Study designIt is a retrospective, real-world observational study to measure the direct cost of treating COVID-19 patients. The evaluation was conducted for all symptomatic patients with confirmed COVID-19 after being tested in inpatient setting. Data were collected from a private hospital in Saudi Arabia between July 2020 and July 2021. The Hospital is a 500-bed tertiary care center, serving a local catchment population of over 1.4 million people with all medical specialties available. Exclusion criteria were COVID-19 vaccinated patients, and patients treated in an outpatient setting.To calculate the minimum required sample size, Walters’s formula for non-normally distributed continuous data were applied. In this calculation, a two-tailed 5% significance level, effect size (PNoether) of 0.51 (consistent with those used in common association analyses), 80% power, and response rate of 80% was considered, which gives the estimated number of subjects as 287.$$n = frac{{2left( {Z_{{1 – {raise0.7exhbox{$alpha $} !mathord{left/ {vphantom {alpha 2}}right.kern-nulldelimiterspace} !lower0.7exhbox{$2$}}}} + Z_{1 – beta } } right)^{2} }}{{6left( {P_{Noether} – 0.5} right)^{2} }}$$COVID-19 severity classificationAccording to the Saudi Ministry of Health Protocol for Patients Suspected of/Confirmed with COVID-19, (Version 3.6), April 14th, 20227, disease severity can be classified as follow:
1.
Mild disease
Symptomatic patients meet the case definition for COVID-19 without evidence of viral pneumonia or hypoxia.
2.
…