Table 1 The number of COVID-19 patients and studies included in the meta-analyses and the side of standardized mean difference (SMD) and the 95% confidence intervals with respect to the zero SMD
Outcome profiles | n studies | Side of 95% confidence intervals | Patient Cases | Control Cases | Total number of participants | |||
|---|---|---|---|---|---|---|---|---|
 < 0 | Overlap 0 and SMD < 0 | Overlap 0 and SMD > 0 |  > 0 | |||||
Cohort 1: COVID-19 patients versus non-COVID-19 control | ||||||||
 KYN/TRP | 10 | 1 | 0 | 2 | 7 | 329 | 475 | 804 |
 KYN | 8 | 0 | 1 | 0 | 7 | 285 | 419 | 704 |
 TRP | 7 | 5 | 1 | 1 | 0 | 275 | 409 | 684 |
 KA | 4 | 0 | 1 | 2 | 1 | 113 | 94 | 207 |
 KA/(KYN + TRP) | 8 | 1 | 1 | 4 | 2 | 285 | 419 | 704 |
 (KYN + KA)/TRP | 10 | 1 | 0 | 3 | 6 | 329 | 475 | 804 |
 KA/KYN | 8 | 3 | 3 | 2 | 0 | 285 | 419 | 704 |
Cohort 2: severe/critical COVID-19 patients versus mild/moderate COVID-19 patients | ||||||||
 KYN/TRP | 9 | 0 | 0 | 1 | 8 | 270 | 503 | 773 |
 KYN | 6 | 0 | 0 | 3 | 3 | 184 | 399 | 583 |
 TRP | 5 | 3 | 2 | 0 | 0 | 153 | 282 | 435 |