Table 13.
Cox Proportional Hazard Modeling Results for PM2.5 Exposurea and MCI and Dementia in the WHIMS Cohort (1999–2007) by BMI, CVD, Diabetes Mellitus, and WBC Count
| Models | MCI | Dementia | Incident MCI or Dementia |
|---|---|---|---|
| Models by BMI | |||
| Crude | |||
| Main |
N = 6,845, n = 320 1.06 (0.93 to 1.21), P = 0.38 |
N = 7,012, n = 213 1.09 (0.92 to 1.29), P = 0.31 |
N = 6,974, n = 449 1.05 (0.94 to 1.18), P = 0.38 |
| BMI < 25 kg/m2 |
N = 1,990, n = 110 1.02 (0.81 to 1.27), P = 0.90 |
N = 2,048, n = 80 1.13 (0.86 to 1.47), P = 0.37 |
N = 2,036, n = 156 1.02 (0.85 to 1.24), P = 0.81 |
| BMI 25–29 kg/m2 |
N = 2,482, n = 100 0.92 (0.73 to 1.16), P = 0.47 |
N = 2,546, n = 72 1.22 (0.92 to 1.6), P = 0.16 |
N = 2,532, n = 150 1.02 (0.84 to 1.24), P = 0.82 |
| BMI ≥ 30 kg/m2 |
N = 2,373, n = 110 1.28 (1.02 to 1.60), P = 0.03 |
N = 2,418, n = 61 0.89 (0.64 to 1.24), P = 0.49 |
N = 2,406, n = 143 1.12 (0.92 to 1.38), P = 0.26 |
| Interaction P value | 0.12 | 0.34 | 0.74 |
| Adjustedb | |||
| Main |
N = 6,126, n = 256 0.94 (0.80 to 1.10), P = 0.43 |
N = 6,258, n = 167 1.00 (0.81 to 1.23), P = 0.98 |
N = 6,228, n = 358 0.95 (0.83 to 1.08), P = 0.43 |
| BMI < 25 kg/m2 |
N = 1,788, n = 86 0.93 (0.71 to 1.22), P = 0.61 |
N = 1,830, n = 55 1.06 (0.75 to 1.49), P = 0.74 |
N = 1,819, n = 117 0.96 (0.76 to 1.20), P = 0.70 |
| BMI 25–29 kg/m2 |
N = 2,225, n = 81 0.78 (0.60 to 1.03), P = 0.08 |
N = 2,277, n = 58 1.07 (0.77 to 1.48), P = 0.70 |
N = 2,267, n = 123 0.89 (0.71 to 1.10), P = 0.27 |
| BMI ≥ 30 kg/m2 |
N = 2,113, n = 89 1.12 (0.86 to 1.46), P = 0.38 |
N = 2,151, n = 54 0.85 (0.59 to 1.24), P = 0.40 |
N = 2,142, n = 118 1.01 (0.80 to 1.28), P = 0.91 |
| Interaction P value | 0.16 | 0.60 | 0.69 |
| Models by CVD | |||
| Crude | |||
| Main |
N = 6,778, n = 313 1.06 (0.93 to 1.21), P = 0.40 |
N = 6,943, n = 211 1.09 (0.92 to 1.29), P = 0.32 |
N = 6,906, n = 441, 1.05 (0.94 to 1.18), P = 0.41 |
| No |
N = 5,613, n = 243 1.03 (0.89 to 1.20), P = 0.69 |
N = 5,746, n = 167 1.09 (0.91 to 1.32), P = 0.34 |
N = 5,720, n = 350 1.04 (0.91 to 1.18), P = 0.58 |
| Yes |
N = 1,165, n = 70 1.17 (0.88 to 1.55), P = 0.29 |
N = 1,197, n = 44 1.06 (0.73 to 1.55), P = 0.75 |
N = 1,186, n = 91 1.10 (0.85 to 1.42), P = 0.46 |
| Interaction P value | 0.46 | 0.89 | 0.68 |
| Adjustedb | |||
| Main |
N = 6,126, n = 256 0.94 (0.80 to 1.10), P = 0.43 |
N = 6,258, n = 167 1.00 (0.81 to 1.23), P = 0.98 |
N = 6,228, n = 358 0.95 (0.83 to 1.08), P = 0.43 |
| No |
N = 5,084, n = 194 0.92 (0.77 to 1.10), P = 0.36 |
N = 5,191, n = 130 1.02 (0.82 to 1.28), P = 0.84 |
N = 5,169, n = 279 0.94 (0.81 to 1.09), P = 0.43 |
| Yes |
N = 1,042, n = 62 1.00 (0.73 to 1.37), P = 0.99 |
N = 1,067, n = 37 0.90 (0.58 to 1.40), P = 0.64 |
N = 1,059, n = 79 0.97 (0.73 to 1.29), P = 0.83 |
