Abstract
Purpose: The PaO2/FiO2 (P/F) ratio is a parameter used to assess oxygenation in coronavirus disease 2019 (COVID-19) patients. This study aimed to investigate the prognostic value of the P/F ratio in predicting clinical outcomes, including disease severity, length of stay, and mortality.
Methods: A retrospective analysis was conducted on COVID-19 patients admitted to a single center in Houston, Texas between March 2020 and February 2022, where 753 patients were included out of 994 that were admitted. Patients were categorized into four groups based on the Berlin Criteria (P/F ratio): Group 1 (severe) with P/F ratio <100 mmHg, Group 2 (moderate) with P/F ratio 101-200 mmHg, Group 3 (mild) with P/F ratio 201-300 mmHg, and Group 4 (normal) with P/F ratio >300 mmHg. Data analysis was performed using IBM SPSS Statistics version 25.0. Descriptive statistics, chi-square, and logistic regression tests were employed to determine statistical significance.
Results: Seven hundred and fifty-three patients were included in this study. The median age was 56 years (44-66.50), the median length of stay was 7 days (4-13), and the P/F was 252 (149-328.50). Four hundred and thirty-three (57.5%) were male, and 320 (43,5%) patients survived.
There were 125 (16.6%) patients in Group 1, 166 (22%) in Group 2, 196 (26%) in Group 3, and 266 (35.3%) in Group 4. A chi-square analysis revealed a significant correlation between P/F and clinical outcomes (p<0.0001). As far as mortality, 74 (48.7%) patients in Group 1, 47 (30.9%) in Group 2, 17 (11.2%) in Group 3, and 14 (9.2%) in Group 4 died. There was a correlation between P/F and gender (p<0.0001). There were 108 (72%) patients in Group 1, 94 (55%) patients in Group 2, 133 (61.6%) patients in Group 3, and 155 (49.2%) patients in Group 4 were male.
In the logistic regression analysis, where significance was determined at p<0.05 and a confidence interval (CI) of 95%, it was observed that being male was strongly associated with a higher risk of mortality within these groups (p=0.041). Group 1 was also significantly linked to increased mortality (p<0.001). Belonging to Group 2 showed an association with the risk of death (p<0.001), while in Group 3, the Wald test score was 0.800 and indicated a lower likelihood of mortality, suggesting a protective factor (p=0.371). We found that with an increase in the length of stay, the probability of mortality rose (p=0.007). Of all the variables belonging to Group 1 exhibited the strongest association with mortality, as evidenced by a Wald test score of 59.075, with a p-value of <0.001.
Conclusions: In our cohort, there was a strong association between the P/F ratio, clinical outcomes, gender, and the length of hospital stay in COVID-19 patients. Those patients with more severe P/F ratio impairment experienced higher mortality rates and longer hospital stays.
Ana Cecilia Canto-Costal, Paloma Areli Molina, Rosapaulina Huerta, Ana Paula Villalobos-Hernandez, Joseph Varon
