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

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.

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.

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.

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.