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Table 1 Participation and reasons for non-participation in ISAAC Phase Two, SOLAR I and SOLAR II

From: Study on Occupational Allergy Risks (SOLAR II) in Germany: Design and methods

  Total Munich Dresden
  n (%) n (%) n (%)
ISAAC Phase Two
Questionnaire study
6399 (85.3)1 3354 (87.6) 3045 (83.0)
SOLAR I 3785 (77.4)2 2043 (81.5) 1742 (73.0)
of these:    
Agreed to be re-contacted 3053 (80.7) 1534 (75.1) 1519 (87.2)
SOLAR II    
Drop-outs in total 149 (4.9) 85 (5.5) 64 (4.2)
Address could not be found via population registries 143 (4.7) 82 (5.3) 61 (4.0)
Deceased 6 (0.2) 3 (0.2) 3 (0.2)
Eligible study population 2904 (100.0) 1449 (100.0) 1455 (100.0)
Refusals in total 853 (29.4) 441 (30.4) 412 (28.3)
of these    
Could not be reached by phone/no phone number available 454 (53.3) 184 (41.7) 270 (65.5)
Lack of interest/time 262 (30.7) 146 (33.0) 116 (28.2)
Absence from study location during the entire field phase 59 (6.9) 41 (9.3) 18 (4.4)
Other reasons 78 (9.1) 70 (15.8) 8 (1.9)
Response: questionnaire part 2051 (70.6) 1008 (69.6) 1043 (71.1)
Response: clinical study 1167 (40.2) 568 (39.2) 599 (41.2)
  1. 1 6399 of 7498 invited children
  2. 2 3785 of 4893 invited adolescents who could be re-contacted