title: Age at starting smoking and number of cigarettes smoked in Catalonia, Spain.
abstract: BACKGROUND
  Few studies have investigated the association between age at starting smoking and the average number of cigarettes smoked per day in adulthood. To provide further evidence on this issue, we analyzed data from the Catalan Health Interview Survey (CHIS).
  
  
  METHODS
  The CHIS was conducted in 1994 on a randomly selected sample (N = 15,000) of the population of Catalonia, Spain. A total of 4,897 current or exsmokers (3,276 males and 1,621 females) were included for analysis. Age-standardized proportions of subjects smoking <15, 15-24, and >/=25 cigarettes/day, age-standardized mean number of cigarettes smoked per day, and multivariate odds ratios (OR) of being a heavy smoker (>/=25 cigarettes/day) according to age at starting smoking (<15, 15-17, 18-19, >/=20 years) were computed.
  
  
  RESULTS
  Men who started smoking before the age of 15 smoked on average 5.5 cigarettes more than those who started at age 19 or over. Women who started smoking early in life smoked, on average, 6.8 cigarettes/day more than women who started later. The proportion of smokers of <15 cigarettes/day was higher among subjects who started smoking later. Both for males and for females, the OR of being a heavy smoker significantly increased with decreasing age at starting smoking (OR = 2.4 for males and 4.5 for females who started at age <15 versus >/=20 years). The level of education did not modify the relationship in males, whereas the association with age at starting was only apparent for more educated women.
  
  
  CONCLUSIONS
  This study confirms that age at starting smoking is inversely and strongly associated to the number of cigarettes smoked per day. Thus, actions aimed at the prevention or delay of smoking onset among adolescents would have an important beneficial effect.
authors: Institut Universitari de Salut Pública de Catalunya, L'Hospitalet, Barcelona, Spain. efernandez@bell.ub.es
authors: E
authors: E
authors: Fernandez
authors: A
authors: A
authors: Schiaffino
authors: C
authors: C
authors: La Vecchia
authors: J M
authors: JM
authors: Borrás
authors: M
authors: M
authors: Nebot
authors: E
authors: E
authors: Saltó
authors: R
authors: R
authors: Tresserras
authors: L
authors: L
authors: Rajmil
authors: J R
authors: JR
authors: Villalbí
authors: A
authors: A
authors: Segura
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D017668:Age of Onset; D003430:Cross-Sectional Studies; D004522:Educational Status; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D012494:Sampling Studies; D012720:Severity of Illness Index; D017678:Sex Distribution; D012907:Smoking / Q000453:epidemiology*; D013030:Spain / Q000453:epidemiology; D013223:Statistics as Topic