Repeat Adverse Drug Reaction-Related Hospital Admissions in Elderly Australians: A Retrospective Study at the Royal Hobart Hospital

Drug treatment associated problems are common and are the cause of a large proportion of hospitalizations in old people. People with dementia are especially at risk of drug-related problems. The objectives of this study were to assess the occurrence and character of drug-related problems that lead to acute hospital admissions among old people (≥65 years) with dementia or cognitive impairment.

Recent studies show that nearly half of the hospitalized patients are readmitted within 6 months from discharge. No data exist about the relationship between adverse drug reactions (ADRs) and readmittance to a department of internal medicine. The primary aims of the study were to determine if ADRs could be used as predictors for recurrent hospitalizations in internal medicine and to evaluate the economic impact of ADRs on hospitalization costs. A cohort-based, prospective, 18-month pharmacoepidemiological survey was conducted in the Department I of Internal Medicine at the University Hospital of Erlangen. All patients were intensively monitored for ADRs by a pharmacoepidemiological team. ADRs were evaluated for their offending drugs, probability, severity, preventability and classified by WHO-ART. During a 6-month period ADR-positive patients were matched to non-ADR patients applying diagnosis-related group categorization in order to measure the impact of ADRs on the duration and frequency of hospitalization. Of 1000 admissions 424 patients had single admissions and 206 patients had recurrent readmissions (min 1, max 9). The prevalence of readmissions was 37% (n = 370). In 145 (23%) of 630 patients, 305 ADRs were observed. The ADR incidence was similar in first admissions and readmissions. ADRs were not found to predict further readmissions and lack of ADRs did not preclude readmissions. ADRs caused hospitalizations in 6.2% of first admissions and in 4.2% of readmissions. According to the Schumock algorithm 135 (44.3%) ADRs were found to be preventable. The occurrence and numbers of ADRs per admission were found to prolong hospitalization period significantly (r = 0.48 and 0.51, P 973 days) of all treatment days were judged to be preventable. Intensified drug monitoring supported by information technology in internal medicine is essential for early detecting and prevention of ADRs and saving hospital resources.

To examine trends in the rate of repeat adverse drug reactions (ADRs) causing hospitalization in older Australians and to identify the most common ADRs and drugs most often implicated in repeat and first-time ADRs. Analysis of routinely collected hospital record administrative data, with International Classification of Diseases external cause codes for ADRs extracted from the Western Australia (WA) Hospital Morbidity Data System and WA Death Register, for people aged > or =60 years in 1980-2003. A total of 37 296 people aged > or =60 years with an ADR-related hospitalization were identified. Among them, 6853 (18.4%) patients had 10 212 repeat ADRs. Repeat ADRs consistently increased from 1980 and reached 30.3% of all ADRs by 2003. The mean time interval declined with each successive repeat ADR (810, 606 and 299 days for the first, second and higher ranked repeat episodes, respectively). The most common repeat ADRs were nausea/vomiting (8.0%), haemorrhage due to anticoagulants (5.5%), drug-induced osteoporosis (4.8%) and poisoning by cardiovascular agents (3.9%). The drugs most often involved in repeat ADRs were cardiovascular agents (15.6%), antineoplastic drugs (11.0%), corticoids (10.1%), anticoagulants (8.6%), antirheumatics/nonsteroidal anti-inflammatory drugs (5.1%) and opioids (4.9%). The trends of anticoagulants and antineoplastic drugs implicated in repeat ADRs were still rising at the end of the study. The specific drug classes involved in repeat ADRs differed in relative importance from first-time ADRs. Repeat ADR-related hospitalizations have consistently increased in elderly Australians from 1980 to 2003. Strategies to ensure the safer use of medicines, in particular anticoagulants, in this population are warranted.