Adherence to oral anticancer chemotherapy: What influences patients' over or non-adherence? Analysis of the OCTO study through quantitative-qualitative methods

"Take the tablet or don't take the tablet?"-A qualitative study of patients' experiences of self-administering anti-cancer medications related to adherence and managing side effects

PURPOSE

Medication non-adherence is a well-recognised problem in cancer care, negatively impacting health outcomes and healthcare resources. Patient-related factors influencing medication adherence (MA) are complicated and interrelated. There is a need for qualitative research to better understand their underlying interaction processes and patients' needs to facilitate the development of effective patient-tailored complex interventions. This study aimed to explore experiences, perceptions, and needs relating to MA and side effect management of patients who are self-administering anti-cancer treatment.

METHODS

Semi-structured audio-recorded interviews with patients who have haematological cancer were conducted. A comparative, iterative, and predominantly inductive thematic analysis approach was employed.

RESULTS

Twenty-five patients from a specialist cancer hospital were interviewed. While self-administering cancer medications at home, patients' motivation to adhere was affected by cancer-related physical reactions, fears, cancer literacy and beliefs, and healthcare professional (HCP) and informal support. Patients desired need for regular follow-ups from respectful, encouraging, informative, responsive, and consistent HCPs as part of routine care. Motivated patients can develop high adherence and side effect self-management over time, especially when being supported by HCPs and informal networks.

CONCLUSION

Patients with cancer need varied support to medically adhere to and manage side effects at home. HCPs should adapt their practices to meet the patients' expectations to further support them during treatment. We propose a multi-dimensional and technology- and theory-based intervention, which incorporates regular HCP consultations providing tailored education and support to facilitate and maintain patient MA and side effect self-management.

Barriers and Facilitators of Adherence to Oral Anticancer Medications Among Women with Breast Cancer: A Qualitative Study

Purpose

Despite the life-saving benefits of oral anticancer medications (OAMs) to women with breast cancer (BC), adherence remains suboptimal and, in many cases, not well documented. The study examined barriers and facilitators of adherence to OAMs among women receiving BC treatment in Nigeria.

Patients and Methods

The study was framed within the World Health Organization (WHO) Multidimensional Model of Adherence. We conducted qualitative in-depth interviews of 16 purposively sampled women in two tertiary hospitals in Southern Nigeria. The interviews were audio-recorded and transcribed verbatim. The interview data were analyzed using the Framework Method.

Results

The key barriers to OAM adherence mentioned were socioeconomic factors (high cost of medication) and therapy-related factors (medication side effects). The key facilitating mechanisms for adherence to OAMs mentioned included; (i) patient-related psychosocial factors such as self-encouragement and self-discipline in sticking to the prescription, taking the medication at a particular time each day, receiving practical support from family members; and (ii) healthcare team/system factors such as obtaining an adequate supply of the medication at the pharmacy.

Conclusion

Barriers and facilitators to OAM adherence are multidimensional. The study findings highlight the potential benefit of a multifaceted intervention (such as patient education and monitoring or strategies promoting cost-containment and side effects management) to optimize adherence. Therefore, our findings may inform the designing and evaluating of context-specific adherence measures and multifaceted intervention strategies targeting key barriers and approaches that enable adherence to enhance patient outcomes.

Adherence to antiretroviral and cancer chemotherapy, and associated factors among patients with HIV-cancer co-morbidity at the Uganda Cancer Institute: a cross sectional study

BACKGROUND

Human Immunodeficiency Virus is a major global public health issue affecting millions of people, and sub-Saharan Africa where Uganda lies is disproportionately affected. There has been an increase in cancer among HIV patients which has resulted into use of co-medications that sometimes affect ART and cancer chemotherapy adherence. We aimed to determine adherence to antiretroviral and cancer chemotherapy and the associated factors among patients with HIV-cancer co-morbidity at the Uganda Cancer Institute.

METHODS

We conducted a cross-sectional study among 200 randomly selected adult cancer patients infected with HIV and attending the Uganda cancer institute. Antiretroviral and anti-cancer chemotherapy adherence with associated factors were assessed quantitatively. We collected the data using interviewer administered semi-structured questionnaires. Modified Poisson regression with robust standard errors was used to estimate the prevalence ratios (PR) and its 95% confidence intervals (CI) for the factors associated with adherence to Antiretroviral Therapy (ART) and cancer chemotherapy.

