Table 2. - Estimate of the number of contacts to receive chemoprophylaxis needed to prevent one case of leprosy (NNT) among contacts.
| Study: Author, year of first publication, references | Estimate of baseline risk (%) in contacts controls | Estimate of risk in intervention group | Years of follow-up | Estimate of NNT2 |
|---|---|---|---|---|
| Moet, 2008 24 | 1-2 years: 67 cases in 10,006 = 0.66% | 1-2 years 29 in 9951 = 0.29% | 2 | 2653 |
| Neelan, 1983 25 | 42 cases in 351 = 12.0% | 22/358 = 6.1% | 3 1/2 | 17 |
| Noordeen, 1976 29 | "non-lepromatous" 109/1000 = 10.9% "lepromatous" 38/319 = 11.9% | 72/1000 = 7.2% 53/636 = 8.3% | 31/2 5 | 27 27 |
| Dharmendra, 1967 10 | 2nd survey1 41/316 = 13% | 19/316 = 6% | 3 1/2 | 14 |
| Neelan, 1986 26 | 30/280 = 10.7 % | 13/280 = 4.6% | ~ 4.2 | 16 |
| Wardekar, 1967 49 | 119/11697 = 1.01% | 43/11676 = 0.37% | 2 | 154 |
Note 1: There is a report with results for the 3rd survey with 5 1/2 years28, but because the amount of missing data, it was chosen to use data from the 2nd survey; 2 the NNT was calculated as 1 ÷ (incidence proportion in control - incidence proportion in intervention); 3 as in the reference.