Table 1.
Distribution of participant characteristics by case status.
| Characteristic | Case N (%) |
All Controls N (%) |
Original Controls N (%) |
Later Controls N (%) |
|---|---|---|---|---|
| Sex | ||||
| Male | 62 (62.0) | 83 (42.8) | 28 (77.8) | 55 (34.8) |
| Female | 38 (38.0) | 111(57.2) | 8 (22.2) | 103 (65.2) |
| p-value | <0.01 | <0.001 | ||
| Age (yrs) | ||||
| <60 | 49 (49.0) | 34 (17.5) | 12 (33.3) | 22 (13.9) |
| 60–69 | 27 (27.0) | 61 (31.4) | 15 (41.7) | 46 (29.1) |
| 70+ | 24 (24.0) | 99 (51.0) | 9 (25.0) | 90 (57.0) |
| p-value | <0.001 | <0.01 | ||
| Education | ||||
| High school or below | 35 (35.0) | 25 (12.9) | 3 (8.3) | 22 (13.9) |
| Some college or above | 65 (65.0) | 169 (87.1) | 33 (91.7) | 136 (86.1) |
| p-value | <0.001 | 0.58 | ||
| Pack-years of smoking | ||||
| Never | 29 (29.0) | 92 (47.4) | 15 (41.7) | 77 (48.7) |
| <10 | 19 (19.0) | 40 (20.6) | 3 (8.3) | 37 (23.4) |
| 10–30 | 25 (25.0) | 39 (20.1) | 9 (25.0) | 30 (19.0) |
| >30 | 27 (27.0) | 23 (11.9) | 9 (25.0) | 14 (8.9) |
| p-value | <0.01 | 0.02 | ||
| Control groups | ||||
| Original ALS Case-Control Study | 100 (100) | 36 (18.6) | 36 (100) | - |
| Controls recruited later | - | 158 (81.4) | - | 158 (100) |
p-values in the All Controls column refer to differences between cases and all controls, and those in the Later Controls column refer to differences between the two control groups.