Acien 1989.

Study characteristics
Patient sampling	Primary objective: to measure the levels of CA‐125 in the serum of normal women and in patients with endometriosis before, during and after treatment with danazol or a luteinising hormone‐releasing hormone agonist, to evaluate the influence of these treatments on the levels of CA‐125 and the possible relation with reactivation of endometriosis after treatment Participants: women with endometriosis confirmed by laparoscopy and a group of regularly menstruating women with a normal pelvis at laparoscopy Selection criteria: not specified Study design: longitudinal, two‐gate design, prospective collection of samples
Patient characteristics and setting	Clinical presentation: endometriosis group ‐ infertility in 70.4%, not specified otherwise Age: range 22‐43 years Number of participants enrolled: 68 women (11 postmenopausal women were enrolled and analysed separately ‐ not considered in this review) Number of participants available for analysis: 68 women (all in luteal cycle phase) Setting: not stated; authors' affiliations: the Royal Free (University) Hospital, London; and School of Medicine, University of Alicante, Spain Place of study: not specified, Europe Period of study: not stated Language: English
Index tests	Index test: CA‐125 Details of the index test procedure as stated: serum CA‐125 was measured with an immunoradiometric assay (Abbot CA‐125 RIA); working assay range was 6‐500 U/ml. sample processing and experiments not described Threshold for positive result: > 30 U/ml, not pre‐specified Examiners: no information provided; unclear if blinded to the result of reference standard Interobserver variability: interassay and intra‐assay CV 3.5%‐6.4%
Target condition and reference standard(s)	Target condition: endometriosis Prevalence of target condition in the sample: n = 54/68 (79%): stage I‐II 40, stage III‐IV 14; controls n = 14 Reference standard: laparoscopy N = 68 (100%) Description of positive case definition by reference standard as reported: visual inspection, staging according to the rAFS classification Examiners: no information provided
Flow and timing	Time interval between index test and reference standard: samples were taken at laparoscopy Withdrawals: none
Comparative
Key conclusions by the authors	Increases in CA‐125 values above 30 U/ml were more likely to indicate reactivation of endometriosis than when CA‐125 did not increase
Conflict of interest	Not reported
Notes	The reported CA‐125 values during and after treatment with Danazol or GnRH analogues are not included in this review Additional control group of postmenopausal women (N = 11) was not considered in calculation of diagnostic estimates
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	No
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
		Unclear	Low
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
		Unclear	Low
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Yes
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Yes
		Low