Role of Pharmacists in enhancing medication adherence in chronic disease patients :A review

Chronic non-communicable diseases such as hypertension, type 2 diabetes mellitus, dyslipidemia, chronic kidney disease, chronic obstructive pulmonary disease, and psychiatric disorders  accounts for the majority of the global morbidity and mortality. Effective management of these conditions typically requires lifelong pharmacotherapy and the benefits of treatment are only realized when patients take their medications largely as prescribed. According to the World Health Organization, adherence to long-term therapy for chronic illness averages approximately 50% in developed countries and in developing countries the rate are even lower¹. .The gap between prescribed and actual medication taking behavior is widely regarded as one of the most under recognized contributors to poor disease control among worldwide.

The consequences of poor adherence goes beyond the individual patient. Non-adherence is associated with disease progression, avoidable hospitalizations and premature mortality and it imposes a substantial economic burden on healthcare systems through increased inpatient, outpatient and emergency care costs because pharmacists are typically the most accessible and most frequently visited healthcare professionals for patients on long term therapy and they are uniquely positioned to identify non adherence early and intervene before it results in clinical changes^5,28.

The conceptual foundation for this expanded pharmacist role wasintroduced by Hepler and Strand in 1990² through the philosophy of pharmaceutical care  defined as the responsible provision of drug therapy for the purpose of achieving proper outcomes that improve a patient's quality of life. This shift reoriented pharmacy practice away from a purely product and dispensing centered function toward a patient centered, outcomes oriented one  in which the pharmacists actively identify, resolve and prevent drugrelated problems including the problems of medication adherence.

Over the past two decades, a substantial body of evidence has accumulated evaluating the effectiveness of pharmacist-led interventions ranging from simple counseling to structured medication therapy management, adherence oriented packaging and telepharmacy in improving medication-taking behavior across a range of chronic disease conditions. This review aims to synthesize this evidence, describe the principal types of pharmacist led interventions and the tools used to measure their effect and summarize disease-specific outcomes, discuss the economic implications of non-adherence, and outline the barriers that continue to limit the scale-up of pharmacist led adherence services with particular attention to implications for practice in resource limited settings such as India

From Dispensing to Pharmaceutical Care: The Evolving Role of the Pharmacist

Mainly the pharmacists role is centered on the accurate dispensing of medications. The pharmaceutical care movement initiated by Hepler and Strand redefined this role around direct responsibility for a patient's drug-related needs including the prevention and resolution of drug therapy problems such as non-adherence. In parallel, professional bodies worldwide have progressively expanded the scope of community and clinical pharmacy practice to include medication reviews, chronic disease monitoring, and collaborative prescribing arrangements. Despite this the studies continue to find that pharmaceutical care services, including structured adherence support  are inconsistently implemented in routine community pharmacy practice  with gaps particularly evident in follow-up, documentation and interprofessional

communication^8,49.This gap between the stated philosophy of pharmaceutical care and its everyday implementation underscores the continued relevance of reviewing what pharmacist led adherence interventions actually achieve in practice.

Types of Pharmacist-Led Interventions to Improve Medication Adherence

Pharmacist-led adherence interventions can be broadly grouped into several categories , patient counseling and education, medication therapy management, medication synchronization , adherence packaging, telephonic and reminder-based follow-up, telepharmacy and digital health tools, behavioral interventions, and interprofessional collaboration³. A recent systematic review classified interventions across 26 randomized controlled trials into counseling (53.8%), tailored interventions (26.9%), technology based monitoring (3.85%), and multiple/combined interventions (15.4%), of which 69.2% demonstrated a significant positive association with medication adherence⁴.

1.Patient Counseling and Education

Patient counseling and education is face to face counseling which remains as the most frequently studied and most commonly implemented pharmacist led adherence intervention. Counseling typically addresses disease and medication knowledge, correction of misconceptions, side-effect management and practical strategies for incorporating medication taking into daily routines. In a multifactorial pharmacist-led intervention protocol combining face-to-face counseling, patientspecific medication booklets, and a mobile application in patients with type 2 diabetes in the United Arab Emirates, the intervention group showed significantly greater improvement in composite medication possession ratio at 12 months compared with usual care¹³. Similarly, a collaborative pharmacist-psychiatrist patient education intervention in patients with depression in India produced statistically significant improvements in both medication adherence and health related quality of life compared with usual care¹⁶.

