Sensitivity Analysis About a Possible Interaction of Physical Activity and BMI

Supplementary Material:

Appendix 1: Population characteristics (DM/BMI/PA) by ethnicity and 10yr age group used for analysis in this paper:

EUROPEAN
No physical activity
25-34yr
DM / No DM
Underweight / 2
Average / 7
Overweight / 3
Obese / 6
Unknown / 12
30
35-44yr
DM / No DM
Underweight
Average / 0 / 18
Overweight / 0 / 7
Obese / 1 / 2
Unknown / 0 / 8
36
45-54yr
DM / No DM
Underweight
Average / 0 / 7
Overweight / 2 / 16
Obese / 1 / 10
Unknown / 1 / 4
41
55-64yr
DM / No DM
Underweight / 0 / 2
Average / 0 / 15
Overweight / 1 / 13
Obese / 2 / 16
Unknown / 1 / 7
57
65-74yr
DM / No DM
Underweight / 0 / 1
Average / 0 / 9
Overweight / 0 / 22
Obese / 7 / 28
Unknown / 2 / 3
72
75+yr
DM / No DM
Underweight / 0 / 2
Average / 5 / 58
Overweight / 11 / 45
Obese / 8 / 27
Unknown / 3 / 41
200
>0-<450METmin/wk
25-34yr
DM / No DM
Underweight / 0 / 1
Average / 0 / 27
Overweight / 0 / 12
Obese / 0 / 18
Unknown / 1 / 6
65
35-44yr
DM / No DM
Underweight
Average / 0 / 20
Overweight / 1 / 21
Obese / 2 / 21
Unknown / 0 / 13
78
45-54yr
DM / No DM
Underweight
Average / 0 / 22
Overweight / 2 / 20
Obese / 4 / 24
Unknown / 1 / 5
78
55-64yr
DM / No DM
Underweight
Average / 0 / 13
Overweight / 1 / 18
Obese / 5 / 20
Unknown / 0 / 4
61
65-74yr
DM / No DM
Underweight / 0 / 1
Average / 1 / 13
Overweight / 1 / 21
Obese / 4 / 12
Unknown / 1 / 9
63
75+yr
DM / No DM
Underweight / 0 / 2
Average / 3 / 23
Overweight / 4 / 31
Obese / 2 / 10
Unknown / 6
81
≥450METmin/wk
25-34yr
DM / No DM
Underweight / 0 / 7
Average / 0 / 175
Overweight / 1 / 96
Obese / 0 / 76
Unknown / 0 / 48
403
35-44yr
DM / No DM
Underweight / 1 / 4
Average / 3 / 230
Overweight / 3 / 175
Obese / 5 / 116
Unknown / 2 / 46
585
45-54yr
DM / No DM
Underweight / 0 / 2
Average / 1 / 206
Overweight / 0 / 166
Obese / 8 / 110
Unknown / 3 / 25
521
55-64yr
DM / No DM
Underweight / 0 / 3
Average / 2 / 162
Overweight / 11 / 169
Obese / 12 / 154
Unknown / 3 / 34
550
65-74yr
DM / No DM
Underweight / 0 / 5
Average / 5 / 115
Overweight / 10 / 118
Obese / 15 / 90
Unknown / 2 / 31
391
75+yr
DM / No DM
Underweight / 0 / 3
Average / 10 / 89
Overweight / 13 / 107
Obese / 6 / 34
Unknown / 2 / 23
287

