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Table 1 Comparison of the participants and nonparticipants of the influenza vaccination study in terms of demographic and health-related variables, %

From: Motivations for (non)participation in population-based health studies among the elderly – comparison of participants and nonparticipants of a prospective study on influenza vaccination

  Participants of the study
(n = 200)
Nonparticipants of the study
(n = 531)
p value*
Sex    0.08
 Female 43 50  
 Male 57 50  
Median age in years (interquartile range) 72 (68–76) 73 (69–76) 0.11a
Body Mass Indexb    0.37
 Underweight (≤18.49 kg/m2) 1.0 1.6  
 Normal weight (18.50-24.99 kg/m2) 36 42  
 Overweight (25.00-29.99 kg/m2) 45 38  
 Obesity (≥30.00 kg/m2) 18 18  
Myocardial infarction    0.68
 Yes 6.0 6.8  
 No 93 91  
 Don’t know 0.50 0.38  
 Missing values 0.50 1.7  
Cancer    0.54
 Yes 20 22  
 No 80 76  
 Don’t know 0 1.1  
 Missing values 0 1.7  
Diabetes mellitus    0.008
 Yes 7.5 15  
 No 92 83  
 Don’t know 0.50 0.57  
 Missing values 0 1.7  
Self-perceived health status    <0.0001
 Poor 0 0.19  
 Fair 9.0 15  
 Good 64 62  
 Very good 21 14  
 Excellent 4.0 0.19  
 Missing values 2.0 8.0  
Ever vaccinated against influenza    0.93
 Yes 78 78  
 No 21 21  
 Don’t know 1.0 0.19  
 Missing values 1.5 1.1  
  1. *Chi-square test, the category “don’t know” and missing values were not considered in this test
  2. aMann–Whitney test
  3. bBody Mass Index (BMI) was calculated using the formula “weight/height2” (kg/m2). Weight and height were objectively measured at the study center in the influenza vaccination study and self-reported by the nonparticipants