Antimicrobial prescribing in hospitalized adults stratified by age: data from the ESAC point-prevalence surveys.

Background: Geriatric infectious diseases are a major health care issue. Infections in the elderly occur more frequently than in younger adults, are often associated with higher morbidity and mortality, and may present atypically. Elderly patients are also often taking multiple medications, which increases the likelihood of drug-drug interactions. Dosing decisions should take into consideration the reduced lean body mass and declining renal function in this age group. Objective: Antimicrobial prescribing in three age groups (65-74, 75-84 and >= 85 years) was compared with a reference age group (18-64 years), with the aim of identifying quality of care indicators specific to the elderly. Methodology: The ESAC (European Surveillance of Antimicrobial Consumption) final phase performed two hospital point-prevalence surveys in 2008 and 2009, respectively, using the defined daily dose (DDD) and Anatomical Therapeutic Chemical (ATC) classification system. The prescribed daily dose (PDD) was compared with the DDD. Differences in prescribing were assessed using multivariate logistic regression analyses. Results: The majority of patients (19 549 [64% of 30 836]) were from Northern Europe and 13 830 (48%) belonged to the reference group. The largest proportion of patients was admitted through the hospital's medical specialty (55% of patients) [range: 49% in the reference group to 72% in the >= 85 years age group]. Penicillins were the most frequently used antimicrobials in all age groups (range: 32% in the reference group to 41% in the >= 85 years age group). Multivariate analyses showed three significant variations between the 65-74 years age group and the reference group (quinolones: odds ratio [OR] 1.17 [95% CI 1.05, 1.29]; tetracyclines: OR 1.58 [95% CI 1.26, 1.98]; aminoglycosides: OR 0.81 [95% CI 0.70, 0.93]). The number of significant variations increased to seven and eight in the 75-84 and >= 85 years age groups, respectively. A lower likelihood for PDD > DDD was observed in the 65-74 years age group for three parenteral antimicrobials (amoxicillin/clavulanic acid, gentamicin and vancomycin). This was reiterated in the older age groups (75-84 and >= 85 years), where piperacillin/tazobactam, meropenem and oral ciprofloxacin also showed a lower likelihood for PDD > DDD. Conclusions: Despite the methodology not being dedicated to elderly patients, the study identified elevated use of antimicrobial agents that are associated with serious adverse effects or a narrow therapeutic index as a target for quality of care improvement in elderly patients.