Table 4. Comparison of post-treatment vivax incidence rate by risk factor.

	Risk present					Risk absent
	P. vivax relapse		No P. vivax relapse		Incidence rate/1000/30days	P. vivax relapse		No P. vivax relapse		Incidence rate/1000/30days
Risk factor	no.	days of follow-up	no.	days of follow-up		no.	days of follow-up	no.	days of follow-up		Incidence Rate Ratio	95%CI	p value
Male gender	50	1378	125	4662	248	9	244	59	2016	119	2.08	1.01, 4.81	0.03
History of malaria in previous 12 mos	32	881	68	2338	298	27	741	115	4298	161	1.86	1.08, 3.22	0.02
Duration of symptoms >3 days	25	728	55	1946	280	34	894	129	4732	181	1.55	0.88, 2.67	0.10
Baseline parasitemia (/µl) <10 K	35	937	93	3248	251	24	685	91	3430	175	1.43	0.83, 2.52	0.17
Baseline parasitemia (/µl) >50 K	3	77	24	952	87	56	1545	160	5726	231	0.38	0.08, 1.16	0.07
Fever (T>37.9°C)	31	804	104	3822	201	28	818	80	2856	229	0.88	0.51, 1.52	0.62
Anemia (Hct<30%)	4	133	10	336	256	55	1489	174	6324	211	1.21	0.32, 3.29	0.67
Baseline platelet count <150 K	14	413	80	3360	111	10	294	18	756	286	0.39	0.16, 0.98	0.03
Abnormal ALT (>40 U/L)	3	70	19	798	104	24	749	88	3696	162	0.64	0.12, 2.11	0.49
Gametocytes on admit	23	609	20	686	533	36	1013	164	5992	154	3.46	1.96, 5.99	<0.001
Gametocytes on admit by PCR*	16	469	13	546	473	11	350	96	4032	75	6.28	2.74, 15.0	<0.001
Gametocytes on day 14	14	364	13	420	536	44	1223	171	6258	176	3.04	1.54, 5.64	0.001
Gametocytes anytime during follow up	39	1071	37	1260	502	20	551	147	5418	101	4.99	2.84, 9.04	<0.001
Parasite clearance time ≥72 hrs	25	707	100	3766	168	34	915	84	2912	267	0.63	0.36, 1.09	0.08
Fever clearance time >24 hrs	14	378	74	2716	136	45	1244	109	3934	261	0.52	0.26, 0.97	0.03
Bioassay positive*,**	2	77	6	252	182	25	742	103	4326	148	1.23	0.14, 4.94	0.72

*Data only available for ARC2 patients (Pv n = 27, no Pv n = 109).

**Antimalarial activity of sera against P. falciparum lab strains in a previously published ex-vivo bioassay, used as a surrogate measure of prior use of antimalarial drugs [15].