The health impact of smoking in manual and non-manual social class men andwomen: a test of the Blaxter hypothesis

Blaxter has hypothesized that harmful behavioral habits like smoking have a greater impact on health in the nonmanual than in the manual social classe s, possibly because other adverse exposures have a more important role in t he manual social classes. However, the outcome measure used was a composite measure of physiological indices of morbidity and the relevance of this to other health problems is uncertain. We have therefore investigated the eff ect of smoking on mortality, to test whether the risk of death associated w ith smoking differs between manual and nonmanual social classes. Data on 68 31 men and 7993 women, aged 45-64 when screened in the Renfrew and Paisley study, a large prospective observational study in the West of Scotland, hav e been analyzed. All cause mortality rate ratios for smokers compared with never smokers have been calculated within manual and non-manual social clas ses. Although the age adjusted rate ratios are slightly higher among the no n-manual men and women (2.19 [1.83-2.61] versus 1.92 [1.71-2.17] for non-ma nual and manual men respectively, and 1.75 [1.54-1.99] versus 1.65 [1.50-1. 82] for non-manual and manual women), this difference between social classe s is not statistically significant (p-values for test of difference 0.26 an d 0.47 for men and women respectively). When additionally adjusted for othe r risk factors, cardiorespiratory symptoms and deprivation, this picture re mained the same (p-values for test of difference are 0.41 and 0.50 for men and women respectively). Similar results were found when the cohort was div ided by deprivation categories rather than social classes or when smoking r elated mortality rather than mortality from all causes was used as the outc ome measure. We therefore conclude that the health impact of smoking is sim ilar in each socioeconomic group. The relative health improvement consequen t on smoking cessation is thus similar in different socio-economic groups. (C) 1999 Elsevier Science Ltd. All rights reserved.