Evaluating the effectiveness of IPTi on malaria using routine health information from sentinel health centres in southern Tanzania

Table 3 Incidence of first or only episode of mild and severe anaemia, and incidence of anaemia in all time at risk, and within 28 days of IPTi dose one

	Intervention Area			Comparison Area			Effect
Intention to treat *	Events	PYAR	Rate	Events	PYAR	Rate	RR (95% CI)	p value	PE (95% CI)
Mild anaemia incidence (first or only)
Crude	1268	1771.8	0.716	1170	1689.7	0.694	1.03 (0.95-1.12)	0.424	-3% (-12%,5%)
adjusted ^‡							1.13 (0.65-1.97)	0.597	-13% (-97%,35%)
Severe anaemia incidence (first or only)
crude	318	2046.8	0.155	206	1944.1	0.106	1.47 (1.23-1.75)	< 0.001	-47% (-75%,-23%)
adjusted ^‡							1.59 (0.54-4.68)	0.360	-59% (-368%,46%)
	IPTi Intervention Area			Corresponding EPI vaccine Comparison Area			Effect
Per protocol **	Events	PYAR	Rate	Events	PYAR	Rate	RR (95% CI)	p value	PE (95% CI)
Mild anaemia incidence (first or only) in ATAR since IPTi dose
IPTi dose 1
crude	289	543.8	0.531	257	455.6	0.564	0.93 (0.78-1.10)	0.383	7% (-10%,22%)
adjusted ^‡							1.04 (0.58-1.87)	0.878	-4% (-87%,42%)
Severe anaemia incidence (first or only) in ATAR since IPTi dose
IPTi dose 1
crude	65	615.2	0.106	26	518.3	0.050	2.10 (1.34-3.32)	0.001	-110% (-232%,-34%)
adjusted ^‡							2.12 (0.41-11.03)	0.277	-112% (-1000%,59%)
Mild anaemia incidence (first or only) within 28 days of IPTi dose
IPTi dose 1
crude	45	93.8	0.480	31	80.5	0.385	1.25 (0.79-1.97)	0.343	-25% (-97%,21%)
adjusted ^‡							1.30 (0.42-4.07)	0.579	-30% (-307%,58%)
Severe anaemia incidence (first or only) within 28 days of IPTi dose
IPTi dose 1
crude	4	95.1	0.042	2	81.4	0.025	1.71 (0.31-9.35)	0.530	-71% (-835%,69%)
adjusted ^‡							1.57 (0.11-22.93)	0.700	-57% (-2190%,89%)

* Intention to treat analyses comparing IPTi intervention and comparison areas
** Per protocol analyses comparing children who received IPTi in intervention areas to those that received corresponding EPI vaccines in comparison areas
EPI = expanded programme on immunization, PAYR = person years at risk, ATAR = all time at risk, RR = rate ratio,
CI = confidence interval, PE = protective efficacy,
Hb = haemoglobin
^‡ Using intervention and comparison area mean rate, unpaired t test p value and approximate 95% CI that adjust for clustering by health centre

ISSN: 1475-2875