2. Medication Therapy Management (MTM)

Medication therapy management involves a comprehensive structured review of a patients complete medication regimen to identify and resolve drug-related problems  including medication adherence barriers. In an analysis of 59 studies comprising over 28,000 patients medication therapy management was associated with the greatest improvement in adherence among all intervention types examined (odds ratio 2.89), followed by telephonic follow-up (odds ratio 2.41) and patient counseling (odds ratio 2.18), with the largest benefit observed in hypertension and diabetes groups⁶.

3. Medication Synchronization and Adherence Packaging

Clarifying complex regimens through medication synchronization, unit-dose or blister packaging, and pill organizers reduces the cognitive and logistical burden of daily medication-taking, particularly in patients with polypharmacy. Older adults prescribed multiple medications commonly experience adherence difficulties related to regimen complexity and pilot studies of community pharmacy delivered, theory guided interventions that combine adherence-barrier identification with tailored solutions including packaging and reminder aids have demonstrated feasibility for improving adherence in this population^18,37.

4. Telephonic Follow up and Reminder Based Interventions

Structured telephone follow up calls and reminder systems including text-message and application based reminders  allow pharmacists to actively identify emerging non adherence between clinic or pharmacy visits. In a randomized controlled trial among Vietnamese patients with asthma, pharmacist led interventions addressing individualized non adherence reasons, disease and device education  and reminder strategies produced significant improvements in adherence relative to usual care⁵².

5. Telepharmacy and Digital Health Tools

Telepharmacy mainly include remote prescription verification, virtual counseling and digital adherence monitoring has expanded rapidly particularly for patients in geographically underserved areas. Retrospective analysis of a multicomponent digital therapeutic mobile application incorporating gamification, dosage reminders, incentives, and educational content found sustained improvements in adherence rates among adults with chronic conditions over both three and sixmonth follow up periods⁴⁰. Similarly, a telepharmacy based adherence service delivered through a mobile application platform showed a positive association between telepharmacy use and medication adherence, measured using the Morisky Medication Adherence Scale, among chronic disease patients^41,44. While digital tools offer adaptability their integration into routine pharmacy workflows continues to be constrained by regulatory uncertainity and reimbursement

barriers^38,39.

6 .Tailored and Behavioral Theory Based Interventions

Interventions that identify each patient's specific, individualized barriers to adherence rather than applying a uniform counseling script appear to produce more consistent benefit than generic education alone. A cluster randomized controlled trial in Indonesia targeted only patients with type 2 diabetes who reported non-adherence to antihypertensive therapy, delivering interventions tailored to each patient's specific adherence barriers rather than a standardized message¹⁵. Likewise, a behavioral-theory-based New Medicine Service toolkit developed for community pharmacists in Türkiye was designed around the Theoretical Domains Framework to systematically identify and address individual reasons for non-adherence to newly prescribed cardiometabolic medications⁴³.

7.Interprofessional Collaboration

Pharmacists increasingly work alongside physicians, community health workers, and other healthcare professionals to support adherence. A systematic review of interprofessional collaboration between pharmacists and community health workers found that combined interventions could extend the reach of adherence support, particularly in resource-limited and rural settings⁴⁶. Primary care physicians themselves have identified closer collaboration with pharmacists as a desirable strategy for addressing the adherence challenges they encounter in everyday practice³¹.

Tools Used to Measure Medication Adherence

Accurate measurement of adherence is essential to evaluating the effectiveness of pharmacist-led interventions, yet no single method is considered as a gold standard. Adherence measurement approaches are broadly classified as subjective (self-report questionnaires) or objective (pharmacy refill data, pill counts, electronic monitoring). The 8-item Morisky Medication Adherence Scale (MMAS-8) remains among the most widely used self-report tools in pharmacist-led adherence research; a systematic review and meta-analysis of 28 validation studies found acceptable internal consistency and reproducibility in certain disease groups such as type 2 diabetes, although criterion validity at the standard cut-off score was found to be limited^20,21.Objective measures such as the Medication Possession Ratio (MPR) and Proportion of Days Covered (PDC), derived from pharmacy dispensing records, are less susceptible to social-desirability bias than self-report tools but require access to reliable refill data, which may not be available in all practice settings²². Many of the studies reviewed here used self-reported questionnaires, which likely overestimate true adherence rates²³; findings should therefore be interpreted with this limitation in mind.

Disease-Wise Summary of Pharmacist-Led Adherence Evidence

Table 1 summarizes representative randomized controlled trials and pilot studies evaluating pharmacist-led adherence interventions across major chronic disease categories, illustrating the range of intervention types, settings, and outcomes reported in the literature.

Table 1. Representative randomized controlled trials and pilot studies of pharmacist-led

interventions on medication adherence, by disease category.