Summary of a systematic review on the effectiveness and optimal method of hair removal

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Global Guidelines for the Prevention of Surgical Site Infection. Geneva: World Health Organization; 2018.

Web Appendix 7Summary of a systematic review on the effectiveness and optimal method of hair removal

1. Introduction

Removal of hair from the intended site of surgical incision has traditionally been part of the routine preoperative preparation of patients undergoing surgery. Hair removal may be necessary to facilitate adequate exposure to the site and preoperative skin marking. Furthermore, suturing and the application of wound dressings can be complicated by the presence of hair. Apart from these practical issues, hair has been associated with a lack of cleanliness and the potential to cause surgical site infection (SSI). However, there is also the belief that hair removal inversely increases the risk of SSI by causing microscopic trauma of the skin. To minimize the potential of skin trauma, the use of clippers instead of razors has been proposed for preoperative hair removal. Clippers cut the hair close to the skin without actually touching it, whereas razors involve a sharp blade drawn directly over the skin. A third method for hair removal is the application of depilatory creams containing chemicals. The drawbacks are the necessity to leave the cream in place for approximately 15–20 minutes for the hair to be dissolved and the potential for allergic reactions. A Cochrane review, published in 2009 and updated in 2011, concluded that there was no statistically significant effect on SSI rates of hair removal¹. However, a significant harm was seen when hair removal with razors was compared with clipping.

2. PICO questions

Does hair removal affect the incidence of SSI?
What method and timing of hair removal is associated with the reduction of SSI?
- Population: adult patients undergoing any type of surgical procedure
- Intervention: avoidance of hair removal
- Comparator: hair removal (different methods and timing)
- Outcomes: SSI, SSI-attributable mortality

3. Methods

The following databases were searched: Medline (PubMed); Excerpta Medica Database (EMBASE); Cumulative Index to Nursing and Allied Health Literature (CINAHL); Cochrane Central Register of Controlled Trials (CENTRAL); and WHO regional medical databases.

The time limit for the review was between 1 January 1900 and 17 January 2014. Of note, the usual time limit of 1990 for the systematic reviews conducted for the WHO SSI prevention guidelines was extended to include important relevant literature published prior to this date. Language was restricted to English, French and Spanish. A comprehensive list of search terms was used, including Medical Subject Headings (MeSH) (Appendix 1).

Two independent reviewers screened titles and abstracts of retrieved references for potentially relevant studies. The full text of all potentially eligible articles was obtained. Two authors independently reviewed the full-text articles for eligibility based on inclusion criteria. Duplicate studies were excluded.

Two authors extracted data in a predefined evidence table (Appendix 2) and critically appraised the retrieved studies using the Cochrane collaboration tool² for assessing risk of bias (Appendix 3). Any disagreements were resolved through discussion or after consultation with the senior author, when necessary. Publication bias was assessed using a funnel plot³.

Meta-analyses of available comparisons related to hair removal or not and the different methods used were performed using Review Manager v5.3 as appropriate⁴ (Appendix 4). Odds ratios (OR) and mean differences with 95% confidence intervals (CI) were extracted and pooled for each comparison with a random effects model. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology (GRADE Pro software, http://gradepro.org/)⁵^,⁶ was used to assess the quality of the body of retrieved evidence (Appendix 5).

4. Study selection

Flow chart of the study selection process

5. Summary of the findings

Overall, 15 randomized or quasi-randomized trials⁷^–²¹ comparing the effect of preoperative hair removal vs. no hair removal or different methods of hair removal (shaving, clipping and depilatory cream) were identified as relevant to the research question. Any kind of surgical procedure was included. As no hair removal and clipping are similar in terms of reduced potential to cause microscopic skin trauma, an additional analysis was performed combining these two comparisons. Based on these considerations, we were able to make the following comparisons:

Hair removal vs. no hair removal
1. Shaving vs. no hair removal
2. Clipping vs. no hair removal
3. Depilatory cream vs. no hair removal
Comparisons of methods of hair removal
1. Clipping vs. shaving
2. Shaving vs. depilatory cream
3. Clipping and no hair removal vs. shaving
Timing of hair removal
1. Night before vs. day of surgery

The results of the meta-analyses based on these comparisons are as follows (Appendix 4).

