TABLE 1.
Descriptive characteristics of Health ABC study participants at baseline by sex-specific quintiles (Q) of energy-adjusted total protein intake residuals1
| Q1 (n = 312) | Q2 (n = 312) | Q3 (n = 313) | Q4 (n = 312) | Q5 (n = 312) | P 2 | |
|---|---|---|---|---|---|---|
| Age, y | 73.4 (73.0, 73.7) | 73.4 (73.1, 73.7) | 73.4 (73.0, 73.7) | 73.5 (73.2, 73.8) | 73.2 (72.9, 73.6) | 0.631 |
| Female | 51.9 | 51.9 | 52.1 | 51.9 | 51.9 | 1.000 |
| Black | 42.3 | 33.0 | 29.7 | 29.8 | 31.1 | 0.002 |
| Current smoker | 7.4 | 7.4 | 6.4 | 7.7 | 4.8 | 0.291 |
| Alcohol consumption, >1 unit/d | 11.5 | 6.1 | 6.1 | 7.7 | 8.0 | 0.295 |
| Walking and exercise, kcal/wk | 892 (711, 1074) | 1066 (868, 1264) | 1176 (989, 1362) | 1350 (1066, 1634) | 1446 (1188, 1704) | <0.001 |
| Prevalent health conditions | ||||||
| Diabetes | 16.5 | 17.3 | 23.5 | 21.5 | 24.7 | 0.005 |
| Coronary heart disease | 20.0 | 18.2 | 17.6 | 18.5 | 20.8 | 0.788 |
| Congestive heart failure | 1.3 | 0.6 | 2.3 | 2.9 | 1.9 | 0.140 |
| Cerebrovascular disease | 6.8 | 6.8 | 4.5 | 6.1 | 6.5 | 0.792 |
| COPD | 13.3 | 20.1 | 17.1 | 17.1 | 15.2 | 0.932 |
| Cancer | 14.1 | 15.4 | 18.9 | 20.0 | 17.7 | 0.083 |
| Oral steroid use | 2.6 | 1.3 | 2.6 | 2.6 | 1.9 | 1.000 |
| BMI, kg/m2 | 27.2 (26.7, 27.8) | 27.2 (26.7, 27.7) | 27.1 (26.6, 27.6) | 26.8 (26.3, 27.3) | 27.9 (27.4, 28.5) | 0.108 |
| Obese (BMI ≥ 30 kg/m2) | 24.4 | 21.5 | 19.8 | 26.0 | 28.8 | 0.701 |
| Body composition | ||||||
| FFM DXA, kg | 49.0 (47.8, 50.0) | 48.4 (47.3, 49.6) | 48.6 (47.4, 49.8) | 48.3 (47.0, 49.5) | 49.5 (48.4, 50.7) | 0.504 |
| FM DXA, kg | 27.0 (26.0, 27.9) | 26.8 (25.9, 27.8) | 26.4 (25.6, 27.4) | 26.1 (25.2, 27.0) | 27.5 (26.5, 28.5) | 0.600 |
| Thigh muscle area, cm2 | 225 (219, 231) | 222 (216, 228) | 222 (216, 228) | 219 (213, 225) | 229 (223, 236) | 0.391 |
| Dietary intake | ||||||
| Total energy, kcal | 2052 (1983, 2120) | 1700 (1634, 1766) | 1690 (1629, 1751) | 1714 (1649, 1780) | 2014 (1942, 2085) | 0.652 |
| Fat, % of energy | 34.8 (34.0, 35.6) | 33.2 (32.4, 34.0) | 33.6 (32.8, 34.4) | 32.0 (31.2, 32.8) | 32.0 (31.1, 32.9) | <0.001 |
| Carbohydrate, % of energy | 54.8 (53.9, 55.7) | 55.1 (54.2, 56.1) | 53.1 (52.2, 54.0) | 53.1 (52.3, 54.0) | 50.4 (49.4, 51.3) | <0.001 |
| Protein, % of energy | 10.9 (10.8, 11.0) | 12.8 (12.8, 12.9) | 14.3 (14.2, 14.3) | 16.0 (15.8, 16.1) | 18.7 (18.4, 19.0) | <0.001 |
| Protein, g/d | 56.2 (54.2, 58.2) | 54.5 (52.4, 56.7) | 59.7 (57.7, 61.8) | 67.2 (65.0, 69.3) | 92.2 (89.2, 95.3) | <0.001 |
| Protein, g · kg–1 · d–1 | 0.77 (0.74, 0.80) | 0.75 (0.72, 0.78) | 0.82 (0.79, 0.85) | 0.94 (0.91, 0.98) | 1.23 (1.19, 1.27) | <0.001 |
| Protein, g · kg FFM–1 · d–1 | 1.19 (1.14, 1.24) | 1.17 (1.12, 1.21) | 1.27 (1.22, 1.32) | 1.45 (1.40, 1.50) | 1.91 (1.85, 1.97) | <0.001 |
| Animal protein, g/d | 26.6 (25.4, 27.8) | 28.1 (26.8, 29.4) | 33.8 (32.5, 35.0) | 40.2 (38.8, 41.6) | 61.6 (59.3, 63.9) | <0.001 |
| Vegetable protein, g/d | 29.5 (28.3, 30.7) | 26.5 (25.3, 27.7) | 26.0 (24.9, 27.0) | 27.0 (25.8, 28.1) | 30.6 (29.2, 32.0) | 0.045 |
1
Values are means (95% CIs) or percentages. COPD, chronic obstructive pulmonary disease; DXA, dual-energy X-ray absorptiometry; FFM, fat-free mass; FM, fat mass; Health ABC, Health, Aging, and Body Composition; Q, quintile.
2
P for trend across quintiles. For continuous variables: by using the median value in each quintile as a continuous variable in the linear regression model; for the dichotomous variables: by using the linear-by-linear association within chi-square tests.