TABLE 2.
Quality assessment of the included studies according to the National Institutes of Health Quality Assessment Tool for case series studies
| Study | Criteriaa |
Quality rating | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | ||
| Sun et al.20 | Yes | Yes | Yes | CD | N/A | CD | Yes | Yes | Yes | Fair |
| Chen et al.21 | Yes | Yes | Yes | CD | N/A | CD | CD | Yes | Yes | Fair |
| Liu et al.8 | Yes | Yes | Yes | CD | N/A | Yes | Yes | NR | Yes | Fair |
| Lu et al.22 | Yes | Yes | Yes | Yes | N/A | CD | CD | Yes | Yes | Fair |
| Zheng et al.23 | Yes | Yes | Yes | CD | N/A | NR | NR | Yes | Yes | Fair |
| Lu et al.24 | Yes | Yes | Yes | CD | N/A | Yes | Yes | Yes | Yes | Fair |
| Li et al.25 | Yes | Yes | Yes | CD | N/A | Yes | CD | Yes | Yes | Fair |
| Li et al.26 | Yes | Yes | Yes | CD | N/A | Yes | CD | Yes | Yes | Fair |
| Li et al.27 | Yes | Yes | Yes | CD | N/A | Yes | CD | Yes | Yes | Fair |
| Liu et al.28 | Yes | Yes | Yes | CD | N/A | Yes | NR | Yes | Yes | Fair |
| Ma et al.29 | Yes | Yes | Yes | Yes | N/A | Yes | Yes | Yes | Yes | Fair |
| Steinberger et al.30 | Yes | Yes | Yes | Yes | N/A | Yes | Yes | Yes | Yes | Fair |
| Wang et al.31 | Yes | Yes | Yes | Yes | N/A | CD | CD | Yes | Yes | Fair |
| Xia et al.32 | Yes | Yes | Yes | CD | N/A | Yes | CD | Yes | Yes | Fair |
| Du et al.33 | Yes | Yes | Yes | CD | N/A | CD | CD | Yes | Yes | Fair |
| Liu et al.34 | Yes | Yes | Yes | CD | N/A | Yes | NR | Yes | Yes | Fair |
| Qiu et al.35 | Yes | Yes | Yes | Yes | N/A | CD | NR | Yes | Yes | Fair |
| Shen et al.36 | Yes | Yes | Yes | CD | N/A | Yes | CD | Yes | Yes | Fair |
| Song et al.37 | Yes | Yes | Yes | Yes | N/A | Yes | Yes | Yes | Yes | Fair |
| Tan et al.38 | Yes | Yes | Yes | CD | N/A | Yes | CD | Yes | Yes | Fair |
| Wu et al.39 | Yes | Yes | Yes | Yes | N/A | CD | NR | Yes | Yes | Fair |
| Zhu et al.40 | Yes | Yes | Yes | Yes | N/A | CD | NR | Yes | Yes | Fair |
| Du et al.41 | Yes | Yes | Yes | Yes | N/A | CD | Yes | Yes | Yes | Fair |
| Korkmaz et al.42 | Yes | Yes | Yes | Yes | N/A | Yes | Yes | Yes | Yes | Fair |
| Li et al.43 | Yes | Yes | Yes | Yes | N/A | Yes | Yes | Yes | Yes | Fair |
| Zhang et al.44 | Yes | Yes | Yes | Yes | N/A | Yes | Yes | Yes | Yes | Fair |
| Zhang et al.45 | Yes | Yes | Yes | Yes | N/A | NR | CD | Yes | Yes | Fair |
| Bai et al.46 | Yes | Yes | Yes | Yes | N/A | CD | NR | Yes | Yes | Fair |
| Lan et al.47 | Yes | Yes | Yes | CD | N/A | Yes | Yes | Yes | Yes | Fair |
Abbreviations: CD, cannot determine; N/A, not applicable; NR, not reported.
The questions of the NIH quality assessment tool for case series studies are: (1) Was the study question or objective clearly stated? (2) Was the study population clearly and fully described, including a case definition? (3) Were the cases consecutive? (4) Were the subjects comparable? (5) Was the intervention clearly described? (6) Were the outcome measures clearly defined, valid, reliable, and implemented consistently across all study participants? (7) Was the length of follow-up adequate? (8) Were the statistical methods well-described? (9) Were the results well described?