Hair removal vs. no hair removal
1. Seven studies⁷^,¹¹^,¹²^,¹⁵^–¹⁷^,¹⁹ comparing shaving vs. no hair removal were identified. Meta-analysis of these studies showed that shaving had neither benefit nor harm when compared to no hair removal (OR: 1.78; 95% CI: 0.96–3.29).
  The quality of evidence for this comparison was low (Appendix 5).
2. One study⁷ comparing clippers vs. no hair removal was identified. This study showed that hair removal with clippers had neither benefit nor harm when compared to no hair removal (OR: 1.00; 95% CI: 0.06–16.34).
  The quality of evidence for this comparison was very low (Appendix 5).
3. One study¹² comparing depilatory cream vs. no hair removal was identified. This study showed that hair removal with depilatory cream had neither benefit nor harm when compared to no hair removal (OR: 1.02; 95% CI: 0.42–2.49). The quality of evidence for this comparison was very low (Appendix 5).
Comparisons of methods of hair removal
1. Four studies⁷^,⁹^,¹⁰^,¹⁴ comparing clipping vs. shaving were identified. Meta-analysis of these studies showed a significantly lower risk of SSI following hair removal with clippers compared to shaving (OR: 0.51; 95% CI: 0.29–0.91).
  The quality of evidence for this comparison was low (Appendix 5).
2. Six studies⁸^,¹²^,¹³^,¹⁸^,²⁰^,²¹ comparing shaving vs. depilatory cream were identified. Meta-analysis of these studies showed neither benefit nor harm when shaving was compared to hair removal with depilatory cream (OR: 2.78; 95% CI: 0.86–9.03).
  The quality of evidence for this comparison was very low (Appendix 5).
3. Ten studies⁷^,⁹^–¹²^,¹⁴^–¹⁷^,¹⁹ comparing clipping or no hair removal vs. shaving were identified. Meta-analysis of these studies showed a significantly lower risk of SSI following hair removal with clippers or no hair removal compared to shaving (OR: 0.51; 95% CI: 0.34–0.78).
  The quality of evidence for this comparison was moderate (Appendix 5).
Timing of hair removal
1. One study⁹ comparing hair removal the night before surgery vs. hair removal on the day of surgery by either shaving or clipping was identified. The study showed that hair removal on the night before surgery had neither benefit nor harm when compared to hair removal on the day of surgery (OR: 1.22; 95% CI: 0.44–3.42).
  The quality of evidence for this comparison was very low (Appendix 5).

In conclusion the retrieved evidence can be summarized as follows:

Comparison no.	Subgroup	Summary results
1.	a	Overall, a low quality of evidence shows that shaving, clipping or the use of depilatory cream has neither benefit nor harm when compared to no hair removal in reducing the risk of SSI.
	b	Overall, a very low quality of evidence shows that clipping has neither benefit nor harm when compared to no hair removal in reducing the risk of SSI.
	c	Overall, a very low quality of evidence shows that the use of depilatory cream has neither benefit nor harm when compared to no hair removal in reducing the risk of SSI.
2.	a	Overall, a low quality of evidence shows that clipping has a significant benefit in reducing the risk of SSI when compared to shaving.
	b	Overall, a very low quality of evidence shows that depilatory cream has neither benefit nor harm when compared to shaving in reducing the risk of SSI.
	c	Overall, a moderate quality of evidence shows that clipping or no hair removal has a significant benefit in reducing the risk of SSI when compared to shaving.
3.	a	Overall, a very low quality of evidence shows that the timing of hair removal on the night before surgery has neither benefit nor harm when compared to the day of surgery in reducing the risk of SSI.

6. Other factors considered in the review of studies

The systematic review team identified the following other factors to be considered.

Values and preferences

Ilankovan and colleagues studied patient and surgeon preferences regarding hair removal before maxillofacial surgery. They showed that patients prefer no hair removal over shaving, while the surgeon’s assessment of the difficulty of wound closure did not differ between the two methods¹⁶.

