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Table 1 Personal and environmental characteristics of the baseline study population, those lost to follow-up, the 6-year cohort and the 20-year cohort, the espoo cohort study 1991–2011, Finland

From: Allergic diseases and asthma in the family predict the persistence and onset-age of asthma: a prospective cohort study

  Baseline Lost to follow-up 6-year cohort Lost to follow-up 20-year cohort Participation in all surveys
No. (% of baseline population) 2568 (100.0) 584 (22.7) 1984 (77.3) 945 (36.8) 1623 (63.2) 1298 (50.5)
Age (years)
  1 424 (16.5) 100 (17.1) 324 (16.3) 156 (16.5) 268 (16.5) 210 (16.2)
  2 405 (15.8) 104 (17.8) 301 (15.2) 147 (15.6) 258 (15.9) 199 (15.3)
  3 411 (16.0) 92 (15.8) 319 (16.1) 145 (15.3) 266 (16.4) 211 (16.3)
  4 400 (15.6) 67 (11.5) 333 (16.8) 159 (16.8) 241 (14.9) 209 (16.1)
  5 415 (16.2) 101 (17.3) 314 (15.8) 151 (16.0) 264 (16.3) 208 (16.0)
6-7 513 (20.0) 120 (20.6) 393 (19.8) 187 (19.8) 326 (20.1) 261 (20.1)
Sex
  male 1311 (51.1) 309 (52.9) 1002 (50.5) 557 (58.9) 754 (46.5) 592 (45.6)
  female 1257 (49.0) 275 (47.1) 982 (49.5) 388 (41.1) 869 (53.5) 706 (54.4)
Family socioeconomic status at baseline
  low 667 (26.1) 169 (29.1) 498 (25.2) 296 (31.5) 371 (22.9) 292 (22.5)
  middle/high 1889 (73.9) 411 (70.9) 1478 (74.8) 643 (68.5) 1246 (77.1) 1003 (77.5)
Duration of breast-feeding in months
  < 4 481 (19.3) 135 (24.1) 346 (17.9) 192 (21.0) 289 (18.3) 221 (17.5)
  4 ≤ x < 8 670 (26.9) 159 (28.3) 511 (26.4) 250 (27.4) 420 (26.6) 333 (26.3)
  ≥ 8 1343 (53.9) 267 (47.6) 1076 (55.7) 471 (51.6) 872 (55.2) 711 (56.2)
SHS 0–3
  yes 299 (11.6) 66 (11.3) 233 (11.7) 105 (11.1) 194 (12.0) 153 (11.8)
  no 2269 (88.4) 518 (88.7) 1751 (88.3) 840 (88.9) 1429 (88.1) 1145 (88.2)
Mold 0–3
  yes 138 (5.4) 21 (3.6) 117 (5.9) 55 (5.8) 83 (5.1) 73 (5.6)
  no 2428 (94.6) 569 (96.4) 1867 (94.1) 888 (94.2) 1540 (94.9) 1225 (94.4)
SHS 0–13 *
  yes 468 (18.2) 121 (20.7) 347 (17.5) 161 (17.0) 307 (18.9) 234 (18.0)
  no 2100 (81.8) 463 (79.3) 1637 (82.5) 784 (83.0) 1316 (81.1) 1064 (82.0)
Mold 0–13 *
  yes 385 (15.0) 35 (6.0) 350 (17.6) 150 (15.9) 235 (14.5) 220 (17.0)
  no 2183 (85.0) 549 (94.0) 1634 (82.4) 795 (84.1) 1388 (85.5) 1078 (83.1)
Maternal smoking in pregnancy
  yes 364 (14.2) 104 (17.9) 260 (13.1) 160 (17.0) 204 (12.6) 156 (12.0)
  no 2199 (85.8) 477 (82.1) 1722 (86.9) 784 (83.1) 1415 (87.4) 1141 (88.0)
  1. Abbreviations: SHS0–3 = exposure to second-hand smoke at the age of 0–3, SHS0–13 = exposure to second-hand smoke at the age of 0–13.
  2. Missing information: 12 for family socioeconomic status at baseline, 74 for duration of breast-feeding, 5 for maternal smoking in pregnancy, 2 from mold-exposure from 0 to 3 years.
  3. *Used for adjustment when studying late-onset asthma as the outcome.
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