Women are about 50 per cent more likely than men to develop chronic obstructive pulmonary disease (COPD) – even if they have never smoked or smoked much less than their male counterparts.

That is the finding of a study based on observational research that was published today (9 May) in the open access journal BMJ Open Respiratory Research.

The study was conducted by a US-based team including Alexander Steinberg, who works in pulmonary and critical care at the University of Washington in Seattle. The team’s findings challenge the widely held belief that women’s increased vulnerability to cigarette smoke likely explains this disparity, conclude the researchers.

Research approach

To clarify the associations between gender, cigarette smoke, and COPD, and to update previous estimates of the prevalence and impact of COPD, Dr Steinberg and his fellow researchers drew on a large nationally representative US survey of adults from the 2020 National Health Interview Survey (NHIS). 

Respondents (12,638 women and 10,390 men aged at least 40) were asked about their smoking history, what tobacco products they used, and whether they vaped. Women reported lower rates of both current and former cigarette, cigar, and pipe smoking, and smokeless tobacco use than men, but similar rates of vaping.

The prevalence of COPD was just under 8 per cent for women and 6.5 per cent for men. Women with COPD were more likely to have never smoked cigarettes than men with COPD (26.5 per cent vs just over 14 per cent), and less likely to use other tobacco products except for e-cigarettes (26.5 per cent vs 20 per cent).

Women also reported smoking fewer daily cigarettes than men, averaging around 18 compared with around 22, and to have done so for fewer years. And they were less likely than men to have started smoking before the age of 15:19 per cent vs 28 per cent.

Yet the prevalence of COPD was higher among women who had ever smoked than it was among men: 16 per cent vs 11.5 per cent.  And among women who had never smoked the prevalence of COPD was almost twice as high as it was in male non-smokers: just over 3 per cent compared with just over 1.5 per cent. 

In further analysis, female gender was associated with a significantly (47 per cent) higher risk of being diagnosed with COPD after accounting for potentially influential factors. 

This gender difference in risk persisted, irrespective of smoking history: among those who had never smoked, women were 62 per cent more likely to be diagnosed with COPD, and among those who had ever smoked they were 43 per cent more likely to do so. 

‘Our findings refine prior estimates of COPD among those without a smoking history and re-emphasise the high burden of COPD in women, underscoring the need for thoughtful efforts to prevent, diagnose, and treat their disease’ [Alexander Steinberg et al]

Caveats and conclusions

Dr Steinberg and colleagues acknowledge that their study relied on self-report rather than objectively measured data. And they lacked potentially important information on hormonal influences, family history, or infectious, occupational, and environmental exposures.

But they nevertheless suggest: ‘These findings should raise questions about whether differing susceptibility to tobacco smoke is the key factor driving the increased COPD prevalence in women in the USA. 

‘If women were more susceptible to the effects of smoking, we would not expect to see a nearly identical risk per 10 pack-year exposure, nor would we expect to see a similarly.’

Dr Steinberg and the team conclude: ‘Our findings refine prior estimates of COPD among those without a smoking history and re-emphasise the high burden of COPD in women, underscoring the need for thoughtful efforts to prevent, diagnose, and treat their disease.’ 

Fact file

• Smoking is the principal cause of COPD. But despite significant falls in cigarette smoking over the past 50 years, it remains a leading cause of death in the USA, with the prevalence of COPD in women approaching that of men. 

• Women with COPD tend to have more severe symptoms, and at a younger age, than their male counterparts, prompting the suggestion that the explanation may lie in a heightened susceptibility to the effects of cigarette smoke, according to Dr Steinberg and colleagues.

To access the full version of the article – titled Gender, tobacco and chronic obstructive pulmonary disease: analysis of the 2020 National Health Interview Survey article – see: https://doi.org/10.1136/bmjresp-2024-002462

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