Table 3.

Results of Cox Proportional Hazards Models Examining the Relation of Ondansetron-Taking in the First 48 Hours of Hospital Admission to 30-Day Mortality in Hospitalized Patients

	Total Population (n = 10 741)		ICU (n = 2369)		Non-ICU (n = 8372)
Characteristic	Hazard Ratio (95% CI)	P Value	Hazard Ratio (95% CI)	P Value	Hazard Ratio (95% CI)	P Value
All COVID-19 inpatients	1		1.83 (1.68–2.00)	<.001***
Ondansetron therapy
<8 mg within 48 h (group 1)	0.75 (0.61–0.91)	.004**	0.9 (0.64–1.25)	.527	0.7 (0.54–0.9)	.005**
≥8 mg within 48 h (group 2)	0.58 (0.44–0.77)	<.001***	0.53 (0.3–0.94)	.029*	0.63 (0.45–0.88)	.006**
Remdesivir therapy	1.12 (1.02–1.23)	.015*	1.06 (0.91–1.25)	.441	1.08 (0.96–1.22)	0.18
Dexamethasone therapy	1.45 (1.33–1.59)	<.001***	1.28 (1.1–1.5)	.002**	1.47 (1.31–1.65)	<.001***
Risk factors
Charlson Comorbidity Index ≥7	1.88 (1.72–2.07)	<.001***	1.74 (1.49–2.04)	<.001***	1.96 (1.74–2.19)	<.001***
Obesity	0.72 (0.65–0.79)	<.001***	0.8 (0.68–0.95)	.011*	0.65 (0.57–0.74)	<.001***
Hypertension	1.4 (1.24–1.58)	<.001***	1.13 (0.92–1.38)	.236	1.52 (1.3–1.77)	<.001***
Diabetes	1.14 (1.04–1.25)	.004**	1.16 (0.99–1.36)	.058	1.11 (0.99–1.25)	.062
Cancer	1.4 (1.24–1.57)	<.001***	1.28 (1.05–1.57)	.016*	1.45 (1.25–1.67)	<.001***
Age
50–59 y	2.16 (1.34–3.49)	.002**	2.3 (1.04–5.09)	.041*	1.99 (1.09–3.64)	.026*
60–69 y	5.37 (3.52–8.21)	<.001***	5.67 (2.78–11.59)	<.001***	4.94 (2.92–8.37)	<.001***
70+ y	10.85 (7.19–16.38)	<.001***	9.06 (4.5–18.23)	<.001***	11.58 (6.95–19.29)	<.001***
Female	0.49 (0.37–0.65)	<.001***	0.72 (0.48–1.09)	.125	0.4 (0.27–0.58)	<.001***
Race
African American or Black	0.79 (0.71–0.88)	<.001***	0.89 (0.75–1.07)	.225	0.73 (0.64–0.84)	<.001***
American Indian or Alaska Native	1.46 (0.96–2.2)	.075	2.03 (1.04–3.93)	.037*	1.26 (0.74–2.14)	.393
Asian	1.09 (0.66–1.82)	.728	0.75 (0.24–2.34)	.619	1.26 (0.71–2.22)	.435
Hispanic or Latino	0.85 (0.71–1.02)	.081	1.39 (1.06–1.83)	.018*	0.67 (0.53–0.85)	<.001***
Native Hawaiian or Pacific Islander	1.05 (0.68–1.61)	.838	0.83 (0.31–2.23)	.715	1.16 (0.72–1.88)	.536
Unknown	1.11 (0.93–1.32)	.259	1.23 (0.9–1.68)	.201	1.08 (0.88–1.34)	.453
Ondansetron controlling for age
Ondansetron group 1	0.95 (0.77–1.16)	.595	1.11 (0.8–1.56)	.523	0.9 (0.7–1.16)	.413
Ondansetron group 2	0.84 (0.63–1.12)	.228	0.69 (0.39–1.23)	.206	0.94 (0.67–1.31)	.698
Age 50–59 y	2.14 (1.32–3.46)	.002**	2.29 (1.03–5.08)	.041*	1.98 (1.08–3.62)	.027*
Age 60–69 y	5.29 (3.46–8.08)	<.001***	5.64 (2.76–11.53)	<.001***	4.89 (2.88–8.29)	<.001***
Age 70+ y	10.63 (7.03–16.07)	<.001***	8.99 (4.46–18.11)	<.001***	11.41 (6.84–19.03)	<.001***
Ondansetron controlling for CCI
Ondansetron group 1	0.79 (0.65–0.97)	.023*	0.91 (0.65–1.27)	.592	0.75 (0.58–0.97)	.026*
Ondansetron group 2	0.65 (0.49–0.87)	.003**	0.56 (0.32–0.99)	.047*	0.72 (0.51–1)	.05
CCI score	1.1 (1.09–1.11)	<.001***	1.09 (1.07–1.11)	<.001***	1.11 (1.09–1.12)	<.001***

Patients receiving ≥8 mg of ondansetron in the first 48 hours (group 2) had better mortality outcomes than those receiving none across all patients, whether ICU or non-ICU. Patients receiving 0–8 mg of ondansetron (group 1) also had better outcomes, although the small sample size (n = 150) prevented statistical significance from being attained for ICU patients. The reference group for the hazard ratio for each risk factor is the group of all patients in the study without that risk factor. Results for ondansetron, remdesivir, and dexamethasone therapies are from univariate analysis; adding the Charlson Comorbidity Index or other therapies as covariates did not significantly alter the results.

Abbreviations: CCI, Charlson Comorbidity Index; COVID-19, coronavirus disease 2019; ICU, intensive care unit.

*P < .05; ^**P < .01; ^***P < .001.