This systematic review shows that hospitalisation can serve as an important opportunity for improving QUM in older adults, but that this potential is inconsistently realised in routine practice. Approximately half of the included studies demonstrated meaningful improvement in at least one QUM indicator between admission and discharge, while the remainder showed persistent or increased medication-related risks at discharge.

Studies that reported improvements in QUM shared several features. Medication-related concerns were identified early in the admission, through structured medication reconciliation and formal medication review, resulting in up to 49% of errors being corrected before discharge [6, 9, 30, 34, 42]. Multidisciplinary collaboration particularly involving geriatricians and clinical pharmacists was central, and QUM processes were documented systematically using validated tools and standardised forms. Hospitalisation functioned as a meaningful stage to reassess complex regimens, discontinue PIMs, optimise anticoagulant and psychotropic therapy, and align treatment with guideline recommendations and patient goals [6, 30, 34, 37, 42]. This is consistent with previous literature which shows hospitalisation provides a feasible opportunity to reassess medicines, and rationalise and initiate deprescribing of PIMs, with the availability of specialty services to conduct a comprehensive review to improve patient outcomes and reduce healthcare costs [52,53,54,55].

By contrast, where QUM activities were less structured or inconsistently implemented, hospitalisation did not reliably improve prescribing. In some cohorts, patients with initially appropriate therapy were discharged on suboptimal regimens, illustrating that hospitalisation can introduce new risks when decisions are made under time pressure, with incomplete information or without robust review processes [8, 30, 32, 33].

Across studies, several patient, clinician, and system-level factors were associated with persistent or worsening QUM issues, with limited discussion on barriers to sustainability of QUM. At the clinician level, variability in knowledge, attitudes, and confidence influenced prescribing decisions [9, 33, 40]. Reluctance to modify regimens initiated by other physicians, concerns about adverse effects or withdrawal symptoms, and limited familiarity with deprescribing principles and QUM tools contributed to continued use of high-risk medications, including drugs for conditions such as GORD with no clear indication [6, 8, 9, 30,31,32,33, 38, 40, 42, 44, 45]. Long-term PPI therapy initiated for short-term indications, or sedatives started for agitation or insomnia without clear plans for review, were common examples of hospital-initiated PIMs that persisted beyond discharge [32, 42, 44, 45]. International initiatives such as the US Deprescribing Research Network and Canadian deprescribing resources provide important frameworks for advancing deprescribing in practice through the development of evidence-based tools, implementation strategies, and evaluation frameworks [56, 57]. These align with the WHO Global Patient Safety Challenge: Medication Without Harm, which emphasises reducing medication-related harm through safer prescribing, improved monitoring, and enhanced communication, particularly during transitions of care [1].

System-level factors included under-resourced teams with high workload and time pressure, inconsistent availability of clinical pharmacists, and fragmented communication between physicians [6, 19,20,21, 31, 58]. This is consistent with barriers outlined in previous research [21, 22, 58]. In several studies, incomplete or inconsistent documentation of indications, monitoring plans, and medication changes hindered continuity of care [7,8,9, 30, 31, 36, 42, 44, 45]. Similarly, the lack of integrated electronic systems linking inpatient prescribing with outpatient and primary care records also contributed to missed opportunities for review and rationalisation of chronic therapies [6, 33, 39]. The role of EHRs in facilitating deprescribing and QUM activities was not consistently described in the included studies. EHRs have the potential to support structured medication reviews through clinical decision support systems, prompts for identifying PIMs, and improved documentation and communication at discharge [6]. Greater integration and reporting of digital health-enabled interventions may strengthen future efforts to optimise medication use and sustain deprescribing practices across healthcare settings [33].

Meaningful QUM improvements were achieved through integrated systematic medication reconciliation at admission, structured pharmacist review for high-risk patients, comprehensive geriatric assessment, and pre-discharge planning that explicitly addressed medications [6, 9, 30, 33,34,35, 37, 40]. Where these processes were documented in a consistent and accessible way, inappropriate prescribing and PIM prevalence were more likely to decline during hospitalisation.

Geriatric-focused care emerged as a key factor reflecting the influence of specialist expertise and focused risk–benefit assessment. Admission to geriatric or specialised units such as neurology or cardiology, and the use of comprehensive geriatric assessment, were consistently associated with more appropriate prescribing, including both deprescribing of unnecessary or potentially harmful medications and optimisation of underused guideline-recommended medications [6, 9, 33, 35, 37, 40, 42]. This is consistent with findings from previous research [54, 59].

Almost half of the studies acknowledged and supported the crucial integration of pharmacists into the multidisciplinary team to optimise QUM [6, 8, 10, 35,36,37, 39,40,41,42]. A systematic review by Mueller et al. (2012) showed that up to one-third of all medication discrepancies at admission or discharge have the potential to cause patient harm [16]. Clinical pharmacists participated in admission workflow processes, ward rounds and discharge planning to identify drug-related problems, reconcile medications across care transitions, enhance deprescribing, and communicate therapy changes, including the rationale to patients and primary care providers [6, 10, 35, 40, 42]. This is consistent with previous research [60,61,62,63]. The routine use of extensively validated explicit QUM tools, such as Beers criteria [46], STOPP/START [47], EU-PIM [48], or NORGEP [49], provided a structured framework for systematically identifying PIMs and PPOs, and for supporting collaborative discussion of changes. Elements such as structured documentation and communication, including standardised medication review notes, clear discharge summaries, and consistent recording of medication changes assist in reducing discrepancies between inpatient medication charts and discharge prescriptions, thereby supporting continuity of care and improved patient goals [6, 33, 39].

For hospitalisation to serve as an opportunity to improve QUM in older adults, QUM activities need to be embedded as core components of routine care, rather than treated as add-ons or time-limited projects. There is limited literature demonstrating that hospitalisation leads to consistent improvements in QUM among older adults. Several studies report persistent rates of PIMs, polypharmacy, and prescribing errors at discharge, suggesting that usual care provided in hospital does not always optimise medication regimens [7, 8, 31, 33, 35, 36, 39]. This inconsistency highlights a critical gap in current practice for implementing and evaluating interventions. Previous research has demonstrated interventions, such as an increase in pharmacist involvement within a multidisciplinary team, can improve drug-related problems by enhanced uptake of drug recommendations, management of adverse drug events, and improved appropriateness of prescribing and quality of life for patients [60, 62,63,64].

Medication reconciliation at admission and discharge should be standard practice with high-risk patients, such as those with frailty, polypharmacy, multimorbidity, anticoagulant therapy, or a history of falls prioritised for comprehensive pharmacist review [6, 8, 10, 31, 33,