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Care of the older person
Learn, recognise and prevent adverse drug reactions/events in elderly hospitalised patients
  1. Kishore Karri1,
  2. Pradeep Yarra2
  1. 1 Department of Medicine, University of Kentucky, Lexington, Kentucky, USA
  2. 2 Internal Medicine, University of Kentucky, Lexington, Kentucky, USA
  1. Correspondence to Dr Pradeep Yarra, Internal Medicine, University of Kentucky, Lexington, KY 40506, USA; pya227{at}

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Commentary on: Jennings ELM, Murphy KD, Gallagher P, O'Mahony D. In-hospital adverse drug reactions in older adults; prevalence, presentation and associated drugs-a systematic review and meta-analysis. Age Ageing. 2020;49(6):948–958. doi:10.1093/ageing/afaa188

Implications for practice and research

  • Adverse drug reactions (ADRs) are highly prevalent in hospitalised older patients, caused by commonly used drugs and present as clinical scenarios seen in daily clinical practice.

  • Future research should focus on standardisation of ADR ascertainment and assessment, hopefully leading to reporting of patient-related health outcomes.


WHO defines an adverse drug reaction (ADR) as a response to a medicine which is noxious and unintended, and which occurs at doses normally used in man and adverse drug event or experience (ADEs) as any untoward medical occurrence that may present during treatment with a medicine but which does not necessarily have a causal relationship with this treatment.1 ADRs and ADEs represent a significant proportion of older adult acute hospital admissions (8.7%–16.6%) likely resulting in higher costs and increase in length of stay.2 Evidence shows that older, hospitalised patients are at higher risk of ADRs, yet a dedicated pooled estimate of ADR prevalence is lacking. Jennings et al tried to identify common clinical presentations, causative medications and estimated prevalence of hospital-acquired ADRs from recent literature.3


Jennings et al performed a systematic review and meta-analysis of studies on ADRs in a population aged ≥65 years and reported ADRs or ADEs from PubMed, CINAHL, Cochrane and Embase since inception. Twenty-seven studies (2 randomised control trials and 2 retrospective and 23 prospective observational studies) have been included in a final qualitative synthesis with a combined total of 128 580 participants who met the inclusion criteria. Statistical outcomes were prevalence of ADRs, clinical presentations, causative drugs, polypharmacy, baseline multimorbidity and ADRs outcomes. Random effects model was used for assessing prevalence; linear mixed effects models were used for meta-analysis; and heterogenicity was addressed by sensitivity analysis.


Pooled proportion of ADR prevalence was 16% (95% CI 12% to 22%, I 2 98% and n=20 153 ADRs) but with substantial heterogenicity. Approximately 1 in 6 older adults experienced ADRs during hospitalisation, including 2479 patients who experienced ≥1 ADR, and 20 variable clinical presentations from 16 routinely prescribed medications accounted for 90% of ADRs. Most common clinical presentation was fluid/electrolyte disturbances (17.3%) followed by gastrointestinal motility/defecation, renal, hypotension/blood pressure dysregulation disorders/shock and delirium. Four drug classes accounted for 58% of causative medications, that is, diuretics (19.8%), antibacterial (14.8%), antithrombotic agents (12.2%) and analgesics (10.9%). Pooled analysis of severity was not feasible. Clinical outcomes like mortality and/or length of stay was poorly reported. Four studies reported the majority of ADRs as preventable (55%–95%).


This study investigated hospital-acquired ADRs, specifically in older adults, and observed pooled prevalence of 16% ADRs during hospitalisation but with significant heterogenicity in study reporting. Although there were limitations due to differences in reporting of ADRs in studies, with most studies being prospectively observational, leading to risk of reporting bias, these findings provide focus with some specific targets for future studies. Most common clinical presentations of ADRs like fluid/electrolyte disturbances, gastrointestinal and renal can be diverse and difficult to differentiate from chronic diseases in older populations. This complexity and heterogenicity of ADRs can lead to misinterpretation by practitioners of these clinical presentations and can lead to misreporting or under-reporting.

Further complicating these clinical pictures, which practitioners should be aware, are the common causative agents. Based on analysis by Jennings et al, diuretics, which are commonly used for cardiovascular conditions followed by antibiotics, antithrombotic agents and analgesics were attributed to cause ADRs in hospitalised older patients. Non-steroidal anti-inflammatory drugs (NSAIDs) commonly contributed to ADRs among outpatients in analysis by Oscanoa et al, whereas this study showed only 1.68% of ADRs were by NSAIDs.2 3 All these medications are commonly used in older populations, and this study focuses on outlining them for practising physicians. Similar to Gray et al, significant heterogenicity was noted in analysis, relating to variance in the studies included, which spanned over many decades, heterogenous populations, differing ADR assessment methodologies and reporting.4 Nevertheless, considering the high proportion of hospitalised older adults experiencing ADRs, this study outlines common presentations and causative drugs, and confirms the need for prediction and/or prevention of ADRs. Future research should also focus on developing internationally standardised ADR assessment methodology for better quality of reporting and facilitate means for meaningful patient-related health outcomes.



  • Competing interests None declared.

  • Provenance and peer review Commissioned; internally peer reviewed.