Table 4.

 Crude and adjusted odds ratios with 95% confidence intervals (95% CI) for developing schizophrenia in years 5+ after conscription in subjects having ever used cannabis

Drug use	No of subjects	No (%) of subjects developing schizophrenia	Odds ratio (95% CI)
			Crude	Adjusted*
Cannabis ever†	5287	40 (0.8)	1.6 (1.1 to 2.2)	1.2 (0.8 to 1.8)
Frequency of use of cannabis (ever):
None	36 382	168 (0.5)	1.0†	1.0†
Once	608	2 (0.3)	0.7 (0.2 to 2.9)	0.8 (0.2 to 3.2)
2-4 times	1378	6 (0.4)	0.9 (0.4 to 2.1)	0.9 (0.4 to 2.0)
5-10 times	802	5 (0.6)	1.4 (0.6 to 3.3)	1.0 (0.4 to 2.5)
11-50 times	685	9 (1.3)	2.9 (1.5 to 5.6)	2.1 (1.0 to 4.5)
>50 times	718	15 (2.1)	4.6 (2.7 to 7.8)	2.5 (1.2 to 5.1)
Linear trend for frequency of use	—	—	1.3 (1.2 to 1.4)	1.2 (1.0 to 1.3)

^*Adjusted for diagnosis at conscription, IQ score, poor social integration, disturbed behaviour, cigarette smoking, and place of upbringing. 

^†No drug use as baseline comparison.