TABLE 2—
Tobit Estimates of Disability at Wave 2 of the National Health and Nutrition Examination Survey I: Epidemiologic Follow-Up Study
| Upper Body | Upper Body | Lower Body | Lower Body | ||||||
| Coding Algorithm | Unstandardized Coefficient | SE | Unstandardized Coefficient | SE | Unstandardized Coefficient | SE | Unstandardized Coefficient | SE | |
| BMI | kg/m2 | 0.047 | 0.027 | 0.154*** | 0.030 | ||||
| Normal weighta | 1 = (18.5 ≥ BMI < 25), 0 = no | ||||||||
| Obesity | 1 = (BMI ≥ 30), 0 = no | 1.068** | 0.394 | 2.397*** | 0.439 | ||||
| Overweight | 1 = (25 ≥ BMI < 30), 0 = no | –0.223 | 0.326 | 0.3780 | .361 | ||||
| Underweight | 1 = (BMI < 18.5) | 2.753*** | 0.768 | 3.272*** | 0.878 | ||||
| Restricted activity | 1 = yes, 0 = no | 2.404*** | 0.499 | 2.488*** | 0.496 | 2.640*** | 0.562 | 2.793*** | 0.559 |
| Serious illness | 0–4, 4 = 4+ | 1.205*** | 0.221 | 1.184*** | 0.221 | 1.364*** | 0.250 | 1.371*** | 0.249 |
| Chronic illness | 0–4, 4 = 4+ | 2.310*** | 0.278 | 2.339*** | 0.277 | 2.709*** | 0.311 | 2.772*** | 0.311 |
| Age, y | 24–77 | 0.069** | 0.024 | 0.077** | 0.024 | 0.088*** | 0.026 | 0.097*** | 0.026 |
| Female | 1 = female, 0 = male | 2.391*** | 0.393 | 2.213*** | 0.395 | 3.167*** | 0.435 | 2.965*** | 0.438 |
| Black | 1 = yes, 0 = no | –2.128*** | 0.567 | –2.109*** | 0.565 | –2.412*** | 0.628 | –2.345*** | 0.626 |
| Live alone | 1 = yes, 0 = no | –0.347 | 0.505 | –0.358 | 0.505 | –0.219 | 0.563 | –0.186 | 0.562 |
| Widowed | 1 = yes, 0 = no | –0.314 | 0.546 | –0.307 | 0.546 | 0.196 | 0.610 | 0.186 | 0.609 |
| Education | 0–7, 7 = graduate school | –0.408*** | 0.108 | –0.408*** | 0.108 | –0.376** | 0.120 | –0.376** | 0.120 |
| Income | 1–12, 12 = ≥ $25 000 | –0.005 | 0.079 | 0.006 | 0.079 | 0.007 | 0.088 | 0.023 | 0.088 |
| Regular physician | 1 = yes, 0 = no | 0.148 | 0.427 | 0.109 | 0.426 | 0.390 | 0.476 | 0.339 | 0.476 |
| Other health insurance | 1 = yes, 0 = no | 0.058 | 0.416 | 0.101 | 0.415 | –0.072 | 0.462 | –0.068 | 0.461 |
| Medicaid | 1 = yes, 0 = no | 1.161 | 0.734 | 1.104 | 0.733 | 1.922* | 0.814 | 1.879* | 0.813 |
| Nonsmokera | 1 = yes, 0 = no | ||||||||
| Past smoker | 1 = yes, 0 = no | 0.242 | 0.360 | 0.284 | 0.360 | 0.135 | 0.401 | 0.197 | 0.400 |
| Heavy smoker | 1 = yes, 0 = no | 0.837* | 0.377 | 0.731 | 0.377 | 1.516*** | 0.417 | 1.382*** | 0.418 |
| Light smoker | 1 = yes, 0 = no | 1.100** | 0.382 | 1.042** | 0.382 | 1.410*** | 0.428 | 1.341** | 0.428 |
| Mortality lambda | 7.832*** | 1.514 | 7.578*** | 1.512 | 11.727*** | 1.704 | 11.392*** | 1.702 | |
| Nonresponse lambda | 7.414** | 2.454 | 7.450** | 2.451 | 6.851* | 2.737 | 7.007* | 2.734 | |
| Constant | –6.615*** | 1.807 | –5.877*** | 1.673 | –10.751*** | 2.006 | –7.795*** | 1.851 | |
| n | 5071 | 5071 | 5072 | 5072 | |||||
| Log likelihood | –4867.6 | –4857.9 | –6112.3 | –6104.9 | |||||
Note. BMI = body mass index.
aReference group.
*P < .05; **P < .01; ***P < .001.