Table 2. ORs and 95% CIs for the detection of localised gastric cancer for ever-screened patients compared with never-screened patientsa.

	Including ‘unknown stage'		Excluding ‘unknown stage'
	OR	(95% CI)	OR	(95% CI)
Overall	1.71	(1.60–1.82)	1.81	(1.68–1.96)
Genderb
Male	1.74	(1.62–1.88)	1.84	(1.68–2.01)
Female	1.64	(1.45–1.84)	1.76	(1.53–2.02)
Age at diagnosis, yearsb
⩽49	1.91	(1.56–2.35)	1.97	(1.56–2.49)
50–59	1.80	(1.58–2.04)	2.02	(1.74–2.34)
60–69	1.85	(1.65–2.07)	1.92	(1.68–2.19)
70⩽	1.47	(1.32–1.64)	1.51	(1.32–1.73)
Socioeconomic statusb
NHI with premium under 50%	1.48	(1.35–1.62)	1.63	(1.46–1.82)
NHI with premium over 50%	1.95	(1.77–2.14)	2.03	(1.82–2.26)
MAP recipients	1.95	(1.50–2.55)	1.73	(1.24–2.41)
Screening method
Never-screened	1.00	Reference	1.00	Reference
UGIS	1.24	(1.13–1.36)	1.28	(1.14–1.43)
Endoscopy	2.10	(1.90–2.33)	2.31	(2.04–2.60)
Both modalitieis, alternatively	2.63	(2.20–3.15)	2.83	(2.29–3.51)
Screening frequency
Never screened	1.00	Reference	1.00	Reference
Once	1.51	(1.39–1.63)	1.59	(1.45–1.75)
Twice	2.00	(1.76–2.27)	2.16	(1.86–2.51)
Three times or more	2.78	(2.22–3.49)	2.91	(2.22–3.82)
Time interval since screening, months
Never screened	1.00	Reference	1.00	Reference
⩽11	1.82	(1.69–1.96)	1.91	(1.75–2.09)
12–23	1.48	(1.26–1.73)	1.64	(1.36–1.97)
24–35	1.53	(1.13–2.07)	1.50	(1.05–2.15)
⩾36 months or over	1.38	(1.09–1.75)	1.55	(1.18–2.04)

Abbreviations:CI=confidence interval; MAP=medical aids programme; NHI=national health insurance; OR=odds ratio; UGIS=upper gastrointestinal series.

^aAnalyses were conducted using conditional logistic regression model.

^bOdds ratio of detecting localised gastric cancer in screened group vs never-screened group in a subgroup