Smoking, smoking cessation and aortic arch calcification in older ...

2 downloads 0 Views 98KB Size Report
Mar 14, 2008 - Cigarette smoking is the most important preventable risk factor for ..... and possibly calcification, it would be too late to reverse the calcification ...
Atherosclerosis 202 (2009) 529–534

Smoking, smoking cessation and aortic arch calcification in older Chinese: The Guangzhou Biobank Cohort Study Chao Qiang Jiang a , Xiang Qian Lao a,b , Peng Yin c , G. Neil Thomas b , Wei Sen Zhang a , Bin Liu a , Peymane Adab c , Tai Hing Lam b,∗ , Kar Keung Cheng c a b

Guangzhou No. 12 Hospital (Guangzhou Occupational Disease Prevention and Treatment Centre), Guangzhou, People’s Republic of China Department of Community Medicine and School of Public Health, The University of Hong Kong, Hong Kong SAR, People’s Republic of China c Department of Public Health and Epidemiology, University of Birmingham, Birmingham B15 2TT, UK Received 13 August 2007; received in revised form 4 March 2008; accepted 10 March 2008 Available online 14 March 2008

Abstract Objective: To study the association between smoking, smoking cessation and aortic arc calcification (AAC) in an older Chinese population. Methods: A total of 3022 men and 7279 women aged 50–85 years were recruited and received a medical check-up including measurement of fasting plasma vascular risk factors. Two radiologists reviewed the posterior–anterior plain chest X-ray radiographs and assessed AAC together. Information on smoking status, socioeconomic and lifestyle factors was collected. Results: The crude prevalence of AAC in men (38.58%) was lower than that in women (41.37%). The adjusted odds ratios of AAC increased significantly across never, ex- and current smokers in both genders. Dose–response relationships were observed among current smokers for smoking amount (cigarettes/day), smoking duration (years) and cigarette pack-years in both genders (all p < 0.01). The odds ratios decreased significantly (p = 0.018) with longer duration of quitting in light ex-smoking men (50 years) subjects from Guangzhou in southern China. The first phase recruitment of 10,413 subjects has been completed in November 2004 and further recruitment is ongoing. The study has received ethical approval from the Guangzhou Medical Ethics Committee of Chinese Medical Association, Guangzhou, China. Details of the participants of the first recruitment, fasting biochemical and anthropometric measurements, 12-lead electrocardiography, pulmonary function testing and the posterior–anterior plain chest X-ray have been described elsewhere [12–14]. Two aliquots of bar-code plasma and two aliquots of bar-code white blood cell extracted using Ficoll-paque extraction are stored in liquid nitrogen for future analysis. The information of smoking was collected through standard interview. Smoking was defined as at least 1 cigarette/day or 7 cigarettes/week for at least half a year. “Current smokers” was defined by answering “yes” to the question: “Do you smoke cigarettes now?” “Former smoker” was defined as “used to smoke”. Information on duration of abstinence of smoking (years) was also collected. Validation of the questionnaire was performed six months into recruitment by recalling 200 randomly selected subjects for re-interview. Kappa values were: smoking (0.96 and 0.88 for the two questions on smoking status), drinking (0.60), moderate physical activity (0.58) and education (0.90). Posterior–anterior plain chest X-ray radiographs were obtained during deep inspiration in a standing position using a Toshiba KSO-15R machine. Two radiologists were blinded to patient data and they reviewed the radiographs together. Radiographs were assessed for the presence or absence of aortic arch calcification. The presence of aortic arch calcification include: small spots of calcification, single thin calcification of the aortic arch, one or more areas of thick calcification, and circular calcification of the aortic arch. To evaluate the reliability of the AAC diagnosis, 300 random

