Table 3.
Risk of Incident Alzheimer's Disease According to Central Obesity and Change in Waist Circumference at Different Ages (Cox Proportional Hazards Models), Baltimore Longitudinal Study of Aging, 1958–2006a
| Range of Valuesb | WC (cm) | |||||||
| Men | Range of Valuesb | Women | ||||||
| HR | 95% CI | P Value | HR | 95% CI | P Value | |||
| Quintile of WC statusc |
Range, cm |
Range, cm |
||||||
| At age 30 years | ||||||||
| Q1 (<20th percentile) | 60.6–77.4 | 1 | 45.4–61.2 | 1 | ||||
| Q2 | 77.4–81.0 | 0.69 | 0.42, 1.14 | 0.148 | 61.3–64.8 | 1.71† | 0.93, 3.12 | 0.083 |
| Q3 | 81.0–84.8 | 0.55* | 0.31, 0.99 | 0.048 | 64.8–70.3 | 1.38 | 0.64, 2.97 | 0.412 |
| Q4 | 84.8–89.9 | 1.26 | 0.72, 2.22 | 0.413 | 70.3–77.3 | 2.23 | 0.81, 6.18 | 0.112 |
| Q5 (>80th percentile) | 89.9–126.3 | 0.64 | 0.28, 1.46 | 0.294 | 77.4–112.9 | 4.60* | 1.28, 16.43 | 0.019 |
| At age 35 years | ||||||||
| Q1 (<20th percentile) | 64.4–79.2 | 1 | 50.1–63.3 | 1 | ||||
| Q2 | 79.2–82.8 | 0.84 | 0.52, 1.37 | 0.486 | 63.3–67.0 | 1.05 | 0.56, 1.95 | 0.885 |
| Q3 | 82.8–86.6 | 0.62 | 0.34, 1.12 | 0.115 | 67.0–72.8 | 1.22 | 0.61, 2.45 | 0.577 |
| Q4 | 86.6–91.8 | 1.16 | 0.65, 2.06 | 0.611 | 72.8–79.9 | 2.07 | 0.75, 5.71 | 0.159 |
| Q5 (>80th percentile) | 91.9–126.2 | 0.95 | 0.43, 2.08 | 0.898 | 80.1–114.4 | 3.17† | 0.91, 11.03 | 0.069 |
| At age 40 years | ||||||||
| Q1 (<20th percentile) | 67.2–80.9 | 1 | 53.7–65.3 | 1 | ||||
| Q2 | 80.9–84.6 | 0.73 | 0.45, 1.21 | 0.228 | 65.3–69.2 | 0.89 | 0.48, 1.65 | 0.706 |
| Q3 | 84.6–88.4 | 0.85 | 0.50, 1.45 | 0.556 | 69.2–75.2 | 0.91 | 0.44, 1.89 | 0.795 |
| Q4 | 88.4–93.6 | 0.99 | 0.56, 1.75 | 0.978 | 73.3–82.7 | 2.18 | 0.80, 5.97 | 0.127 |
| Q5 (>80th percentile) | 93.6–127.5 | 0.57 | 0.20, 1.62 | 0.294 | 82.8–115.8 | 2.52 | 0.73, 8.68 | 0.141 |
| At age 45 years | ||||||||
| Q1 (<20th percentile) | 68.5–82.7 | 1 | 55.8–67.2 | 1 | ||||
| Q2 | 82.7–86.5 | 0.92 | 0.56, 1.52 | 0.760 | 67.2–71.4 | 1.08 | 0.59, 1.97 | 0.808 |
| Q3 | 86.5–90.2 | 0.90 | 0.52, 1.55 | 0.702 | 71.4–77.8 | 0.76 | 0.34, 1.71 | 0.513 |
| Q4 | 90.2–95.6 | 1.07 | 0.60, 1.88 | 0.819 | 77.8–84.9 | 2.75* | 1.07, 7.06 | 0.035 |
| Q5 (>80th percentile) | 95.6–131.3 | 0.64 | 0.22, 1.82 | 0.400 | 85.0–117.3 | 2.45 | 0.71, 8.39 | 0.155 |
| At age 50 years | ||||||||
| Q1 (<20th percentile) | 69.8–84.1 | 1 | 57.9–69.2 | 1 | ||||
| Q2 | 84.2–88.3 | 0.85 | 0.52, 1.40 | 0.527 | 69.2–73.7 | 1.15 | 0.63, 2.11 | 0.647 |
| Q3 | 88.3–92.2 | 0.79 | 0.45, 1.36 | 0.396 | 73.8–80.1 | 0.88 | 0.41, 1.92 | 0.753 |
