Association of Different Surgical Sterile Prep Solutions With Infection Risk After Cutaneous Surgery of the Head and Neck

Abstract

This study assesses the association between the type of preoperative sterile prep solution used and infection risk after cutaneous surgery of the head and neck in a large cohort of patients.

Factors to be considered when selecting an optimal sterile prep solution prior to cutaneous surgery include the underlying health status of the patient, the expected extent of the surgery, the anatomic location of the tumor to be removed or planned reconstruction, and the inherent effectiveness of the prep solution. Recently, it has been suggested that different prep solutions may pose varying risks to patients. For instance, 83% of surgical dermatologists use chlorhexidine on the face. On the one hand, it has been suggested that chlorhexidine use may contribute to the very low incidence of infection seen in cold-steel skin surgery and in minimally invasive cosmetic procedures such as filler injections. On the other hand, the ocular risks of chlorhexidine may outweigh the benefits. The purpose of this analysis was to compare the safety and effectiveness of prep solutions for skin surgery of the head and neck.

Methods

Data from a multicenter, prospective cohort study of Mohs micrographic surgery of the head and neck were compared to determine whether different prep solutions were associated with different rates of adverse events, particularly postoperative infection. Unpaired χ² test was performed to assess these associations, and 2-sided P = .05 indicated statistical significance. This study was performed under 2 expedited Northwestern University institutional review board protocols, which collectively authorized data collection and managed transmittal of data across institutions to enable analysis. All data collected were deidentified, and patient informed consent was waived per the direction of Northwestern University’s institutional review board. Data were collected from November 29, 2010, through April 2, 2012, and were analyzed between October 4, 2016, and January 8, 2017.

Results

The risk of postoperative infection varied on the basis of the surgical prep solution used for Mohs surgery. The Table displays the total number of cases that used each type of sterile prep solution as well as the number and percentage of wound infections associated with each prep solution as detected by signs and symptoms or by culture positivity. The proportion of those who had an infection in each sterile prep group was significantly different (17 459 cases; χ²₄ = 91.32; P < .001). Surgical cases pretreated with chlorhexidine sterile prep or 3.0% chloroxylenol (Techni-Care surgical scrub; Care-Tech Laboratories) were associated with the lowest rate of infection (0.06% for both solutions), while those pretreated with povidone iodine were associated with the highest rate (1.3%). (Techni-Care was recalled in the past because of manufacturing issues and was not available at the time of this writing.) Overall, the infection rate associated with chlorhexidine and Techni-Care was statistically significantly lower (17 459 cases; χ²₁ = 59.08; P < .001) than the rate associated with all other prep solutions. There were no reports of ocular injury or other adverse events associated directly with the application of any prep solutions.

Table. Association of Sterile Prep Solution With Infection.

Sterile Prep Solution	Total Cases Using Solution, No.	Signs and Symptoms of Infection, No.	Culture Positive for Infection, No.	Any Infection, No. (%)a
Chlorhexidine	6559	4	0	4 (0.06)
Povidone iodine	4438	19	39	58 (1.3)
Chlorhexidine and povidone	2475	1	11	12 (0.48)
Alcohol	2326	3	8	11 (0.47)
Techni-Care surgical scrub	1661	0	1	1 (0.06)

^aCalculated as [(No. of any infections within a prep solution group)/(total No. of cases in which that prep solution was used)] × 100.

Discussion

Previously, Mohs micrographic surgery has been shown to be an exceedingly safe procedure, with an overall risk of adverse events of less than 1% and a risk of surgery-associated wound infection of 0.44%. Use of chlorhexidine has been found to be inversely associated with infection risk. However, prior to our study, no large-sample comparative analysis had been performed of the risk of infection associated with different types of prep solutions used in dermatologic surgery.

There are limitations to this study. Most notably, because this was a cohort study and not a randomized clinical trial, there may be unknown confounders affecting the data. However, this study used a large consecutive sample (N = 17 459) and included many centers (23), which increases confidence that physician-specific or center-specific practices did not skew the results. In the future, it would be useful to stratify the obtained results by the type of reconstruction, the anatomic site of the tumor, and patient characteristics, such as immune status. Of note, the extremely low postoperative infection rates observed for chlorhexidine and Techni-Care (0.06% for both solutions) are markedly lower than the previously reported rates, which possibly indicates some patient selection bias in the cohort. Alternatively, the rates we detected may be accurate compared with prior estimates because the large sample we analyzed may be more representative of current clinical practice.

Conclusions

To our knowledge, this study is the first comparison of the clinical effectiveness of prep solutions in a large prospective sample. Moreover, the differences detected are clinically significant in that they confirm that chlorhexidine is a safe and effective prep solution for cutaneous surgery of the head and neck. Further research is required to validate the findings presented. Anti-infective properties of surgical prep solutions are just a single feature that should be considered by physicians when they select an appropriate prep solution for a particular patient.