for deriving the PDC, were often not reported/unclear: switching (53%), early refills (45%), in‐hospital supplies (45%), presupply (28%) and survival (7%). Of the 46 articles where dosing information was unavailable, 59% reported how doses were imputed. To improve the transparent and systematic reporting of the PDC, we propose the TEN‐SPIDERS tool, covering the following PDC parameters: Threshold, Eligibility criteria, Numerator and denominator, Survival, Presupply, In‐hospital supplies, Dosing, Early Refills, and Switching. Use of this tool will standardize reporting of the PDC to facilitate reliable comparisons of medication adherence estimates between studies.

Methodological considerations on estimating medication adherence from self-report, electronic monitoring, and electronic healthcare databases using the TEOS framework

AIM

Measuring adherence to medication is complex due to the diversity of contexts in which medications are prescribed, dispensed, and used. The Timelines-Events-Objectives-Sources (TEOS) framework outlined a process to operationalize adherence. We aimed to develop practical recommendations for quantification of medication adherence using self-report (SR), electronic monitoring (EM), and electronic healthcare databases (EHD) consistent with the TEOS framework for adherence operationalization.

METHODS

An adherence methodology working group of the International Society for Medication Adherence (ESPACOMP) analysed implications of the process of medication adherence for all data sources and discussed considerations specific to SR, ED, and EHD regarding the information available on the prescribing, dispensing, recommended and actual use timelines, the four events relevant for distinguishing the adherence phases, the study objectives commonly addressed with each type of data, and the potential sources of measurement error and quality criteria applicable.

RESULTS

Four key implications for medication adherence measurement are common to all data sources: adherence is a comparison between two series of events (recommended and actual use); it refers to one or more specific medication(s); it applies to regular repeated events coinciding with known recommended dosing; and it requires separate measurement of the three adherence phases for a complete picture of patients' adherence. We propose recommendations deriving from these statements, and aspects to be considered in study design when measuring adherence with SR, EM and EHD using the TEOS framework.

CONCLUSION

The quality of medication adherence estimates is the result of several design choices that may optimize the data available.

Comparison of Approaches for Measuring Adherence and Persistence to Oral Oncologic Therapies in Patients Diagnosed with Metastatic Renal Cell Carcinoma

BACKGROUND

Adherence and persistence studies face several methodologic difficulties, including short-term mortality. We compared approaches to quantify adherence and persistence to first line (1L) oral targeted therapy (TT) in patients diagnosed with metastatic renal cell carcinoma (mRCC).

METHODS

Patients with mRCC ages 66 years or more who initiated TTs within 4 months of diagnosis were identified in the Surveillance, Epidemiology, and End Results Medicare-linked database (2007-2015). Adherence [proportion of days covered (PDC) >80%] was calculated using (i) PDC with a fixed 6-month denominator including then excluding patients who died within the 6 months and (ii) PDC with a denominator measuring time on treatment. Risk of nonpersistence was obtained by censoring death or treating death as a competing risk using cumulative incidence functions.

RESULTS

Among 485 patients with mRCC initiating a 1L oral TT (sunitinib, 64%; pazopanib, 25%; other, 11%), 40% died within 6 months. Adherence was higher after restricting to patients who survived (60%) compared with including those patients and assigning zero days covered after death (47%). Risk of nonpersistence was higher when censoring patients at death, 0.91 [95% confidence interval (CI), 0.88-0.94], compared with treating death as a competing risk, 0.75 (95% CI, 0.71-0.79).

CONCLUSIONS

Different approaches to handling death resulted in different adherence and persistence estimates in the metastatic setting. Future studies should explicitly report the proportion of patient deaths over time and explore appropriate methods to account for death as competing risk.

IMPACT

Use of several approaches can provide a more comprehensive picture of medication-taking behavior in the metastatic setting where death is a major competing risk.

Prior Cardiovascular Treatments-A Key Characteristic in Determining Medication Adherence After an Acute Myocardial Infarction

Objective: To investigate long-term adherence to guideline-recommended cardioprotective medications following hospitalization for an acute myocardial infarction (AMI), and identify characteristics associated with adherence.

Methods: An Australian population-based cohort study was used to identify participants who had their first AMI between 2006 and 2014 and were alive after 12 months. Linked routinely collected hospital, and prescription medication claims data was used to study adherence over time. Predictors and rates of adherence to both lipid-lowering medication and renin-angiotensin system blockade at 12 months post-AMI was assessed.

Results: 14,200 people (mean age 69.9 years, 38.7% female) were included in our analysis. At 12 months post-AMI, 29.5% (95% CI: 28.8–30.3%) of people were adherent to both classes of medication. Individuals receiving treatment with both lipid-lowering medication and renin-angiotensin system blockade during the 6 months prior to their AMI were over 9 times more likely to be adherent to both medications at 12 months post-AMI (66.2% 95% CI: 64.8–67.5%) compared to those with no prior medication use (treatment naïve) (7.1%, 95% CI: 6.4–7.9%). Prior cardiovascular treatment was the strongest predictor of long-term adherence even after adjusting for age, sex, education and income.

Conclusions: Despite efforts to improve long-term medication adherence in patients who have experienced an acute coronary event, considerable gaps remain. Of particular concern are people who are commencing guideline-recommended cardioprotective medication at the time of their AMI. The relationship between prior cardiovascular treatments and post AMI adherence offers insight into the support needs for the patient. Health care intervention strategies, strengthened by enabling policies, are needed to provide support to patients through the initial months following their AMI.

Delta T, a Useful Indicator for Pharmacy Dispensing Data to Monitor Medication Adherence

INTRODUCTION

Calculating patients' medication availability from dispensing or refill data is a common method to estimate adherence. The most often used measures, such as the medication possession ratio (MPR), average medication supplies over an arbitrary period. Averaging masks the variability of refill behavior over time.

GOAL

To derive a new absolute adherence estimate from dispensing data.

