Table 2 The results of subgroup analysis by characteristics of the studies
Subgroup | No. of studies | Prevalence (95%CI) | I2 (%) | p-value |
|---|---|---|---|---|
Publication year | ||||
 Before 2010 | 3 | 13.08 (7.37, 18.78) | 89.2% | < 0.001 |
 After 2010 | 21 | 12.60 (10.34,14.86) | 93.7% | < 0.001 |
Region | ||||
 Amhara | 8 | 9.36 (6.71,12.00) | 93% | < 0.001 |
 Oromia | 4 | 11.78 (9.56,13.99) | 52% | < 0.001 |
 Tigray | 3 | 13.11 (4.86, 21.36) | 94.4% | < 0.001 |
 Addis Ababa | 7 | 14.26 (9.87, 18.65) | 91.8% | < 0.001 |
 SNNPR | 2 | 17.19 (13.30,21.09) | 0.0% | 0.562 |
Study design | ||||
 Cross-sectional | 15 | 11.0 (8.56,13.43) | 93.9% | < 0.001 |
 Cohort | 9 | 14.18 (11.88, 16.48) | 72.8% | < 0.001 |
Sample size | ||||
  ≤ 300 | 11 | 15.54 (12.26, 18.82) | 77.9% | < 0.001 |
  > 300 | 13 | 10.15 (7.54, 12.93) | 95.7% | < 0.001 |
Sampling technique | ||||
 Probability | 5 | 13.38 (8.983, 17.78) | 84.2% | < 0.001 |
 Non probability | 17 | 12.16(9.20, 15.12) | 94.9% | < 0.001 |
 Not specified | 2 | 11.88 (7.90, 15.87) | 92.4% | < 0.001 |
Type of surgery | ||||
 General surgery | 20 | 12.68 (10.24,15.11) | 94.8% | < 0.001 |
 Obstetric surgery | 4 | 10.39 (8.91,11.81) | 0.0% | 0.61 |