Table 3.

 Effect of rifampicin prophylaxis in contacts of patients with newly diagnosed leprosy by variable category at two years’ follow-up

Variable	Follow-up at two years
	Placebo			Rifampicin		Odds ratio (95% CI)*	P value	NNT†
	No leprosy	Leprosy		No leprosy	Leprosy
Age (years):
5-9	1552	5		1608	4	0.77 (0.21 to 2.87)	0.6992	1370
10-14	1645	12		1616	2	0.17 (0.04 to 0.76)	0.0205	167
15-19	1107	7		1042	5	0.76 (0.24 to 2.39)	0.6372	663
20-29	1705	10		1688	1	0.10 (0.01 to 0.79)	0.0285	191
≥30	3962	33		4011	17	0.51 (0.28 to 0.91)	0.0237	248
Genetic distance to index patient:
Closely related‡	1585	18		1507	13	0.76 (0.35 to 1.65)	0.4862	374
Not closely related§	8386	49		8458	16	0.32 (0.18 to 0.57)	<0.0001	251
Male	4658	37		4660	17	0.46 (0.26 to 0.82)	0.0088	247
Female	5313	30		5305	12	0.40 (0.20 to 0.82)	0.0120	298
Type of disease in index patient:
Multibacillary	2846	21		2626	10	0.52 (0.22 to 1.19)	0.1201	283
Paucibacillary with 2-5 lesions	3133	22		3408	9	0.38 (0.16 to 0.87)	0.0218	230
Single lesion paucibacillary	3992	24		3931	10	0.42 (0.20 to 0.89)	0.0233	291
BCG scar absent	5878	52		5917	22	0.42 (0.26 to 0.69)	0.0007	197
BCG scar present	4023	15		3962	7	0.47 (0.18 to 1.26)	0.1342	513
Physical distance:
Shares house and kitchen	912	13		924	6	0.46 (0.15 to 1.38)	0.1652	132
Shares kitchen only	730	5		705	7	1.45 (0.38 to 5.52)	0.5863	NA
Shares house plus is next door neighbour	2770	17		2544	8	0.51 (0.22 to 1.19)	0.1208	337
Neighbour of neighbour plus social contact	5559	32		5792	8	0.24 (0.11 to 0.52)	0.0003	230
Negative ELISA result¶	8054	52		8115	22	0.42 (0.25 to 0.70)	0.0009	269
Positive ELISA result**	511	4		492	2	0.52 (0.08 to 3.25)	0.4834	269

ELISA=enzyme linked immunosorbent assay.

*Odds ratio for leprosy in rifampicin group versus placebo group.

†Number needed to treat to prevent one case of leprosy.

‡Parent, child, or sibling.

§Other than parent, child, or sibling.

¶Optical density <0.2.

**Optical density ≥0.2.