METHOD

Dispensing histories of patients with 19 refills of direct oral anticoagulants (DOAC) between 1 January 2008 and 31 December 2017 were extracted from 39 community pharmacies in Switzerland. The difference between the calculated and effective refill day (ΔT) was determined for each refill event. We graphed ΔT and its dichotomized version (dΔT) against the MPR, calculated mean ΔT and mean dΔT per refill, and applied cluster analysis.

RESULTS

We characterized 2204 refill events from 116 DOAC patients. MPR was high (0.975 ± 0.129) and showed a positive correlation with mean ΔT. Refills occurred on average 17.8 ± 27.9 days "too early", with a mean of 75.8 ± 20.2 refills being "on time". Four refill behavior patterns were identified including constant gaps within or at the end of the observation period, which were critical.

CONCLUSION

We introduce a new absolute adherence estimate ΔT that characterizes every refill event and shows that the refill behavior of DOAC patients is dynamic.

Mental health conditions and adherence to direct oral anticoagulants in patients with incident atrial fibrillation: A nationwide cohort study

OBJECTIVE

Medication adherence is essential for effective stroke prevention in patients with atrial fibrillation (AF). We aimed to assess whether adherence to direct oral anticoagulants (DOACs) in AF patients is affected by the presence of mental health conditions (MHCs).

METHODS

The nationwide FinACAF cohort covered 74,222 AF patients from all levels of care receiving DOACs during 2011-2018 in Finland. Medication possession ratio (MPR) was used to quantify adherence. Patients with MPR ≥0.90 were defined adherent. MHCs of interest were depression, bipolar disorder, anxiety disorder and schizophrenia.

RESULTS

The patients' (mean age 75.4 ± 9.5 years, 50.8% female) mean MPR was 0.84 (SD 0.22), and 59.5% had MPR ≥0.90. Compared to patients without MHC, the adjusted ORs (95% CI) for adherent DOAC use emerged slightly lower in patients with depression (0.92 (0.84-0.99)) and bipolar disorder (0.77 (0.61-0.97)) and unsignificant in patients with anxiety disorder (1.08 (0.96-1.21)) and schizophrenia (1.13 (0.90-1.43)). However, when only persistent DOAC therapy was analyzed, no MHC was associated with poor adherence, and instead anxiety disorder was associated with adherent DOAC use (1.18 (1.04-1.34)).

CONCLUSION

Adherence to DOACs in AF patients in Finland was relatively high, and no meaningful differences between patients with and without MHCs were observed.

Nonadherence in Hypertension: How to Develop and Implement Chemical Adherence Testing

Nonadherence to antihypertensive medication is common, especially in those with apparent treatment-resistant hypertension (true treatment-resistant hypertension requires exclusion of nonadherence), and its routine detection is supported by clinical guidelines. Chemical adherence testing is a reliable and valid method to detect adherence, yet methods are unstandardized and are not ubiquitous. This article describes the principles of chemical adherence testing for hypertensive patients and provides a set of recommendations for centers wishing to develop the test. We recommend testing should be done in either of two instances: (1) in those who have resistant hypertension or (2) in those on 2 antihypertensives who have a less than 10 mm Hg drop in systolic blood pressure on addition of the second antihypertensive medication. Furthermore, we recommend that verbal consent is secured before undertaking the test, and the results should be discussed with the patient. Based on medications prescribed in United Kingdom, European Union, and United States, we list top 20 to 24 drugs that cover >95% of hypertension prescriptions which may be included in the testing panel. Information required to identify these medications on mass spectrometry platforms is likewise provided. We discuss issues related to ethics, sample collection, transport, stability, urine versus blood samples, qualitative versus quantitative testing, pharmacokinetics, instrumentation, validation, quality assurance, and gaps in knowledge. We consider how to best present, interpret, and discuss chemical adherence test results with the patient. In summary, this guidance should help clinicians and their laboratories in the development of chemical adherence testing of prescribed antihypertensive drugs.

Does a pharmacist-led medication use review improve medication adherence in polymedicated aged patients? Methodological choices matter!

RATIONALE, AIMS AND OBJECTIVES

The rise in chronic diseases urges for an identification of interventions that improve adherence. However, no golden standard exists for evaluating adherence in polymedicated patients. The objectives were to investigate the impact of a pharmacist-led medication use review (MUR) service on adherence implementation rates for chronic medication, and to evaluate the appropriateness of two adherence calculation approaches in this regard.

METHOD

Before-after study (SIMENON study) including ambulatory, aged, polymedicated patients. Refill data were used to calculate the proportion of days covered (PDC) per medication before and after the MUR. Adherence was assessed for chronic, solid, oral medication using a prescription-based and interval-based approach, and the performance of both approaches was compared.

RESULTS

Adherence was evaluated for 1483 medications from 316 patients. The median baseline PDC per medication was 0.95 (prescription-based method) and 0.91 (interval-based approach). Pearson correlation between both approaches was 0.616 (P < .0001). The prescription-based approach found less medication below the adherence threshold of 0.80 (319 medications; 21.5% vs 481 medications; 32.4%). Using the prescription-based approach, the proportion of non-adherent patients at baseline was 61.7% (195/316 patients), of which 54.9% (107/195 patients) was only non-adherent for one medication. Median PDC scores increased significantly from 0.95 to 0.99 and 0.91 to 0.99 with the prescription-based and interval-based approach respectively (both P < .0001). Only considering the 319 medications with baseline PDC scores <0.8 using the prescription-based approach, the median PDC scores significantly increased from 0.67 to 0.84 (P < .0001), with a median score improvement of 18.3%.

CONCLUSIONS

Although baseline adherence was high in this population of polymedicated aged patients, both calculation methods showed the MUR significantly improved adherence. The prescription-based approach was considered the most appropriate method. Based on these findings and literature evidence, it is recommended to implement the MUR service in Belgium and target non-adherent patients for maximal effect.

Strategies for measuring prescription medication switching with pharmacy claims data: a scoping review protocol

OBJECTIVE

This scoping review will aim to compare strategies for measuring prescription medication switching with pharmacy claims data, with a focus on psychotropic vs non-psychotropic medications.

