Patient demographic and clinical characteristics
| Characteristics | AD case (n=3 44 628) | Control (n=3 44 628) | P value |
| Age | 1.0 | ||
| Mean (SD) | 73.39 (5.48) | 73.39 (5.48) | |
| Median (Q1, Q3) | 73 (71, 77) | 73 (71, 77) | |
| Age group, n (%) | 1.0 | ||
| 50–64 | 22 991 (6.67) | 22 991 (6.67) | |
| 65–74 | 180 432 (52.36) | 180 432 (52.36) | |
| 75+ | 141 205 (40.97) | 141 205 (40.97) | |
| Gender | 1.0 | ||
| Female | 224 378 (65.11) | 224 378 (65.11) | |
| Male | 120 250 (34.89) | 120 250 (34.89) | |
| Region, n (%) | 1.0 | ||
| Northeast | 78 418 (22.75) | 78 418 (22.75) | |
| Midwest | 103 247 (29.96) | 103 247 (29.96) | |
| South | 89 231 (25.89) | 89 231 (25.89) | |
| West | 73 732 (21.39) | 73 732 (21.39) | |
| Comorbidities, n (%) | <0.0001 | ||
| None | 101 458 (29.44) | 119 351 (34.63) | |
| 1 | 69 603 (20.20) | 69 552 (20.18) | |
| Two or more | 173 567 (50.36) | 155 725 (45.19) | |
| CCI | <0.0001 | ||
| Mean (SD) | 2.61 (2.89) | 2.41 (2.93) | |
| Median (Q1, Q3) | 2 (0,4) | 1 (0, 4) | |
| Follow-up time, mo | |||
| Mean (SD) | 47.86 (46.24) | 53.98 (39.97) | <0.0001 |
| Median (Q1, Q3) | 33 (9, 74) | 48 (24, 72) | |
| HSV-1, n (%) | 1507 (0.44) | 823 (0.24) | <0.0001 |
| HSV-2, n (%) | 595 (0.17) | 364 (0.11) | <0.0001 |
| VZV, n (%) | 16 547 (4.80) | 11 210 (3.25) | <0.0001 |
| CMV, n (%) | 63 (0.02) | 67 (0.02) | 0.7257 |
| COPD, n (%) | 66 241 (19.22) | 68 485 (19.87) | <0.0001 |
AD, Alzheimer’s disease; CCI, Charlson comorbidity index; CMV, cytomegalovirus; COPD, chronic obstructive pulmonary disease; HSV, herpes simplex virus; Q, quartiles; VZV, varicella zoster virus.