Table 2. Association between Confounding Variables and Hospitalization Due to Covid-19, According to Age Group.^*.

Variable	Hazard Ratio for Hospitalization Due to Covid-19 (95% CI)
	40–64 yr (N=66,433)	≥65 yr (N=42,821)
Demographic and other variables at baseline
Nirmatrelvir therapy	0.74 (0.35–1.58)	0.27 (0.15–0.49)
Male sex	1.41 (1.13–1.75)	1.65 (1.43–1.91)
Age	1.06 (1.04–1.08)	1.09 (1.08–1.09)
Score for socioeconomic status	1.01 (0.95–1.07)	0.89 (0.86–0.93)
No previous immunity	5.79 (4.58–7.32)	5.82 (4.99–6.78)
Clinical risk factors
Recent hospitalizations	3.36 (2.66–4.24)	2.09 (1.80–2.43)
Obesity	1.29 (1.03–1.63)	1.07 (0.91–1.25)
Diabetes	1.34 (1.04–1.74)	1.36 (1.18–1.58)
Chronic hepatic disease	1.78 (1.24–2.53)	1.11 (0.82–1.50)
Neurologic disease	1.82 (1.30–2.53)	1.58 (1.34–1.87)
Chronic heart failure	2.41 (1.61–3.61)	1.44 (1.17–1.78)
Chronic obstructive pulmonary disease	2.26 (1.52–3.35)	1.74 (1.40–2.15)
History of stroke	1.81 (1.24–2.63)	1.39 (1.16–1.67)
Chronic kidney failure	1.82 (0.96–3.44)	1.78 (1.33–2.38)

^*The association between nirmatrelvir therapy and hospitalization due to coronavirus disease 2019 (Covid-19) was estimated with the use of a multivariate Cox proportional-hazards regression model after adjustment for sociodemographic factors, coexisting illnesses, and SARS-CoV-2 immunity status. Variables that met the testing criteria and were significantly associated with the outcome served as the inputs for the multivariate regression analysis. CI denotes confidence interval.