Statistical Methods in Medical Research 4ed

Study start
year, code
and name
Deaths/patients Ablation deaths Annual odds of death
Ovarian
ablation
(a) Ovarian ablation in the absence of cytotoxics
57A
64A
65B
68B
71A
74J2
Subtotal (a)*
(b) Ovarian ablation in the presence of cytotoxics
74J2 Bradford RI
78B 2 + 3 Toronto−Edmonton
78G1 CCABC Vancouver
78K2 Ludwig II
79B2 SWOG 7827 B
Subtotal (b)
Norwegian RH
Saskatchewan CF
PMH Toronto
Ontario CTRF
CRFB Caen A
Bradford RI
Total (a + b)*
24/68
49/143
133/216
5/6
1/1
5/22
3/21
35/116
14/57
69/139
18/145
Control
group
43/83
56/112
96/133*
3/3
0/0
5/20
217/456 250/422
3/17
33/119
15/52
84/142
25/131
O − E Variance
of O − E
−8 . 7
−11 . 0
−11 . 2
1 . 0
−0 . 3
−30 . 1
−0 . 4
0 . 5
−1 . 6
−9 . 6
−3 . 6
90 . 8
139/478 160/461 −14 . 7 68 . 4
356/934
(38 . 1%)
410/883
(46 . 4%)
14 . 2
24 . 6
48 . 0
1 . 6
2 . 4
1 . 4
15 . 7
6 . 7
34 . 4
10 . 2
−44 . 8 15 9 . 3
99% or 95% limits
Test for heterogeneity: χ
Test for interaction (a) vs (b):
*For balance, controls from 65B2 count twice just in totals of deaths/patients.
2
9
χ 2
= 5
1
. 4; p > 0 . 1; NS.
= 0 . 5; p > 0 . 1; NS.
Ratio (and
confidence limits),
ablation : control
Ablation better
Reduction
(% and SD)
0 0 . 5 1 . 1 5
2
Ablation worse
Treatment effect 2p = 0 . 0004
28%, SD 9
19%, SD 11
25%, SD 7
Fig. 18.2 A meta-analysis of mortality results from trials of ovarian ablation in women with early breast cancer below age 50, subdivided by the presence or
absence of cytotoxic chemotherapy (Early Breast Cancer Trialists' Collaborative Group, 1992, Fig. 9). In this presentation the area of a black square is
proportional to Vi, and thus represents the precision of the estimate from that trial or group of trials. The significance level for a two-sided test is shown as `2p'.
Reproduced by permission of the authors and publishers.