7. Key uncertainties and future research priorities

Available evidence is mostly underpowered and limited by flawed methodological design. Certain comparisons (depilatory cream vs. clipping) have not been made yet. Furthermore, the timing of hair removal and the location (ward or operating room [OR]) have not been sufficiently studied. Future well-designed and adequately-powered studies are needed to draw more firm conclusions.

Appendices

Appendix 1. Search terms

Medline

1.: surgical wound infection/ or (surgical site infection* or SSI or SSIs or surgical wound infection* or surgical infection* or post-operative wound infection* or postoperative wound infection*).ti,ab,kw.
2.: wound infection.mp. or exp wound infection/
3.: hair removal/ or (hair remov* or shaving or shave).ti,ab,kw.
4.: 1 or 2
5.: 3 and 4
8.: limit 5 to yr=“1900 -current”

EMBASE

esthetic surgery/ or (hair remov* or shaving or shave).ti,ab,kw.
surgical infection/ or (surgical site infection* or SSI or SSIs or surgical wound infection* or surgical infection* or post-operative wound infection* or postoperative wound infection*).ti,ab,kw.
exp wound infection/
2 or 3
1 and 4
limit 5 to yr=“1990 -current”

CINAHL

(MH “wound infection+”)
(MH “surgical wound infection”)
(“wound infection”)
(MH “hair removal”)
(“hair removal”)
1 or 2 or 3
4 or 5
6 and 7

Cochrane CENTRAL

wound infection:ti,ab,kw
surgical wound infection:ti,ab,kw
hair removal:ti,ab,kw
shaving:ti,ab,kw
1 or 2
3 or 4
5 and 6

WHO regional medical databases

(ssi)
(surgical site infection)
(surgical site infections)
(wound infection)
(wound infections)
(postoperative wound infection)
(hair removal)
(shaving)

African Index Medicus

infection [Key Word]
surgical [Key Word]
surgery [Key Word]
2 or 3
1 and 4

ti:: title;
ab:: abstract;
kw:: key word.

Appendix 2. Evidence table

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Appendix 3. Risk of bias assessment of the included studies

Author, year	Sequence generation	Allocation concealment	Participants blinded	Care providers blinded	Outcome assessors blinded	Incomplete outcome data	Selective outcome reporting	Other sources of bias
Abouzari, 2009 ⁷	Unclear	Unclear	High risk	High risk	Unclear	Unclear	Low risk	-
Adisa, 2011 ⁸	Low risk	Low risk	High risk	Low risk	Low risk	Low risk	Low risk	-
Alexander, 1983⁹	Low risk	Unclear	High risk	Unclear	Unclear	Low risk	Low risk	-
Balthazar, 1982 ¹⁰	Low risk	Unclear	High risk	Unclear	Unclear	Low risk	Low risk	-
Celik, 2007 ¹¹	Low risk	Unclear	High risk	High risk	Unclear	High risk	Low risk	-
Court-Brown, 1981 ¹²	Unclear	Unclear	High risk	High risk	Unclear	Unclear	High risk	-
Goëau-Brissonnière, 1987 ¹³	Low risk	Unclear	High risk	High risk	Unclear	Unclear	Unclear	-
Grober, 2013 ¹⁴	Unclear	Unclear	Low risk	High risk	Unclear	Unclear	Low risk	-
Horgan, 1999 ¹⁵	Unclear	High risk	High risk	High risk	Unclear	Low risk	Low risk	-
Ilankovan, 1992 ¹⁶	Low risk	Unclear	Low risk	High risk	Unclear	Low risk	High risk	-
Kattipattanapong, 2012 ¹⁷	Low risk	Low risk	High risk	High risk	Unclear	Low risk	Low risk	-
Powis, 1976 ¹⁸	High risk	Unclear	High risk	Unclear	Low risk	Low risk	Low risk	-
Rojanapirom, 1992 ¹⁹	Unclear	Unclear	High risk	High risk	Unclear	Low risk	Low risk	-
Seropian, 1971 ²⁰	High risk	Unclear	High risk	Unclear	Unclear	Low risk	High risk	-
Thur de Koos, 1983 ²¹	High risk	Unclear	High risk	Unclear	Unclear	Low risk	Unclear	-