Clinically important drug-disease interactions and their prevalence in older adults

Background: Older adults may have decreased homeostatic reserve, have multiple chronic diseases, and take multiple medications. Therefore, they are at risk for adverse outcomes after receiving a drug that exacerbates a chronic disease. Objectives: The aims of this study were to compile a list of clinically important drug-disease interactions in older adults, obtain the consensus of a multidisciplinary panel of geriatric health care professionals on these interactions, and determine the prevalence of these interactions in a sample of outpatients. Methods: This analysis included a 2-round modified Delphi survey and cross-sectional study. Possible drug-disease interactions in patients aged ≥65 years were identified through a search of the English-language literature indexed on MEDLINE and International Pharmaceutical Abstracts (1966-July 2004) using terms that included drug-disease interaction, medication errors, and inappropriate prescribing. Nine health care professionals with expertise in geriatrics (2 geriatricians, 7 geriatric clinical pharmacist specialists) were selected based on specialty training and continuing clinical work in geriatrics, academic appointments, and geographic location. The panel rated the importance of the potential drug-disease interactions using a 5-point Likert scale (from 1 = definitely not serious to 5 = definitely serious). Consensus on a drug-disease interaction was defined as a lower bound of the 95% CI ≥4.0. The prevalence of drug-disease interactions was determined by applying the consensus criteria to a convenience sample of frail older veterans at hospital discharge who were enrolled in a health services intervention trial. Results: The panel reached consensus on 28 individual drug-disease interactions involving 14 diseases or conditions. Overall, 205 (15.3%) of the 1340 veterans in the sample had >_1 drug-disease interaction. The 2 most common drug-disease interactions were use of first-generation calcium channel blockers in patients with congestive heart failure and use of aspirin in patients with peptic ulcer disease (both, 3.7%). Conclusions: A survey of multidisciplinary geriatric health care professionals resulted in a concise consensus list of clinically important drug-disease interactions in older adults. Further research is needed to examine the impact of these drug-disease interactions on health outcomes and their applicability as national measures for the prevention of drug-related problems.