Pitfalls in dosing vancomycin.

BACKGROUND: Vancomycin is a frequently used antibiotic for the treatment of methicillin-resistant gram-positive bacteria. Newer guidelines suggest dosing vancomycin to achieve a trough concentration between 15 and 20 mg/L. Achieving this higher concentration requires greater doses of the antibiotic. Even when using a nomogram, these higher doses often result in excessively elevated trough levels and increase the risk for vancomycin-associated acute kidney injury. We undertook this quality improvement project to better understand the reasons contributing to a toxic vancomycin trough level. METHODS: Over a 9-month period, we examined all vancomycin trough concentrations greater than 25 mg/L to determine their cause. RESULTS: Fifty-four elevated levels were identified in 38 patients. In 47 instances, adequate data were available for analysis. We could classify the etiology of the excessive levels into 4 groups: (1) incorrect timing of the blood collection, (2) improper dosing, (3) changing renal function and (4) abnormal pharmacokinetics/pharmacodynamics. CONCLUSIONS: Educational programs could correct the first 3 problems. However, only more frequent therapeutic drug monitoring or use of another, less toxic, antibiotic would remedy the last one.

Masked hypertension and white-coat hypertension in chronic kidney disease: a meta-analysis.

BACKGROUND AND OBJECTIVES: Poor hypertension control observed in patients with chronic kidney disease (CKD) may in part be due to the suboptimal assessment of BP with clinic BP measurements alone. The goal of this meta-analysis was to estimate the prevalence and determinants of white-coat and masked hypertension in the adult CKD population. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Articles reporting prevalence of masked and white-coat hypertension in patients with CKD were obtained from two major databases. We then performed a meta-analysis to derive pooled estimates of prevalence and determinants of these two conditions. RESULTS: Among 980 patients with CKD identified in six studies, the overall prevalence of masked hypertension was 8.3% and of white-coat hypertension was 18.3%. More alarming, 40.4% of patients who had CKD and were thought to have normotension (or adequately treated hypertension) in fact had hypertension at home. Also 30.0% of patients who had CKD and were thought to have hypertension had normotension at home. The thresholds for classification of clinic and ambulatory BP as hypertensive strongly influenced the risk for diagnosis of masked hypertension in favor of white-coat hypertension. CONCLUSIONS: Because clinic BP measurements alone lead to substantial misclassification in BP, we estimate that the prevalence of poorly controlled hypertension is likely less than currently estimated. Out-of-office BP monitoring may improve the management of hypertension in patients with CKD. Standardized definitions for the diagnosis of masked and white-coat hypertension would facilitate research.