Table 4.

Evaluation of the effect of each wave on death during hospitalization.

	Risk ratio		95%CI		P value
Parameters	Univariable	Multivariable	Univariable	Multivariable	Univariable	Multivariable
Effect of each wave
Wave 1	Reference
Wave 2	0.363	0.398	[0.312-0.423]	[0.40-0.561]	< 0.001	< 0.001
Wave 3	0.783	0.473	[0.694-0.886]	[0.325-0.487]	< 0.001	< 0.001
Other risk factors
Transfer from other facilities	3.916	1.629	[3.479-4.401]	[1.390-1.906]	< 0.001	< 0.001
Age	1.092	1.103	[1.088-1.097]	[1.096-1.110]	< 0.001	< 0.001
Male sex	1.322	1.872	[1.195-1.464]	[1.621-2.165]	< 0.001	< 0.001
Obesity (BMI>=25)	0.678	1.098	[0.593-0.773]	[0.940-1.281]	< 0.001	0.236
Cardiovascular and peripheral vascular diseaseA	4.989	1.521	[4.394-5.654]	[1.277-1.805]	< 0.001	< 0.001
Chronic Respiratory DiseaseB	4.728	1.675	[4.055-5.492]	[1.367-2.043]	< 0.001	< 0.001
Liver disease	2.281	2.459	[1.793-2.865]	[1.780-3.347]	< 0.001	< 0.001
Diabetes mellitus	2.377	1.388	[2.132-2.647]	[1.199-1.605]	< 0.001	< 0.001
Cerebrovascular Disease	3.965	1.370	[3.482-4.504]	[1.455-1.632]	< 0.001	< 0.001
Hypertension	2.291	0.790	[2.075-2.530]	[0.688-0.906]	< 0.001	< 0.001
Severe condition at admission	6.766	3.026	[6.075-7.546]	[2.624-3.493]	< 0.001	< 0.001

Abbreviations. BMI, body mass index; CI, confidence interval. ^A Cardiovascular and peripheral vascular disease includes myocardial infarction, congestive heart failure, and peripheral vascular disease. ^B Chronic respiratory disease was defined as pulmonary disease in patients who were dyspneic with slight activity and included chronic obstructive pulmonary disease.