Sex and Age Specific Projections of Smoking Prevalence in Spain: A Bayesian Approach.

Objectives: To project future smoking prevalence rates in Spain by sex and age groups using Bayesian methods and to estimate the probability of a 30% relative reduction between 2010 and 2025.

Methods: We used the data from the Spanish National Health Surveys (2003, 2006, and 2011) to obtain information about current and former smoking. We reconstructed annual smoking rates from 1989 through 2011 by sex and 5-year age groups. The prevalence were projected for the period 2012-2025 using a Bayesian logistic binomial model and estimated the probability to achieve the 30% relative reduction endorsed by the WHO. We calculated the 95% credible interval (CrI) of the posterior distribution, which includes a 95% of the distribution of potential smoking prevalences.

Results: In men, the projections show a decline for crude (-2.64% annually, 95% CrI: -3.32; -1.97) and adjusted (-2.50%, 95% CrI:-3.14; -1.87) prevalence. In women, the projections show a decline for crude prevalence (-0.36%, 95% CrI: -1.02; -0.30)) and the age-adjusted prevalence (-1.02%, 95% CrI: -1.61, -0.47). By age groups, the decline is greater among women aged 15-39 years (-3.92%, 95% CrI: -4.92; -2.96)) while for women aged 40-64 years an increase (1.84%, 95% CrI: 1.06; 2.58) is expected. In men, the probability to achieve the WHO target is 0.728 and in women is less than 0.001. The age group 15-39 shows the highest probability to achieve the target.

Conclusions: The results suggest smoking prevalence will decrease during 2012-2025 in all age groups for both sexes except for women aged 40-64. We found that the WHO target of a 30% reduction in prevalence is likely to be achieved overall and in the 15-39 years age groups for both sexes, but not achieved for older women and it is uncertain whether it will be achieved for older men. These results highlight the need to strengthen public health interventions that focus on reducing tobacco use in adult women aged 40-64 years old.

Implications: We project a decrease in smoking prevalence in during 2012-2025 except for women aged 40-64. The WHO Target of a 30% relative reduction could be achieved in the population aged 15-39; but not in women and the results are inconclusive in men. These results highlight the need to strengthen public health interventions that focus on reducing tobacco use in adult women aged 40-64 years old.