Table 3.
Quality of systematic reviews
| Parameter | No. of Systematic Reviews | OQAQ Score of Methodologic Quality (9 Points)
|
Overall Quality Score as per OQAQ Question 10 (Scale 1 to 7)
|
OQAQ Methodologic Errors
|
||||
|---|---|---|---|---|---|---|---|---|
| Mean (SD) | P | Mean (SD) | P | Major (n [%])a | Minor (n [%])a | P | ||
| All systematic reviews | 90 | 6.0 (2.9) | 3.4 (2.2) | 49 (54) | 41 (46) | |||
| Systematic reviews published in | ||||||||
| Journals | 72 | 5.3 (2.8) | <0.001 | 2.8 (1.9) | <0.001 | 49 (68) | 23 (32) | <0.001 |
| Cochrane Reviews | 18 | 8.8 (0.6) | 5.9 (0.8) | 0 (0) | 18 (100) | |||
| Systematic reviews published in | ||||||||
| journals that require adherence to consensus guidelines for reporting of systematic reviews | 11 | 8.0 (1.7) | <0.001 | 4.7 (1.6) | <0.001 | 2 (18) | 9 (82) | <0.001 |
| journals that do not require adherence to consensus guidelines for reporting of systematic reviews | 61 | 4.8 (2.7) | 2.4 (1.7) | 47 (77) | 14 (23) | |||
| Systematic reviews published in | ||||||||
| journals that require adherence to consensus guidelines for reporting of systematic reviews | 11 | 8.0 (1.7) | 0.650 | 4.7 (1.6) | 0.140 | 2 (18) | 9 (82) | 0.420 |
| Cochrane reviews | 18 | 8.8 (0.6) | 5.9 (0.8) | 0 (0) | 18 (100) | |||
| Systematic reviews published in | ||||||||
| nephrology or transplant journals | 25 | 6.2 (2.8) | 0.090 | 3.3 (2.0) | 0.140 | 14 (56) | 11 (44) | 0.180 |
| non-nephrology, non-transplant journals | 47 | 4.9 (2.7) | 2.5 (1.8) | 35 (74) | 12 (26) | |||
| Language restrictions | ||||||||
| no | 32 | 8.4 (1.1) | <0.001 | 5.5 (1.3) | <0.001 | 4 (13) | 28 (87) | <0.001 |
| yes | 24 | 5.6 (2.4) | 2.6 (1.7) | 17 (71) | 7 (29) | |||
| not reported | 34 | 4.0 (2.6) | 1.9 (1.4) | 28 (82) | 6 (18) | |||
| Primary study authors contacted | ||||||||
| yes | 41 | 7.8 (1.9) | <0.001 | 4.8 (1.8) | <0.001 | 10 (24) | 31 (76) | <0.001 |
| no | 49 | 4.5 (2.7) | 2.1 (1.7) | 39 (80) | 10 (20) | |||
| Funding | ||||||||
| reported | 52 | 7.3 (2.4) | <0.001 | 4.3 (1.9) | <0.001 | 18 (35) | 34 (65) | <0.001 |
| not reported | 38 | 4.3 (2.6) | 2.1 (1.8) | 31 (82) | 7 (18) | |||
| Impact factorb | ||||||||
| 0.00 to 2.99 | 29 | 4.0 (2.4) | <0.001 | 1.8 (1.2) | <0.001 | 26 (90) | 3 (10) | <0.001 |
| ≥3.00 | 35 | 6.5 (2.5) | 3.6 (2.0) | 17 (49) | 18 (51) | |||
a
Studies were deemed to contain major methodological errors if the overall OQAQ score was less than or equal to 3. Studies were deemed to contain minor methodological errors if the overall OQAQ score was greater than or equal to 4.
b
Institute for Scientific Information impact factor was not available for 26 systematic reviews as ISI does not calculate an impact factor for the Cochrane database and nine journals (Chinese Journal of Evidence-Based Medicine, Clinical & Developmental Immunology, Core Evidence, Edtna-Erca Journal, Health Technology Assessment, Hemodialysis International and Minerva Uroloica E Nefrologica).