Table 2.

Negative binomial models for intervention effect on repetitions of deliberate self poisoning and for subgroup analyses by sex

	Incidence risk ratio	SE (95% CI)	Z value*	P value*
Group (unadjusted)
Control	1.00
Postcards	0.55	0.13 (0.35 to 0.87)	−2.56	0.010
Subgroup analyses
Men (n=247):
Control	1.00
Postcards	0.97	0.35 (0.48 to 1.98)	−0.08	0.937
Women (n=524):
Control	1.00
Postcards	0.54	0.16 (0.30 to 0.96)	−2.09	0.037

^*Wald test.