Accuracy of a rapid diagnostic test on the diagnosis of malaria infection and of malaria - attributable fever during low and high transmission season in Burkina Faso

Table 4 Attributable fractions (AF) and population attributable fractions (PAF) of fever to malaria by parasite density and age group (rainy season)

Age	Parasite density	Cases^†		Controls^‡
(years)	(/μL)	n	%^¥	n	%^¥	OR	AF	PAF
< 1	0	27	17	32	64	1
	1-400	14	9	1	2	16.6	0.94
	401-4000	40	25	9	18	5.3	0.81
	4001-40000	41	26	4	8	12.1	0.92
	40000+	37	23	4	8	11.0	0.91
	Total	159		50			0.88	0.73
1 - 4	0	111	22	88	55	1
	1-400	40	8	14	9	2.3	0.56
	401-4000	132	26	32	20	3.3	0.69
	4001-40000	100	20	21	13	3.8	0.74
	40000+	121	24	6	4	16.0	0.94
	Total	504		161			0.77	0.60
5 - 14	0	77	28	66	48	1
	1-400	34	12	31	23	0.9	0^£
	401-4000	57	21	26	19	1.9	0.47
	4001-40000	52	19	12	9	3.7	0.73
	40000+	55	20	2	1	23.6	0.96
	Total	275		137			0.59	0.43
15+	0	261	69	434	74	1
	1-400	36	10	98	17	0.6	0^£
	401-4000	36	10	36	6	1.7	0.40
	4001-40000	41	11	21	4	3.2	0.69
	40000+	5	1	1	0	8.3	0.88
	Total	379		590			0.40	0.12
All	0	476	36	620	66	NA^¶
	1-400	124	9	144	15	NA^¶	0.29
	401-4000	265	20	103	11	NA^¶	0.62
	4001-40000	234	18	58	6	NA^¶	0.76
	40000+	218	17	13	1	NA^¶	0.94
	Total	1317		938			0.69	0.44

^† Cases: with fever, axillary temperature ≥ 37.5°C at hospital visit.
^‡ Controls: without fever, axillary temperature < 37.5°C at hospital visit and no reported history of fever during the preceding 3 days.
^¥ Percentage of patients in a certain parasite density class among cases/controls.
OR: odds-ratio (of fever at each stratum of parasite density and age, versus uninfected patients); AF: attributable fraction, calculated as: ;
^¶ ORs not calculated as overall AF calculated from results by age-category.
^£ AF by definition ≥ 0.
PAF: population attributable fraction (calculated as showed in Table 3).
NA: Not applicable.

ISSN: 1475-2875