Table 1 Characteristics of the included studies and diagnostic test performance of NLR for disease severity and mortality
| Â | Study | Country | Publication language | No. of patients | Male/ female | Mean age | Cut-off | AUC | TP | FP | FN | TN | SEN (%) | SPE (%) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Severity | Yang2020 [33] | China | English | 93 | 56/37 | 46.4 ± 17.6 | 3.3 | 0.84 | 21 | 25 | 3 | 44 | 88.0 | 63.6 |
|  | Wang2020 [31] | China | English | 45 | 23/22 | 39.0 ± 11.5 | 13.4 | 0.89 | 8 | 6 | 2 | 29 | 83.3 | 82.4 |
|  | Fesih2020 [44] | Turkey | English | 139 | 62/77 | 55.5 ± 18.5 | 3.3 | 0.87 | 43 | 25 | 11 | 60 | 79.0 | 71.0 |
| Â | Jingyuan Liu2020 [27] | China | English | 115 | 64/51 | NA | 3.1 | NA | 28 | 13 | 9 | 65 | 75.7 | 83.3 |
|  | Asghar2020 | Pakistan | English | 100 | 69/31 | 52.6 ± 15.7 | 3.7 | 0.80 | 29 | 25 | 4 | 42 | 87.9 | 62.1 |
|  | Sun2020 [30] | China | English | 116 | 60/56 | 50.0 ± 4.0 | 4.5 | 0.89 | 20 | 9 | 7 | 80 | 74.1 | 89.9 |
|  | Shang2020 [29] | China | English | 443 | 220/223 | 56.0 ± 17.4 | 4.3 | 0.74 | 78 | 50 | 61 | 254 | 56.3 | 83.7 |
|  | Yueping Liu2020 [28] | China | English | 84 | 47/37 | 53.0 ± 17.8 | 4.9 | 0.76 | 13 | 8 | 10 | 53 | 56.5 | 86.9 |
|  | Basbus2020 [42] | Spain | Spanish | 131 | 71/60 | 52.0 ± 30.4 | 3.0 | NA | 17 | 36 | 4 | 74 | 80.9 | 67.3 |
|  | Li2020 [43] | China | Chinese | 93 | 55/38 | 62.1 ± 16.8 | 11.3 | NA | 34 | 4 | 9 | 46 | 79.1 | 92.0 |
|  | Zha2020 [34] | China | Chinese | 85 | 57/28 | 54.2 ± 16.0 | 5.6 | 0.77 | 25 | 10 | 12 | 38 | 68.8 | 78.4 |
|  | Fei2020 [26] | China | Chinese | 72 | 32/40 | 58.0 ± 13.8 | 3.0 | 0.89 | 20 | 14 | 0 | 38 | 100 | 73.1 |
|  | Xia2020 [32] | China | Chinese | 63 | 33/30 | 63.4 ± 14.9 | 4.8 | 0.83 | 26 | 8 | 5 | 24 | 83.9 | 75.0 |
Mortality | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â |
|  | Cheng2020 [36] | China | English | 456 | 211/245 | 55.0 ± 18.6 | 3.2 | 0.81 | 26 | 107 | 10 | 303 | 78.3 | 73.9 |
|  | Tatum2020 [38] | America | English | 125 | 57/68 | 58.7 ± 14.8 | 10.0 | 0.71 | 12 | 4 | 11 | 98 | 52.4 | 96.7 |
|  | Chen2020 [35] | China | English | 681 | 362/219 | 65.0 ± 13.3 | 6.7 | 0.86 | 87 | 130 | 17 | 447 | 83.7 | 77.5 |
|  | Fesih2020 [44] | Turkey | English | 139 | 62/77 | 55.5 ± 18.5 | 5.7 | 0.85 | 11 | 13 | 2 | 113 | 83.0 | 90.0 |
|  | Asghar2020 [41] | Pakistan | English | 100 | 69/31 | 52.6 ± 15.7 | 4.2 | 0.81 | 20 | 29 | 2 | 49 | 90.9 | 62.6 |
| Â | Yan2020 [39] | China | English | 1004 | 493/511 | NA | 11.8 | 0.95 | 39 | 211 | 1 | 753 | 97.5 | 78.1 |
|  | Basbus2020 [42] | Spain | Spanish | 131 | 71/60 | 52.0 ± 30.4 | 3 | NA | 7 | 46 | 2 | 76 | 77.8 | 62.3 |
|  | Li2020 [43] | China | Chinese | 93 | 55/38 | 62.1 ± 16.8 | 11.3 | 0.92 | 28 | 10 | 3 | 52 | 90.3 | 83.9 |
|  | Song2020 [37] | China | Chinese | 84 | 56/28 | 66.5 ± 12.2 | 6.1 | 0.87 | 32 | 5 | 10 | 37 | 76.2 | 88.1 |
|  | Zhang2020 [40] | China | Chinese | 154 | 81/73 | 69.2 ± 7.5 | 9.4 | 0.86 | 21 | 10 | 6 | 117 | 76.2 | 92.0 |