INTRODUCTION

Medication switching (ie, the replacement of one medication for another) is common and occurs due to several factors (such as adverse effects to a specific medication). In pharmacoepidemiology studies that use pharmacy claims data, it is important to identify and account for switches; however, due to data limitations and lack of a methodological standard, this can be challenging. The aim of this scoping review is to describe how studies have previously measured medication switching with pharmacy claims data in order to create a repository of common strategies and highlight areas for future research.

INCLUSION CRITERIA

This review will include studies that have used pharmacy claims data to measure medication switching as their primary independent or dependent variable. Studies conducted at the individual level (ie, not ecological), published between January 1, 1980, and October 31, 2020, and investigating orally administered, non-anti-infective medications will be considered. No age, population, or context restrictions are specified as inclusion criteria.

METHODS

JBI methodology and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews were used for this protocol. MEDLINE (PubMed), Embase (Ovid), Central (Cochrane Library), CINAHL (EBSCO), and Google Scholar will be searched with the assistance of a health sciences research librarian. Two reviewers will independently screen titles, abstracts, and full-text articles. Strategies for measuring medication switching will be narratively described and summarized overall and by broad medication class.

Effects of a transitional care programme on medication adherence in an older cardiac population: A randomized clinical trial

AIMS

Medication non-adherence post-discharge is common among patients, especially those suffering from chronic medical conditions, and contributes to hospital admissions and mortality. This study aimed to evaluate the effect of the Cardiac Care Bridge (CCB) intervention on medication adherence post-discharge.

METHODS

We performed a secondary analysis of the CCB randomized single-blind trial, a study in patients ≥70 years, at high risk of functional loss and admitted to cardiology departments in six hospitals. In this multi-component intervention study, community nurses performed medication reconciliation and observed medication-related problems (MRPs) during post-discharge home visits, and pharmacists provided recommendations to resolve MRPs. Adherence to high-risk medications was measured using the proportion of days covered (PDC), using pharmacy refill data. Furthermore, MRPs were assessed in the intervention group.

RESULTS

For 198 (64.7%) of 306 CCB patients, data were available on adherence (mean age: 82 years; 58.9% of patients used a multidose drug dispensing [MDD] system). The mean PDC before admission was 92.3% in the intervention group (n = 99) and 88.5% in the control group (n = 99), decreasing to 85.2% and 84.1% post-discharge, respectively (unadjusted difference: -2.6% (95% CI -9.8 to 4.6, P = .473); adjusted difference -3.3 (95% CI -10.3 to 3.7, P = .353)). Post-hoc analysis indicated that a modest beneficial intervention effect may be restricted to MDD non-users (P_interaction  = .085). In total, 77.0% of the patients had at least one MRP post-discharge.

CONCLUSIONS

Our findings indicate that a multi-component intervention, including several components targeting medication adherence in older cardiac patients discharged from hospital back home, did not benefit their medication adherence levels. A modest positive effect on adherence may potentially exist in those patients not using an MDD system. This finding needs replication.

Persistence and adherence to non-vitamin K antagonist oral anticoagulant treatment in patients with atrial fibrillation across five Western European countries

AIMS

To assess persistence and adherence to non-vitamin K antagonist oral anticoagulant (NOAC) treatment in patients with atrial fibrillation (AF) in five Western European healthcare settings.

METHODS AND RESULTS

We conducted a multi-country observational cohort study, including 559 445 AF patients initiating NOAC therapy from Stockholm (Sweden), Denmark, Scotland, Norway, and Germany between 2011 and 2018. Patients were followed from their first prescription until they switched to a vitamin K antagonist, emigrated, died, or the end of follow-up. We measured persistence and adherence over time and defined adequate adherence as medication possession rate ≥90% among persistent patients only.

RESULTS

Overall, persistence declined to 82% after 1 year and to 63% after 5 years. When including restarters of NOAC treatment, 85% of the patients were treated with NOACs after 5 years. The proportion of patients with adequate adherence remained above 80% throughout follow-up. Persistence and adherence were similar between countries and was higher in patients starting treatment in later years. Both first year persistence and adherence were lower with dabigatran (persistence: 77%, adherence: 65%) compared with apixaban (86% and 75%) and rivaroxaban (83% and 75%) and were statistically lower after adjusting for patient characteristics. Adherence and persistence with dabigatran remained lower throughout follow-up.

CONCLUSION

Persistence and adherence were high among NOAC users in five Western European healthcare settings and increased in later years. Dabigatran use was associated with slightly lower persistence and adherence compared with apixaban and rivaroxaban.

Medication-Related Hospital Readmissions Within 30 Days of Discharge: Prevalence, Preventability, Type of Medication Errors and Risk Factors

Background: Hospital readmission rates are increasingly used as a measure of healthcare quality. Medicines are the most common therapeutic intervention but estimating the contribution of adverse drug events as a cause of readmissions is difficult.

Objectives: To assess the prevalence and preventability of medication-related readmissions within 30 days after hospital discharge and to describe the risk factors, type of medication errors and types of medication involved in these preventable readmissions.

Design: A cross-sectional observational study.

Setting: The study took place across the cardiology, gastroenterology, internal medicine, neurology, psychiatry, pulmonology and general surgery departments in the OLVG teaching hospital, Netherlands.

Participants: Patients with an unplanned readmission within 30 days after discharge from an earlier hospitalization (index hospitalization: IH) were reviewed.

Measurements: The prevalence and preventability of medication-related readmissions were assessed by residents in multidisciplinary meetings. A senior internist and hospital pharmacist reassessed the prevalence and preventability of identified cases. Generalized estimating equation with logistic regression was performed to identify risk factors of potentially preventable medication-related readmissions.

Results: Of 1,111 included readmissions, 181 (16%) were medication-related, of which 72 (40%) were potentially preventable. The number of medication changes at IH (Adjusted odds ratio [OR_adj]: 1.14; 95% CI: 1.05–1.24) and having ≥3 hospitalizations 6 months before IH (ORadj: 2.11; 95% CI: 1.12–3.98) were risk factors of a preventable medication-related readmission. Of these preventable readmissions, 35% were due to prescribing errors, 35% by non-adherence and 30% by transition errors. Medications most frequently involved were diuretics and antidiabetics.

