Table 1.

Study population characteristics of the Xuanwei cohort study (1976–2011)

MenWomen
n = 21,701n = 20,721
Age in 1976, years, mean, SD39.5 (10.6)39.0 (10.6)
Birth cohort, n, %
 1917–193610,285 (47.4)9,529 (46.0)
 1937–19455,710 (26.3)5,267 (25.4)
 1946–19515,706 (26.3)5,925 (28.6)
 Ever actively smoked (≤ 1992), n, %20,010 (92.2)61 (0.3)
 Duration of active smoking, years, mean, SD31.1 (13.5)
n = 21,686
Respondent, n, %
 Self12,624 (58.2)12,519 (60.4)
 Surrogate9,077 (41.8)8,202 (39.6)
Ethnicity, n, %
 Han Chinese21,122 (97.3)20,116 (97.1)
 Other579 (2.7)605 (2.9)
Education, n, %
 Illiterate11,748 (54.1)15,885 (76.7)
 Primary school8,073 (37.2)4,352 (21.0)
 Middle/vocational school or higher1,880 (8.7)484 (2.3)
 Other work besides farming (≤ 1992), n, %4,816 (22.2)1,193 (5.8)
 Ever worked as a miner (≤ 1992), n, %1,117 (5.1)28 (0.1)
 Age at which started cooking, years, mean, SD27.8 (14.7)18.3 (3.7)
n = 1,836n = 20,315
Average sleep duration (≤ 1992), hours/day, mean, SD
 21–30 years8.3 (0.8)8.3 (0.7)
n = 21,700n = 20,721
 31–40 years8.1 (0.7)8.1 (0.7)
n = 21,647n = 20,684
 41–50 years8.0 (0.7)8.0 (0.7)
n = 21,308n = 20,419
 51–60 years7.9 (0.8)7.9 (0.8)
n = 12,590n = 11,527
 61–70 years7.8 (1.0)7.8 (1.0)
n = 6,184n = 5,698
 ≥71 years7.7 (1.2)7.7 (1.2)
n = 1452n = 1275
Average time indoor activities (≤1992), hours/day, mean, SD
 21–30 years3.3 (1.3)3.5 (1.3)
n = 21,693n = 20,721
 31–40 years3.4 (1.3)3.6 (1.3)
n = 21,639n = 20,682
 41–50 years3.5 (1.3)3.7 (1.3)
n = 21,299n = 20,415
 51–60 years3.7 (1.3)3.9 (1.4)
n = 12,585n = 11,525
 61–70 years3.9 (1.4)4.0 (1.4)
n = 6,183n = 5,693
 ≥71 years4.2 (1.5)4.3 (1.5)
n = 1,448n = 1,273
Fuel type used in first residence (≤1992), n, %
 Smoky coal14,306 (65.9)13,153 (63.5)
 Smokeless coal5,447 (25.1)4,848 (23.4)
 Coal cakes and others1,948 (9.0)2,720 (13.1)
 Stove improvement (≤ 1992), n, %12,529 (58.0)12,186 (59.0)
 Average tons of fuel used in residences (≤1992), mean, SD3.2 (1.2)3.2 (1.2)
 Average number people in residences (≤1992), mean, SD5.2 (1.2)5.3 (1.1)
 Average number of rooms in residences (≤1992), mean, SD1.7 (0.8)1.7 (0.8)
 Cases of lung cancer death (1976–1991), n, %1,094 (5.0)1,064 (5.1)
 Cases of lung cancer death (1992–1993), n, %164 (0.8)153 (0.7)
 Cases of lung cancer death (1994–2011), n, %1,337 (6.2)1,017 (4.9)
 Average age of death from lung cancer (1976–2011), mean, SD60.0 (10.2)59.2 (9.9)
 Family history of any cancer (≤ 1992), n, %1,023 (4.7)710 (3.4)