Statistical analysis of factors affecting efficacy and safety of vancomycin

Abstract

Factors affecting the efficacy and safety of vancomycin, which was given for treatment of methicillin-resistant Staphylococcus aureus infections, were investigated. The factors of patient background, vancomycin concentration, laboratory findings, and treatment by vancomycin were obtained from patients who were therapeutically monitored and what were statistically analyzed in relation to the clinical results. The rates of abnormal laboratory findings in regard to liver and kidney functions were chosen as the safety index because adverse effects on liver and kidney functions were most frequently observed. Only pretreatment with an aminoglycoside was found to significantly affect the efficacy in elderly patients. The daily dose was found to be significantly related to the incidence of abnormal laboratory findings in liver and kidney. The same relation between trough concentration and that in kidney was observed. For elderly patients, severity and total bilirubin concentration are useful warning signals for prevention of kidney and liver impairment, respectively. Nonparametric binary regression analysis of the relationship between trough concentration and the rate of incidence of the abnormality in the kidney showed that the rate increased with coadministration of aminoglycoside. It is possible to reduce the rate to less than 15% as long as the trough concentration is kept below 10 μg/ml.