Table 1.
Baseline Characteristics of Patients with and without Tdap/Td during the Follow-up period before and after PSM
| Panel 1: Before propensity score matching | Panel 2: After propensity score matching | |||||
| No Tdap vaccinations during follow-up (n = 1,529,214) | ≥1 Tdap vaccinations during follow-up (n = 122,777) | SMD | No Tdap vaccinations during follow-up (n = 116,400) | ≥1 Tdap vaccinations during follow-up (n = 116,400) | SMD | |
| Age, y, mean (SD) | 73.1 (5.7) | 71.9 (5.0) | 0.2101 | 72.0 (5.2) | 72.0 (5.0) | –0.0072 |
| Sex | ||||||
| Unknown | 214 (0.01%) | 11 (0.01%) | 0.0047 | NA | NA | |
| Female | 854,745 (55.89%) | 70,836 (57.69%) | –0.0364 | 67,025 (57.58%) | 67,114 (57.66%) | –0.0015 |
| Male | 674,256 (44.09%) | 51,930 (42.3%) | 0.0121 | 49,375 (42.42%) | 49,286 (42.34%) | 0.0015 |
| Race | ||||||
| Unknown | 114,104 (7.46%) | 6,315 (5.14%) | 0.0955 | NA | NA | |
| Asian | 43,079 (2.82%) | 3,554 (2.89%) | –0.0047 | 3,035 (2.61%) | 3,553 (3.05%) | –0.0268 |
| Black | 135,762 (8.88%) | 11,087 (9.03%) | –0.0053 | 10,152 (8.72%) | 11,085 (9.52%) | –0.0278 |
| Hispanic | 134,543 (8.8%) | 8,636 (7.03%) | 0.0669 | 9,367 (8.04%) | 8,627 (7.41%) | 0.0238 |
| White | 1,101,727 (72.05%) | 93,185 (75.9%) | –0.0879 | 93,846 (80.62%) | 93135 (80.01%) | 0.0154 |
| Geographic region | ||||||
| Unknown | 1,048 (0.07%) | 56 (0.05%) | 0.0096 | NA | NA | |
| Northeast | 138,212 (9.04%) | 11,409 (9.29%) | –0.0088 | 10,788 (9.27%) | 10,821 (9.3%) | –0.001 |
| North central | 344,302 (22.51%) | 29,280 (23.85%) | –0.0316 | 27,113 (23.29%) | 28,037 (24.09%) | –0.0187 |
| South | 566,337 (37.03%) | 42,670 (34.75%) | 0.0476 | 43,156 (37.08%) | 41,018 (35.24%) | 0.0382 |
| West | 479,316 (31.34%) | 39,362 (32.06%) | –0.0154 | 35,343 (30.36%) | 36,524 (31.38%) | –0.022 |
| No. of health care encountersa, mean (SD) | 24.9 (26.1) | 22.9 (21.7) | 0.0828 | 22.1 (22.2) | 23.1 (21.8) | –0.0454 |
| No. of routine annual check-ups (“well visits”) | 0.6 (1.0) | 0.7 (1.0) | –0.1418 | 0.7 (1.1) | 0.7 (1.0) | –0.0149 |
| Comorbidities | ||||||
| Asthma | 119,583 (7.82%) | 9,276 (7.56%) | 0.0099 | 7,898 (6.79%) | 8,863 (7.61%) | –0.0321 |
| Atrial fibrillation or flutter | 152,609 (9.98%) | 8,831 (7.19%) | 0.0996 | 7,819 (6.72%) | 8,452 (7.26%) | –0.0213 |
| B12 deficiency | 53,072 (3.47%) | 3,559 (2.9%) | 0.0326 | 3,151 (2.71%) | 3,406 (2.93%) | –0.0132 |
| Congestive heart failure | 139,821 (9.14%) | 6,144 (5%) | 0.1594 | 5,353 (4.6%) | 5,901 (5.07%) | –0.022 |
| COPD | 221,648 (14.49%) | 12,163 (9.91%) | 0.1405 | 10,907 (9.37%) | 11,663 (10.02%) | –0.022 |
| Hyperlipidemia | 1,069,831 (69.96%) | 88,677 (72.23%) | –0.05 | 83,731 (71.93%) | 84,339 (72.46%) | –0.0117 |
| Hypertension | 1,096,354 (71.69%) | 84,550 (68.86%) | 0.0619 | 79,900 (68.64%) | 80,535 (69.19%) | –0.0118 |
| Ischemic heart disease | 353,523 (23.12%) | 22,514 (18.34%) | 0.1181 | 20,766 (17.84%) | 21,516 (18.48%) | –0.0167 |
| Obesity | 116,184 (7.6%) | 9,060 (7.4%) | 0.0083 | 7966 (6.84%) | 8,676 (7.45%) | –0.0236 |
| Traumatic brain injury | 6,961 (0.46%) | 417 (0.34%) | 0.0183 | 399 (0.34%) | 401 (0.34%) | –0.0003 |
| Type II diabetes | 388,303 (25.39%) | 27,155 (22.12%) | 0.077 | 24,722 (21.24%) | 25,955 (22.3%) | –0.0257 |
| Stroke | 52,951 (3.46%) | 2,780 (2.26%) | 0.0719 | 2,366 (2.03%) | 2,656 (2.28%) | –0.0171 |
| Alcohol use disorder | 14,171 (0.93%) | 767 (0.62%) | 0.0344 | 690 (0.59%) | 733 (0.63%) | –0.008 |
