Table 1 |
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|
Illustrating how the "Intention to treat" approach ascribing indeterminate treatment outcomes as failures overestimates the true failure rate. High failure rate: |
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| Follow-up |
A (%) |
R = F(%) |
FITT (%) |
Overestimation of failure rate (%) |
|
|
||||
| 6 weeks |
6 |
15 |
15.3 |
2% |
| 8 weeks |
20 |
25 |
26 |
4% |
| 10 weeks |
45 |
25 |
27.25 |
9% |
| 12 weeks |
68 |
25 |
28.4 |
14% |
| 20 weeks |
75 |
25 |
28.75 |
15% |
|
|
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|
Assume that the entomological inoculation rate is 1/month (Figure 4), the true failure rate (F) is 25%, and 5% of PCR pairs are indeterminate. The patients are censored when a recurrent infection occurs. Then at 4 weeks follow-up in the trial, the recurrence rate = 3.5% (2.5% true recrudescence, 1% true recurrence) True failure rate = 2.5%, ITT analysis failure rate = 2.55%, overestimation 1.275%. FITT (%) = A + 0.05 R A – cumulative probability of developing a patent new infection R – cumulative probability of developing a patent recrudescence |
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|
Stepniewska and White Malaria Journal 2006 5:127 doi:10.1186/1475-2875-5-127 |
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