Conclusion: This study shows that 16% of readmissions are medication-related, of which 40% are potentially preventable. If the results are confirmed in larger multicentre studies, this may indicate that more attention should be paid to medication-related harm in order to lower the overall readmission rates.

Optimal cut-off points for adherence measure among patients with type 2 diabetes in primary care clinics: a retrospective analysis

Background

Medication adherence measures are often dichotomized to classify patients into those with good or poor adherence using a cut-off value ⩾80%, but this cut-off may not be universal across diseases or medication classes. This study aimed to examine the cut-off value that optimally distinguish good and poor adherence by using the medication possession ratio (MPR) and proportion of days covered (PDC) as adherence measures and glycated hemoglobin (HbA1c) as outcome measure among type 2 diabetes mellitus (T2DM) patients.

Method

We used pharmacy dispensing data of 1461 eligible T2DM patients from public primary care clinics in Malaysia treated with oral antidiabetic drugs between January 2018 and May 2019. Adherence rates were calculated during the period preceding the HbA1c measurement. Adherence cut-off values for the following conditions were compared: adherence measure (MPR versus PDC), assessment period (90-day versus 180-day), and HbA1c target (⩽7.0% versus ⩽8.0%).

Results

The optimal adherence cut-offs for MPR and PDC in predicting HbA1c ⩽7.0% ranged between 86.1% and 98.3% across the two assessment periods. In predicting HbA1c ⩽8.0%, the optimal adherence cut-offs ranged from 86.1% to 92.8%. The cut-off value was notably higher with PDC as the adherence measure, shorter assessment period, and a stricter HbA1c target (⩽7.0%) as outcome.

Conclusion

We found that optimal adherence cut-off appeared to be slightly higher than the conventional value of 80%. The adherence thresholds may vary depending on the length of assessment period and outcome definition but a reasonably wise cut-off to distinguish good versus poor medication adherence to be clinically meaningful should be at 90%.

Consistent use of lipid lowering therapy in HIV infection is associated with low mortality

BACKGROUND

In people living with HIV (PLWH), statins may be disproportionately effective but remain underutilized. A large prospective trial in patients with low to moderate cardiovascular (ASCVD) risk will reveal whether they should be considered in all PLWH. But its effect size may not apply to real-world PLWH with higher ASCVD and mortality risk. Also, the clinical role of non-statin lipid-lowering therapy (LLT) and LLT adherence in this population is unknown.

METHODS

Comparative multi-level marginal structural model for all-cause mortality examining four time-updated exposure levels to LLT, antihypertensives, and aspirin in a virtual cohort of older PLWH. Incident coronary, cerebrovascular, and overall ASCVD events, serious infections, and new cancer diagnoses served as explanatory outcomes.

RESULTS

In 23,276 HIV-infected US-veterans who were followed for a median of 5.2 years after virologic suppression overall mortality was 33/1000 patient years: > 3 times higher than in the US population. Use of antihypertensives or aspirin was associated with increased mortality. Past LLT use (> 1 year ago) had no effect on mortality. LLT exposure in the past year was associated with a reduced hazard ratio (HR) of death: 0.59, 95% confidence interval (CI) 0.51-0.69, p < 0.0001 for statin containing LLT and 0.71 (CI: 0.54-0.93), p = 0.03 for statin-free LLT. For consistent LLT use (> 11/12 past months) the HR of death was 0.48 (CI: 0.35-0.66) for statin-only LLT, 0.34 (CI: 0.23-0.52) for combination LLT, and 0.27 (CI: 0.15-0.48) for statin-free LLT (p < 0.0001 for all). The ASCVD risk in these patients was reduced in similar fashion. Use of statin containing LLT was also associated with reduced infection and cancer risk. Multiple contrasting subgroup analyses yielded comparable results. Confounding is unlikely to be a major contributor to our findings.

CONCLUSIONS

In PLWH, ongoing LLT use may lead to substantially lower mortality, but consistent long-term adherence may be required to reduce ASCVD risk. Consistent non-statin LLT may be highly effective and should be studied prospectively.

TEOS: A framework for constructing operational definitions of medication adherence based on Timelines-Events-Objectives-Sources

AIMS

Managing adherence to medications is a priority for health systems worldwide. Adherence research is accumulating, yet the quality of the evidence is reduced by various methodological limitations. In particular, the heterogeneity and low accuracy of adherence measures have been highlighted in many literature reviews. Recent consensus-based guidelines advise on best practices in defining adherence (ABC) and reporting of empirical studies (EMERGE). While these guidelines highlight the importance of operational definitions in adherence measurement, such definitions are rarely included in study reports. To support researchers in their measurement decisions, we developed a structured approach to formulate operational definitions of adherence.

METHODS

A group of adherence and research methodology experts used theoretical, methodological and practical considerations to examine the process of applying adherence definitions to various research settings, questions and data sources. Consensus was reached through iterative review of discussion summaries and framework versions.

RESULTS

We introduce TEOS, a four-component framework to guide the operationalization of adherence concepts: (1) describe treatment as four simultaneous interdependent timelines (recommended and actual use, conditional on prescribing and dispensing); (2) locate four key events along these timelines to delimit the three ABC phases (first and last recommended use, first and last actual use); (3) revisit study objectives and design to fine-tune research questions and assess measurement validity and reliability needs, and (4) select data sources (e.g., electronic monitoring, self-report, electronic healthcare databases) that best address measurement needs.

CONCLUSION

Using the TEOS framework when designing research and reporting explicitly on these components can improve measurement quality.

Patterns of Use and Discontinuation of Secondary Prevention Medications After Stroke

OBJECTIVE

To investigate whether certain patient, acute care, or primary care factors are associated with medication initiation and discontinuation in the community after stroke or TIA.

