In the present study, DRPs and subsequent interventions were evaluated at the MTM clinic of a community pharmacy over three years. The significant impact of clinical pharmacy-based MTM services on identifying DRPs and recommendations of interventions was evident. Of all the 838 patients, 1116 DRPs were identified, with difficulty using dosage forms, desire for more information about medications, and any toxicity, allergic reaction, or adverse effect related to medications topping the list. The most common interventions included education and counseling, referral to the prescriber, and dosage recommendation. Interestingly, higher numbers of medications and underlying chronic conditions were associated with more DRPs. Finally, a specific category of diseases contributed to a higher number of DRPs. The results showed that only 11 (1.3%) patients had no DRPs. However, even these patients benefited from MTM services provided by clinical pharmacists, such as education. Additionally, both medication adherence and satisfaction regimens improved after MTM services.
Several studies have previously examined DRPs in hospitalized patients (11, 21–23); however, few data are available from regular community pharmacies (24). While we found our most common DRPs, studies with predominantly inpatient settings have shown that DRPs such as the need for a new medication or dose increase (9), suboptimal drug effect (22), and lack of therapy (25) are significant problems in inpatients. On the other hand, the most common DRPs in community pharmacies included information problems, therapeutic errors (26), drug interactions, contraindications (27), need for additional therapy, unnecessary drug therapy, and poor adherence (28). The different outcomes may be due to differences in the healthcare system, deficiencies in data documentation, and a lack of appropriate infrastructure. The finding that "seeking more information about medications" is the most common DRP indicates that many patients are not informed about their medications and treatment, underscoring the importance of pharmacists' MTM services.
Regarding the drug classes associated with the occurrence of DRPs, the results of previous studies conducted in the outpatient setting are similar. For example, the results for the alimentary tract and metabolism (29, 30), blood and hematopoietic organs, cardiovascular system, nervous system (29), and antineoplastic and immunomodulatory agents were the same. In the inpatient setting, in chronic kidney disease (CKD) clinics, cardiovascular drugs, gastrointestinal agents, and analgesics are more likely to be responsible for DRPs. In an intensive care unit, systemic antimicrobial agents are more likely to be accountable for DRPs (7, 12, 31).
Both the number of drugs and underlying chronic diseases were critical factors contributing to the rate of DRPs. Previous studies have shown that the number of medications in both outpatient and inpatient settings could significantly determine the incidence of DRPs (32). In this regard, polypharmacy is a critical factor leading to a higher risk of DRPs, necessitating a move away from the classic thresholds of 4 + or 5 + medications to a realistic linear approach (29). To address this issue and reduce the rate of preventable adverse drug events, studies have suggested the use of advanced computerized drug prescribing systems (33).
In addition, the current study results showed that the presence of some diseases was significantly related to the increased risk of DRPs, which is discussed below. In the category of endocrine disorders, more patients had diabetes mellitus who used insulin pens. They had difficulty in using their medication due to inadequate education. A prospective study showed that patients with circulatory diseases were taking more than five medications, which is a risk predictor for developing DRPs. The number of chronic diseases per patient was almost four, indicating obvious multiple morbidities (33). Visual impairment may also affect patients' taking prescribed medications (34). This is mainly because they have difficulty reading prescription labels, recognizing expiration dates, understanding the name of the drug, and keeping their medications. Of the group factors affecting health status or contact with health services for illness, most patients were those who had undergone organ transplantation. It seems that these patients are more prone to DRPs due to their polypharmacy and use of immunosuppressive drugs (35). Patients with severe mental illnesses are less likely to receive standard treatment for their comorbidities, making them more susceptible to DRPs (36).
As we showed that pharmacist-led MTM services could improve patient adherence to the treatment regimen, Daniel A. Ercu et al. also demonstrated that MTM services provided by pharmacists markedly increased medication adherence in patients with type 2 diabetes mellitus by 9.2% at baseline to 61% at six months in a prospective randomized controlled study (37). This may be because patients with chronic conditions like diabetes mellitus have complex treatment regimens, so educating and clarifying the treatment regimen can make them more adherent.
This study found that patients were more satisfied with their treatment regimen after MTM services than before. In a study conducted in a large, integrated healthcare system, 95.3% of patients agreed or strongly agreed that their overall health and well-being had improved due to pharmacist-led MTM services (8). This may be because pharmacists assume responsibility for patients’ medication therapy outcomes and collaborate with other healthcare providers to facilitate high-quality patient care (38).
This study has some limitations. First, as the data were not collected longitudinally, it does not allow us to identify causal relationships. Second, our results may differ from those of other geographic areas with different healthcare characteristics, particularly concerning domestic pharmaceutical care. Third, the diversity of patients referred to the pharmacy of the study site was high. Although this diversity was an advantage, this amount of variety in patients may not be seen in the usual community pharmacies and affect the generalizability of our results. The following limitation of the study is the non-detection of DRP by the pharmacist, especially in the case of uncommon DRPs that are also related to the pharmacist's professional experience. A standard validated DRP classification system was used in this study to minimize this.