RESULTS

Overall, 54% of the study participants adhered to both ART and chemotherapy, and 55% adhered to ART while 65% adhered to cancer chemotherapy. The mean age of the respondents was 42 (SD ± 11years), and a majority, 61% were males.More than half, 56.5% were married and at least 45% had attained a primary level of education. Patients with good adherence to antiretroviral therapy and chemotherapy were 54%. No knowledge of cancer stage (PR = 0.4, 95% CI = 0.3-0.6, P < 0.0001), having an AIDS defining cancer (PR = 0.7, 95% CI = 0.5-0.9, P = 0.005), ART clinic in district not near Uganda Cancer Institute (PR = 0.7,95% CI = 0.8-1.0, P = 0.027) and affordability of cancer chemotherapy (PR = 1.4, 95% CI = 1.0-1.9, P = 0.037) were associated with adherence to both ART and cancer chemotherapy.

CONCLUSION

Adherence to both ART and cancer chemotherapy was low. Factors significantly associated with adherence were: knowledge of the cancer stage by the patient, the type of cancer diagnosis, source of ART and affordability/ availability of medications. There is a need to provide information on the stage of cancer and adherence counseling to patients. Furthermore, Integration of HIV- cancer care will be necessary for efficient and effective care for the patients.

Adherence to Adjuvant Endocrine Therapy and Survival Among Older Women with Early-Stage Hormone Receptor-Positive Breast Cancer

BACKGROUND AND OBJECTIVE

Although improving adherence to adjuvant endocrine therapies (AETs) is critical to ensure better patient outcomes, the evidence is still lacking on differences in 5-year AET adherence trajectories. This study aimed to estimate the time trend of adherence by the type of individual AET and the association of adherence to AETs with overall survival among older women with hormone receptor-positive breast cancer.

METHODS

This study used the Surveillance, Epidemiology, and End Results-Medicare database 2006-2016. We included women aged ≥ 65 years with newly diagnosed hormone receptor-positive breast cancer and who had initiated AET (anastrozole, letrozole, exemestane, or tamoxifen). Adherence to AETs was defined as the proportion of days covered that was calculated for the follow-up period (5 years). The overall survival time was defined as the time from the date of AET initiation to death. The linear mixed models with repeated measures were used to estimate the changes in adherence to AETs. The Cox proportional hazard model was used to assess the relationships (hazard ratio [HR] and 95% confidence interval [CI]) between adherence to AETs and death.

RESULTS

A total of 11,617 patients were included. Anastrozole was the most commonly used (n = 6,908), followed by letrozole (n = 2,586), tamoxifen (n = 1,750), and exemestane (n = 373). The mean (standard deviation) of proportion of days covered for 5 years was 57.4 (34.6), indicating the highest proportion of days covered in the anastrozole group [61.1 (34.1)] and the lowest proportion of days covered in the exemestane group [44.0 (35.1)]. Overall, adherence to AET decreased over the 5-year follow-up period in all AET groups, but the decrease in the tamoxifen group was steeper (42.3% decreased) compared with other AETs. Anastrozole, letrozole, and exemestane groups were associated with a lower risk of death compared with the tamoxifen group (HR = 0.80, 95% CI 0.71-0.89 for anastrozole; HR = 0.82, 95% CI 0.72-0.93 for letrozole; HR = 0.82, 95% CI 0.63-1.07 for exemestane).

CONCLUSIONS

Patients who initiated with tamoxifen had a steeper decrease in adherence over the 5 years compared with anastrozole, letrozole, and exemestane groups. Furthermore, higher adherence was associated with a decreased risk of mortality. Physicians should be cognizant of decreasing adherence over time and choose effective treatment options with minimal side-effect profiles to better support adherence by patients with breast cancer.

Adherence to Oral Anticancer Medications Among Women With Breast Cancer in Africa: A Scoping Review

PURPOSE

Oral anticancer medications (OAMs) improve treatment outcomes and survival in women with breast cancer (BC). However, adherence to OAM therapy remains suboptimal. This scoping review provides evidence of adherence to OAMs among African women with BC.

METHODS

We searched four databases and gray literature, using guidance from the Joanna Briggs Institute. Thirteen studies on adherence rates, determinants, and interventions were included. NVivo 12 software was used to perform thematic analysis of the included studies. The determinants (barriers and facilitators) associated with adherence were analyzed according to the five dimensions of the WHO multidimensional adherence model.