METHODS

This is a retrospective cohort study using prospective data on adult patients with first-ever acute stroke/TIA from the Australian Stroke Clinical Registry (April 2010 to June 2014), linked with nationwide medication dispensing and Medicare claims data. Medication users were those with ≥1 dispensing in the year postdischarge. Discontinuation was assessed among medication users and defined as having no medication supply for ≥90 days in the year postdischarge. Multivariable competing risks regression, accounting for death during the observation period, was conducted to investigate factors associated with time to medication discontinuation.

RESULTS

Among 17,980 registry patients with stroke/TIA, 91.4% were linked to administrative datasets. Of these, 9,817 adults with first-ever stroke/TIA were included (45.4% female, 47.6% aged ≥75 years, and 11.4% intracerebral hemorrhage). While most patients received secondary prevention medications (79.3% antihypertensive, 81.8% antithrombotic, and 82.7% lipid-lowering medication), between one-fifth and one-third discontinued treatment over the subsequent year postdischarge (20.9% antihypertensive, 34.1% antithrombotic, and 28.5% lipid-lowering medications). Prescription at hospital discharge (sub-hazard ratio [SHR] 0.70; 95% confidence interval [CI] 0.62-0.79), quarterly contact with a primary care physician (SHR 0.62; 95% CI 0.57-0.67), and prescription by a specialist physician (SHR 0.87; 95% CI 0.77-0.98) were all inversely associated with antihypertensive discontinuation.

CONCLUSIONS

Patterns of use of secondary prevention medications after stroke/TIA are not optimal, with many survivors discontinuing treatment within 1 year postdischarge. Improving postdischarge care for patients with stroke/TIA is needed to minimize unwarranted discontinuation.

Statistical considerations for medication adherence research

OBJECTIVE

Medication non-adherence is a widespread problem and has been known to be associated with worse health outcomes and increased healthcare costs. Although many measures of adherence have been developed, their usage is not consistent across studies. Furthermore, statistical methods for analyzing adherence measures have not been rigorously evaluated.

METHODS

Using Proportion of Days Covered (PDC), a commonly used adherence measure, we examine the variability inherent to study inclusion criteria and several variations of the PDC calculation method using a motivating data example. We illustrated via sensitivity analyses the potential for flawed inference when modeling PDC as an outcome measure. We also performed simulation studies to investigate the statistical properties of three statistical models: logistic regression, negative binomial, and ordinal logistic regression models.

RESULTS

Our sensitivity analysis showed that parameter estimates can vary greatly depending on the rules for determining the study end date in calculating PDC, or the minimum number of fills in defining the cohort. In simulation studies, logistic regression had lower power than ordinal logistic and negative binomial regression models. Naivete to treatment was an important predictor of adherence and omitting it from statistical models can lead to inflated type I errors.

CONCLUSIONS

We discourage dichotomizing adherence data as it results in low power. The negative binomial model offers advantages in modeling adherence data, as it avoids the problematic use of a ratio in regression models. The ordinal logistic regression is robust to distributional assumptions with greater power, but naivete to treatment should be adjusted to reserve type I error rate. We also provide a recommendation for defining the observation window in calculating PDC.

The Need to Develop Standard Measures of Patient Adherence for Big Data: Viewpoint

Despite half a century of dedicated studies, medication adherence remains far from perfect, with many patients not taking their medications as prescribed. The magnitude of this problem is rising, jeopardizing the effectiveness of evidence-based therapies. An important reason for this is the unprecedented demographic change at the beginning of the 21st century. Aging leads to multimorbidity and complex therapeutic regimens that create a fertile ground for nonadherence. As this scenario is a global problem, it needs a worldwide answer. Could this answer be provided, given the new opportunities created by the digitization of health care? Daily, health-related information is being collected in electronic health records, pharmacy dispensing databases, health insurance systems, and national health system records. These big data repositories offer a unique chance to study adherence both retrospectively and prospectively at the population level, as well as its related factors. In order to make full use of this opportunity, there is a need to develop standardized measures of adherence, which can be applied globally to big data and will inform scientific research, clinical practice, and public health. These standardized measures may also enable a better understanding of the relationship between adherence and clinical outcomes, and allow for fair benchmarking of the effectiveness and cost-effectiveness of adherence-targeting interventions. Unfortunately, despite this obvious need, such standards are still lacking. Therefore, the aim of this paper is to call for a consensus on global standards for measuring adherence with big data. More specifically, sound standards of formatting and analyzing big data are needed in order to assess, uniformly present, and compare patterns of medication adherence across studies. Wide use of these standards may improve adherence and make health care systems more effective and sustainable.

Assuming one dose per day yields a similar estimate of medication adherence in patients with stroke: An exploratory analysis using linked registry data

PURPOSE

Prescribed daily dose (PDD), the number of doses prescribed to be taken per day, is used to calculate medication adherence using pharmacy claims data. PDD can be substituted by (i) one dose per day (1DD), (ii) an estimate based on the 75th percentile of days taken by patients to refill a script (PDD₇₅ ) or (iii) the World Health Organization's defined daily dose (DDD). We aimed to compare these approaches for estimating the duration covered by medications and whether this affects calculated 1-year adherence to antihypertensive medications post-stroke.

METHODS

We conducted a retrospective review of prospective cohort data from the ongoing Australian Stroke Clinical Registry linked with pharmacy claims data. Adherence was calculated as the proportion of days covered (PDC) for 1DD, PDD₇₅ and DDD. Differences were assessed using Wilcoxon rank-sum tests.

RESULTS

Among 12 628 eligible patients with stroke, 10 057 (80%) were prescribed antihypertensive medications in the year after hospital discharge (78.2% aged ≥65 years, 45.2% female). Overall, the 75th percentile of patient time until next medication refill was 39 days. The greatest variations in dose regimens, estimated using person- and dose-level refill times, were for beta blockers (11.4% taking two tablets/day). There were comparable levels of adherence between 1DD and the PDD₇₅ (median PDC 91.0% vs 91.2%; P = 0.70), but adherence was slightly higher using DDD (92.3%; both P < 0.001). However, this would represent a clinically nonsignificant difference.

CONCLUSION

Adherence to antihypertensive medications shows similar estimates across standard measures of dosage in patients during the first year after an acute stroke.

