Table 4.

Comparison of the mean day hospitalization in case and control groups by smoking, independent sample t-test

Groups	Smoking	n	Mean (SD)	t	df	Significance (two-tailed)	95% CI
							Lower	Upper
Case COVID-19 positive	Smoker	136	13.8 (3.4)	7.8	426	0.00	2.02	3.37
	Nonsmoker	908	9.91 (2.8)	2.4	1845	0.16	0.05	0.55
Control COVID-19 negative	Smokers	292	11.1 (3.2)	7.7	249	0.00	2.00	3.38
	Nonsmoker	939	9.6 (2.5)	2.4	1815	0.16	0.5	0.55

CI: Confidence interval, SD: Standard deviation