Practices (n)
|
Records reviewed (n)**
|
Power (%)
|
---|
rHR = 2
|
rHR = 5
|
rHR = 10
|
rHR = 20
|
---|
| |
R = 50%
|
R = 20%
|
R = 50%
|
R = 20%
|
R = 50%
|
R = 20%
|
R = 50%
|
R = 20%
|
---|
1
|
40
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
50
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
100
|
0
|
0
|
0
|
0
|
0
|
0
|
1
|
1
|
200
|
0
|
0
|
0
|
0
|
2
|
1
|
9
|
5
|
300
|
0
|
0
|
0
|
0
|
3
|
2
|
19
|
7
|
400
|
0
|
0
|
1
|
1
|
11
|
4
|
27
|
7
|
10
|
40
|
0
|
0
|
1
|
0
|
8
|
4
|
30
|
8
|
50
|
0
|
0
|
2
|
1
|
16
|
5
|
37
|
8
|
100
|
1
|
0
|
14
|
5
|
38
|
7
|
64
|
14
|
200
|
9
|
4
|
36
|
8
|
66
|
13
|
93
|
22
|
300
|
21
|
5
|
57
|
10
|
84
|
16
|
98
|
32
|
400
|
28
|
8
|
65
|
12
|
91
|
22
|
100
|
41
|
20
|
40
|
0
|
0
|
10
|
4
|
28
|
7
|
53
|
11
|
50
|
0
|
0
|
17
|
6
|
37
|
8
|
66
|
15
|
100
|
10
|
4
|
37
|
10
|
63
|
13
|
93
|
24
|
200
|
28
|
7
|
67
|
13
|
91
|
22
|
100
|
38
|
300
|
43
|
9
|
81
|
19
|
98
|
31
|
100
|
54
|
400
|
56
|
11
|
92
|
20
|
100
|
40
|
100
|
69
|
50
|
40
|
9
|
3
|
34
|
8
|
65
|
13
|
93
|
24
|
50
|
14
|
5
|
45
|
10
|
75
|
16
|
96
|
28
|
100
|
36
|
10
|
74
|
16
|
96
|
25
|
100
|
48
|
200
|
64
|
12
|
97
|
27
|
100
|
48
|
100
|
79
|
300
|
84
$
|
18
$
|
100
|
41
|
100
|
64
|
100
|
92
|
400
|
94
|
21
|
100
|
48
|
100
|
79
|
100
|
97
|
100
|
40
|
31
|
6
|
64
|
11
|
92
|
20
|
100
|
40
|
50
|
35
|
10
|
76
|
14
|
96
|
29
|
100
|
53
|
100
|
66
|
12
|
97
|
26
|
100
|
47
|
100
|
77
|
200
|
90
|
22
|
100
|
48
|
100
|
76
|
100
|
96
|
300
|
98
|
34
|
100
|
64
|
100
|
92
|
100
|
100
|
400
|
100
|
38
|
100
|
78
|
100
|
97
|
100
|
100
|
150
|
40
|
45
|
10
|
84
|
16
|
99
|
33
|
100
|
56
|
50
|
51
|
11
|
89
|
21
|
100
|
38
|
100
|
64
|
100
|
82
|
15
|
100
|
39
|
100
|
64
|
100
|
91
|
200
|
99
|
32
|
100
|
64
|
100
|
91
|
100
|
100
|
300
|
100
|
46
|
100
|
81
|
100
|
99
|
100
|
100
|
400
|
100
|
57
|
100
|
92
|
100
|
100
|
100
|
100
|
200
|
40
|
53
|
12
|
91
|
23
|
100
|
38
|
100
|
68
|
50
|
64
|
12
|
96
|
28
|
100
|
47
|
100
|
77
|
100
|
92
|
22
|
100
|
49
|
100
|
78
|
100
|
97
|
200
|
100
|
36
|
100
|
79
|
100
|
96
|
100
|
100
|
300
|
100
|
56
|
100
|
92
|
100
|
100
|
100
|
100
|
400
|
100
|
67
|
100
|
96
|
100
|
100
|
100
|
100
|
250
|
40
|
64
|
14
|
98
|
25
|
100
|
49
|
100
|
77
|
50
|
76
|
13
|
99
|
36
|
100
|
58
|
100
|
85
|
100
|
97
|
30
|
100
|
55
|
100
|
86
|
100
|
99
|
200
|
100
|
50
|
100
|
87
|
100
|
99
|
100
|
100
|
300
|
100
|
67
|
100
|
95
|
100
|
100
|
100
|
100
|
400
|
100
|
79
|
100
|
99
|
100
|
100
|
100
|
100
|
300
|
40
|
74
|
15
|
99
|
31
|
100
|
55
|
100
|
84
|
50
|
82
|
18
|
99
|
37
|
100
|
64
|
100
|
90
|
100
|
98
|
29
|
100
|
65
|
100
|
91
|
100
|
100
|
200
|
100
|
54
|
100
|
91
|
100
|
100
|
100
|
100
|
300
|
100
|
73
|
100
|
99
|
100
|
100
|
100
|
100
|
|
400
|
100
|
85
|
100
|
100
|
100
|
100
|
100
|
100
|
- *Power below the type I error rate of 5% is possible because analyses where the estimates failed to converge are counted as failure to detect change in the harm rate.
- **The total number of records reviewed during the twelve month period is shown. Each patient record was reviewed twice during this time.
-
$Example: In this CRR scenario, 50 practices each reviewed 300 records (150 at the beginning and 150 at the end of twelve months) and had a baseline rHR of 2 incidents/100patients/year. Reductions of 50% and 20% over a twelve month period were detected with 84% (adequate) and 18% (inadequate) power respectively.
- Scenarios vary by numbers of practices reviewing records, number of records reviewed in each practice and rHR. Median rate ratios (MRR) between patients and practices are 2 and 1.2 respectively.