Community pharmacy-based study of adherence to non-vitamin K antagonist oral anticoagulants

Objective

This study aimed to assess implementation adherence (how well the patient’s actual intake matches the prescribed dosing regimen) to non-vitamin K antagonist oral anticoagulants (NOACs) and to explore experiences with and beliefs about NOACs in a real-world sample of long-term NOAC users.

Methods

A cross-sectional observational study was conducted in home-dwelling adults who started taking a NOAC at least 1 year prior to inclusion. Pharmacy dispensing data were used to calculate the Medication Possession Ratio (MPR). Patients were recruited in 158 community pharmacies in Flanders, Belgium. They completed a questionnaire collecting basic characteristics and exploring self-reported adherence to NOACs (using the Medication Adherence Report Scale, MARS) and experiences with and beliefs about NOACs (using the Beliefs about Medicines Questionnaire, BMQ).

Results

A total of 766 patients (mean age 76.2±8.8 years, median CHA2DS2-VASc score 4 (IQR=3–4)) were included. The majority (93.5%) used NOAC for stroke prevention in atrial fibrillation. The median MPR was 95.2% (IQR=87.8–99.7) which corresponds with half of the study population not taking their NOAC on at least 17 cumulative days per year. Almost 21% of participants reported non-adherence on the MARS (score <25), with unintentional non-adherence (forgetfulness) most frequently reported (15.4%). Although two-thirds of NOAC users indicated to experience adverse drug reactions, the BMQ demonstrated a positive attitude towards NOAC therapy, where necessity beliefs outweigh the concerns.

Conclusions

Our data indicate that long-term NOAC users have high implementation adherence and a positive attitude towards NOAC therapy. However, taking into account patients’ thromboembolic risk and NOACs’ short half-lives, further optimisation of NOAC use seems warranted in this population.

Long-term persistence and adherence with non-vitamin K oral anticoagulants in patients with atrial fibrillation and their associations with stroke risk

Aims 

Studies on adherence and persistence with non-vitamin K oral anticoagulant (NOAC) treatment have relied on data from the early years of NOAC availability. We aimed to study long-term adherence and persistence with NOACs and their association with stroke risk.

Methods and results 

From the Stockholm Healthcare database, we included 21 028 atrial fibrillation patients claiming a first NOAC prescription from July 2011 until October 2018, with more than 1000 patients having more than 5 years of follow-up (median: 2.0, interquartile range: 1.0–3.2). Persistence rates, defined as continuing to claim NOAC prescriptions within a 90-day gap, decreased to 70% at the end of follow-up. However, 85% of the patients were treated at the end of the study due to reinitiations. Adherence, calculated as medication possession rate (MPR) in 3 and 6-month intervals among persistent users, remained stable at 90%, with 75% of patients having an MPR >95% throughout the study period. Using a case–control design, we calculated associations of persistence and adherence with stroke risk, adjusting for potential confounders. The outcome was a composite of ischaemic or unspecified stroke and transient ischaemic attack. Non-persistence and poor adherence were both associated with increased stroke risk [non-persistence adjusted odds ratio (aOR): 2.05; 95% confidence interval (CI): 1.49–2.82, 1% reduction MPR aOR: 1.03; CI: 1.01–1.05]. There was no association between non-persistence or poor adherence and the falsification endpoints; fractions and respiratory infections, indicating no ‘healthy-adherer’ effect.

Conclusion 

Persistence rates decreased slowly over time, but persistent patients had high adherence rates. Both non-persistence and poor adherence were associated with an increased stroke risk.

Impact of medication nonadherence on stroke recurrence and mortality in patients after first-ever ischemic stroke: Insights from registry data in Singapore

PURPOSE

This retrospective cohort study aims to examine adherence to secondary stroke preventive medications and their association with risk of stroke recurrence and mortality in patients after first-ever ischemic stroke.

METHODS

Using data from the National Healthcare Group and Singapore Stroke Registry, patients with first-ever ischemic stroke between 2010 and 2014 were included, and categorized based on antithrombotic or statin adherence using the proportion of days covered: high (≥75%), intermediate (50%-74%), low (25%-49%), and very low (<25%). The primary outcome was first recurrent ischemic stroke within a year after hospital discharge, while the secondary composite outcomes were (a) stroke recurrence and all-cause mortality and (b) stroke recurrence and cardiovascular mortality. The Cox proportional hazard model was used to examine the association between medication adherence and outcomes. Adjusted hazard ratios (aHRs) and the corresponding 95% confidence intervals (CIs) were reported.

RESULTS

Among ischemic stroke patients prescribed with antithrombotics (n = 1139) or statins (n = 1160) at hospital discharge, about one-third were highly adherent to their medications. Patients with lower medication adherence tended to be younger, were admitted to private ward classes, and were without hypertension. Compared with the patients with high medication adherence, the risk of stroke recurrence was higher in patients with very low antithrombotic (aHR = 4.65; 95% CI: 1.45-14.89) or statin (aHR = 3.44; 95% CI: 0.93-12.74) adherence. Similar findings were observed for the secondary outcomes.

CONCLUSIONS

Poor adherence to antithrombotic and statin treatment increases the risk of recurrent stroke and mortality in patients after first-ever ischemic stroke. Further measures are needed to improve medication adherence among stroke survivors.

