Study	Reason for exclusion
Amorín 1989	Unable to trace
Awad 2007	Methodology and interventions did not satisfy inclusion criteria
Baier 2002	Fully translated: retrospective, not a clinical trial
Bascom 2002	Case study
Christensen 1985	Paper translated: participant group contained acute abscess
Collazo 1994	RCT stopped prior to endpoints being reached: 11 participants only: poor description of results and outcomes
De Falco 2007	Paper translated: retrospective cohort study
Duxbury 2003	Interventions did not satisfy inclusion criteria
Faltz 1990	Translated: interventions did not satisfy inclusion criteria
Golz 1980	Case series description without comparison group
Gupta 2004	Interventions did not satisfy inclusion criteria
Gupta 2005	Interventions did not satisfy inclusion criteria
Hell 1971	Translated: unclear study design
Hodgson 1981	Poor methodology: inadequate description of results: large losses to follow up
Hollingworth 1992	Series of letters
Hosseini 2006	Included participants with acute abscess
Khalid 2001	Unable to trace
Maniscalco 2001	Paper translated: retrospective cohort study
Mann 1987	Case series
Marks 1985	Not an RCT: interventions did not satisfy inclusion criteria
Morrison 1985	Large proportion of cases were pilonidal abscesses
Notaras 1970	Review article
Oncel 2002	Interventions did not appear to satisfy inclusion criteria: attempt to contact author: no reply
Ortiz 1977a	Interventions did not appear to satisfy inclusion criteria: attempt to contact author: no reply
Ortiz 1977b	Spanish language version of Ortiz 1977a
Petersen 2002	Review article
Reidler 1978	Translated: retrospective review
Sturniolo 1984	Translated: not a clinical trial
Søndenaa 2002	Intervention is antibiotic usage
Søreide 2009	Review article
Watson 2005	Letter
Werkgartner 2004	Editorial
Wienart 2004	Review article