8 Table 6. Sex differences of COPD patients with CVD complica- tions from 2000 to 2010. Heart failure Arrhythmia Ischemic heart failure Time M (%) F (%) M (%) F (%) M (%) F (%) <2003 75.3 24.7 78.6 21.4 83.4 16.6 2003.1~ 67.3 32.7 62.2* 37.8 59.6* 40.4 2004.12 2005.1~ 65.7 34.3 63.0* 37.0 55.8* 44.2 2006.12 2007.1~ 62.2* 37.8 67.8 32.2 55.8* 44.2 2008.12 2009.1~ 58.6* 41.4 64.4* 35.6 50.8* 49.2 2010.5 *P < 0.05, annual differences compared with 2003. CVD: cardiovascular disease; COPD: chronic obstructive pulmonary disease. M: male; F: female. Figure 2. The prevalent of CVD in COPD patients in the past ten years. CVD: cardiovascular disease; COPD: chronic obstructive pul- monary disease. 4 Discussion It has been confirmed that CVD is a major complication of COPD and COPD is an independent risk factor for CVD. COPD is characterized by systemic inflammation and airflow obstruction. Hypoxia, systemic inflammation, and oxidative stress affect blood vessels, the heart, and the lungs, leading to early subclinical CVD in COPD patients.[5,6] However, investigation of the exact incidence of CVD in patients with COPD has been lacking. In the present study, 4960 subjects aged more than 40 years old hospitalized for COPD were retrospectively analyzed using data from three general hospitals in Beijing. The number of COPD patients with CVD was 2562 (51.7%), and the prevalence gradually increased with age. The prevalence of ischemic heart disease was higher in male COPD patients than in female patients. The prevalence of heart failure and hypertension were lower in male COPD patients than in female patients. The prevalence of ischemic heart disease in COPD patients decreased year on year. COPD patients with heart failure, ischemic heart disease and arrhythmia tended to be younger as the study progressed. More females with COPD and major CVD were observed year on year as the study progressed. Cui H et al. Cardiovascular diseases in COPD The present study showed the prevalence of ischemic heart disease in subjects hospitalized for COPD decreased year on year. The age of new patients with COPD tended to decrease as the study progressed. The proportion of male patients declined, whereas the proportion of female patients increased as the study progressed. COPD patients tend to be younger due to the extensive development of the economy, which has led to air pollution and an increasing population of smokers.[7,8] Several studies have found that the older the patient with COPD, the higher is the prevalence of CVD. Hence, aging itself may be a common risk factor in the increased prevalence of CVD complications in patients with COPD. The trends of CVD occurring in younger subjects may be due to the changes in lifestyle and diet as more Chinese adults relocate to cities, as well as the higher morbidity associated with hypertension, hyperlipidemia and diabetes.[9,10] Consequently, over the last decade, the mean age of COPD patients with CVD has declined as the result of several factors. A retrospective investigation of the prevalence of compli- cations in COPD patients showed that the diagnosis of various complications differed according to sex.[11] More female subjects with COPD tend to have osteoporosis, non-psychotic mental disorders or depression, whereas more men tend to have the complications of ischemic heart disease, diabetes and lung cancer.[12] The present study showed there were more male COPD patients with ischemic heart disease than female COPD patients (P < 0.05), which was in accordance with the results of similar studies.[11,12] Basili et al.[13] showed an increased risk of cardiovascular events in COPD patients could not be simply attributed to metabolic disorders in induced atherosclerosis. The difference between smoking and the protective effect of estrogen may explain (at least in part) the different types and proportions of CVD complications between men and women,[14] but further studies are needed. The present study demonstrated a gradual declining trend in the prevalence of ischemic heart disease in COPD patients in the decade. It has been showed that the tobacco- control programs contributed to the decreased mortality in CVD in the USA from 1955 and 2007.[15,16] From 2000 to 2010, the decreased prevalence of ischemic heart disease in COPD patients may be firstly due to the gradually enhanced tobacco-control programs of the government and increasing awareness of tobacco health affects and control in Chinese society. Secondly, the declining trend may also be related to the promotion of primary prevention of CVD among physicians. For example, the use of statins has prompted the rapid progress in the prevention and treatment for ischemic Journal of Geriatric Cardiology | jgc@jgc301.com; http://www.jgc301.com