Navigating the Wild West of Medication Adherence Reporting in Specialty Pharmacy

Estimating medication adherence through the use of pharmacy claims-based adherence calculations such as medication possession ratio (MPR) and proportion of days covered (PDC) plays a significant role in specialty pharmacy practice. Although MPR and PDC are frequently used in clinical practice, calculation methodologies vary, making meaningful comparisons of adherence rates difficult. In addition, MPR and PDC are increasingly used by insurance companies, pharmacies, accrediting bodies, and drug manufacturers to demonstrate quality differences or clinical benefit across the specialty pharmacy industry. Therefore, recognizing the source and effect of calculation variability is necessary to fully understand reported adherence results. This article highlights the challenges in standardizing adherence methodologies, minimum methodology considerations that should be reported with MPR and PDC results, and key elements to consider when interpreting and applying adherence results. Further, recommendations are provided to promote a more consistent description of calculation methods and to aid pharmacies in adherence measure analysis, interpretation, and application to practice, with a focus on specialty pharmacy programs. A detailed description of methodology as outlined in this article must be provided to ensure reproducibility, external validation, and scientific rigor. In the absence of standardization, specialty pharmacies should be prudent in their use of adherence calculations as a clinical benchmarking tool or comparative quality indicator with outside organizations. Furthermore, specialty pharmacies should consider using current adherence measure calculations to identify and provide targeted interventions to patients with potential adherence problems and strive to better demonstrate ties between adherence measures and direct clinical and cost outcomes. DISCLOSURES: No outside funding supported the writing of this article. Anguiano is a speaker and research consultant for United Therapeutics. The other authors have nothing to disclose.

Effects of a Proactive Interdisciplinary Self-Management (PRISMA) program on medication adherence in patients with type 2 diabetes in primary care: a randomized controlled trial

PURPOSE

The present study aims to investigate the effect of the group-based Proactive Interdisciplinary Self-Management (PRISMA) training program on medication adherence in patients with type 2 diabetes (T2DM) treated in primary care.

PATIENTS AND METHODS

The current study is a two-arm, parallel group, randomized, open label trial (1:1) of 6-month duration with a 6-month extension period in which both groups received the intervention (wait-list control). People 18 years old or older who were diagnosed with T2DM were included. The intervention consisted of two group meetings about T2DM guided by care providers. The control group received usual care only (visits at the general practice). The primary outcome was adherence based on pharmacy refill data and was measured using medication possession ratio (MPR). The secondary outcomes were the number of drug holidays and self-reported adherence, measured by the 5-item Medication Adherence Rating Scale (MARS-5).

RESULTS

Of the total sample (n=108), 66.6% were male. The mean age was 69.3 years (SD=9.1). In the 6-month period, patients were more adherent in the intervention group (n=56) (median MPR =100.0 [51.1-100.0]) than in the control group (n=52) (median MPR =97.7 [54.1-100.0]) (U=1,042, z=-2.783, P=0.005). The intervention group had less drug holidays than the control group (relative risk 0.55, 95% CI, 0.37-0.80). The sum scores of the MARS did not differ between the intervention group (median =23.98, SD=0.91) and the control group (median =24.00, SD=1.54).

CONCLUSION

The PRISMA program resulted in a small improvement in MPR and fewer drug holidays, while no improvement has been found in self-reported adherence. However, health care providers and policy makers could take into account that adherence might be influenced by PRISMA.

Beyond Adherence Thresholds: A Simulation Study of the Optimal Classification of Longitudinal Adherence Trajectories From Medication Refill Histories

Background: The description of adherence based on medication refill histories relies on the estimation of continuous medication availability (CMA) during an observation period. Thresholds to distinguish adherence from non-adherence typically refer to an aggregated value across the entire observation period, disregarding differences in adherence over time. Sliding windows to divide the observation period into smaller portions, estimating adherence for these increments, and classify individuals with similar trajectories into clusters can retain this temporal information. Optimal methods to estimate adherence trajectories to identify underlying patterns have not yet been established. This simulation study aimed to provide guidance for future studies by analyzing the effect of different longitudinal adherence estimates, sliding window parameters, and sample characteristics on the performance of a longitudinal clustering algorithm.

Methods: We generated samples of 250–25,000 individuals with one of six longitudinal refill patterns over a 2-year period. We used two longitudinal CMA estimates (LCMA1 and LCMA2) and their dichotomized variants (with a threshold of 80%) to create adherence trajectories. LCMA1 assumes full adherence until the supply ends while LCMA2 assumes constant adherence between refills. We assessed scenarios with different LCMA estimates and sliding window parameters for 350 independent samples. Individual trajectories were clustered with kml, an implementation of k-means for longitudinal data in R. We compared performance between the four LCMA estimates using the adjusted Rand Index (cARI).

Results: Cluster analysis with LCMA2 outperformed other estimates in overall performance, correct identification of groups, and classification accuracy, irrespective of sliding window parameters. Pairwise comparison between LCMA estimates showed a relative cARI-advantage of 0.12–0.22 (p < 0.001) for LCMA2. Sample size did not affect overall performance.

Conclusion: The choice of LCMA estimate and sliding window parameters has a major impact on the performance of a clustering algorithm to identify distinct longitudinal adherence trajectories. We recommend (a) to assume constant adherence between refills, (b) to avoid dichotomization based on a threshold, and (c) to explore optimal sliding windows parameters in simulation studies or selecting shorter non-overlapping windows for the identification of different adherence patterns from medication refill data.

Comparison of Different Strategies to Measure Medication Adherence via Claims Data in Patients With Chronic Heart Failure

Medication adherence correlates with morbidity and mortality in patients with chronic heart failure (CHF), but is difficult to assess. We conducted a retrospective methodological cohort study in 3,808 CHF patients, calculating adherence as proportion of days covered (PDC) utilizing claims data from 2010 to 2015. We aimed to compare different parameters’ influence on the PDC of elderly CHF patients exemplifying a complex chronic disease. Investigated parameters were the assumed prescribed daily dose (PDD), stockpiling, and periods of hospital stay. Thereby, we investigated a new approach using the PDD assigned to different percentiles. The different dose assumptions had the biggest influence on the PDC, with variations from 41.9% to 83.7%. Stockpiling and hospital stays increased the values slightly. These results queries that a reliable PDC can be calculated with an assumed PDD. Hence, results based on an assumed PDD have to be interpreted carefully and should be presented with sensitivity analyses to show the PDC's possible range.

Real-world adherence to oral anticoagulants in atrial fibrillation patients: a study protocol for a systematic review and meta-analysis

INTRODUCTION

Atrial fibrillation (AF) is one of the leading causes of cerebrovascular mortality and morbidity. Oral anticoagulants (OACs) have been shown to reduce the incidence of cardioembolic stroke in patients with AF, adherence to treatment being an essential element for their effectiveness. Since the release of the first non-vitamin K antagonist oral anticoagulant, several observational studies have been carried out to estimate OAC adherence in the real world using pharmacy claim databases or AF registers. This systematic review aims to describe secondary adherence to OACs, to compare adherence between OACs and to analyse potential biases in OAC secondary adherence studies using databases.

