Table 2

Summary of lung cancer risk estimates by treatment group

Analysis period	Number of cases selenium/placebo			RR (95% CI)	P	HR^a (95% CI)	P
1983–1993^b	17	31	0.54 (0.30, 0.98)	0.04	0.56 (0.31, 0.76)	0.05
1983–1996	25	35	0.70 (0.40, 1.21)	0.18	0.74 (0.44, 1.24)	0.26

^a Cox proportional hazards model; adjusted for age, smoking status (current, former, never).
^b Clark et al.(3) .