DISCUSSION
The participants in all included studies had a high prevalence of polypharmacy (mean number of medications ranged from 4.6 to 23.2 [SD 4.7]), multimorbidity, and use of PIMS. The studies were heterogenous with regards to how medication count was captured. Some studies incorporated ‘when required (pro re nata, PRN) ’ medications or self-prescribed (over-the-counter) medications. Pill burden (as assessed by a living with medicines questionnaire) and tablet count was examined in one study.36 The definition of polypharmacy was consistent between studies with five or more medicines classified as polypharmacy. The mean number of medications for study participants varied between settings, with medication load being highest for individuals attending the heart-failure clinic and renal dialysis units.35,38 Polypharmacy and increase in pill burden has previously been associated with reduced compliance and quality of life scores in dialysis patients50 and negative medication interactions in heart-failure patients.51 A high medication burden was also notable for oncology patients ≥65 years, where polypharmacy and use of PIM is associated with an increased risk of postoperative complications, lower adherence to medication, and increased chemotherapy toxicity.52
The prevalence of PIM use between settings varied from 55% to 100% of patients depending on the assessment tools used.26,34It is known that the sole use of explicit tools such as Beers or STOPP is insufficient to address all medication concerns. Use of a combination of three validated instruments (STOPP, Beers, and MAI) was found to be superior and identified significantly more PIMS than a single instrument alone when reviewed in the oncology setting.34 Another recent study in an oncology unit noted that while 46% of patients were identified as taking a PIM using Beers criteria, the number of patients identified with ‘drug-related problems’ was 95%.53‘Drug related problems’ not revealed using explicit tools may include under treatment, dosing concerns, lack of monitoring, and compliance with therapy. It should be noted that adverse drug-reactions may also occur with so called ‘appropriate medications’; anticoagulants, antiplatelets, and antidiabetics (both oral and insulin) have been found to be more frequently implicated in hospital admissions, than the usual ‘medications to avoid’ lists.54 Thus, accurately assessing the medication burden and appropriateness of medication for each individual is a complicated process.
The identified studies could be grouped into those where the deprescribing intervention was physician-led and implemented, delivered from a multidisciplinary team with pharmacist support, or pharmacist-led, physician implemented.