RESULTS

Most studies (n = 11, 85%) focused on endocrine medication. Depending on the definition, measurements, and assessment period, the nonadherence rates ranged from 4.3% to 65.4% for endocrine medications, 80.9% for cytotoxic chemotherapies, and 32.7% for combined medications. The significant barriers associated with adherence include Islamic religion, concurrent comorbidities, mastectomy, anastrozole treatment, side effects, unawareness of treatment insurance coverage, and seeking treatment from traditional healers. Thorough therapeutic communication regarding treatment, neoadjuvant chemotherapy, and adequate social support significantly facilitate adherence. A randomized controlled trial of breast nursing interventions reported improved patient adherence.

CONCLUSION

The evidence mapped from studies that evaluated OAM adherence in women with BC indicates that nonadherence to OAMs is common. Applying context-specific standardized measures to assess adherence and facilitators or strategies targeting the identified barriers can optimize adherence and treatment outcomes. Effective interventions to improve adherence are limited. Therefore, further empirical and interventional studies in Africa are required to enhance the evidence.

Real World Adherence to and Persistence With Oral Oncolytics in Multiple Myeloma: A Systematic Review and Meta-analysis

INTRODUCTION

Oral oncolytic treatments (OOTs) have improved the prognosis of patients with multiple myeloma (MM). However, the effectiveness of these therapies is undermined by poor adherence. We aimed to characterize the real-world adherence to, and persistence with, OOTs for MM.

MATERIALS AND METHODS

MEDLINE, EMBASE, and the International Pharmaceutical abstracts databases were searched for relevant observational studies published in English up to November 21, 2021. This was supplemented by manual searches of abstracts from the annual meetings of the American Society of Hematology, the American Society for Clinical Oncology, and the European Hematology Association as well as screening the references of included articles. Random-effects meta-analysis was performed.

RESULTS

Following screening of 11,557 articles, 19 studies involving 27,129 patients in 8 countries (France, the US, Germany, Italy, the UK, Brazil, South Korea, and Belgium) prescribed OOTs (lenalidomide, thalidomide, pomalidomide, panobinostat, ixazomib, and melphalan) for MM were included. The overall pooled proportion of adherent patients was 67.9% (95% confidence interval [CI]: 57.1%-77.8%). The pooled proportion of adherent patients was higher in self-reported questionnaire-based studies compared to those using prescription/dispensing data (81.6% vs. 61.0%; P-value for difference = .08). Across 5 studies involving 15,363 patients, a pooled proportion of 35.8% (95% CI: 22.0-50.9) discontinued treatment. Factors reported to be associated with nonadherence included increasing age, higher comorbidity, polypharmacy, and a lack of social support.

CONCLUSION

In patients with MM, adherence to and persistence with OOTs remains suboptimal. To achieve desired clinical outcomes, interventions to improve adherence and minimize discontinuation may be warranted.

Influence of the implementation of a multidisciplinary consultation program on adherence to the first ever course of oral antineoplastic treatment in patients with cancer

PURPOSE

To evaluate adherence (as measured by the medication possession ratio) to the first ever course of oral antineoplasic treatment in cancer patients before and after the implementation of a multidisciplinary consultation program (involving an oncologist, a pharmacist, and a nurse) and to investigate the program's impact on adverse events and drug-related problems.

PATIENTS AND METHODS

In a retrospective single-center study, we compared the medication possession ratio 2 months after treatment initiation in a control group (before multidisciplinary consultation program implementation) versus an interventional group (after multidisciplinary consultation program implementation).

RESULTS

Two months after oral antineoplasic treatment initiation, the mean ± standard deviation medication possession ratio did not differ significantly when comparing the interventional (multidisciplinary consultation program) group (n = 33; 0.99 ± 0.06) with the control group (n = 64; 0.94 ± 0.16) (p = 0.062). Patients in the multidisciplinary consultation program group had fewer adverse events in general (41, vs 109 in the control group; p = 0.048) and digestive adverse events in particular (6 vs 29, respectively; p = 0.007). A total of 53 and 40 drug-related problems were identified in the control and multidisciplinary consultation program groups, respectively (p = 0.074).

