Table 6

Estimated incidence rates and relative risks for moderate or greater MR. The number of expected cases were based on estimated incidence rates utilizing the pooled control (unexposed) groups of these studies. Relative risks and z statistics were calculated within each study. No cases of MR were observed in unexposed groups of the Khan and Hensrud studies making relative risks inestimable. These studies did contribute to the summary estimates.

Author, year
Duration (months)
"Incident" MR cases
Expected cases
p-value by Poisson
Relative Risk (RR)
Lower 95% CI of RR
Upper 95% CI of RR
z
p-value

Khan, 1998
20.6
2.00
0.873
0.059
-
-
-
2.7
0.0033
Weissman, 1998
2.4
3.87
0.289
0.00023
14.9
5.2
42.5
5.0
<0.00001
Shively, 1999
6.9
1.82
0.279
0.032
29.7
6.2
142.8
4.2
0.000012
Hensrud, 1999
9.6
0.00
0.033
0.97
-
-
-
-
-
Ryan, 1999
16.7
1.00
0.241
0.025
-
-
-
-
-
Gardin, 2000
11.9
8.69
0.950
<0.00001
5.0
2.4
10.4
4.3
<0.00001

6
8.06
0.500
<0.00001
10.5
5.3
20.5
6.8
<0.00001
Jollis, 2000
2
0.00
0.009
0.99
0.0
0.0
-
-0.1
0.54

4.5
2.31
0.253
0.0022
9.5
3.0
30.5
3.8
0.000079

9
5.83
0.666
0.000069
9.1
3.9
21.1
5.1
<0.00001

18
3.28
1.018
0.020
3.3
1.0
10.8
2.0
0.022

30
0.71
0.463
0.37
1.6
0.1
17.3
0.4
0.35
Davidoff, 2001
2.5
0.96
0.120
0.11
3.6
0.5
25.3
1.3
0.096
Summary, 2002
8.89
38.5
5.7
<0.00001
5.9
4.0
8.6
9.1
<0.00001

Hopkins and Polukoff BMC Cardiovascular Disorders 2003 3:5   doi:10.1186/1471-2261-3-5