Summary of the survey
| Primary survey | |||||
| Northern Japan | Southern Japan | P value | Total | ||
| Japanese population in 2011 (×103) | 17 078 | 110 719 | 127 797 | ||
| NMO (category 1) | Number of patients | 178 (199) | 1101 (1939) | 1279 (2093) | |
| Prevalence (/105) | 1.16 | 1.75 | <0.001 | 1.64 | |
| NMOsd (category 2) | Number of patients | 68 (193) | 303 (714) | 371 (883) | |
| Prevalence (/105) | 1.13 | 0.64 | <0.001 | 0.69 | |
| NMOsd (category 3) | Number of patients | 81 (129) | 341 (887) | 422 (1031) | |
| Prevalence (/105) | 0.76 | 0.80 | 0.053 | 0.81 | |
| NMOsd (category 4) | Number of patients | 48 (26) | 207 (384) | 255 (370) | |
| Prevalence (/105) | 0.15 | 0.35 | <0.001 | 0.29 | |
| Total | Number of patients | 375 (547) | 1952 (3924) | 2327 (4377) | |
| Prevalence (/105) | 3.20 | 3.54 | <0.001 | 3.42 | |