Table 1

Effect of exposure on mortality according to age from February 1996 to June 1998

Age (months)	Exposed (N=841)			Unexposed (N=12483)
Age (months)	Deaths	100 PYO	Rate	Deaths	100 PYO	Rate	HR (95% CI)^*	HR (95% CI)^†
3–11	4	0.73	5.5	191	28.0	6.8	0.80 (0.3 to 2.2)	0.79 (0.3 to 2.1)
12–35	22	3.60	6.1	247	65.9	3.8	1.68 (1.1 to 2.6)	1.67 (1.1 to 2.6)
36–60	15	4.18	3.6	88	57.2	1.5	2.38 (1.4 to 4.1)	2.28 (1.3 to 4.1)
All	41	8.51	4.8	526	151	3.5	1.66 (1.2 to 2.3)	1.63 (1.2 to 2.3)

↵* HR from a model with age as underlying time.
↵† HR from a model with age as underlying time, adjusted for gender, ethnicity, district, socioeconomic status, schooling of the mother and child crowding.
PYO, person-years of observation.