Table 2. Grade table for evaluating the level of evidence.
| Certainty assessment | N o of patients | Effect | Certainty | Importance | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| N o of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | Intervention (%) | Comparison (%) | Relative (95%CI) | Absolute (95%CI) | ||
| 1. Linear wear (mm/y) XLPE | ||||||||||||
| 9 | Randomized trials | Serious a,b | Not serious | Not serious | Not serious | None | 448 | 443 | – | MD 0 (0.01 minor to 0) | ⊕⊕⊕◯ moderate | |
| 2. Linear wear (mm/y) UHMWPE | ||||||||||||
| 4 | Randomized trials | Serious a,b | Not serious | Not serious | Not serious | None | 67 | 71 | – | MD 0 (0.04 minor to 0.05 higher) | ⊕⊕⊕◯ moderate | |
| 3. Surgical reviews | ||||||||||||
| 7 | Randomized trials | Serious a,b | Not serious | Not serious | Serious c | None | 2/400 (0.5) | 5/400 (1.3) | Not estimable | 10 more for 1.000 (from 10 less to 20 more) | ⊕⊕◯◯ low | |
| 4. Head size | ||||||||||||
| 11 | Randomized Trials | Very serious a,b,d | Very serious e | Very serious e | Serious c | None | 518 | 536 | – | SMD 0.75 higher (0.52 lowest to 2.03 highest) | ⊕◯◯◯ very low | |
| 5. Harris hip score (HHS) | ||||||||||||
| 5 | Randomized trials | Very serious a,b,d | Not serious | Not serious | Serious c | None | 147 | 155 | – | MD 5.02 smaller (7.3 minor to 2.73 minor) | ⊕◯◯◯ very low | |
CI: confidence interval; SMD: standardized mean difference.
a
Absence of analysis by intention of treatment;
b
Absence of blinding;
c
Long confidence interval;
d
Absence of sample calculation;
e
High heterogeneity.