Risk factors of worsening renal function in hospitalized elderly patients.

Background: Worsening renal function during hospital treatment is a substantial hazard, especially for elderly hospitalized patients. However, data concerning the prevalence and significance of potential risk factors is lacking.

Methods: All patients admitted during a 6-month observation period to a department of general internal medicine and geriatrics were enrolled. Patients <65 yrs old were excluded. Data was assessed using a retrospective analysis of patient charts; 343/583 charts provided sufficient data for the analysis. Renal function was estimated by the Cockcroft and Gault formula. Worsening renal function was defined as a decline to <66.7% of the initial value. Laboratory values at admission (serum albumin, sodium and potassium), activities of daily living at admission (ADL-score), established medical diagnosis and medication prior to and during in-patient treatment were included in the analysis of potential risk factors.

Results: Renal function worsened in 6.1% of patients included. Risk factors were prescription of loop diuretics, trimethoprim/sulfamethoxazole or non-steroidal antiphlogistics during hospitalization. Hypernatremia, lower serum albumin and lower ADL-score at admission also demonstrated an association with a decline in renal function. However, an established diagnosis of heart failure, diabetes and hypertension were not predictive.

Conclusion: Reduced physiological resources to maintain fluid and sodium balance are more predictive for worsening renal function than medical diagnosis alone. ADL-score and serum albumin could help further to identify patients at risk. Non-steroidal antiphlogistics are still frequently prescribed during in-patient treatment, although they are significant risk factors for renal function decline.