Multimorbidity in elderly hospitalised patients and risk of Clostridium difficile infection: a retrospective study with the Cumulative Illness Rating Scale (CIRS).

OBJECTIVES: To identify the role of chronic comorbidities, considered together in a literature-validated index (Cumulative Illness Rating Scale, CIRS), and antibiotic or proton-pump inhibitor (PPI) treatments as risk factors for hospital-acquired Clostridium difficile infection (CDI) in elderly multimorbid hospitalised patients. DESIGN: Retrospective cohort study. SETTING: Subacute hospital geriatric care ward in Italy. PARTICIPANTS: 505 (238 male (M), 268 female (F)) elderly (age ≥65) multimorbid patients. MAIN OUTCOME MEASURES: The relationship between CDI and CIRS Comorbidity Score, number of comorbidities, antibiotic, antifungal and PPI treatments, and length of hospital stay was assessed through age-adjusted and sex-adjusted and multivariate logistic regression models. The CIRS Comorbidity Score was handled after categorisation in quartiles. RESULTS: Mean age was 80.7±11.3 years. 43 patients (22 M, 21 F) developed CDI. The prevalence of CDI increased among quartiles of CIRS Comorbidity Score (3.9% first quartile vs 11.1% fourth quartile, age-adjusted and sex-adjusted p=0.03). In the multivariate logistic regression analysis, patients in the highest quartile of CIRS Comorbidity Score (≥17) carried a significantly higher risk of CDI (OR 5.07, 95% CI 1.28 to 20.14, p=0.02) than patients in the lowest quartile (<9). The only other variable significantly associated with CDI was antibiotic therapy (OR 2.62, 95% CI 1.21 to 5.66, p=0.01). PPI treatment was not associated with CDI. CONCLUSIONS: Multimorbidity, measured through CIRS Comorbidity Score, is independently associated with the risk of CDI in a population of elderly patients with prolonged hospital stay.