Table 2.

Risk of DSM-IV nicotine dependence by the sum score in five groups (N=1259 smokers)

NDSS sum score groups (values in parenthesis)	Age-sex adjusted risk	Crude risk	% of DSM-IV nicotine dependent	% of subjects
Group 1(reference) (14–24)	1.00	1.00	21.3	17.3
Group 2 (25–32)	2.24 (1.49– 3.38)*	2.28 (1.54 – 3.39)	38.2	25.9
Group 3 (33–41)	4.79 (3.21–7.12)*	5.00 (3.39 – 7.38)	57.6	27.6
Group 4 (42–54)	11.9 (7.75 –18.4)*	12.4 (8.17 – 18.9)	76.9	24.5
Group 5 (55–70)	36.7 (13.0–103)*	39.2 (14.8 – 104)	91.4	4.6
Age (years)	0.97 (0.96 – 0.99)*
Sex (1=men, 2=women)	0.96 (0.71– 1.21)*

^*Robust 95% confidence intervals in parentheses, i.e. adjusted for dependence of family members within families