[Secular trends in smoking according to educational level between 1986 and 1996: The MONICA study. Catalonia].

Objective: To describe trends from 1986-1996 in the prevalence of cigarette smoking between ages 25 to 64 in the MONICA-Catalonia study, according to educational level, and to validate these trends biochemically.

Methods: Three cross-sectional surveys in independent random samples of the general population of central Catalonia area carried out in 1986-88, 1990-92 and 1994-96 following the World Health Organization's MONICA protocol. Serum thiocyanate was determined by the Bowler method.

Results: A total of 2,571, 2,934 and 3,485 men and women were examined with response rates of 74, 67 and 72% in each survey respectively. The age-adjusted cigarette smoking prevalence decreased in men by 5.1% (95% CI: 1.5 to 8.7) and increased in women by +8.5% (95% CI: +5.6 to +11.4). The prevalence was 46.5% in men and 23.9% in women in 1994-96. The greatest decrease was in men aged 55-64 (9.9%) and the greatest increase was in women aged 35-44 (+14.8%). These trends were confirmed by serum thiocyanate levels, which decreased from 78.9 to 73.9 μmol/l (p = 0.07) in men and increased from 43.7 to 49.8 μmol/l (p < 0.01) in women during the study period. Cigarette smoking increased in less educated women (+10%) and decreased in university women (6%), while cigarette smoking in men decreased irrespective of educational level. Serum thiocyanate levels confirmed the relationship with educational level.

Conclusions: The prevalence of cigarette smoking decreased in men between 1986 and 1996 but remained high in 1996. Women showed a pattern of progressive adoption of smoking, especially those with lower educational level.