PACIFIC

No physical activity
25-34yr
DM / No DM
Underweight
Average / 3
Overweight / 3
Obese / 9
Unknown / 5
20
35-44yr
DM / No DM
Underweight
Average
Overweight / 1 / 5
Obese / 0 / 9
Unknown
15
45-54yr
DM / No DM
Underweight
Average
Overweight
Obese / 1 / 6
Unknown
7
55-64yr
DM / No DM
Underweight
Average
Overweight / 1 / 0
Obese / 1 / 3
Unknown / 0 / 1
6
65-74yr
DM / No DM
Underweight
Average
Overweight / 1 / 1
Obese / 1 / 5
Unknown / 0 / 1
9
75+yr
DM / No DM
Underweight
Average
Overweight / 0 / 3
Obese
Unknown
3
>0-<450METmin/wk
25-34yr
DM / No DM
Underweight
Average
Overweight / 6
Obese / 9
Unknown / 5
20
35-44yr
DM / No DM
Underweight
Average / 0 / 1
Overweight
Obese / 1 / 6
Unknown
8
45-54yr
DM / No DM
Underweight
Average
Overweight / 0 / 2
Obese / 0 / 6
Unknown / 1 / 1
10
55-64yr
DM / No DM
Underweight
Average
Overweight
Obese / 3 / 5
Unknown
8
65-74yr
DM / No DM
Underweight
Average
Overweight / 0 / 2
Obese / 1 / 0
Unknown / 1 / 0
4
75+yr
DM / No DM
Underweight
Average
Overweight
Obese / 2 / 1
Unknown
3
≥450METmin/wk
25-34yr
DM / No DM
Underweight
Average / 0 / 12
Overweight / 0 / 23
Obese / 3 / 64
Unknown / 0 / 14
116
35-44yr
DM / No DM
Underweight / 0 / 0
Average / 1 / 12
Overweight / 0 / 22
Obese / 2 / 64
Unknown / 0 / 10
111
45-54yr
DM / No DM
Underweight
Average / 0 / 6
Overweight / 0 / 12
Obese / 12 / 33
Unknown / 2 / 5
70
55-64yr
DM / No DM
Underweight
Average / 0 / 1
Overweight / 0 / 6
Obese / 5 / 18
Unknown / 3 / 1
34
65-74yr
DM / No DM
Underweight
Average / 0 / 1
Overweight / 1 / 2
Obese / 2 / 11
Unknown
17
75+yr
DM / No DM
Underweight
Average / 0 / 2
Overweight
Obese / 0 / 1
Unknown / 1 / 0
4
MAORI
No physical activity
25-34yr
DM / No DM
Underweight
Average / 0 / 6
Overweight / 0 / 8
Obese / 0 / 13
Unknown / 0 / 4
31
35-44yr
DM / No DM
Underweight
Average / 0 / 4
Overweight / 0 / 7
Obese / 3 / 16
Unknown / 0 / 2
32
45-54yr
DM / No DM
Underweight
Average / 0 / 2
Overweight / 1 / 4
Obese / 3 / 10
Unknown / 0 / 2
22
55-64yr
DM / No DM
Underweight
Average / 0 / 4
Overweight / 1 / 3
Obese / 1 / 14
Unknown / 1 / 2
26
65-74yr
DM / No DM
Underweight
Average / 0 / 4
Overweight / 0 / 3
Obese / 2 / 7
Unknown / 0 / 3
19
75+yr
DM / No DM
Underweight / 0 / 1
Average / 0 / 1
Overweight / 2 / 5
Obese / 2 / 0
Unknown / 0 / 3
14
>0-<450METmin/wk
25-34yr
DM / No DM
Underweight
Average / 0 / 13
Overweight / 1 / 14
Obese / 0 / 30
Unknown / 0 / 13
71
35-44yr
DM / No DM
Underweight
Average / 0 / 9
Overweight / 1 / 6
Obese / 1 / 13
Unknown / 0 / 5
35
45-54yr
DM / No DM
Underweight
Average / 0 / 6
Overweight / 0 / 6
Obese / 6 / 12
Unknown
30
55-64yr
DM / No DM
Underweight
Average / 0 / 1
Overweight / 1 / 4
Obese / 4 / 5
Unknown / 1 / 2
18
65-74yr
DM / No DM
Underweight / 0 / 1
Average / 0 / 1
Overweight / 0 / 1
Obese / 2 / 4
Unknown / 0 / 1
10
75+yr
DM / No DM
Underweight / 0 / 1
Average
Overweight / 0 / 2
Obese / 1 / 4
Unknown / 0 / 2
10
≥450METmin/wk
25-34yr
DM / No DM
Underweight / 0 / 1
Average / 1 / 91
Overweight / 0 / 111
Obese / 1 / 137
Unknown / 0 / 46
388
35-44yr
DM / No DM
Underweight / 0 / 5
Average / 0 / 73
Overweight / 1 / 73
Obese / 12 / 143
Unknown / 2 / 15
324
45-54yr
DM / No DM
Underweight / 0 / 3
Average / 0 / 51
Overweight / 4 / 64
Obese / 10 / 96
Unknown / 1 / 19
248
55-64yr
DM / No DM
Underweight / 0 / 2
Average / 0 / 23
Overweight / 0 / 29
Obese / 13 / 72
Unknown / 1 / 5
145
65-74yr
DM / No DM
Underweight / 0 / 2
Average / 0 / 10
Overweight / 5 / 19
Obese / 15 / 31
Unknown / 0 / 5
87
75+yr
DM / No DM
Underweight / 0 / 2
Average / 1 / 9
Overweight / 3 / 10
Obese / 1 / 8
Unknown / 1 / 1
36

Sensitivity Analysis about a possible interaction of physical activity and BMI

As stated in the main text of the paper, we believe it is most likely that there is not a statistical interaction (on the multiplicative scale) of physical activity and BMI in the association with endometrial cancer. However, it remains a source of contention. For example, Gierach et al report a near statistically significant interaction. Therefore, we present a sensitivity analyses about this possibility by slightly reducing the strength of association of physical (in)activity among those with a BMI < 25, and slightly increasing the strength of association among those with a BMI > 30 (Appendix Table 1). Using these relative risks in our simulation resulted in the PAR% shown in Appendix Table 2 – little different from those reported in the paper in the presence of no interaction. This absence of difference arises because we assumed that ‘on average’ across strata of BMI the strength of association of physical activitiy with endometrial cancer is still the same – just weaker among <25 and stronger among >30.

Appendix 2: Relative risk estimates for combination of risk factor exposures and association with Endometrial Cancer – sensitivity analysis allowing interaction of physical activity and BMI

METmin/week / BMI
25kg/m2 / 25-30 kg/m2 / ≥30kg/m2
No Diabetes Mellitus / ≥450 / 1 (referent) / 1.6 / 2.73
>0-450 / 1.2x0.95=1.14 / 1.92 / 3.28x1.05=3.44
None / 1.47x0.9=1.32 / 2.35 / 4.01x1.1=4.41
Diabetes Mellitus / ≥450 / 2.47 / 3.95 / 7.14
>0-450 / 2.96x0.95=2.81 / 4.74 / 8.09x1.05=8.49
None / 3.63x0.9=3.27 / 5.81 / 9.9x1.1=10.90

Appendix 3: PAR% for combined effects of DM, physical inactivity and overweight/ obesity on endometrial cancer, calculations for 10-year age groups and age groups combined (with 2.5% and 97.5% simulation intervals) – sensitivity analysis about interaction of BMI and physical inactivity.

Ethnicity / 25-34yr / 35-44yr / 45-54yr / 55-64yr / 65-74yr / 75+yr
European / 39 (32-48) / 43 (36-51) / 46 (39-56) / 52 (46-60) / 56 (47-65) / 53 (42-65)
Pacific / 60 (54-66) / 61 (56-67) / 69 (61-77) / 73 (63-83) / 71 (62-81) / 67 (45-87)
Maori / 51 (45-59) / 57 (52-64) / 60 (53-69) / 64 (57-73) / 69 (59-79) / 63 (50-76)