Table 1. Clinical and demographic features of the LHS participants, by quartiles of leukocyte telomere length, in the LHS (N = 4271).
| Characteristic | Quartile | P value for trend | |||
| 1 | 2 | 3 | 4 | ||
| Number of subjects | 1068 | 1068 | 1068 | 1067 | |
| Age (years) | 53.9±6.7 | 53.4±6.7 | 53.3±6.9 | 53.4±6.7 | 0.145 |
| Gender (% male) | 62.3 | 64 | 62.6 | 62.6 | 0.965 |
| BMI | 25.5±4.0 | 25.5±3.8 | 25.6±3.8 | 25.6±4.0 | 0.639 |
| Race (% Caucasian) | 96.7 | 96.9 | 95.5 | 96.0 | 0.157 |
| Continuous smokers (%) | 51.2 | 55.8 | 56.9 | 53.6 | 0.850 |
| Intermittent smokers (%) | 30.6 | 28.1 | 26.6 | 26.4 | |
| Sustained quitters (%) | 18.2 | 16.1 | 16.5 | 20.0 | |
| Pack years | 40.2±18.0 | 40.2±18.0 | 39.6±18.4 | 39.7±19.0 | 0.194 |
| FEV1(% predicted) at baseline | 78.4±8.8 | 78.7±8.7 | 78.3±9.9 | 78.4±10.6 | 0.415 |
| FEV1 (% predicted) after 5 years | 75.2±11.6 | 75.4±11.9 | 74.4±12.7 | 75.6±12.6 | 0.486 |
Abbreviations: FEV1, forced expiratory volume in 1 second; BMI, body mass index. Study participants were divided into 4 identical groups based on the telomere length, 1st quartile being the shortest and 4th quartile being the longest. Data are presented as mean ± SD and tested with Cochran-Armitage test for trend.