Secondhand smoke exposure and intermittent claudication: a Scotland-wide study of 4231 non-smokers

Objective Active smoking is an important risk factor for peripheral arterial disease. In contrast, published evidence on the association with secondhand smoke (SHS) is very limited. The aim of this study was to examine the association between SHS exposure and intermittent claudication (IC) among middle aged non-smokers. Design Multivariate logistic regression analyses were used to adjust for potential confounders. Setting The Scottish Health Survey, a pan-Scotland, representative survey of the general population. Patients We conducted a cross-sectional study using the Scottish Health Surveys undertaken between 1998 and 2010. Inclusion was restricted to participants aged >45years. Main outcome measures Of the 4231 confirmed non-smokers (self-reported non-smokers with salivary cotinine concentrations <15ng/mL), 134 (3.2%) had IC based on the Edinburgh Claudication Questionnaire. Results There was evidence of a dose relationship, whereby the risk of IC increased with increasing cotinine concentration. Following adjustment for potential confounders, participants with a cotinine concentration 2.7ng/mL were still significantly more likely to have IC (OR 1.76, 95% CI 1.04 to 3.00; p=0.036) compared with those with a cotinine concentration <0.7ng/mL. Among non-smokers, 5.6% (95% CI -0.8% to 11.7%) of cases of IC were attributable to cotinine concentrations 2.7ng/mL and a further 3.6% (95% CI -6.6% to 12.8%) to cotinine concentrations of 0.7-2.6ng/mL. Conclusions As with coronary heart disease and stroke, SHS exposure was independently associated with IC. Our findings add to the published evidence in support of protecting the general public from SHS exposure.