BACKGROUND:
We performed a case control study to identify the effects of multiple comorbidities as potential risk factors for developing vertebral artery occlusive disease (VAOD). 
METHODS:
We identified 56 patients with angiographically confirmed VAOD from a prospective registry. A total of 747 control subjects were selected who were matched for age, sex, and race/ethnicity from a nationally representative cohort of adults who participated in the Third National Health and Nutrition Examination Survey (NHANES) 2015 - 2016. None of the control population had any history of stroke. 
Statistical analysis: We used chi-squared and ANOVA for categorical and continuous variables, respectively. Case control matching function was utilized to exactly match age, sex and ethnicity variables with controls at a ratio of 50:1. A step wise logistic regression analysis was performed for risk factors. 
RESULTS:
The demographic and clinical characteristics of controls matched according to age, sex and ethnicity are listed in Table 2. The frequency of hypertension was higher in VAOD group (83.9%) compared with controls (54.1%, p-value <.0001). The frequency of diabetes mellitus was higher in VAOD patients (46.4%) compared with NHANES matched controls (20.9%, p-value <.0001). The proportion of patients with hyperlipidemia, and those with coronary artery disease was also significantly higher in the VAOD compared with controls. (Table 2). The serum total cholesterol concentrations were significantly lower in patients with VAOD. The proportion of patients using antihypertensive medication and insulin was significantly higher among patients with VAOD. 
In the multivariate model, hypertension (odds ratio [OR], 3.0; 95% confidence interval [CI], 1.4-6.5; p-value- .004) diabetes mellitus (OR, 2.5; 95% CI, 1.4 – 4.6; p-value .002), coronary artery disease (OR, 3.2; 95% CI, 1.7-6.0; p-value <.0001) and active cigarette smoking (OR, 3.1; 95% CI, 1.5 – 6.3; p-value .002) were independently associated with increased risk of VAOD. There was no increased risk associated with past cigarette smoking (OR, 1.2; 95% CI, 0.6 – 2.3; p-value 0.7).
CONCLUSION:
Hypertension, diabetes mellitus, coronary artery disease, and active cigarette smoking were significantly associated with occurrence of VAOD.

Risk factors for vertebral artery steno-occlusive disease