articleSelf-reported medication side effects in an older cohort living independently in the community-the Melbourne Longitudinal Study on Healthy Ageing ( MELSHA ) : cross-sectional analysis of prevalence and risk factors

Background: Medication side effects are an important cause of morbidity, mortality and costs in older people. The aim of our study was to examine prevalence and risk factors for self-reported medication side effects in an older cohort living independently in the community. Methods: The Melbourne Longitudinal Study on Healthy Ageing (MELSHA), collected information on those aged 65 years or older living independently in the community and commenced in 1994. Data on medication side effects was collected from the baseline cohort (n = 1000) in face-to-face baseline interviews in 1994 and analysed as crosssectional data. Risk factors examined were: socio-demographics, health status and medical conditions; medication use and health service factors. Analysis included univariate logistic regression to estimate unadjusted risk and multivariate logistic regression analysis to assess confounding and estimate adjusted risk. Results: Self-reported medication side effects were reported by approximately 6.7% (67/1000) of the entire baseline MELSHA cohort, and by 8.5% (65/761) of those on medication. Identified risk factors were increased education level, co-morbidities and health service factors including recency of visiting the pharmacist, attending younger doctors, and their doctor's awareness of their medications. The greatest increase in risk for medication side effects was associated with liver problems and their doctor's awareness of their medications. Aging and gender were not risk factors. Conclusion: Prevalence of self-reported medication side effects was comparable with that reported in adults attending General Practices in a primary care setting in Australia. The prevalence and identified risk factors provide further insight and opportunity to develop strategies to address the problem of medication side effects in older people living independently in the community setting. Background Medication side effects also referred to as adverse drug reactions (ADRs) and/or adverse drug events (ADEs) are potentially associated with all medications and include side effects listed in product information, as well as medication-related side effects due to interactions, non-compliance [1,2], prescribing errors [3] and allergic reactions [4]. Medication side effects are an important cause of morbidity, mortality, costs [5-16], and dissatisfaction with care [16]. Prevalence of medication side effects depends on the surveillance system and setting [17]. Surveillance systems vary in case definitions, case finding, and the duration of monitoring [14]. Mostly, medication side effects have been examined in inpatient hospital settings and to a lesser extent in hospital outpatient or ambulatory clinic settings by chart review and self report. Information on medication side effects in the community is more limited and is mostly provided by national surveillance systems * Correspondence: jennifer.thomson@med.monash. edu.au 1 School of Primary Health Care, Monash University, Melbourne, Australia Full list of author information is available at the end of the article © 2010 Thomson et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Thomson et al. BMC Geriatrics 2010, 10:37 http://www.biomedcentral. com/1471-2318/10/37 Page 2 of 11 that rely on voluntary reporting and lack denominator data. Similarly, potential risk factors for medication side effects have been examined mostly in hospital inpatient or outpatient or ambulatory clinic settings. The most consistently identified risk factors include older age, female gender, increasing number of medications, and increasing number of medical conditions/co-morbidities as well as specific co-morbidities [13,14,16,18]. Other risk factors include those related to compliance, comprehension and general patient knowledge, types of medications (in hospital settings such medications include antibiotics, anti-coagulants, digoxin, diuretics, hypoglycaemic, NSAIDs, chemotherapeutics, other cardiovascular medications and analgesics), hospitalisations, medical knowledge, multiple treating doctors, and multiple filling pharmacies [18-20]. Data from the 1994 Melbourne Longitudinal Study on Healthy Ageing (MELSHA) baseline cohort, offers a unique opportunity to examine prevalence and risk factors for self-reported medication side effects in an older cohort aged 65 years and over living independently in the community. Methods Study Design The Melbourne Longitudinal Study on Healthy Ageing (MELSHA) is a prospective cohort study initiated in 1994. A cross sectional analysis was conducted on data collected at baseline in 1994. MELSHA was approved by the Human Ethics Committees of Latrobe University and Melbourne University.