Selected Characteristics of the study population (n = 939).

*P-value generated using X2 test. Info on some variables was missing or not applicable, some totals may be less than 939.*P值（P-value）通过卡方检验（X2 test）生成。 部分变量存在信息缺失或不适用的情况，部分统计总计值可能小于939。