Polypharmacy, length of hospital stay, and in-hospital mortality among elderly patients in internal medicine wards. The REPOSI study.

Background: Although the association between multimorbidity and polypharmacy has been clearly documented,
no study has analyzedwhether or not specific combinations of diseases influence the prescription of polypharmacy
in older persons.We assessedwhich clusters of diseases are associated with polypharmacy in acute-care elderly inpatients.
Methods: This cross-sectional study was held in 38 Italian internal medicine and geriatric wards participating in the
Registro Politerapie SIMI (REPOSI) study during 2008. The study sample included 1155 in-patients aged 65 years
or older. Clusters of diseases, defined as two or more co-occurring specific chronic diseases, were identified using
the odds ratio (OR) for the associations between pairs of diseases followed by cluster analysis. Polypharmacy was
defined as the prescription of five or more different medications at hospital discharge. Logistic regression models
were run to analyze the association between clusters of diseases and polypharmacy.
Results: Among clusters of diseases, the highest mean number of drugs (N8) was found in patients affected by
heart failure (HF) plus chronic obstructive pulmonary disease (COPD), HF plus chronic renal failure (CRF), COPD
plus coronary heart disease (CHD), diabetes mellitus plus CRF, and diabetesmellitus plus CHD plus cerebrovascular
disease (CVD). The strongest association between clusters of diseases and polypharmacy was found for diabetes
mellitus plus CHD plus CVD, diabetes plus CHD, and HF plus atrial fibrillation (AF).
Conclusions: The observed knowledge of the relationship among co-occurring diseases and polypharmacy should
help to identify and monitor older in-patients at risk of polypharmacy.