Table 1.
Baseline Characteristics According to Quintiles of Pulmonary Function*
| Pulmonary Function | ||||||
|---|---|---|---|---|---|---|
| Quintile 1 (n = 1649) | Quintile 2 (n = 1643) | Quintile 3 (n = 1646) | Quintile 4 (n = 1654) | Quintile 5 (n = 1655) | p Value† | |
| Age (years), mean (SD) | 61.8 (7.3) | 62.5 (7.6) | 61.6 (7.5) | 61.1 (7.2) | 62.5 (7.8) | .91 |
| Age (years), range | 50.0–86.9 | 50.0–90.5 | 50.0–89.9 | 50.0–90.3 | 50.0–94.6 | — |
| Female, n (%) | 848 (51.3) | 822 (50.0) | 823 (49.9) | 832 (50.2) | 790 (47.8) | <.0001 |
| Education, n (%) | <.0001 | |||||
| Illiterate (0 year) | 527 (31.9) | 527 (32.0) | 476 (28.9) | 473 (28.6) | 386 (23.3) | |
| Low (1–9 years) | 757 (45.8) | 736 (44.8) | 730 (44.2) | 699 (42.2) | 707 (42.7) | |
| High (≥10 years) | 370 (22.4) | 380 (23.2) | 442 (26.8) | 482 (29.2) | 561 (33.9) | |
| Rural residents, n (%) | 1029 (62.2) | 1050 (63.9) | 1006 (61.0) | 1044 (63.0) | 1040 (62.8) | <.0001 |
| Non-alcohol drinkers, n (%) | 1102 (66.6) | 1094 (66.5) | 1123 (68.1) | 1092 (66.0) | 1056 (63.7) | <.0001 |
| Smoking, n (%) | 530 (32.1) | 575 (35.0) | 534 (32.4) | 538 (32.5) | 473 (28.6) | <.0001 |
| Physical activity (MET-min/wk), mean (SD) |
1878 (4401) | 1900 (4644) | 2042 (4770) | 1954 (4484) | 1701 (4594) | .38 |
| Height (cm), mean (SD) | 157.0 (8.5) | 157.2 (8.2) | 157.6 (8.6) | 158.5 (9.4) | 159.9 (9.7) | <.0001 |
| Weight (kg), mean (SD) | 56.6 (11.5) | 57.0 (11.1) | 57.8 (10.9) | 59.6 (11.6) | 62.0 (11.7) | <.0001 |
| BMI (kg/m2), mean (SD) | 22.8 (3.9) | 23.0 (3.6) | 23.3 (3.6) | 23.6 (3.7) | 24.1 (3.8) | <.0001 |
| Physical function limitation‡, mean (SD) | 3.70 (4.46) | 3.12 (4.30) | 2.63 (3.75) | 2.29 (3.53) | 2.05 (3.26) | <.0001 |
| Peak expiratory flow (L/min), mean (SD) | 141.7 (52.8) | 226.1 (54.5) | 292.2 (65.4) | 352.7 (74.4) | 438.2 (101.6) | <.0001 |
| Global cognitive score, mean (SD) | 13.98 (5.15) | 14.56 (5.23) | 15.00 (5.26) | 15.50 (5.12) | 16.49 (5.23) | <.0001 |
| Immediate memory, mean (SD) | 3.70 (1.59) | 3.85 (1.56) | 3.98 (1.62) | 4.03 (1.56) | 4.37 (1.69) | <.0001 |
| Delayed memory, mean (SD) | 2.77 (1.81) | 2.91 (1.82) | 3.08 (1.91) | 3.05 (1.89) | 3.33 (1.92) | <.0001 |
| Subtraction calculation, mean (SD) | 2.50 (2.00) | 2.62 (1.99) | 2.72 (1.97) | 2.90 (1.96) | 3.13 (1.94) | <.0001 |
| Date orientation, mean (SD) | 3.56 (1.37) | 3.61 (1.37) | 3.70 (1.33) | 3.89 (1.27) | 4.05 (1.17) | <.0001 |
Notes: ANOVA = analysis of variance; MET = metabolic equivalent of task; SD = standard deviation; BMI = body mass index.
*Pulmonary function was standardized by age and region.
†ANOVA was used to test the difference of continuous variables across quintiles of pulmonary function and chi-square for categorical variables.
‡Physical function limitation score was calculated by summing subscores of all tasks with a higher score representing higher physical function limitation.