Influence of smoking by family and best friend on adolescent tobacco smoking: results from the 2002 New Zealand national survey of year 10 students.

OBJECTIVE To compare the relative importance on adolescent smoking of the influence from parental smoking and peer smoking. METHOD National New Zealand crosssectional survey of 14,936 female and 14,349 male Year 10 students (aged 14 and 15 years) who answered an anonymous self-administered questionnaire in November 2002. RESULTS Adolescents with both parents smoking had the highest smoking risk compared with those with one or neither parent smoking. The relative risk of adolescent daily smoking associated with both parents smoking, compared with neither, varied with ethnicity, being 2.34 (95% Cl 2.05-2.67) in Maori, 2.87 (2.21-3.73) in Pacific Islanders, 11.37 (7.87-16.42) in Asian, and 4.92 (4.35-5.55) in European/Other students, adjusting for age and sex. These values were lower than the adjusted relative risks of daily adolescent smoking associated with having a best friend who smoked: 4.18 (3.59-4.88) in Maori, 5.19 (3.98-6.76) in Pacific Island, 14.35 (9.48-21.71) in Asian and 10.18 (9.07-11.43) in European/Other students. Adolescent smoking was also positively associated with pocket money amount and living in a home where smoking was allowed, both parental-related factors. Combined exposure to one or more of the following factors - parental smoking, pocket money >$5 per week and smoking in the house - explained 64% of daily adolescent smoking, very similar to the 67% attributable to best friend smoking. CONCLUSION Parental behaviour is a key determinant of smoking by New Zealand adolescents and explains a similar proportion of daily adolescent smoking to that by peer smoking.