Elevated vancomycin trough is not associated with nephrotoxicity among inpatient veterans

Vancomycin troughs of 15-20 mg/L are recommended in the treatment of invasive staphylococcal disease, higher levels than previously recommended.

We sought to determine if there was an association between vancomycin trough and nephrotoxicity, defined as 0.5 mg/L or 50% increase in serum creatinine, at a large Veterans Affairs medical center.

We reviewed records of 348 inpatients at our institution who received ≥5 days of vancomycin during 2 time periods when vancomycin dosing protocols differed (May 2005-April 2006 and January 2007-December 2007). Potential risk factors for nephrotoxicity were collected prior to nephrotoxicity onset, and all patients with nephrotoxicity events occurring within 5 days of starting vancomycin were excluded.

Overall incidence of nephrotoxicity was 31/348 patients (8.9%). A similar percentage of patients experienced nephrotoxicity in 2005-2006 versus 2007 (16/201 vs 15/147, respectively; P = 0.57), despite a rise in mean (9.7 mg/L in 2005-2006 vs 13.2 mg/L in 2007; P < 0.0001) and highest (11.8 mg/L in 2005-2006 vs 15.7 mg/L in 2007; P < 0.0001) vancomycin trough levels achieved. In a multivariate logistic regression model, only receipt of intravenous contrast dye was significantly associated with nephrotoxicity (OR 4.01, P < 0.001), though there was a trend toward an association between maximum vancomycin trough ≥15 mg/L and nephrotoxicity (OR 2.05, P = 0.082). Overall reversibility of nephrotoxicity either prior to or within 72 hours of vancomycin discontinuation was 77.8%.

We conclude that nephrotoxicity, with higher trough levels occurring at ≥5 days of vancomycin therapy, was uncommon at our institution and typically reversible.