biostudies-literatureOsanlou RMedical Research Councile055551https://www.ebi.ac.uk/biostudies/studies/S-EPMC9255409biostudies-literatureUnknown12(7)<h4>Objective</h4>To ascertain the burden and associated cost of adverse drug reactions (ADRs), polypharmacy and multimorbidity through a prospective analysis of all medical admissions to a large university teaching hospital over a 1-month period.<h4>Design</h4>Prospective observational study.<h4>Setting</h4>Liverpool University Hospital Foundation National Health Service (NHS) Trust, England.<h4>Participants</h4>All medical admissions with greater than 24-hour stay over a 1-month period.<h4>Main outcome measures</h4>Prevalence of admissions due to an ADR and associated mortality, prevalence and association of multimorbidity and polypharmacy with ADRs, and estimated local financial cost of admissions where an ADR was a contributing or main reason for admission with projected costs for NHS in England.<h4>Results</h4>There were 218 identified patient admissions with an ADR giving a prevalence of 18.4%. The majority of these (90.4%) were ADRs that directly resulted in or contributed to admission. ADRs thus accounted for 16.5% of total admissions. Those with an ADR were on average taking more medicines (10.5 vs 7.8, p<0.01) and had more comorbidities than those without an ADR (6.1 vs 5.2, p<0.01). Drugs most commonly implicated were diuretics, steroid inhalers, anticoagulants and antiplatelets, proton pump inhibitors, chemotherapeutic agents and antihypertensives. 40.4% of ADRs were classified avoidable or possibly avoidable. The mortality rate due to an ADR was 0.34%. The average length of stay for those with an ADR was 6 days. Direct 1-month cost to the Trust from ADR admissions was £490 716. Extrapolated nationally, the projected annual cost to the NHS in England is 2.21 billion.<h4>Conclusion</h4>The local prevalence of admission and mortality from ADRs is higher than previously reported. Important factors that could be contributing to this include polypharmacy and multimorbidity. ADRs place a significant burden on patients and healthcare services with associated financial implications. Reducing inappropriate polypharmacy should be a major aim for preventing ADRs.BMJ openAdverse drug reactions, multimorbidity and polypharmacy: a prospective analysis of 1 month of medical admissions.PMC9255409MR/L006758/1Burnside GWalker LHughes DAPirmohamed MOsanlou RfalseAdverse drug reactions, multimorbidity and polypharmacy: a prospective analysis of 1 month of medical admissions.<h4>Objective</h4>To ascertain the burden and associated cost of adverse drug reactions (ADRs), polypharmacy and multimorbidity through a prospective analysis of all medical admissions to a large university teaching hospital over a 1-month period.<h4>Design</h4>Prospective observational study.<h4>Setting</h4>Liverpool University Hospital Foundation National Health Service (NHS) Trust, England.<h4>Participants</h4>All medical admissions with greater than 24-hour stay over a 1-month period.<h4>Main outcome measures</h4>Prevalence of admissions due to an ADR and associated mortality, prevalence and association of multimorbidity and polypharmacy with ADRs, and estimated local financial cost of admissions where an ADR was a contributing or main reason for admission with projected costs for NHS in England.<h4>Results</h4>There were 218 identified patient admissions with an ADR giving a prevalence of 18.4%. The majority of these (90.4%) were ADRs that directly resulted in or contributed to admission. ADRs thus accounted for 16.5% of total admissions. Those with an ADR were on average taking more medicines (10.5 vs 7.8, p<0.01) and had more comorbidities than those without an ADR (6.1 vs 5.2, p<0.01). Drugs most commonly implicated were diuretics, steroid inhalers, anticoagulants and antiplatelets, proton pump inhibitors, chemotherapeutic agents and antihypertensives. 40.4% of ADRs were classified avoidable or possibly avoidable. The mortality rate due to an ADR was 0.34%. The average length of stay for those with an ADR was 6 days. Direct 1-month cost to the Trust from ADR admissions was £490 716. Extrapolated nationally, the projected annual cost to the NHS in England is 2.21 billion.<h4>Conclusion</h4>The local prevalence of admission and mortality from ADRs is higher than previously reported. Important factors that could be contributing to this include polypharmacy and multimorbidity. ADRs place a significant burden on patients and healthcare services with associated financial implications. Reducing inappropriate polypharmacy should be a major aim for preventing ADRs.2022-01-01T00:00:00Z2022 Jul2025-04-04T12:40:39.371Z2025-04-04T12:40:39.371ZS-EPMC92554093578807110.1136/bmjopen-2021-055551