Table 3.
ITT analysis of anaemia prevalence by main effect and for each individual intervention at 4, 9, 16 and 21 months after intervention
| n/N (%) | OR (95% CI) | p value | ||
|---|---|---|---|---|
| Survey A, 2015, 4 months after intervention | ||||
| Main effect comparison (factorial analysis) | ||||
| No PBO LLIN* | 28/664 (4%) | 1 (ref) | .. | |
| PBO LLIN† | 15/675 (2%) | 0·39 (0·11–1·30) | 0·1221 | |
| No IRS‡ | 23/665 (3%) | 1 (ref) | .. | |
| IRS§ | 20/674 (3%) | 0·69 (0·24–1·98) | 0·4792 | |
| Interaction coefficient | .. | 1·75 (0·37–8·14) | 0·4696 | |
| Individual group comparison | ||||
| Standard LLIN | 16/320 (5%) | 1 (ref) | .. | |
| PBO LLIN | 7/345 (2%) | 0·39 (0·11–1·30) | 0·1221 | |
| Standard LLIN plus IRS | 12/344 (3%) | 0·69 (0·24–1·98) | 0·4792 | |
| PBO LLIN plus IRS | 8/330 (2%) | 0·47 (0·18–1·25) | 0·1268 | |
| Survey B, 2015, 9 months after intervention | ||||
| Main effect comparison (factorial analysis) | ||||
| No PBO LLIN* | 20/580 (3%) | 1 (ref) | .. | |
| PBO LLIN† | 13/603 (2%) | 0·31 (0·11–0·88) | 0·0292 | |
| No IRS‡ | 23/584 (4%) | 1 (ref) | .. | |
| IRS§ | 10/599 (2%) | 0·16 (0·04–0·69) | 0·0149 | |
| Interaction coefficient | .. | 7·51 (1·09–51·69) | 0·0408 | |
| Individual group comparison | ||||
| Standard LLIN | 17/281 (6%) | 1 (ref) | .. | |
| PBO LLIN | 6/303 (2%) | 0·31 (0·11–0·88) | 0·0292 | |
| Standard LLIN plus IRS | 3/299 (1%) | 0·16 (0·04–0·69) | 0·0149 | |
| PBO LLIN plus IRS | 7/300 (2%) | 0·37 (0·11–1·22) | 0·1004 | |
| Survey C, 2016, 16 months after intervention | ||||
| Main effect comparison (factorial analysis) | ||||
| No PBO LLIN* | 20/577 (3%) | 1 (ref) | .. | |
| PBO LLIN† | 7/574 (1%) | 0·23 (0·08–0·65) | 0·0068 | |
| No IRS‡ | 20/571 (4%) | 1 (ref) | .. | |
| IRS§ | 7/580 (1%) | 0·22 (0·08–0·64) | 0·0064 | |
| Interaction coefficient | .. | 3·46 (0·48–24·80) | 0·2108 | |
| Individual group comparison | ||||
| Standard LLIN | 16/279 (6%) | 1 (ref) | .. | |
| PBO LLIN | 4/292 (1%) | 0·23 (0·08–0·65) | 0·0068 | |
| Standard LLIN plus IRS | 4/298 (1%) | 0·22 (0·08–0·64) | 0·0064 | |
| PBO LLIN plus IRS | 3/282 (1%) | 0·18 (0·05–0·84) | 0·0301 | |
| Survey D, 2016, 21 months after intervention | ||||
| Main effect comparison (factorial analysis) | ||||
| No PBO LLIN* | 19/586 (3%) | 1 (ref) | .. | |
| PBO LLIN† | 24/582 (4%) | 1·67 (0·49–5·75) | 0·4080 | |
| No IRS‡ | 19/564 (3%) | 1 (ref) | .. | |
| IRS§ | 24/604 (4%) | 1·55 (0·36–6·58) | 0·5468 | |
| Interaction coefficient | .. | 0·63 (0·12–3·43) | 0·5881 | |
| Individual group comparison | ||||
| Standard LLIN | 7/276 (3%) | 1 (ref) | .. | |
| PBO LLIN | 12/288 (4%) | 1·67 (0·49–5·75) | 0·4080 | |
| Standard LLIN plus IRS | 12/310 (4%) | 1·55 (0·36–6·58) | 0·5468 | |
| PBO LLIN plus IRS | 12/294 (4%) | 1·64 (0·47–5·65) | 0·4287 | |
ORs for the factorial analysis compared the two main intervention effects (no PBO LLIN vs PBO LLIN, and no IRS vs IRS) and their interaction, and compared each of the intervention to the standard LLIN in the individual group analysis. OR was unadjusted for baseline anaemia prevalence. Prevalence of moderate-to-severe anaemia reported in children younger than 5 years with haemoglobin concentrations <8 g/dL. OR=odds ratio. LLIN=long-lasting insecticidal net. PBO=piperonyl butoxide. IRS=indoor residual spraying. ITT=intention to treat.
Standard LLIN and standard LLIN plus IRS.
PBO LLIN and PBO LLIN plus IRS.
Standard LLIN and PBO LLIN.
Standard LLIN plus IRS and PBO LLIN plus IRS.