Outcomes reported in comparative studies of surgical management of pilonidal disease: Systematic review to inform a core outcome set

BACKGROUND: Evidence synthesis in pilonidal disease surgery is limited by heterogeneity in outcome selection, definition, measurement and follow-up. This systematic review aimed to identify and describe outcomes reported in comparative studies of surgical management of pilonidal disease to inform development of a core outcome set. METHODS: PubMed, Embase and CENTRAL were searched from inception to 28 November 2025. Randomised controlled trials and comparative observational studies evaluating surgical interventions for pilonidal disease were eligible. Two reviewers independently screened studies and extracted study characteristics and outcome data. Verbatim outcomes were standardised, grouped into domains and summarised descriptively. Because the objective was to map outcome reporting rather than estimate treatment effects, risk-of-bias assessment and GRADE appraisal were not undertaken. RESULTS: A total of 155 studies were included, comprising 93 randomised trials and 62 observational studies. Ten outcome domains were identified. Recurrence was reported most frequently (112 studies, 72.3%), followed by non-infective complications (103, 66.5%), pain (83, 53.5%), wound healing (82, 52.9%) and return to normal activities (63, 40.6%). Patient-important domains were less frequently reported, including health-related quality of life or satisfaction (50, 32.3%) and cosmesis (17, 11.0%). Among outcomes designated as primary, wound healing was most common (51 studies, 32.9%), followed by recurrence (35, 22.6%) and postoperative complications (25, 16.1%). Pain (6, 3.9%), return to normal activities/work (9, 5.8%), and psychological or quality-of-life outcomes (3, 1.9%) were rarely primary outcomes. Definitions, measurement instruments, assessment timepoints and overall follow-up duration varied substantially across studies. CONCLUSIONS: Comparative studies of pilonidal disease surgery predominantly prioritise recurrence, healing and complications, whereas patient-important outcomes are reported less consistently and are infrequently prioritised. Standardisation of outcome selection, definitions and measurement is needed. These findings support development of a core outcome set for future trials in pilonidal disease surgery. TRAIL REGISTRATION: CRD420251128698.