Skip to main content

Table 1 Characteristics of the study participants

From: Feasibility of self-sampled dried blood spot and saliva samples sent by mail in a population-based study

Overall (N = 4597) Adequate/valid blood samples Inadequate blood samples or did not return blood samples
  (N = 3038/66%)1 (N = 1559/34%)
Variables N Mean (SD) 2 N % Mean (SD) 2 N % Mean (SD) 2
Age (years) 4573 57 (4.7) 3014   57 (4.1) 1559   57 (5.1)
50-54 1499   953 32   546 35  
55-59 1528   1012 34   516 33  
60-64 1409   963 32   446 29  
65-69 137   86 3   51 3  
Chi-square p-value5 0.045        
Body mass index (kg/m 2 ) 4 4243 25 (4.6) 2714   25 (4.4) 1529   25 (4.9)
<25 1562   1244 46   318 21  
>25 < 29 1680   1082 40   598 39  
>29 1001   388 14   613 40  
Chi-square p-value5 <0.001        
Education (in years) 4542   3013    1529   
<=10 830   512 17   318 21  
11-14 1830   1232 41   598 39  
15+ 1882   1269 42   613 40  
Chi-square p-value5 0.007        
Physical activity (less strenuous) 3 3661   2414    1247   
Hours per week         
0 86   47 2   39 3  
1 422   275 11   147 12  
2 to 3 1620   1082 45   538 43  
4 to 5 917   605 25   312 25  
6+ 616   405 17   211 17  
Chi-square p-value5 0.24        
Physical activity (strenuous) 3557   2353    1204   
Hours per week         
0 1521   986 42   535 44  
1 859   571 24   288 24  
2 to 3 929   638 27   291 24  
4 to 5 180   116 5   64 5  
6+ 68   42 2   26 2  
Chi-square p-value5 0.32        
Smoking 3649   2397    1252   
Never 1583   1096 46   487 39  
Current 778   431 18   347 28  
Past 1288   870 36   418 33  
Chi-square p-value5 <0.001        
  1. 1Adequate/valid samples were samples returned in an aluminium bag with a desiccant pouch while invalid samples were samples without a dessicant pouch or aluminium bag.
  2. 2Unadjusted mean and standard deviation.
  3. 3Physical activity: less strenuous = walking, bicycling, working in the garden more strenuous = aerobic, running, bicycling at high intensity.
  4. 4excluded women with height <125, and weight < 30 kg >170 kg.
  5. 5Compared the adequate (n = 3038) with the inadequate blood samples (n = 1559).