Table 5 |
||||||
|
Sample size estimates for GP Presentation Study estimating a single UK-wide pyramid. |
||||||
|
England |
Wales |
|||||
|
|
||||||
|
Organism |
Baseline incidence* |
Reduction to be detected |
Person-years |
GP practices |
Person-years |
GP practices |
|
|
||||||
|
Campylobacter |
4.10% |
20% |
115,000 |
20 |
7,000 |
2 |
|
|
||||||
|
Salmonella |
0.16% |
50% |
41,000 |
7 |
3,000 |
1 |
|
|
||||||
|
Salmonella |
0.16% |
40% |
67,000 |
12 |
4,000 |
1 |
|
|
||||||
|
Salmonella |
0.16% |
30% |
127,000 |
22 |
8,000 |
2 |
|
|
||||||
|
Salmonella |
0.16% |
20% |
302,000 |
51 |
18,000 |
3 |
|
|
||||||
|
C. perfringens |
0.13% |
20% |
364,000 |
61 |
22,000 |
4 |
|
|
||||||
|
Scotland |
Northern Ireland |
UK |
||||
|
|
||||||
|
Organism |
Person-years |
GP practices |
Person-years |
GP practices |
Person-years |
GP practices |
|
|
||||||
|
Campylobacter |
12,000 |
2 |
4,000 |
1 |
138,000 |
25 |
|
|
||||||
|
Salmonella |
5,000 |
1 |
2,000 |
1 |
51,000 |
10 |
|
|
||||||
|
Salmonella |
7,000 |
2 |
3,500 |
1 |
81,500 |
16 |
|
|
||||||
|
Salmonella |
13,000 |
3 |
4,500 |
1 |
152,500 |
28 |
|
|
||||||
|
Salmonella |
31,000 |
6 |
10,500 |
2 |
361,500 |
62 |
|
|
||||||
|
C. perfringens |
38,000 |
7 |
13,000 |
3 |
434,500 |
75 |
|
|
||||||
|
* Incidence of GP presentation in original IID study Note: Based on the ability to detect at least a 20% reduction in incidence with 90% power and 95% precision. Required number of person-years and GP practices (assuming an average GP practice size of 6,000 patients) by country, based on the relative populations of the 4 countries. |
||||||
|
O'Brien et al. BMC Medical Research Methodology 2010 10:39 doi:10.1186/1471-2288-10-39 |
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