[Are there any male-to-female disparities in recurrence rates after surgery for Pilonidal Disease? A meta-analysis comparing differing mixed-gender cohorts].

[OBJECTIVE] Pilonidal Sinus Disease (PSD) manifests globally with a prevalence in adult men fourfold greater than in adult women. Due to the lower incidence in females the course of female PSD remains largely unexplored. In this study we aimed to assess the postoperative recurrence rate in women with PSD.

[MATERIAL AND METHODS] A systematic search of the existing PSD world literature between 1833 and 2023 employing search terms "pilonid" or "dermoid" AND "cyst" was conducted across all databases available including MEDLINE, PubMed, PubMed Central, Scopus, Ovid, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL). Studies were segregated into male-only (Mo), female-only (Fo), or male-female mixed cohorts (mixG) Kaplan-Meier Survival analysis. Recurrence rates at 5-year and 10-year follow-up following various surgical interventions were compared. Bias estimation was done using Newcastle-Ottawa scale for cohort studies and the Cochrane RoB1 tool for RCTs.

[RESULTS] 880 studies encompassing 113, 021 patients were surveyed, consisting of 133 randomized controlled trials (RCTs) with 13.275 patients and 747 non-randomized observational studies with 99.746 patients. The patient cohort, numbering 113.0219 individuals, was further categorized into male-only (Mo; 16.843 patients), female-only (Fo; 653 patients), or mixed-gender (mixG; 95.525 patients) cohorts.

[UNLABELLED] In RCTs involving mixG, a 5-year recurrence rate (RR) of 16.0% (95% CI 14.6%-17.3%) and a 10-year RR of 30.4% (95% CI 27.1%-33.5%) were observed. Conversely, in non-RCTs, the 5-year RR for mixG was 11.7% (95% CI 11.4%-12.0%), with a Mo RR of 2.2% (95% CI 1.9%-2.4%). The 10-year RR for mixG stood at 22.5% (95% CI 22.8%-23.2%), and 5.8% (95% CI 5.4%-6.3%) for the male-only group (<0.0001; log rank test). These findings were significant consistent across subgroups, including primary midline closure, where the 5-year RR for mixG was 15.1% (95% CI 14.2%-16.0%) versus 7.0% (95% CI 5.7%-8.3%) for Mo, and the 10-year RR for mixG was 29.5% (95% CI 27.6%-31.3%) versus 14.4% (95% CI 12.4%-16.4%) for Mo (<0.0001). Similar significant differences were noted in the primary open and Karydakis/Bascom subgroups.

[UNLABELLED] Due to the limited size of the male-only cohort, which precluded further subgroup analyses, studies were stratified based on the proportion of females above or below the mean of 19.87%. Notably, recurrence rates varied significantly based on female representation in RCTs (across all treatments and subgroups of primary midline and Bascom/Karydakis) and in non-RCT studies (across all treatments and subgroups of primary open, midline closure, and Bascom/Karydakis).

[CONCLUSION] Previously undisclosed, the 5-year recurrence rate in PSD for mixed gender cohorts with female share above mean 19.87% seem to significantly surpass that of their less female cohort counterparts across the analyzed therapeutic modalities in RCT as in non-RCT studies. The substantiation of these observations awaits scrutiny through individual patient data at the population level. Females with PSD seem to have a higher RR as compared to men for all therapies tested.

[UNLABELLED] Therefore, an establishment of Good Pilonidal Practice (GPP) criteria should be considered to protect our female PSD patients from entering the vicious cycle of repeat recurrences.

[UNLABELLED] What does this paper add to the literature? It has not uncovered before that females are an especially vulnerable group concerning PSD recurrences following surgical therapy.

[ABBREVIATIONS] FUP follow-up; GCP Good Clinical Practice; GPP Good Pilonidal Practice; IGF intergluteal fold; mixG mixed gender (male and female participants in published study cohort); Mo male-only; PSD Pilonidal Sinus Disease; pt patient; RCT randomised controlled trial; RR Recurrence rate; ROR return on recurrence; yr year.