TABLE 2.
Outcomes of the subgroup analysis
| Subgroup | Comparison | Studies no. | Mean difference (95% CI) | Heterogeneity | Test for overall effect | |
|---|---|---|---|---|---|---|
| P value | I 2 | P value | ||||
| Renal interlobar vein impedance index | ||||||
| Preeclampsia onset | EOP vs control | 4 | 0.11 (0.09, 0.13) | .70 | 0% | <.001 |
| LOP vs control | 0.05 (0.03, 0.07) | .81 | 0% | <.001 | ||
| EOP vs LOP | 0.07 (0.05, 0.09) | .77 | 0% | <.001 | ||
| Side of measurement | Left kidney PE vs left kidney control | 7 | 0.06 (0.05, 0.07) | .14 | 38% | <.001 |
| Right kidney PE vs right kidney control | 0.09 (0.07, 0.10) | .53 | 0% | <.001 | ||
| Left kidney PE vs right kidney PE | 0.03 (0.01, 0.04) | .61 | 0% | <.001 | ||
| Venous pulse transit time | ||||||
| Preeclampsia onset | EOP vs control | 3 | −0.10 (−0.14, −0.06) | .70 | 0% | <.001 |
| LOP vs control | −0.07 (−0.10, −0.03) | .38 | 0% | <.001 | ||
| EOP vs LOP | −0.04 (−0.07, −0.01) | .77 | 0% | .003 | ||
| Side of measurement | Left kidney PE vs left kidney control | 4 | −0.10 (−0.13, −0.07) | .51 | 0% | <.001 |
| Right kidney PE vs right kidney control | −0.08 (−0.10, −0.05) | .21 | 34% | <.001 | ||
| Left kidney PE vs right kidney PE | 0.00 (−0.01, 0.02) | .94 | 0% | .71 | ||
Abbreviations: CI, confidence intervals; EOP, early‐onset preeclampsia; I 2: inconsistency index; LOP, late‐onset preeclampsia.