Matveeva 1990.

Study characteristics
Patient sampling	Primary objective: to investigate inhibitory and activation motif expression of killer immunoglobulin‐like receptor (KIR) by natural killer (NK) cells, which may be pathogenetically involved in endometriosis Participants: women undergoing laparoscopy for various indications Selection criteria: exclusion criteria: history of pregnancy or history of treatment with GnRH analogues within previous year, complications from apparent pelvic inflammatory disease Study design: cross‐sectional, two‐gate, prospective sample collection
Patient characteristics and setting	Clinical presentation: infertility; all women had regular ovulatory menstrual cycles Age: mean age 30.6 years, range 26‐35 years Number of participants enrolled: 119 participants Number of participants available for analysis: 119/74 participants (in follicular or luteal cycle phase), different number of samples for different tests Setting: National research centre of mother and child health, Ministry of Health Place of study: Moscow, Russia Period of study: not reported Language: Russian
Index tests	Index test: PBMC (CD3, CD4, CD8, CD2), IgA, IgM, IgG Details of the index test procedure as stated: PBMC were measured by flow cytometry using FACScan (Becton Dickinson, USA); serum immunoglobulins were determined by using Manchini method; laboratory technique described Threshold for positive result: not reported Examiners: no information provided, unclear if were blinded to the result of reference standard Interobserver variability: not reported
Target condition and reference standard(s)	Target condition: endometriosis Prevalence of target condition in the sample: n = 62/119 (52%): all stage I‐II; controls n = 57 Reference standard: laparoscopy, n= 119 (100%) Description of positive case definition by reference standard test as reported: staging according to rAFS classification Examiners: no information provided
Flow and timing	Time interval between index test and reference standard: blood samples were collected at surgery Withdrawals: data were not reported for up to 45 participants for some of the index tests, reason not explained
Comparative
Key conclusions by the authors	The tested cells did not markedly differ from those in control fertile patients. Serum concentrations of immunoglobulin M were increased in women with endometriosis. Immunoglobulin concentrations widely varied in the peritoneal fluid, with a statistically significant elevation of IgA and IgM in women with tubal‐peritoneal infertility
Conflict of interest	Not reported
Notes	For PBMC (CD3, CD4, CD8, CD2), IgA and IgG there was no statistically significant difference between the groups ‐ no data available for meta‐analysis For IgM there was statistically significant difference between the groups, but there were insufficient data to construct 2 x 2 tables ‐ not included in this review The data for markers measured in peritoneal fluid are not presented in this review The data for a group of healthy women (n = 10) who did not have laparoscopy are not presented in this review
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Did the study avoid inappropriate exclusions?	Unclear
Was a 'two‐gate' design avoided?	Yes
		Unclear	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?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
		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?	No
		Low