Table 4. Crude hazard ratios of screening, and hazard ratios corrected for selection bias.

	Crude hazard ratio (95% CI)	Corrected hazard ratio (95% CI)
Age at death (years)
50–84	0.39 (0.34–0.44)	0.67 (0.49–0.90)
50–69	0.36 (0.31–0.41)	0.61 (0.45–0.84)
Period of death
1992–1996	0.37 (0.22–0.62)	0.63 (0.35–1.14)
1997–2001	0.33 (0.25–0.44)	0.57 (0.38–0.85)
2002–2006	0.42 (0.33–0.53)	0.72 (0.50–1.04)
2007–2011	0.40 (0.33–0.48)	0.68 (0.49–0.94)
Period of index invitation
1992–1996	0.45 (0.37–0.56)	0.78 (0.55–1.10)
1997–2001	0.35 (0.28–0.44)	0.60 (0.42–0.86)
2002–2006	0.39 (0.29–0.52)	0.66 (0.44–1.00)
2007–2011	0.22 (0.13–0.36)	0.38 (0.21–0.67)
Follow-up time (years)
0–2.9	0.24 (0.19–0.31)	0.41 (0.28–0.60)
3–4.9	0.42 (0.32–0.57)	0.73 (0.49–1.09)
5–7.9	0.43 (0.32–0.57)	0.73 (0.49–1.09)
8–11.9	0.41 (0.31–0.54)	0.70 (0.47–1.03)
12–19.9	0.63 (0.44–0.90)	1.08 (0.69–1.70)

Abbreviation: CI=confidence interval.

Note: Controls are categorised according to case's follow-up time category, that is, time from index invitation to death.

Heterogeneity, that is, the consistency of HRs with the variable category: for the period of death P=0.6344, for the period of index invitation P=0.0450 and for follow-up time P=0.0002.