Diagnostic Value of Blood Oxygen Saturation and C-Reactive Protein (CRP) in Predicting Lung Sequels in COVID-19 Infected Patients Admitted to Hospital: A 12-week Cohort Study

Evidence of COVID-19 respiratory sequels is restricted and predisposing factors are not well studied more than two years passing pandemic. This study followed COVID-19 patients 12 weeks after discharge from hospital for respiratory sequels.

This was a prospective study on discharged COVID-19 patients in 2021, in Jahrom, Iran. Exposure was COVID-19 clinical features at hospitalization, including symptoms and physical examination and laboratory findings, and primary endpoint was 12-week lung sequel, being evaluated by a chest CT scan. Demographics and previous medical history were considered covariates. SPO2 and CRP 6-week changes were followed as an early tool for prediction of 12-week lung sequel.

Totally, 383 participants (17 had sequels) with mean age of 57.43±18.03 years old (50.13% male) completed 12-week study follow-ups. Ninety-one (23.8%) subjects had an ICU admission history. SPO2% in 6th week was statistically significantly associated with a higher rate of 12-week sequelae (p<0.001). Also, patients having CT scan scores between 40% to 50% (p=0.012) and higher than 50% (p=0.040) had higher chance of experiencing lung sequelae than patients with CT scan score of below 40%, as well as having ICU admission history and lower SPO2% at 6th week of discharge. There was a statistically significant increasing trend of SPO2% (P<0.001) and a statistically significant decreasing trend of CRP levels (P<0.001), overall. SPO2% increase after 6 weeks was lower in participants with lung sequels than fully improved ones (P=0.002) and as well as total 12-week change in SPO2% (P=0.001). CRP changes in none of evaluated periods were different among study groups (P>0.05).

Our results were in favor of closely following SPO2 levels after patient discharge, while CRP assessment seems not helpful based on our results.