CONCLUSIONS

Implementation of an multidisciplinary consultation program was not associated with a significant difference in drug adherence (as assessed by the medication possession ratio), which was good before and after implementation. The multidisciplinary consultation program was associated with a lower incidence of adverse events.

The effect of a mobile application on treatment adherence and symptom management in patients using oral anticancer agents: A randomized controlled trial

PURPOSE

The use of mobile health technologies in the management of oral anticancer agents (OAA) can be beneficial in terms of treatment adherence and symptom management. This study was conducted to investigate the effect of a mobile application developed for patients using OAA on treatment adherence and symptom management.

METHOD

The study was conducted using a randomized controlled trial design, and it was carried out on 77 patients. Data were collected from the Oral Chemotherapy Adherence Scale (OCAS), and the Memorial Symptom Assessment Scale (MSAS). Data were collected at the beginning of the research, and face-to-face interviews were conducted after one, three, and six months. Patients in the intervention group were followed up for six months using the mobile application.

RESULTS

It was found that there was no difference between the intervention and control groups in the baseline OCAS mean scores (p > 0.05), and the mean score of the intervention group increased over the first, third- and sixth-month measurements (p < 0.05). It was found that there was no difference between the intervention and control groups in the MSAS mean scores (p > .05), and there was a decrease in the mean MSAS score of the intervention group between the third- and sixth-month follow-up (p < .05).

CONCLUSION

The present study results showed that the mobile application is effective in managing symptoms and increasing treatment adherence. A well-designed mobile health application that increases treatment adherence, decreases symptom severity, and supports patients' self-management could be beneficial for patients using OAA. CLINICALTRIALS.

GOV IDENTIFIER

NCT04626830.

Medication Experience and Adherence to Oral Chemotherapy: A Qualitative Study of Patients' and Health Professionals' Perspectives

Lack of adherence constitutes one of the most important challenges in patients undergoing treatment with oral antineoplastic drugs (ANEO). Understanding cancer patients’ experiences with respect to their medication is key for optimizing adherence and therapeutic results. We aimed to assess the medication experience (ME) in patients with cancer in treatment with ANEO, to describe the barriers and facilitators related to the disease and its treatment and to compare them with the healthcare professionals’ perspectives. We carried out an exploratory qualitative study in the University Hospital of San Juan de Alicante, Spain. Three focus groups and two nominal group discussions were conducted with 23 onco-hematological patients treated with ANEO and 18 health professionals, respectively. The data were analyzed using content analyses and were eventually triangulated. The most impactful aspects in patients’ ME were the presence of adverse effects; lack of information about treatment; beliefs, needs and expectations regarding medications; social and family support; and the relationship with the health professionals. Both patients and professionals agreed on considering the negative side effects and the information about treatment as the main barriers and facilitators of adherence, respectively, although the approaches differed between both profiles. The professionals offered a more technical vision while patients prioritized the emotional burden and motivation associated with the disease and medication. This study allowed us to understand the real-life experiences of patients being treated with ANEO and explore the factors which had an impact on adherence to treatment. This understanding enables professionals to have a positive influence on patients’ behavior and provide individualized care plans. Pharmacists’ assistance is relevant to support patients’ adherence and self-management.

Conditions for the Implementation of a Patient Education Program Dedicated to Cancer Patients Treated by Oral Anticancer Therapy

INTRODUCTION

A patient education program has been developed in the field of cancer for supporting cancer patients undergoing oral anticancer therapies. Its implementation was tested in 3 different settings. The objectives of this study were to 1) identify barriers and facilitators for implementing the patient education program, 2) identify practices encouraging or hindering implementation and 3) produce recommendations for its dissemination.

METHODS

Twenty semi-structured interviews were conducted with caregivers from all three establishments.

RESULTS

The main factors associated with successful implementation were as follows: prescribers' representations on patient education, considered of low value; on oral anticancer therapies, considered too dangerous to be handled by the patient him/herself, the indefinite legitimacy of certain professions in charge of patient education programs; patients' engagement in their care pathway and provision of caregivers.

CONCLUSION

Recommendations include developing patient education culture within the environment of the medical doctors' curriculum, to consider contextual, pre-existing cooperative units for implementing patient education, to systematically send patients to patient education programs without practicing triage. Successful implementation of patient education critically depends on the prescribing physicians' perceived value of patient education. Patient education should become mandatory, integrated as part of the cancer care pathway. Physicians lack the necessary time and/or means to assess patients' capacity for engagement, without adequate strategies for their support. Therefore, physicians should systematically refer all patients to patient education, where nurses can tailor their coaching of cancer patients.