| Anxiety disorderb | 162,626 (10.63%) | 11,050 (9%) | 0.055 | 9667 (8.3%) | 10,561 (9.07%) | –0.0273 |
| Depression | 109,197 (7.14%) | 6,920 (5.64%) | 0.0616 | 5987 (5.14%) | 6,627 (5.69%) | –0.0243 |
| Substance use disorderc | 11,311 (0.74%) | 640 (0.52%) | 0.0276 | 591 (0.51%) | 611 (0.52%) | –0.0023 |
| Tobacco use | 145,973 (9.55%) | 10,088 (8.22%) | 0.0467 | 8,870 (7.62%) | 9,626 (8.27%) | –0.024 |
| Medications (sustained use)d | ||||||
| Anticholinergics | 86,220 (5.64%) | 5,464 (4.45%) | 0.0543 | 5,056 (4.34%) | 5,285 (4.54%) | –0.0095 |
| Antihypertensives | 41,071 (2.69%) | 2,452 (2%) | 0.0456 | 2,146 (1.84%) | 2,362 (2.03%) | –0.0135 |
| Antivirals | 21,062 (1.38%) | 1,996 (1.63%) | –0.0204 | 1,726 (1.48%) | 1,925 (1.65%) | –0.0138 |
| Glucocorticoids | 133,544 (8.73%) | 10,471 (8.53%) | 0.0073 | 9,056 (7.78%) | 10,095 (8.67%) | –0.0325 |
| Metformin | 162,350 (10.62%) | 13,222 (10.77%) | –0.0049 | 11,886 (10.21%) | 12,661 (10.88%) | –0.0217 |
| NSAIDs | 196,438 (12.85%) | 17,278 (14.07%) | –0.036 | 15,247 (13.1%) | 16,569 (14.23%) | –0.0331 |
| Statins | 623,884 (40.8%) | 54,745 (44.59%) | –0.0767 | 51,308 (44.08%) | 52,218 (44.86%) | –0.0157 |
| Sulfonylureas | 121,153 (7.92%) | 8,336 (6.79%) | 0.0434 | 7,542 (6.48%) | 8,008 (6.88%) | –0.016 |
| Vaccination | ||||||
| Influenza vaccination | 86,511 (5.66%) | 10,418 (8.49%) | –0.1105 | 8,980 (7.71%) | 10,003 (8.59%) | –0.0321 |
| HZ vaccination | 19,716 (1.29%) | 2,928 (2.38%) | –0.0816 | 2,412 (2.07%) | 2,752 (2.36%) | –0.0198 |
| Pneumococcal vaccination | 10,189 (0.67%) | 1,404 (1.14%) | –0.0504 | 1,155 (0.99%) | 1,335 (1.15%) | –0.015 |
Variable definitions are provided in Supplementary Table 1. Categorical variables are reported as frequency and percentage, and continuous variables as mean and standard deviation. Because patients with unknown geographic region, race, and sex are excluded prior to performing the propensity score matching (PSM), those rows after PSM are labelled as NA. aNumber of outpatient or inpatient healthcare encounters during the look-back period. b“Anxiety disorder” is a composite variable of post-traumatic stress disorder, panic disorder, anxiety disorder not otherwise specified, obsessive compulsive disorder, social phobia, and generalized anxiety disorder. c“Substance use disorder” is a composite variable of substance use disorders involving any of the following: opioids; cannabis; sedatives, hypnotics, or anxiolytics; cocaine; amphetamines or other stimulants; hallucinogens; inhalants; and/or other psychoactive substances, including polysubstance use. d“Sustained use” is defined as≥2 prescription claims in any 6-month period during the look-back period. COPD, chronic obstructive pulmonary disease; HZ, Herpes zoster; NSAIDs, nonsteroidal anti-inflammatory drugs; SD, standard deviation; SMD, standardized mean difference; Tdap, Tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis; Td, Tetanus toxoid and reduced diphtheria toxoid. Table adapted from Bukhbinder et al. [38]. Reprinted from Journal of Alzheimer’s Disease, vol. 88, no. 3, Bukhbinder AS, Ling Y, Hasan O, Jiang X, Kim Y, Phelps KN, Schmandt RE, Amran A, Coburn R, Ramesh S, Xiao Q, Schulz PE, Risk of Alzheimer’s disease following influenza vaccination: a claims-based cohort study using propensity score matching, pp. 1061-1074, 2022, with permission from IOS Press. The publication is available at IOS Press through http://dx.doi.org/10.3233/JAD-220361.