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Table 1 Dried blood spot collection among breast cancer cases and control who initially declined to provide a venipuncture blood sample, according to incentive, demographic characteristics and selected cancer risk factors

From: Blood spots as an alternative to whole blood collection and the effect of a small monetary incentive to increase participation in genetic association studies

 

Cases (n = 134)

Controls (n = 256)

 

No blood spot

Blood spot

OR (95% CI)

p-valuea

No blood spot

Blood spot

OR (95% CI)

p-valuea

Incentive Group

        

No incentive

49 (73%)

18 (27%)

ref

0.01

95 (74%)

34 (26%)

ref

0.6

$2 incentive

35 (52%)

32 (48%)

2.5b(1.2,5.1)

 

90 (71%)

37 (29%)

1.1 (0.7,2.0)

 

Year of birth

        

< 1935

18 (56%)

14 (44%)

ref

0.8

32 (63%)

19 (37%)

ref

0.4

1935 to 1944

35 (63%)

21 (38%)

0.8 (0.3,1.9)

 

90 (75%)

30 (25%)

0.6 (0.3,1.1)

 

1945 to 1954

24 (67%)

12 (33%)

0.6 (0.2,1.7)

 

53 (29%)

19 (26%)

0.6 (0.3,1.3)

 

≥ 1955

7 (70%)

3 (30%)

0.6 (0.1,2.5)

 

10 (77%)

3 (23%)

0.5 (0.1,2.0)

 

Marital Status

        

Married/Living Together

53 (61%)

34 (39%)

ref

0.8

135 (73%)

50 (27%)

ref

0.9

Widowed/

Divorced/

Seperated

23 (66%)

12 (34%)

1.1 (0.6,2.2)

 

38 (70%)

16 (30%)

1.1 (0.6,2.2)

 

Never Married

8 (67%)

4 (33%)

1.1 (0.4,3.4)

 

12 (71%)

5 (29%)

1.1 (0.4,3.3)

 

Smoking Status

        

Never

39 (56%)

31 (44%)

ref

0.2

99 (71%)

40 (29%)

ref

0.8

Former

36 (71%)

15 (29%)

0.5 (0.2,1.1)

 

60 (75%)

20 (25%)

0.8 (0.4,1.5)

 

Current

9 (69%)

4 (31%)

0.6 (0.6,2.0)

 

26 (72%)

10 (28%)

1.0 (0.4,2.2)

 

Unknown

0 (0%)

0 (0%)

N/A

 

0 (0%)

1(100%)

N/A

 

Region of residencec

        

Northeast

16 (57%)

12 (43%)

ref

0.7

29 (67%)

14 (33%)

ref

0.9

Midwest

19 (63%)

11 (37%)

0.8 (0.3,2.2)

 

48 (73%)

18 (27%)

0.8 (0.3,1.8)

 

South

15 (54%)

13 (46%)

1.2 (0.4,3.3)

 

37 (69%)

17 (31%)

1.0 (0.4,2.2)

 

West

11 (61%)

7 (39%)

0.8 (0.2,2.7)

 

24 (69%)

11 (31%)

0.9 (0.4,2.5)

 

Unknown

23 (77%)

7 (23%)

0.4 (0.1,1.2)

 

47 (81%)

11 (19%)

0.5 (0.2,1.2)

 

Occupational radiation breast dose (Gy)

0 to 0.02

56 (65%)

30 (35%)

ref

0.9

124 (72%)

49 (28%)

ref

0.02

> 0.02 to 0.04

13 (59%)

9 (41%)

1.2 (0.5,3.4)

 

34 (89%)

4 (11%)

0.3 (0.1,0.9)

 

> 0.04 to 0.06

6 (60%)

4 (40%)

1.2 (0.3,4.8)

 

10 (71%)

4 (29%)

1.0 (0.3,3.4)

 

> 0.06

9 (56%)

7 (44%)

1.5 (0.5,4.3)

 

17 (55%)

14 (45%)

2.1 (0.9,4.6)

 

Personal diagnostic radiation breast dose score

0 to 0.02

47 (67%)

23 (33%)

 

0.5

121 (73%)

44 (27%)

 

0.9

> 0.02 to 0.04

12 (50%)

12 (50%)

2.0 (0.8,5.2)

 

33 (70%)

14 (30%)

1.2 (0.6,2.4)

 

> 0.04 to 0.06

9 (60%)

6 (40%)

1.4 (0.4,4.3)

 

14 (74%)

5 (26%)

1.0 (0.3,2.9)

 

> 0.06

16 (64%)

9 (36%)

1.1 (0.4,3.0)

 

17 (68%)

8 (32%)

1.3 (0.5,3.2)

 
  1. aChi-square test excluded Unknown category
  2. bp-value for super-multiplicative effect modification = 0.09
  3. cU.S. Census Bureau definition: Northeast = CT, ME, MA, NH, RI, VT, NJ, NY, PA, DE, DC, MD; Midwest = IL, IN, MI, OH, WI, IA, KS, MN, MO, NE, ND, SD; South = FL, GA, NC, SC, VA, WV, AL, KY, MS, TN, AR, LA, OK, TX; West = AZ, CO, ID, MT, NV, NM, UT, WY, AK, CA, HI, OR, WA
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BMC Medical Research Methodology

ISSN: 1471-2288

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