Light smoking at base-line predicts a higher mortality risk to women than to men; evidence from a cohort with long follow-up.
BACKGROUND
There is conflicting evidence as to whether smoking is more harmful to women than to men. The UK Cotton Workers' Cohort was recruited in the 1960s and contained a high proportion of men and women smokers who were well matched in terms of age, job and length of time in job. The cohort has been followed up for 42 years.


METHODS
Mortality in the cohort was analysed using an individual relative survival method and Cox regression. Whether smoking, ascertained at baseline in the 1960s, was more hazardous to women than to men was examined by estimating the relative risk ratio women to men, smokers to never smoked, for light (1-14), medium (15-24), heavy (25+ cigarettes per day) and former smoking.


RESULTS
For all-cause mortality relative risk ratios were 1.35 for light smoking at baseline (95% CI 1.07-1.70), 1.15 for medium smoking (95% CI 0.89-1.49) and 1.00 for heavy smoking (95% CI 0.63-1.61). Relative risk ratios for light smoking at baseline for circulatory system disease was 1.42 (95% CI 1.01 to 1.98) and for respiratory disease was 1.89 (95% CI 0.99 to 3.63). Heights of participants provided no explanation for the gender difference.


CONCLUSIONS
Light smoking at baseline was shown to be significantly more hazardous to women than to men but the effect decreased as consumption increased indicating a dose response relationship. Heavy smoking was equally hazardous to both genders. This result may help explain the conflicting evidence seen elsewhere. However gender differences in smoking cessation may provide an alternative explanation.
School of Health, University of Central Lancashire, Preston, UK. MAHurley@uclan.ac.uk.
Margaret A
MA
Hurley
D000328:Adult; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000401:mortality; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D016016:Proportional Hazards Models; D012306:Risk; D012720:Severity of Illness Index; D017678:Sex Distribution; D012737:Sex Factors; D012907:Smoking / Q000401:mortality*; D016540:Smoking Cessation / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D016019:Survival Analysis; D014029:Tobacco Use Disorder / Q000401:mortality*; D006113:United Kingdom / Q000453:epidemiology; D016387:Women's Health / Q000706:statistics & numerical data*