Background: Inappropriate polypharmacy is a particular concern in older people and is associated with negative health outcomes. Choosing the best interventions to improve appropriate polypharmacy is a priority, so that many medicines may be used to achieve better clinical outcomes for patients. This is the third update of this Cochrane Review.

Objectives: To assess the effects of interventions, alone or in combination, in improving the appropriate use of polypharmacy and reducing medication-related problems in older people.

Search methods: We searched CENTRAL, MEDLINE, Embase, CINAHL and two trials registers up until 13 January 2021, together with handsearching of reference lists to identify additional studies. We ran updated searches in February 2023 and have added potentially eligible studies to 'Characteristics of studies awaiting classification'.

Selection criteria: For this update, we included randomised trials only. Eligible studies described interventions affecting prescribing aimed at improving appropriate polypharmacy (four or more medicines) in people aged 65 years and older, which used a validated tool to assess prescribing appropriateness. These tools can be classified as either implicit tools (judgement-based/based on expert professional judgement) or explicit tools (criterion-based, comprising lists of drugs to be avoided in older people).

Data collection and analysis: Four review authors independently reviewed abstracts of eligible studies, and two authors extracted data and assessed the risk of bias of the included studies. We pooled study-specific estimates, and used a random-effects model to yield summary estimates of effect and 95% confidence intervals (CIs). We assessed the overall certainty of evidence for each outcome using the GRADE approach.

Main results: We identified 38 studies, which includes an additional 10 in this update. The included studies consisted of 24 randomised trials and 14 cluster-randomised trials. Thirty-six studies examined complex, multi-faceted interventions of pharmaceutical care (i.e. the responsible provision of medicines to improve patients' outcomes), in a variety of settings. Interventions were delivered by healthcare professionals such as general physicians, pharmacists, nurses and geriatricians, and most were conducted in high-income countries. Assessments using the Cochrane risk of bias tool found that there was a high and/or unclear risk of bias across a number of domains. Based on the GRADE approach, the overall certainty of evidence for each pooled outcome ranged from low to very low. It is uncertain whether pharmaceutical care improves medication appropriateness (as measured by an implicit tool) (mean difference (MD) -5.66, 95% confidence interval (CI) -9.26 to -2.06; I(2) = 97%; 8 studies, 947 participants; very low-certainty evidence). It is uncertain whether pharmaceutical care reduces the number of potentially inappropriate medications (PIMs) (standardised mean difference (SMD) -0.19, 95% CI -0.34 to -0.05; I(2) = 67%; 9 studies, 2404 participants; very low-certainty evidence). It is uncertain whether pharmaceutical care reduces the proportion of patients with one or more PIM (risk ratio (RR) 0.81, 95% CI 0.68 to 0.98; I(2) = 84%; 13 studies, 4534 participants; very low-certainty evidence). Pharmaceutical care may slightly reduce the number of potential prescribing omissions (PPOs) (SMD -0.48, 95% CI -1.05 to 0.09; I(2) = 92%; 3 studies, 691 participants; low-certainty evidence), however it must be noted that this effect estimate is based on only three studies, which had serious limitations in terms of risk of bias. Likewise, it is uncertain whether pharmaceutical care reduces the proportion of patients with one or more PPO (RR 0.50, 95% CI 0.27 to 0.91; I(2) = 95%; 7 studies, 2765 participants; very low-certainty evidence). Pharmaceutical care may make little or no difference to hospital admissions (data not pooled; 14 studies, 4797 participants; low-certainty evidence). Pharmaceutical care may make little or no difference to quality of life (data not pooled; 16 studies, 7458 participants; low-certainty evidence). Medication-related problems were reported in 10 studies (6740 participants) using different terms (e.g. adverse drug reactions, drug-drug interactions). No consistent intervention effect on medication-related problems was noted across studies. This also applied to studies examining adherence to medication (nine studies, 3848 participants).

Authors' conclusions: It is unclear whether interventions to improve appropriate polypharmacy resulted in clinically significant improvement. Since the last update of this review in 2018, there appears to have been an increase in the number of studies seeking to address potential prescribing omissions and more interventions being delivered by multidisciplinary teams.