METHODS AND ANALYSIS

We searched on PubMed, SCOPUS and Web of Science databases (completed in 26 September 2018) to identify longitudinal observational studies reporting days' supply adherence measures with OAC in patients with AF from refill databases or AF registers. The main study endpoint will be the percentage of patients exceeding the 80% threshold in proportion of days covered or the medication possession ratio. Two reviewers will independently screen potential studies and will extract data in a structured format. A random-effects meta-analysis will be carried out to pool study estimates. The risk of bias will be assessed using the Newcastle-Ottawa Scale for observational studies and we will also assess some study characteristics that could affect days' supply adherence estimates.

ETHICS AND DISSEMINATION

This systematic review using published aggregated data does not require ethics approval according to Spanish law and international regulations. The final results will be published in a peer-review journal and different social stakeholders, non-academic audiences and patients will be incorporated into the diffusion activities.

PROSPERO REGISTRATION NUMBER

CRD42018095646.

Estimating Adherence Based on Prescription or Dispensation Information: Impact on Thresholds and Outcomes. A Real-World Study With Atrial Fibrillation Patients Treated With Oral Anticoagulants in Spain

Objective: To estimate drug exposure, Proportion of Days Covered (PDC) and percentage of patients with PDC ≥ 80% from a cohort of atrial fibrillation patients initiating oral anticoagulant (OAC) treatment. We employed three different approaches to estimate PDC, using either data from prescription and dispensing (PD cohort) or two common designs based on dispensing information only, requiring at least one (D1) or at least two (D2) refills for inclusion in the cohorts. Finally, we assessed the impact of adherence on health outcomes according to each method. Methods: Population-based retrospective cohort of all patients with Non Valvular Atrial Fibrillation (NVAF), who were newly prescribed acenocoumarol, apixaban, dabigatran or rivaroxaban from November 2011 to December 2015 in the region of Valencia (Spain). Patients were followed for 12 months to assess adherence using three different approaches (PD, D1 and D2 cohorts). To analyze the relationship between adherence (PDC ≥ 80) defined according to each method of calculation and health outcomes (death for any cause, stroke or bleeding) Cox regression models were used. For the identification of clinical events patients were followed from the end of the adherence assessment period to the end of the available follow-up period. Results: PD cohort included all patients with an OAC prescription (n = 38,802), D1 cohort excluded fully non-adherent patients (n = 265) and D2 cohort also excluded patients without two refills separated by 180 days (n = 2,614). PDC ≥ 80% ranged from 94% in the PD cohort to 75% in the D1 cohort. Drug exposure among adherent (PDC ≥ 80%) and non-adherent (PDC < 80%) patients was different between cohorts. In adjusted analysis, high adherence was associated with a reduced risk of death [Hazard Ratio (HR): from 0.82 to 0.86] and (except in the PD cohort) the risk for ischemic stroke (HR: from 0.61 to 0.64) without increasing the risk of bleeding. Conclusion: Common approaches to assess adherence using measures based on days' supply exclude groups of non-adherent patients and, also, misattribute periods of doctors' discontinuation to patient non-adherence, misestimating adherence overall. Physician-initiated discontinuation is a major contributor to reduced OAC exposure. When using the PDC80 threshold, very different groups of patients may be classified as adherent or non-adherent depending on the method used for the calculation of days' supply measures. High adherence and high exposure to OAC treatment in NVAF patients is associated with better health outcomes.

A Systematic Review of Medication Adherence Thresholds Dependent of Clinical Outcomes

Background: In pharmacotherapy, the achievement of a target clinical outcome requires a certain level of medication intake or adherence. Based on Haynes's early empirical definition of sufficient adherence to antihypertensive medications as taking ≥80% of medication, many researchers used this threshold to distinguish adherent from non-adherent patients. However, we propose that different diseases, medications and patient's characteristics influence the cut-off point of the adherence rate above which the clinical outcome is satisfactory (thereafter medication adherence threshold). Moreover, the assessment of adherence and clinical outcomes may differ greatly and should be taken into consideration. To our knowledge, very few studies have defined adherence rates linked to clinical outcomes. We aimed at investigating medication adherence thresholds in relation to clinical outcomes.

Method: We searched for studies that determined the relationship between adherence rates and clinical outcomes in the databases PubMed, Embase^Ⓡ and Web of Science™ until December 2017, limited to English-language. Our outcome measure was any threshold value of adherence. The inclusion criteria of the retrieved studies were (1) any measurement of medication adherence, (2) any assessment of clinical outcomes, and (3) any method to define medication adherence thresholds in relation to clinical outcomes. We excluded articles considered as a tutorial. Two authors (PB and IA) independently screened titles and abstracts for relevance, reviewed full-texts, and extracted items. The results of the included studies are presented qualitatively.

Result: We analyzed 6 articles that assessed clinical outcomes linked to adherence rates in 7 chronic disease states. Medication adherence was measured with Medication Possession Ratio (MPR, n = 3), Proportion of Days Covered (PDC, n = 1), both (n = 1), or Medication Event Monitoring System (MEMS). Clinical outcomes were event free episodes, hospitalization, cortisone use, reported symptoms and reduction of lipid levels. To find the relationship between the targeted clinical outcome and adherence rates, three studies applied logistic regression and three used survival analysis. Five studies defined adherence thresholds between 46 and 92%. One study confirmed the 80% threshold as valid to distinguish adherent from non-adherent patients.

Conclusion: The analyzed studies were highly heterogeneous, predominantly concerning methods of calculating adherence. We could not compare studies quantitatively, mostly because adherence rates could not be standardized. Therefore, we cannot reject or confirm the validity of the historical 80% threshold. Nevertheless, the 80% threshold was clearly questioned as a general standard.