| Interaction P value | 0.63 | 0.60 | 0.85 |
| Models by Diabetes Mellitus | |||
| Crude | |||
| Main |
N = 6,872, n = 321, 1.07 (0.94 to 1.22), P = 0.33 |
N = 7,038, n = 213 1.09 (0.93 to 1.29), P = 0.29 |
N = 7,001, n = 450 1.06 (0.94 to 1.18), P = 0.35 |
| No |
N = 6,448, n = 278 1.06 (0.92 to 1.22), P = 0.42 |
N = 6,604, n = 202 1.08 (0.91 to 1.28), P = 0.39 |
N = 6,574, n = 404 1.06 (0.94 to 1.19), P = 0.38 |
| Yes |
N = 424, n = 43 1.13 (0.78 to 1.64), P = 0.52 |
N = 434, n = 11 1.46 (0.70 to 3.02), P = 0.31 |
N = 427, n = 46 1.06 (0.74 to 1.53), P = 0.74 |
| Interaction P value | 0.75 | 0.43 | 0.97 |
| Adjustedb | |||
| Main |
N = 6,126, n = 256 0.94 (0.80 to 1.10), P = 0.43 |
N = 6,258, n = 167 1.00 (0.81 to 1.23), P = 0.98 |
N = 6,228, n = 358 0.95 (0.83 to 1.08), P = 0.43 |
| No |
N = 5,763, n = 220 0.94 (0.79 to 1.11), P = 0.47 |
N = 5,887, n = 159 1.00 (0.81 to 1.23), P = 0.99 |
N = 5,863, n = 320 0.95 (0.83 to 1.10), P = 0.52 |
| Yes |
N = 363, n = 36 0.92 (0.60 to 1.41), P = 0.71 |
N = 371, n = 8 0.99 (0.39 to 2.53), P = 0.98 |
N = 365, n = 38 0.87 (0.58 to 1.31), P = 0.51 |
| Interaction P value | 0.94 | 0.98 | 0.67 |
| Models by WBC Count | |||
| Crude | |||
| Main |
N = 6,654, n = 303 1.05 (0.92 to 1.21), P = 0.47 |
N = 6,813, n = 203 1.06 (0.90 to 1.26), P = 0.48 |
N = 6,777, n = 426 1.04 (0.92 to 1.16), P = 0.55 |
| WBC ≥5,000/μL |
N = 3,233, n = 139 1.06 (0.87 to 1.30), P = 0.54 |
N = 3,318, n = 97 1.12 (0.87 to 1.42), P = 0.38 |
N = 3,296, n = 202 1.07 (0.90 to 1.26), P = 0.45 |
| WBC < 5,000/μL |
N = 3,421, n = 164 1.04 (0.86 to 1.25), P = 0.67 |
N = 3,495, n = 106 1.02 (0.80 to 1.29), P = 0.89 |
N = 3,481, n = 224 1.01 (0.86 to 1.19), P = 0.92 |
| Interaction P value | 0.88 | 0.60 | 0.63 |
| Adjustedb | |||
| Main |
N = 5,929, n = 242 0.92 (0.78 to 1.08), P = 0.30 |
N = 6,053, n = 157 0.96 (0.78 to 1.19), P = 0.73 |
N = 6,025, n = 338 0.92 (0.80 to 1.06), P = 0.23 |
| WBC ≥5,000/μL |
N = 2,888, n = 109 0.94 (0.74 to 1.18), P = 0.57 |
N = 2,957, n = 80 1.01 (0.76 to 1.33), P = 0.96 |
N = 2,941, n = 162 0.94 (0.78 to 1.14), P = 0.52 |
| WBC < 5,000/μL |
N = 3,041, n = 133 0.90 (0.72 to 1.12), P = 0.34 |
N = 3,096, n = 77 0.91 (0.67 to 1.24), P = 0.56 |
N = 3,084, n = 176 0.89 (0.74 to 1.09), P = 0.26 |
| Interaction P value | 0.80 | 0.63 | 0.71 |
a Expressed as the hazard ratios (95% confidence interval) associated with each interquartile increment (3.9 μg/m3) of time-varying cumulative annual PM2.5 exposures.
b Using Model VI: adjusted for geographic region, age, and race, or ethnicity; SES (education, income, and employment status); lifestyle factors (smoking, alcohol use, and physical activity); HT; depressive symptoms; BMI; conventional CVD risk factors (hypertension, diabetes mellitus, and hypercholesterolemia); and CVD histories.