Table 2 Result summaries of meta-analysis for levels of skin pigmentation and ethnic groups
Subgroup categories | No. of studies (evaluations) | Sample size (data pairs) | Calculated Arms, % | Pooled mean bias (95% CI), % | Pooled SD (95% CI), % | Calculated 95% limits of agreement, % | Overall I2 (between-studies and within-study heterogeneity) in mean bias data pooling |
|---|---|---|---|---|---|---|---|
High (dark) skin pigmentation | |||||||
 Primary analysis | 8 (24) | 221 (3270) | 1.88 | 1.11 (0.29 to 1.93) | 1.52 (1.30 to 1.79) |  − 1.87 to 4.09 | 98.03% (0% and 98.03%) |
 Sensitivity analysis, excluding studies with high overall risk of bias | 6 (15) | 177 (2691) | 1.75 | 0.87 (− 0.46 to 2.19) | 1.52 (1.20 to 1.93) |  − 2.11 to 3.84 | – |
 Sensitivity analysis, excluding studies with no use of standardised scales for measuring skin pigmentation | 5 (9) | 160 (474) | 1.79 | 0.89 (− 1.37 to 3.14) | 1.55 (1.12 to 2.15) |  − 2.16 to 3.93 | – |
 Sensitivity analysis, excluding studies with participants of high skin pigmentation alone | 6 (14) | 88 (2738) | 1.95 | 1.12 (− 0.16 to 2.39) | 1.60 (1.26 to 2.03) |  − 2.02 to 4.26 | – |
Medium pigmentation | |||||||
 Primary analysis | 4 (10) | 406 (1323) | 1.58 |  − 0.58 (− 2.25 to 1.09) | 1.47 (1.08 to 2.00) |  − 3.46 to 2.30 | 92.65% (82.39% and 10.25%) |
 Sensitivity analysis, excluding studies with no use of standardised scales for measuring skin pigmentation | 3 (4) | 399 (399) | 1.66 |  − 0.79 (− 3.03 to 1.45) | 1.46 (1.00 to 2.14) |  − 3.66 to 2.08 | – |
Low (light) skin pigmentation | |||||||
 Primary analysis | 6 (15) | 670 (2865) | 1.53 |  − 0.35 (− 1.36 to 0.67) | 1.49 (1.23 to 1.81) |  − 3.27 to 2.58 | 92.73% (22.42% and 70.31%) |
 Sensitivity analysis, excluding studies with high overall risk of bias | 5 (12) | 660 (2245) | 1.57 |  − 0.47 (− 1.77 to 0.83) | 1.50 (1.21 to 1.87) |  − 3.42 to 2.47 | – |
 Sensitivity analysis (scale) | 4 (6) | 648 (667) | 1.62 |  − 0.54 (− 2.52 to 1.43) | 1.53 (1.18 to 1.98) |  − 3.53 to 2.45 | – |
Participants described as Black/African American | |||||||
 Primary analysis | 9 (22) | 459 (5753) | 2.27 | 1.52 (0.95 to 2.09) | 1.68 (1.32 to 2.14) |  − 1.78 to 4.82 | 96.39% (0% and 96.39%) |
 Sensitivity analysis, excluding studies with high overall risk of bias | 4 (10) | 67 (2892) | 1.99 | 1.47 (− 0.21 to 3.16) | 1.35 (1.08 to 1.69) |  − 1.17 to 4.11 | – |
 Sensitivity analysis, excluding studies with data transformation | 7 (20) | 316 (3110) | 2.26 | 1.55 (0.85 to 2.25) | 1.64 (1.28 to 2.11) |  − 1.67 to 4.77 | – |
 Sensitivity analysis, excluding studies with Black/African American populations alone | 8 (16) | 426 (5621) | 2.35 | 1.63 (0.77 to 2.49) | 1.69 (1.25 to 2.28) |  − 1.68 to 4.94 | – |
Participants from other ethnic groups, described as Asian, Hispanic or mixed ethnicity | |||||||
 Primary analysis | 3 (9) | 522 (2646) | 1.58 | 0.31 (0.09 to 0.54) | 1.55 (0.53 to 4.53) |  − 2.72 to 3.35 | 47.95% (0% and 47.95%) |
 Sensitivity analysis, excluding studies with high overall risk of bias | 2 (7) | 41 (2165) | 1.23 | 0.36 (− 0.24 to 0.95) | 1.18 (0.14 to 9.78) |  − 1.95 to 2.66 | – |
 Sensitivity analysis, excluding studies with data transformation | 2 (8) | 488 (1405) | 2.07 | 0.30 (− 0.80 to 1.40) | 2.04 (0.32 to 12.81) |  − 3.70 to 4.31 | – |
White/Caucasian | |||||||
 Primary analysis | 13 (48) | 2195 (12,870) | 1.64 | 0.55 (− 0.21 to 1.31) | 1.55 (1.31 to 1.82) |  − 2.48 to 3.58 | 94.39% (69.92% and 24.47%) |
 Sensitivity analysis, excluding studies with high overall risk of bias | 8 (26) | 1293 (7770) | 1.42 | 0.36 (− 0.88 to 1.61) | 1.38 (1.19 to 1.59) |  − 2.33 to 3.06 | – |
 Sensitivity analysis, excluding studies with data transformation | 10 (45) | 1044 (5485) | 1.67 | 0.63 (− 0.38 to 1.63) | 1.54 (1.32 to 1.80) |  − 2.40 to 3.65 | – |
 Sensitivity analysis, excluding studies with White/Caucasian populations alone | 8 (16) | 1246 (9791) | 1.84 | 0.98 (− 0.08 to 2.05) | 1.56 (1.16 to 2.10) |  − 2.07 to 4.04 | – |