Mathew 1997.

Study characteristics
Patient sampling	Method of patient selection: Re‐examination of 2069 eligible participants from the 9000 participants recruited in January to May 1996, shortly after commencement of the study. "Subjects were selected by choosing densely inhabited areas to allow re‐examination of as many subjects as possible in two weeks." Study looking at the reproducibility and validity of oral visual inspection by health workers within a randomised controlled intervention trial of visual screening
Patient characteristics and setting	2069 participants Age: Mean 47.7 years, sd 9.1 years (range 35 to 64 years) Sex: 678 males; 1391 females SES: Recorded but not reported Ethnicity: Recorded but not reported Stated risk factors: Details on smoking and alcohol were recorded but not reported Previous history: Recorded but not reported Location: Kerala, India Clinical setting: Participants' homes
Index tests	Index test: Systematic oral visual examination by trained health workers (n = 14) in the inspection and detection of oral lesions Description of positive case definition by index test as reported: "...homogeneous leucoplakia, ulcerated leucoplakia, verrucous leucoplakia, erythroplakia, nodular leukoplakia, submucous fibrosis, and oral cancer" Sequence of tests: Initial screen by health worker followed by second screen (the index test) by same health worker (1 to 6 months later) to establish reliability. 2069 received the index test (second screen by HW) and this formed the sample for the sensitivity and specificity calculations Training or calibration: "Training sessions spread over 6 weeks composed of lectures, practical demonstrations and field work conducted by Faculty... At the end of training sessions written and practical tests were conducted identifying the best health workers.... They were also given manuals and photographic documentation to identify different types of oral lesions." The "best performing" health workers were retained for the study Blinding of examiners: Index test completed before reference Conflict of interests: Supported by a grant from the Association of International Cancer Research, Scotland, UK
Target condition and reference standard(s)	Target condition: As for index test "...homogoneous leukoplakia, ulcerated leukoplakia, verrucous leukoplakia, erythroplakia, nodular leukoplakia, submucous fibrosis, and oral cancer" Reference standard: Visual examination by a specialist physician (decision made by single physician, 1 of 3). "....comparison with pathological findings is not possible as biopsy has not been performed for most case. Biopsy is performed for cases of nodular leucoplakias, erythroplakias and suspicious growths only, and this is currently being undertaken" Training or calibration: 100 participants formed the basis of comparability of findings evaluation. Kappa value of 0.85 was reported for the findings of the 3 physicians Blinding of examiners: Reference test undertaken immediately after index test. Both health worker and specialist in participants' home at the same visit Prevalence of the target condition on the sample: 212/2069 10.3%
Flow and timing	Time interval and any interventions between index test(s) and reference standard: "This was immediately followed by an independent examination of the same subject by one of three physicians" Characteristics and proportion of individuals who did not receive the index test(s) and/or reference standard or excluded from analysis: None Characteristics and proportion of individuals who received a reference standard other than examination and clinical evaluation by a specialist physician: None
Comparative
Notes
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?	Yes
		Low	Unclear
DOMAIN 2: Index Test All tests
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
Was conflict of interest avoided?	Yes
Where multiple index tests were used, were the results of the second index test interpreted without knowledge of the results of the first index test?
		Low	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?	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?	Yes
		Low