Study Design and Participants
Patients were retrospectively collected at Shanghai Ninth People's Hospital from February 2017 to December 2020. The inclusion and exclusion criteria has been listed in our previous study(21). From the coronary tree of individuals, we selected the most severe lesion and the most calcified plaque as our targets. Fig. 1 showed the flowchart of the study. The study protocol was approved by the Ethics Committee of Shanghai Ninth People's Hospital and informed consent was waived. The study complies with the Declaration of Helsinki.
Data collection and measurements
All patients underwent a history taking and physical examination after hospitalization, and clinical data were collected, including demographics, medical history, and medication(antiplatelet drugs, statins, angiotensin-converting enzyme inhibitors/angiotensin II receptor antagonists [ACEI/ARB], beta-blockers, calcium channel blockers [CCB], diuretics, insulin). Blood pressure was taken. Pulse pressure (PP, mmHg) = systolic blood pressure (SBP) - diastolic blood pressure (DBP). Body mass index (BMI, kg/m2) = weight/heightˆ2. Blood samples were routinely collected in the morning after a fasting night of at least 10 hours. Serum creatinine, glycated hemoglobin (HbA1c) and lipids profiles (triglycerides [TG], total cholesterol [TC], high density lipoprotein cholesterol [HDL], low density lipoprotein cholesterol [LDL], serum free fatty acids [FFAs]) were all tested. eGFR was calculated by EPI-CKD formula(22).
Diabetes duration was defined as the time (years) from the first diagnosis of diabetes and divided to 3 levels: 1) no diabetes; 2) diabetes duration is less than 10 years; 3) diabetes duration is more than 10 years.
Drinking and smoking information collection
Drinking and smoking information were acquired by questionnaires. Drinking duration (years), drinking days per week, daily alcohol intake (ml), alcohol type most commonly consumed (beer, red wine, yellow rice wine, and liquor) were recorded. Regular drinkers were defined as drinking ≥1 time per week, occasional drinkers were those drinking ≤ twice per month and were included into non-drinkers. The alcohol concentration is determined according to the average alcohol concentration of the mainstream currently on the market: liquor 45%, yellow rice wine 15%, red wine 12%, beer 4%. Finally, pure ethanol intake (g) per week was calculated according to the formula: weekly alcohol intake (g) =drinking days per week * consumed volume per day (ml) * alcohol concentration * 0.8 (23). Regular drinkers included former and current drinkers in our study. Drinking severity were classified into 4 levels according to weekly alcohol intake (g): non- drinkers, light drinkers (0-100g/week), moderate drinkers (101-250g/week), heavy drinkers (≥251g/week).
Smokers were defined as more than 100 cigarettes consumption in the past. Non-smokers were defined as “never consumed” or consumed less than 100 cigarettes during life-time(24). Smoking duration (years), average consumed cigarettes per day were collected. Cigarettes were converted into packages (each package equals 20 cigarettes). Smoking degree was evaluated by total smoking amount according to the formula: total smoking (package*years) = cigarettes per day/20*smoking duration (years). Smokers included both former and current smokers in our study. According to total smoking (package*years), smoking severity was divided into 4 levels: non-smokers, light smokers (≤20 package*years), moderate smokers (21-40 package*years) and heavy smokers (≥ 41 package*years).
CAG and IVUS procedures, IVUS analysis, CAC grouping
CAG and IVUS procedures were also described in details in our previous study(21). Fig. S1 showed clearly how the plaque parameters were measured. CAC was defined as a brighter plaque than adventitia with acoustic shadowing. The angles of the calcified plaque were measured cross-sectionally. Arc was defined as the maximum angle of the calcified plaque. Calcium length was determined as the length of the calcified plaque with an Arc. CAC was traditionally classified into 4 levels according to Arc: 1) Grade I: less than 90°; 2) Grade II: 91°-180°; 3) Grade III: 181°-270°; 4) Grade IV: 271°- 360° (as showed in Fig. S2).
We divided all patienets into 3 groups according to Arc: 1) None coronary artery calcification (NCAC): no calcium was found in the coronaries; 2) light coronary artery calcification (LCAC): with an Arc less than 180° (Grade I and II); 3) Severe coronary artery calcification (SCAC): with an Arc between 181°-360° (Grade III and IV). When we performed logistic regression, we combined NCAC group and LCAC group into the non-SCAC (NSCAC) group.
Statistical analysis
Statistical analysis was performed with SPSS 20.0(IBM Corp.). Continuous variables are expressed as mean ± standard deviation and are compared by one way Analysis of Variance (ANOVA). Categorical variables are presented as frequencies and proportions, and compared by chi-square tests. For correlation analyses between lifestyles (alcohol and cigarette consumption) and plaque parameters, Pearson and Spearman correlation were used to evaluate the relations between alcohol/cigarette consumption with characteristics of CAC. Logistic regressions were used to evaluate the associations between clinical factors and SCAC. The area under the curve (AUC) was determined by Receiver Operating Characteristics curve (ROC). All P values were two-sided, and P<0.05 was considered statistically significant.