Table 1.

Gender and comorbidities.

Variable	Oxygenation index >250 mmHg (n = 54)	Oxygenation index ≤250 mmHg (n = 76)	Z value	p value
Female	21	16	−2.212	0.027
Male	33	60
Cerebrovascular disease	11	26	−1.717	0.086
Diabetes mellitus	7	21	−1.997	0.046
Coronary heart disease	19	31	−0.645	0.519
Chronic renal damage	4	12	−1.428	0.153
Treated nasopharyngeal carcinoma	0	2	−1.197	0.231