Table 2.
The item-based comparison on the quality of registered (or with a prior protocol) DRMAs and matched controls
| Quality Checklist | Registered | Matched control | Rate difference | P value |
|---|---|---|---|---|
| Modified AMSTAR | ||||
| Item 1: Was there duplicate study selection? | 22/45 | 40/90 | 0.04 (− 0.13, 0.22) | 0.63 |
| Item 2: Was there duplicate data extraction? | 40/45 | 65/90 | 0.17 (0.04, 0.30) | 0.01 |
| Item 3: Was there at least two database searched? | 39/45 | 77/90 | 0.01 (− 0.11, 0.13) | 0.86 |
| Item 4: Was there any search strategy documented? | 30/45 | 30/90 | 0.33 (0.17, 0.50) | < 0.01 |
| Item 5: Was the status of publication used as an inclusion criterion? | 18/45 | 27/90 | 0.10 (−0.07, 0.27) | 0.25 |
| Item 6: Was a list of studies of included provided? | 43/45 | 90/90 | −0.04 (− 0.11, 0.02) | 0.20 |
| Item 7: Was a list of studies of excluded provided? | 20/45 | 21/90 | 0.21 (0.04, 0.38) | 0.02 |
| Item 8: Were the characteristics of the included studies provided? | 45/45 | 89/90 | 0.01 (−0.03, 0.05) | 0.59 |
| Item 9: Was the scientific quality of the included studies assessed? | 22/45 | 50/90 | −0.07 (− 0.25, 0.11) | 0.46 |
| Item 10: Was the scientific quality of the included studies documented (only provide total score should be avoided)? | 13/45 | 28/90 | −0.02 (− 0.19. 0.14) | 0.79 |
| Item 11: Was the scientific quality of the included studies used appropriately in formulating conclusions? | 5/45 | 9/90 | 0.01 (−0.10, 0.12) | 0.84 |
| Item 12: Were the methods used to combine the findings (dose-response) of studies appropriate? | 41/45 | 84/90 | −0.02 (− 0.12, 0.08) | 0.66 |
| Item 13: Was the likelihood of publication bias assessed? | 45/45 | 80/90 | 0.11 (0.04, 0.18) | < 0.01 |
| Item 14: Was the conflict of interest stated? | 43/45 | 80/90 | 0.07 (−0.02. 0.16) | 0.14 |
| Modified PRISMA | ||||
| Item 1 (Title): Identify the report as a systematic review, meta-analysis, or both. | 45/45 | 90/90 | 0.00 (−0.03, 0.03) | ≈ 1 |
| Item 2 (Introduction): Describe the rationale for the review in the context of what is already known. | 45/45 | 90/90 | 0.00 (−0.03, 0.03) | ≈ 1 |
| Item 3 (Introduction): Provide an explicit objective(s) with reference to PICOS principle. | 45/45 | 90/90 | 0.00 (−0.03, 0.03) | ≈ 1 |
| Item 4 (Methods): Specify criteria for eligibility, giving rationale. | 43/45 | 87/90 | −0.01 (− 0.08, 0.06) | 0.76 |
| Item 5 (Methods): Describe all information sources (e.g. databases) in the search and date last searched. | 45/45 | 90/90 | 0.00 (−0.03, 0.03) | ≈ 1 |
| Item 6 (Methods): Present full electronic search strategy for at least one database. | 36/45 | 32/90 | 0.44 (0.29, 0.60) | < 0.01 |
| Item 7 (Methods): State the process for selecting studies (two stage: title and abstract screen, then the full text). | 15/45 | 21/90 | 0.10 (−0.06, 0.26) | 0.23 |
| Item 8 (Methods): Describe method of data extraction and any processes for obtaining and confirming data. | 40/45 | 71/90 | 0.10 (−0.03, 0.23) | 0.12 |
| Item 9 (Methods): List and define all variables for which data were sought and any assumptions made. | 41/45 | 82/90 | 0.00 (−0.10, 0.10) | ≈ 1 |
| Item 10 (Methods): Describe methods used for assessing risk of bias of individual studies. | 26/45 | 56/90 | −0.04 (− 0.22, 0.13) | 0.62 |
| Item 11 (Methods): State the principal summary measures (e.g., risk ratio, difference in means). | 43/45 | 80/90 | 0.07 (−0.02, 0.16) | 0.14 |
| Item 12 (Methods): Describe the methods of handling data and combining results of studies. | 45/45 | 90/90 | 0.00 (−0.03, 0.03) | ≈ 1 |
| Item 13 (Methods): Specify any assessment of risk of bias for the pooled evidence (e.g. publication bias). | 45/45 | 83/90 | 0.08 (0.01, 0.14) | 0.02 |
| Item 14 (Methods): Describe methods of additional analyses (e.g. sensitivity analysis, meta-regression). | 45/45 | 86/90 | 0.04 (−0.01, 0.10) | 0.11 |
| Item 15 (Results): Give numbers of studies screened, assessed for eligibility, and included in the review, with reasons for exclusions at each stage, ideally with a flow diagram. | 41/45 | 83/90 | −0.01 (− 0.11, 0.09) | 0.83 |
| Item 16 (Results): For each study, present characteristics for which data were extracted. | 44/45 | 90/90 | −0.02 (− 0.08, 0.03) | 0.42 |
| Item 17 (Results): Present data on risk of bias of within each study (study level). | 22/45 | 45/90 | −0.01 (− 0.19, 0.17) | 0.90 |
| Item 18 (Results): Present summery data, effect estimates and confidence intervals for each study. | 45/45 | 88/90 | 0.02 (−0.02, 0.07) | 0.34 |
| Item 19 (Results): Present results of each meta-analysis, with confidence intervals and measures of consistency. | 45/45 | 90/90 | 0.00 (−0.03, 0.03) | ≈ 1 |
| Item 20 (Results): Present results of risk of bias across studies (publication bias, outcome level). | 45/45 | 80/90 | 0.11 (0.04, 0.18) | < 0.01 |
| Item 21 (Results): Give results of additional analyses, if done. | 45/45 | 87/90 | 0.03 (−0.02, 0.08) | 0.20 |
| Item 22 (Discussion): Summarize the main findings including the strength of evidence for each main outcome. | 45/45 | 88/90 | 0.02 (−0.02, 0.07) | 0.34 |
| Item 23 (Discussion): Discuss limitations at study and outcome level | 44/45 | 80/90 | 0.09 (0.01, 0.17) | 0.03 |
| Item 24 (Discussion): Provide a general interpretation of the results and implications for future research. | 45/45 | 90/90 | 0.00 (−0.03, 0.03) | ≈ 1 |
| Item 25 (Funding): Describe sources of funding and other support for the systematic review. | 43/45 | 70/90 | 0.18 (0.07, 0.28) | < 0.01 |
Rate difference was the absolute difference of the adherence rate of the two groups, and the statistical inference was conducted by t test. Those in bold were statistically significant (p < 0.05)