selected radiographs were independently read by the two radiologists to assess the reliability of AAC diagnosis and the Kappa value was 0.68. Detailed information about the chest X-ray radiographs and aortic calcification diagnosis has been described elsewhere [6]. Of the 10,413 subjects, 10,301 (98.9%) had chest X-ray radiographs and were included in the present cross-sectional analysis. Logistic regression was used for calculating the odds ratios of having AAC. To analyze the effects of smoking cessation on AAC, we categorized ex-smokers into two groups (light ex-smokers and heavy ex-smokers) using the median pack-years (23.5 pack-years) as the cut-off value and calculated the odds ratios of AAC with smoking cession for light and heavy ex-smokers separately. All statistical analyses were performed using SAS v. 9.13 (SAS Institute, Cary, NC, USA). The potential confounders adjusted were age (years), body mass index (kg/m2 ), waist circumference (cm), education (no formal schooling, primary, junior middle, upper middle, college, university or above), drinking (never, ever), physical activity (inactive, minimally active and regular activity) [15], blood pressure (systolic and diastolic, mmHg), total cholesterol (mmol/l), HDL-cholesterol (mmol/l), triglyceride (mmol/l), and glucose (mmol/l).

3. Results Of the 10,301 subjects, 3022 were male (mean age 66.21 ± 5.77 years) and 7279 were female (mean age 63.99 ± 6.03 years). The crude prevalence of AAC in men (38.58%) was significantly lower than that in women (41.37%, p < 0.001), and the age-adjusted prevalence (95% confidence interval) was 37.7% (35.9%, 39.5%) and 40.6% (39.4%, 41.8%), respectively (p < 0.001). The age-adjusted odds ratio for men vs. women was 0.69 (0.63, 0.76). The prevalence of AAC in ex- and current smokers was significantly higher than that in never smokers for both genders

Table 1 Characteristics of 10,301 subjects by smoking status and sex Men

Women

Never

Ex smoker

Current smoker

Never

Ex smoker

Current smoker

1281 452 (35.28) 66.5 (5.7) 976 (75.60) 529 (40.98) 787 (60.96)

905 379 (41.88)a 67.0 (5.9) 590 (64.48)d 458 (50.00)d 732 (80.35)d

836 335 (40.07)c 64.5 (5.5)e,h 516 (60.49)e 450 (52.75)e 677 (79.55)e

6890 2786 (40.44) 63.8 (6.0) 6959 (43.97) 4869 (69.97) 2484 (35.71)

189 103 (54.50)b 68.2 (5.3)b 189 (17.46)b 151 (79.89)b 109 (57.67)b

200 122 (61.00)e 67.1 (5.15)e,f 201 (20.40)e 163 (81.09)e 96 (47.76)e,f

Physical activity (IPAQ) Inactivity (%) Minimally activity (%) Regular activity (%)

17 (1.32) 495 (38.34) 779 (60.34)

17 (1.86) 358 (39.08) 541 (59.06)

21 (2.46) 369 (43.26)e 463 (54.28)c,g

88 (1.26) 2315 (33.27) 4556 (65.47)

4 (2.12) 56 (29.63) 129 (68.25)

11 (5.47)e 86 (42.79)d,g 104 (51.74)e,h

Obesity (%) Hypertension (%) Diabetes (%)

439 (34.08) 711 (55.16) 182 (14.11)

317 (34.76) 444 (48.63) 142 (15.52)

200 (23.53)b,e,h 347 (40.82)b,e,h 75 (8.81)e,f

2454 (35.37) 3443 (49.56) 1094 (15.74)

82 (43.62) 103 (54.79) 43 (22.75)

All subjects Cases of AAC (%) Age (S.D.), years Education (>primary school, %) Occupation (manual, %) Drinking (ever, %)

61 (30.81)b,e,g 87 (43.28)b,e 29 (14.50)a,h

Never vs. ex-smokers: a < 0.01, b < 0.001. Never vs. current smokers: c < 0.05, d < 0.01, e < 0.001. Ex-smokers vs. current smokers: f < 0.05, g < 0.01, h < 0.001. AAC: aortic arch calcification.

Table 2 Odds ratio of aortic arch calcification (AAC) by smoking status and sex Men Never 1281 452 1.00 1.00 1.00 1.00 1.00

P for interaction with sex

Ex-smoker

Current smoker

P for trend

Never

Ex-smoker

Current smoker

P for trend

905 379 1.32 (1.11, 1.57) 1.29 (1.08, 1.55) 1.28 (1.06, 1.55) 1.28 (1.06, 1.55) 1.29 (1.06, 1.56)

836 335 1.23 (1.03, 1.47) 1.49 (1.23, 1.79) 1.49 (1.22, 1.81) 1.46 (1.20, 1.79) 1.47 (1.20, 1.80)

– – 0.013