TRIAL REGISTRATION

The study protocol was approved by the IRB SUD EST I (N° EudraCT: 2016-A00113-48). All participants were given written and verbal information about the study and gave informed consent to participate.

Over-adherence to capecitabine: a potential safety issue in breast and colorectal cancer patients

PURPOSE

The aim of the OCTO clinical study was to measure patients' adherence to capecitabine-based treatment.

METHODS

A cohort of ambulatory patients treated with capecitabine monotherapy for either locally advanced or metastatic, breast or colorectal cancer was monitored for 6 cycles. Adherence was assessed in all patients by self-completed questionnaires on disease, pill-count and pharmacological dosage of FBAL (metabolite of capecitabine); and in half of the cohort by electronic medication event monitoring systems (MEMS™) recording the opening times of the device.

RESULTS

Forty patients were enrolled between November 2008 and September 2011 and treated by capecitabine for an average of 4.75 cycles (range 1-6). Hand-foot syndrome (HFS) was the most frequently reported toxicity (35% patients), and to a lesser extent fatigue and/or asthenia (21%), nausea and/or vomiting (13%) and diarrhea (11%). In the MEMS™ cohort, 20 patients were included. Patients' adherence was excellent with very few missing occasions (23/2272 records). Close analysis of MEMS™ data revealed unexpected medication patterns, such as patients taking extra days of medication beyond planned cycle, patients taking extra doses per day and patients missing a day of dosing and "compensating" by taking extra the following day (N = 7, 18%). A trend was found between over-adherence and high-grade toxicity (grades 3 and/or 4): OR 4.74 [0.65-45.2], p = 0.13 and higher AUC (p = 0.16). There was a trend towards increased AUC of FBAL in over-adherent patients (p = 0.16).

CONCLUSION

Adherence to oral anticancer chemotherapy was found excellent in this population suggesting over-adherence to capecitabine and potential safety implications for outpatients' drugs.

Patient-doctor relationship and adherence to capecitabine in outpatients of a German comprehensive cancer center

PURPOSE

The prescribing of oral chemotherapy agents has introduced the new challenge of ensuring patients' adherence to therapy. Aspects of a close patient-doctor relationship are reported to be correlated with adherence to oral anticancer drugs, but data on capecitabine are scarce.

PATIENTS AND METHODS

Sixty-four outpatients with a diagnosis of cancer and prescribed capecitabine were recruited from a German Comprehensive Cancer Center. We used the Patient-Doctor Relationship Questionnaire (PDRQ-9), the Medical Adherence Rating Scale (MARS), the Beliefs about Medicines Questionnaire (BMQ), and the Satisfaction with Information about Medicines Scale (SIMS) to assess patients' perceptions and behavior. Medical data were extracted from the charts.

RESULTS

Non-adherence was reported by 20% of the 64 participants. The perceived quality of the patient-doctor relationship was high in general, but it did not emerge as a predictor of adherence in our survey (odds ratio [OR]=0.915, P=0.162, 95% CI=0.808-1.036). However, beliefs about medicine (OR=1.268, P<0.002; 95% CI=1.090-1.475) as well as satisfaction with information about medicine (OR=1.252, P<0.040, 95% CI=1.010-1.551) were predictors of adherence and the quality of the patient-doctor relationship was correlated with both variables (r=0.373, P=0.002 for SIMS sum score; r=0.263, P=0.036 for BMQ necessity/concern difference). Overall, adherence to capecitabine was high with a conviction that the therapy is necessary. However, concerns were expressed regarding the long-term effect of capecitabine use. Patients have unmet information needs regarding interactions of capecitabine with other medicines and the impairment of their intimate life.

CONCLUSIONS

In order to ensure adherence to capecitabine, our results seem to encourage the default use of modern and perhaps more impersonal means of information brokerage (eg, email, internet). However, the contents of some of patients' informational needs as well as the associations of patients' beliefs and satisfaction about the information received suggest a benefit from a trustful patient-doctor relationship.

