Correlation of adherence to the 2012 Infectious Diseases Society of America practice guidelines with patient outcomes in the treatment of diabetic foot infections in an outpatient parenteral antimicrobial programme

AIM

To evaluate adherence to the 2012 Infectious Diseases Society of America practice guidelines for the management of patients with diabetic foot infections and to determine an association between adherence and clinical outcome.

METHODS

A retrospective chart review was performed to evaluate the management and clinical outcomes of patients with diabetic foot infections treated with outpatient parenteral antimicrobial therapy between 1 January 2011 and 30 June 2012 at Wishard Health Services/Eskenazi Health. Adherence to individual Infectious Diseases Society of America diabetic foot infection treatment guideline recommendations was measured, and then assessed in relation to clinical outcome.

RESULTS

A total of 57 patients (61% male, mean age 54 years) with moderate to severe diabetic foot infection met the inclusion criteria. None of the treatment courses of these patients adhered to all the Infectious Diseases Society of America guideline recommendations. The recommendations most frequently adhered to were consultation of appropriate multidisciplinary teams (n=54, 94.7%) and performance of diagnostic imaging (n=52, 89.5%). The recommendations least frequently adhered to were diabetic foot wound classification scoring on admission (n=0, 0%), appropriate culture acquisition (n=12, 21.2%), surgical intervention when indicated (n=32, 46.2%) and appropriate empiric antibiotic selection (n=34, 59.7%). Of 56 patients, 52 (92.9%) experienced clinical cure at the end of outpatient parenteral antimicrobial therapy compared with 34 of 53 patients (64%) at 6 months after the completion of therapy. Adherence to individual guidelines was not associated with clinical outcome. Patients who experienced treatment failure were more likely to have severe diabetic foot infection or peripheral neuropathy.

CONCLUSIONS

Adherence to the Infectious Diseases Society of America diabetic foot infection guideline recommendations was found to be suboptimal in the present study. The effect of adhering to individual Infectious Diseases Society of America diabetic foot infection recommendations on clinical outcome needs to be investigated.

An updated comparison of drug dosing methods. Part IV: Vancomycin

The resurgence of the use of and interest in vancomycin, in conjunction with the high degree of interpatient variability in its pharmacokinetic profile, has prompted the development of many and varied dosing methods. Several dosing nomograms have been proposed and evaluated, methods which are useful for initial dosing but do not allow for individualisation of dosage. Given these constraints, several investigators have attempted to apply conventional least-squares regression techniques and, more recently, Bayesian methodologies using either 1- or 2-compartment pharmacokinetic models. Comparative information evaluating algorithmic methods demonstrates that those of Moellering and Lake offer the least biased and most precise predictions of vancomycin dosage. Patient individualisation using conventional least-squares methodology offers some improvement over nomogram-based methods, both in predictive performance and in dosage adjustment once serum concentration data are available. Overall, the latest data indicate that regimens which incorporate Bayesian principles tend to give better results than nomogram-based or conventional least-squares dosing methods for this drug. Despite the advances in methods for dosing vancomycin, several questions remain to be answered. A lack of convincing evidence of a correlation between serum concentrations and therapeutic outcome has prompted debate over the need for serum concentration monitoring and, if it is needed, over which patient population would most benefit. Secondly, little comparative information is currently available as to the dosing of vancomycin in paediatric and neonatal patient populations. Several nomograms for initial dosing have been proposed, but only 2 have been subject to subsequent testing. Finally, information regarding cost-effectiveness and the quality of patient outcome is lacking from the current literature.

An updated comparison of drug dosing methods. Part III: Aminoglycoside antibiotics

Aminoglycoside antibiotics continue to be useful for the treatment of Gram-negative infections. Available dosing methods include predictive algorithms and nomograms, pharmacokinetics-based dosing methods, and methods that incorporate Bayesian forecasting. The individualised Sawchuk-Zaske and Bayesian methods have been extensively evaluated since the previous review in the Journal. Both methods continue to be rapid and accurate means of individualising dosage requirements for patients with diverse pharmacokinetic profiles. The predictive performance of the Bayesian method can be further enhanced when population-based parameters reflect the patient population being monitored. There are now several cost-effectiveness studies that demonstrate that pharmacokinetic dosing services for aminoglycosides result in cost savings, better therapeutic concentrations, fewer toxic serum concentrations, and shorter mean durations of hospital stay and aminoglycoside therapy. Further studies are needed for cost-effectiveness and comparison of various dosing methods in paediatric and neonatal patients.

An updated comparison of drug dosing methods. Part II: Theophylline

This article updates the previous review in the Journal regarding theophylline dosing methods. Among the predictive algorithms evaluated, the dose-titration scheme of Weinberger and Hendeles was extensively tested in 1073 asthmatic patients. When the scheme was followed appropriately, 78% of initial serum concentrations and 66% of repeat serum concentrations were within the therapeutic range of 10 to 20 mg/L. Several authors have also demonstrated that the 'condition correction factor' method for estimating theophylline clearance is of limited value. The individualised methods of Chiou, Koup and Vozeh have been evaluated in over 300 patients. In addition, numerous authors have reported the relative predictive performance of Bayesian dosing programs for theophylline. All methods continue to be a rapid and accurate means of individualizing dosing requirements for patients with a diverse range of theophylline disposition characteristics. Overall, the Bayesian predictions have been less biased and slightly more precise than the pharmacokinetics-based dosing methods. The most recent cost-effectiveness data has shown that a pharmacokinetic dosing program resulted in fewer toxic serum concentrations (18.9% vs 37.8%), a shorter mean duration of hospital stay (6.3 vs 8.7 days) and more therapeutic concentrations with subsequent oral therapy (71.1% vs 44.4%) than among control patients receiving dosages prescribed by physicians.

An updated comparison of drug dosing methods. Part I: Phenytoin

The relationship between a dose of phenytoin and the resultant serum concentration is difficult to predict, and numerous dosing methods have been developed to quantify the dose required to achieve a specific concentration. This review brings up to date the earlier article in the Journal regarding predictive algorithms, various pharmacokinetics-based dosing techniques and Bayesian feedback methods for phenytoin dosing. The latest data support the original conclusions that dosing methods for phenytoin which incorporate an individualised approach or Bayesian principles tend to offer results superior to those from predictive algorithms. Bayesian methods have the additional advantage of using only 1 serum concentration, obtained under either steady-state or non-steady-state conditions. There is still a need for future investigations that include prospective evaluations of predictive performance and cost-effectiveness data.