| Group | Subgroups | Number of studies | RR | 95%CI | I2 | P-interaction |
| RCTs (n = 6 studies) | ||||||
| Overall | NA | 6 | 2.08 | 1.31, 3.32 | 79% | NA |
| Age | Children | 2 | 1.17 | 0.37, 3.67 | 90% | 0.65 |
| Adults | 4 | 0.83 | 0.66, 1.04 | 25% | ||
| Hydrocephalus type | Obstructive | 2 | 0.63 | 0.47, 0.85 | 0% | 0.03 |
| Communicating | 2 | 0.96 | 0.68, 1.35 | 0% | ||
| Both | 1 | 0.89 | 0.66, 1.20 | NA | ||
| Cohort studies (n = 22 studies) | ||||||
| Overall | NA | 22 | 1.02 | 0.88, 1.18 | 90% | NA |
| Age | Children | 14 | 1.11 | 0.94, 1.31 | 91% | 0.33 |
| Adults | 2 | 0.76 | 0.38, 1.51 | 40% | ||
| Hydrocephalus type | Obstructive | 13 | 1.06 | 0.94, 1.19 | 56% | 0.48 |
| Both | 4 | 1.03 | 0.62, 1.71 | 96% | ||
| Country | Developed | 16 | 0.97 | 0.82, 1.15 | 91% | 0.81 |
| Developing | 5 | 1.29 | 0.96, 1.75 | 61% | ||
| Multinational | 1 | 0.79 | 0.88, 1.18 | NA | ||