Self-Reported Adherence to Capecitabine on XELOX Treatment as Adjuvant Therapy for Colorectal Cancer

Adherence has become an important issue in modern oncology treatment. Most studies have included heterogeneous target tumor types, regimens, and therapy settings. Our study focused on capecitabine during capecitabine plus oxaliplatin (XELOX) treatment as an adjuvant therapy for colorectal cancer. The main aims of this study were to evaluate real-life adherence to capecitabine and to investigate candidate factors that might decrease adherence. We studied 338 consecutive patients who received XELOX treatment between December 1, 2011, and April 30, 2015, at the Cancer Institute Hospital of the Japanese Foundation for Cancer Research. Our study assessed adherence to capecitabine through patient-reported treatment diaries and interviewed nonadherents to determine the reasons for not taking capecitabine at a pharmaceutical outpatient clinic. We calculated the adherence rate in a cycle as: number of times the patient took capecitabine/28. Relative dose intensities and factors associated with deteriorating adherence to capecitabine were retrospectively surveyed from electronic patient records. Uni- and multivariate logistic regression analyses were used to investigate factors associated with optimal adherence. The study covered 282 patients who received 2,055 cycles of XELOX. Median adherence rate was 94.0% in the first cycle, and median relative dose intensity of capecitabine was 77.8%. The most common reasons for nonadherence were nausea/vomiting and diarrhea. The presence of the following factors was not significantly associated with adherence: ECOG performance status ≥1 (p = 0.715), clinical stage (p = 0.408), primary tumor site (p = 0.576), age ≥70 years at study entry (p = 0.757), female gender (p = 0.504), and not living alone (p = 0.579). The adherence rate from this study was significantly higher than the adherence from metastatic settings. Adherence-enhancing interventions for capecitabine in XELOX treatment as adjuvant therapy comprised management of nausea/vomiting and diarrhea.

Medication adherence: A practical measurement selection guide using case studies

OBJECTIVES

Medication adherence is a complex problem and can be evaluated using a variety of methods. There is no single or perfect strategy to assess adherence. The "best" measure depends on contextual factors. Our objective is to provide a practical, illustrative guide for selecting the most appropriate measure of medication adherence in common contexts.

METHODS

We present three case studies - from the perspectives of an academic researcher, health care payer, and clinical care provider - to describe common problems and processes for measuring medication adherence, as well as proposing possible solutions.

RESULTS

The most appropriate measure will depend on the context (tightly controlled clinical trial setting vs. clinical setting), intended purpose (research vs. clinical), available resources (data, personnel, materials, and funding), time (quick screening vs. comprehensive review), and phase of interest (initiation, implementation, or discontinuation). Framing the problem of medication non-adherence and methods for measuring adherence are discussed using three representative case studies.

CONCLUSIONS

A simple tool is provided that may help stakeholders interested in medication adherence make decisions regarding the appropriate selection of measures.

PRACTICE IMPLICATIONS

A medication adherence measure should be selected through the lens of each situation's unique objectives, resources, and needs.

Adherence with capecitabine: A population-based analysis based on prescription refill data

Background

Patient adherence is important with the increasing use of oral anticancer drugs. Recent studies reported different capecitabine adherence rates based on self-reporting and microelectronic monitoring of the medication bottle. Patient’s awareness of being monitored may confound these results. Prescription records provide a larger and more objective dataset for adherence investigation. We report the use of computer algorithm and manual review of prescription and medical documentation to determine the rate of capecitabine adherence.

Methods

Two years of capecitabine prescription records from five ambulatory cancer centres were reviewed. Prescription data were extracted using a custom Java-based software tool to compare the predicted vs. actual dispensing date. The difference between the dates was the primary adherence measure (altered treatment date incident) and estimated using a computer algorithm and by manual review of medical charts.

Results

Of 4412 refill prescriptions, 45.2% was associated with an altered treatment date incident based on the initial computer algorithm. This was reduced to 29.5% after adjusting for clinic scheduling processes and 10.2% after manual chart review to adjust for valid reasons for delay. The reasons for altered treatment date incident were not identified in 52.2% of prescriptions.

Conclusions

Adherence rate of capecitabine based on refill data seem to be high and consistent with other findings based on patient self-report. Population analysis of prescription data with custom computer algorithm may identify trends in capecitabine adherence with some efficiency. Manual review would likely be required to verify these results. The accuracy of using altered prescription refill dates as an adherence measure requires further studies.