Meta-analysis results: subgroup analysis and pooled analysis
| Study type | Proportion FALS cases (95% CI) | |||||
| No of studies | FALS cases | Total ALS cases | Fixed effects | Random effects | I2 | |
| Group 1: prospective population based registry | 8 | 265 | 5283 | 5.0% (4.4 to 5.6) | 5.1% (4.1 to 6.1) | 56% |
| Group 2: retrospective population based study | 14 | 59 | 1666 | 3.7% (2.9 to 4.7) | 3.7% (2.9 to 4.7) | 0% |
| Group 3: prospective case series | 3 | 151 | 2035 | 7.3% (6.2 to 8.4) | 5.7% (2.5 to 9.9) | 91% |
| Group 4: retrospective case series | 8 | 100 | 2237 | 4.4% (3.6 to 5.2) | 4.8% (3.1 to 6.8) | 74% |
| Population based studies (groups 1 and 2) | 22 | 324 | 6949 | 4.7% (4.2 to 5.2) | 4.5% (3.8 to 5.3) | 37% |
| Case series studies (groups 3 and 4) | 11 | 251 | 4272 | 5.7% (5.0 to 6.4) | 5.1% (3.4 to 7.1) | 85% |
| Pooled results for all studies (groups 1–4) | 33 | 575 | 11,221 | 5.1% (4.7 to 5.5) | 4.6% (3.9 to 5.5) | 69% |
FALS, familial amyotrophic lateral sclerosis.