Gazvani 1998.

Study characteristics
Patient sampling	Primary objective: to evaluate the role of IL‐8 in the pathogenesis of endometriosis in relation to the stage of disease Participants: patients undergoing laparoscopic surgery for benign gynaecological indications Selection criteria: not specified Study design: cross‐sectional, two‐gate design, prospective collection of samples, consecutive patients
Patient characteristics and setting	Clinical presentation: indications for surgery: abdominal pain (n = 21), sterilisation (n = 11), infertility (n = 18); none of the patients had been on medication at least 1 month prior to the laparoscopy and none was on any long‐acting drugs Age: mean age 28 ± 8.1 years (endometriosis group) and 29 ± 6.9 years (controls) Number of participants enrolled: 50 women Number of participants available for analysis: 47 (23 in follicular, 24 in luteal cycle phase) Setting: not specified, the authors' affiliations are 2 university hospitals: Liverpool Women's Hospital, University of Liverpool and Department of O&G, University of Aberdeen Place of study: Aberdeen and Liverpool, UK Period of study: not provided Language: English
Index tests	Index test: IL‐8 Details of the index test procedure as stated: IL‐8 levels were measured using an enzyme‐linked immunosorbent assay (CYTokit Red; CYTimmune Sciences, USA) according to the manufacturer's instructions; sample processing described Threshold for positive result: not provided Examiners: no information provided; unclear if were blinded to the results of reference standard Interobserver variability: not provided
Target condition and reference standard(s)	Target condition: endometriosis Prevalence of target condition in the sample: n = 25/105 (24%): stage I‐II 14, stage III‐IV 11; controls n = 22 Reference standard: laparoscopy N = 105 (100%) + histology Description of positive case definition by reference standard test as reported: visualisation at surgery: the condition of tubes, ovaries, pouch of Douglas, and bowels were inspected; staging according to the AFS system Examiners: no information provided
Flow and timing	Time interval between index test and reference standard: not specified, but from the context, samples were obtained at surgery Withdrawals: 3 patients were excluded before analysis because of inadequate peritoneal fluid sample
Comparative
Key conclusions by the authors	Peripheral blood concentrations did not correlate with peritoneal fluid concentrations of IL‐8 or the presence of endometriosis. IL‐8 (in PF) is an important factor that may contribute to the pathogenesis of endometriosis possibly by promoting neovascularisation
Conflict of interest	Not reported
Notes	For IL‐8 there was no statistically significant difference between the groups ‐ no data available for meta‐analysis
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Yes
Did the study avoid inappropriate exclusions?	Unclear
Was a 'two‐gate' design avoided?	No
		High	High
DOMAIN 2: Index Test All tests
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	No
Was a cycle phase considered in interpretation of the result of index test?	Yes
		High	Low
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
		Low	Low
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Yes
		Unclear