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Observational Study
. 2022 Jul 4;12(7):e055551.
doi: 10.1136/bmjopen-2021-055551.

Adverse drug reactions, multimorbidity and polypharmacy: a prospective analysis of 1 month of medical admissions

Rostam Osanlou  1   2 , Lauren Walker  1   2 , Dyfrig A Hughes  3 , Girvan Burnside  4 , Munir Pirmohamed  5   2
Affiliations
Observational Study

Adverse drug reactions, multimorbidity and polypharmacy: a prospective analysis of 1 month of medical admissions

Rostam Osanlou et al. BMJ Open. .

Abstract

Objective: 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.

Design: Prospective observational study.

Setting: Liverpool University Hospital Foundation National Health Service (NHS) Trust, England.

Participants: All medical admissions with greater than 24-hour stay over a 1-month period.

Main outcome measures: 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.

Results: 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.

Conclusion: 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.

Keywords: Adverse events; CLINICAL PHARMACOLOGY; HEALTH ECONOMICS; INTERNAL MEDICINE.

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Conflict of interest statement

Competing interests: None declared.

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