Risk factors of worsening renal function in hospitalized elderly patients

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.

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.

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.

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.