| Q4 | 92.2–97.7 | 1.00 | 0.57, 1.76 | 0.987 | 80.1–87.2 | 2.53† | 1.00, 6.44 | 0.051 |
| Q5 (>80th percentile) | 97.7–138.9 | 0.48 | 0.95, 1.07 | 0.235 | 87.2–118.8 | 3.04† | 0.87, 10.59 | 0.080 |
| Change in WCc |
Range, % |
Range, % |
||||||
| Between ages 30 and 35 years | ||||||||
| <10th percentile | −1.40 to 1.13 | 1.55 | 0.89; 2.69 | 0.118 | −2.98 to 1.10 | 1.37 | 0.41, 4.54 | 0.609 |
| 10th–90th percentile | 1.13 to 4.06 | 1 | 1.14 to 4.05 | 1 | ||||
| >90th percentile | 4.07 to 6.94 | 1.82 | 0.83, 4.01 | 0.133 | 4.08 to 16.20 | 0.50* | 0.26, 0.96 | 0.037 |
| Between ages 35 and 40 years | ||||||||
| <10th percentile | −1.40 to 1.13 | 1.56 | 0.90, 2.71 | 0.110 | −2.96 to 1.10 | 1.37 | 0.41, 4.54 | 0.609 |
| 10th–90th percentile | 1.13 to 3.92 | 1 | 1.15 to 3.92 | 1 | ||||
| >90th percentile | 3.93 to 6.51 | 1.83 | 0.83, 4.01 | 0.133 | 3.94 to 13.97 | 0.50* | 0.26, 0.96 | 0.037 |
| Between ages 40 and 45 years | ||||||||
| <10th percentile | −1.40 to 1.13 | 1.55 | 0.89, 2.69 | 0.118 | −3.03 to 1.11 | 1.37 | 0.41, 4.55 | 0.605 |
| 10th–90th percentile | 1.14 to 3.78 | 1 | 1.16 to 3.78 | 1 | ||||
| >90th percentile | 3.79 to 6.07 | 1.82 | 0.83, 4.01 | 0.133 | 3.79 to 12.28 | 0.49* | 0.26, 0.93 | 0.031 |
| Between ages 45 and 50 years | ||||||||
| <10th percentile | −1.41 to 1.13 | 1.60† | 0.92, 2.78 | 0.093 | −3.11 to 1.11 | 1.37 | 0.41, 4.55 | 0.605 |
| 10th–90th percentile | 1.13 to 3.67 | 1 | 1.17 to 3.67 | 1 | ||||
| >90th percentile | 3.70 to 5.78 | 1.83 | 0.84, 4.03 | 0.130 | 3.67 to 10.95 | 0.49* | 0.26, 0.94 | 0.031 |
Abbreviations: CI, confidence interval; HR, hazard ratio; Q, quintile; WC, waist circumference.
P ≤ 0.10 (borderline-significant); *P < 0.05; **P < 0.01; ***P < 0.001.
z scores were computed for change, and significant decrease and increase corresponded to the 10th and 90th percentiles (based on the whole Baltimore Longitudinal Study of Aging sample (n = 3,005)), respectively, of the standardized distribution of change. Numbers of subjects and failures were 1,343 and 110, respectively, for men and 669 and 64, respectively, for models with women only.
Cutpoints may vary or overlap because of rounding.
WC change was estimated by taking the difference between empirical Bayes predicted values for WC at each age (using model E in Web Appendix 2) and then computing percent change from baseline. Models with WC status and change as exposures controlled for education (years), ethnicity (non-Hispanic black vs. other), and smoking status (former or current smoker vs. nonsmoker).