# Applying Machine Learning Techniques to the Audit of Antimicrobial Prophylaxis
## 4 Discussion  
The National Healthcare Safety Network (NHSN), the CDC surveillance system, provides information on incidence rates for healthcare-associated infections. The NHSN cannot provide national-scale data on the antimicrobial use. Point prevalence surveys provide valuable information on healthcare-associated infections and antimicrobial use globally, and they may facilitate comparisons among different countries [29]. Although the duration of point prevalence survey in a single hospital is limited to three weeks, the criteria of compliance with duration of antimicrobial prophylaxis are less than one day or longer than one day, and the short duration of prevalence survey does not limit the analysis of data or presentation of useful information [17]. The surgical prophylaxis guideline by [PERSON] et al. remains a standard and is still cited by the recent publications [7; 18]. \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Classifier** & **Hyperparameters** & **Sampling Method** & **Execution Time (s)** \\ \hline \multirow{8}{*}{Decision tree} & Reduced error pruning = false & \multirow{8}{*}{No sampling} & \multirow{8}{*}{7.8} \\  & Confidence factor = 0.2 & & \\  & distributionSpread: 2.0 & & SpreadSubsample & 27.9 \\  & Percentage: frequency of minor & & SMOTE & 71.8 \\  & classes adjusted to nearly the & & Bagging & 16.0 \\  & same with that of major class & AdaBoost & 16.1 \\  & Classifier Choose: J48 & & \\ SimpleLogistic & Default & No sampling & 9.8 \\  & Learning rate = 0.3 & & \\ Multilayer perceptron & Training Time = 500 & No sampling & 353.1 \\  & Default & No sampling & 8586 \\  & Time = 15 min & & Estimated \\ Manual review & & & 24,040 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Hyperparameters and execution time for machine learning techniques and manual review. Figure 3: Area under receiver operating characteristics curve (AUC) of 7 algorithms for 5 major specialties. Among the 7377 patients, 1981 patients were never subjected to a surgical procedure, but only 601 instances with antimicrobial prophylaxis were collected. Because only the antimicrobial agents used on the day of survey were recorded, the dataset did not include the data of antimicrobial use for every patient who had been subjected to a surgical procedure before this survey. Some commentators may suggest that some of these patients should have been subjected to surgical prophylaxis, though they were not. If that is the case, such cases are of major importance for the purposes of this work. This issue was not described in the previous publications [8; 9; 30]. However, it is not a major concern in real-world practice except for human error. This is because the question, \"Has antibiotic prophylaxis been given within the last 60 min before skin incision?\", is an item in the timeout surgical safety checklist proposed by WHO [8; 31]. Surgeons will confirm that antibiotic prophylaxis was given within the last 60 min before surgical incision. More importantly, the appropriate use of antimicrobial prophylaxis (choice of antimicrobial agents and duration of antimicrobial use) is not on the checklist and needs to be clarified in the audit. However, we do not have data to verify this issue caused by human error, and we will take it into consideration for a perfect audit in a future study. In this study, 544 instances were surgical prophylaxis. A total of 75.6% (411/544) of antimicrobial choices (Classes A and B) were classified as consistent with guidelines, while 52.6% (286/544) of antimicrobial prescriptions (Classes A and C) were discontinued within 24 h after surgery completion. The combination of cefazolin and gentamicin was the most common type of noncompliance with guideline. Cefazolin was widely used as an appropriate drug for many surgical procedures with its wide spectrum of susceptibility (e.g., against Gram-positive _Staphylococcus_ species and Gram-negative bacilli) and adequate concentrations in the tissue.