Discussion
In this sample of working-age men living in the industrial city of Izhevsk, the age-standardised prevalence of self-reported symptoms of chronic cough and breathlessness was 20.9% (age-standardised prevalence of chronic cough with grade 3 or above breathlessness was 3.7%). The prevalence of chronic cough was 44.0% and breathlessness grade 2 or above was 33.9%. This is high compared with a prevalence of self-reported cough and/or breathlessness from the BREATHE study of 12.2% among 31 418 men living in 11 countries in the Middle East and North Africa.36 The prevalence of cough and breathlessness among men in Izhvesk was higher than for any of the countries included in the BREATHE study (range 6.1% in the United Arab Emirates to15.9% in Pakistan). Chronic cough and breathlessness are both symptoms of COPD and the high prevalence of these symptoms suggests prevalence of COPD is likely to be high in this population. This is consistent with the one previous study which has investigated prevalence of COPD in Russia using spirometry; the study estimated overall prevalence in both men and women of 15.3%9 compared with an international prevalence of 10.1% in the BOLD study (11.8% in men).37 Further studies in Russia using spirometry are needed to provide more reliable estimates of the burden of COPD.
In this study, self-reported symptoms of cough and breathlessness were associated with poorer self-reported physical and mental health as assessed by the SF-12. There was a particularly strong association with physical health; men with chronic cough and grade 3 breathlessness or above had a physical health score 11.6 points (95% CI 9.3 to 13.8) lower than men without any respiratory symptoms, indicating the severe impact of impaired respiratory function on quality of life for these men. Men with chronic cough and grade 3 or above breathlessness also had much higher odds of several comorbidities (hypertension, diabetes, angina pectoris, MI and stroke) compared with men without respiratory symptoms, even after adjusting for smoking status. These strong associations are consistent with the findings from other countries that respiratory diseases, in particular COPD, are associated with substantial cardiovascular morbidity.11–13 ,15 ,17–20 The association between respiratory symptoms and cardiovascular morbidity has not been investigated previously in Russia. The strong associations with other health conditions found in this study have implications for management of patients with respiratory symptoms; these patients could benefit from identification and treatment of comorbidities. Along with increased odds of cardiovascular comorbidities, men in Izhvesk with respiratory symptoms also had on average a worse cardiovascular risk profile with higher BMI and lower HDL-C levels; however, total cholesterol was also lower and no association was found with triglycerides. There was also strong evidence of higher levels of BNP with respiratory symptoms. Some of this association may be due to misclassification of heart failure as a respiratory problem in this study since breathlessness is a symptom of both; however, this finding is consistent with previous studies which have found both higher levels of BNP among patients with COPD compared with healthy controls38 and that heart failure is a common comorbidity among those with COPD.39 There were only weak associations found in this study between alcohol consumption and respiratory symptoms despite strong associations between hazardous alcohol consumption and blood pressure, cardiovascular disease and BNP.32 ,33 ,40–43 Given the very high levels of cardiovascular mortality in Russia, the identification of patients with respiratory problems as a potentially high-risk group who may benefit from primary and secondary prevention could be particularly important. Conversely, respiratory function should also be investigated among those with cardiovascular disease.
In this study the majority of men (87.3%) who reported respiratory symptoms continued to smoke. This was the case even for men experiencing more severe breathlessness (81.6% current smokers). Smoking cessation is a key part of treatment for many respiratory conditions. This is the single most effective treatment for COPD with an important role in slowing the disease progression.14 ,44 An estimated 62% of patients with COPD in the UK are current smokers estimated from a random sample of patients with COPD in the UK population registered with general practitioner practices in the Clinical Practice Research Datalink.45 Although not directly comparable, the findings from Izhvesk are consistent with findings from this study and studies in clinical populations that a large proportion of those with COPD continue to smoke despite their disease.46 Smoking cessation treatment has been found to be effective for reducing smoking in patients with COPD46–49 and should be offered routinely to those reporting respiratory symptoms.
There were several limitations to this study. First spirometry was not carried out at the health check. Self-reported symptoms of cough and breathlessness were used here to make some inference about chronic respiratory disease burden overall and its associations with cardiovascular comorbidities in this population. We would like to use these findings to make some inferences particularly about COPD, but this should be done with caution given that the case definition used here is less specific than COPD as determined by spirometry, and that some men with cough and breathlessness in this study may have had other lung conditions such as asthma or tuberculosis. In addition, all comorbidities were also self-reported which is an additional source of measurement error. A further limitation in considering the prevalence estimates is that the study population was a small subset of men aged 25–59 years living in the city of Izhevsk; therefore, the results on prevalence are not generalisable to women, older men or to men living elsewhere in Russia and estimates of prevalence are likely to be imprecise. However, the finding that prevalence of chronic cough and breathlessness is high is consistent with findings from other studies in Russia.8 ,9 There may also have been some selection bias in the study since only 65% of men interviewed at IFS-2 went on to attend the health check. However, no differences were found between men included in this study and all men taking part in IFS-2.
A further limitation was that no data were collected about clinical diagnoses and data collected on treatment were limited. Men were asked about what medications they were taking. However, this question did not refer specifically to inhalers and it is possible many men did not report these. Only 10 men reported the use of bronchodilators in the sample overall, but it is not possible to disentangle whether this is due to very low levels of treatment with bronchodilators or under-reporting of use of these medications. There seems to be a very low level of use of bronchodilators given that some men are likely to have been prescribed bronchodilators for asthma, though it is worth noting that bronchodilators could be expensive for a substantial proportion of the population as Russian patients need to pay the full cost of their medications. It was, however, possible to look at the prevalence of smoking cessation, an important aspect of treatment for respiratory disease. The high proportion of current smokers with respiratory symptoms supports findings from medication data that treatment levels in this population are low. Finally there was a low prevalence of several of the comorbidities included, in particular stroke, diabetes and MI; therefore, results are based on small numbers and a limited number of potential confounders were included. Despite these limitations, the finding of a high level of self-reported chronic cough and breathlessness in this study is important given the very limited data available on the burden of chronic respiratory conditions in the Russian Federation.
In conclusion, in this sample of working-age men living in Izhevsk, the prevalence of chronic cough and breathlessness was high and associated with worse self-reported physical and mental health and higher levels of cardiovascular comorbidities. Despite the importance of smoking cessation in treatment for respiratory diseases, the majority of men with chronic cough and breathlessness in this population continued to smoke, thus showing that this is not being tackled sufficiently. Chronic respiratory disease is an important public health issue for Russia, but the low levels of research published suggest this is a neglected area. More research is needed, specifically around the levels of diagnosis and treatment in Russia. The association between respiratory symptoms and cardiovascular comorbidity is of particular importance given the extremely high levels of cardiovascular mortality in Russia.