Table 2.

Prevalence ratios of diarrhoea (after vs before intervention) obtained by different regression models

	Total population*			Areas with high baseline risk†
	PR	95% CI	MP‡	PR	95% CI	MP‡
PR, unadjusted	0·79	0·75–0·82	..	0·58	0·55–0·61	..
Model A: PR adjusted for baseline sewerage coverage and potential confounders§	0·78	0·74–0·81	..	0·57	0·54–0.61	..
Model B: PR adjusted for variables of model A and indoor toilet, open sewage nearby, and household excreta disposal	0·81	0·78–0·86	16·7%	0·57	0·55–0·62	0·0%
Model C: PR adjusted for variables of model A and water supply, refuse collection, paving of the road, and satisfactory drainage system	0·80	0·76–0·84	10·8%	0·59	0·56–0·63	4·4%
Model D: PR adjusted for variables of model A and hygiene behaviour	0·76	0·72–0·79	0·0%	0·57	0·54–0·61	0·2%
Model E: PR adjusted for variables of model A and coverage of Bahia Azul sewerage	1·01	0·89–1·15	100·0%	1·02	0·90–1·16	100·0%

PR=prevalence ratio. MP=mediating proportion. Results of the hierarchical effect decomposition are presented as crude and adjusted prevalence ratios.

^*24 areas, 1848 children, median baseline diarrhea 4·5 days per child-year.

^†>8 diarrhoea days per child-year; 12 areas, 878 children, median baseline diarrhoea 6·0 days per child-year.

^‡MP: risk reduction explained by changes in the mediating variables included in the model (MP=[PR_adj − PR_unadj]/[(1-PR_unadj]×100; PR_unadj and PR_adj are the crude and adjusted prevalence ratios, respectively).

^§Child's mean age during the follow-up, birthweight <2·5 kg, exclusive breastfeeding till <6 months old, and height-for-age <−1 Z score; mother's age at child's birth <20 years, marital status (not married) and education (no schooling or <4th grade, or 5th to 8th grade, vs higher education); housing type (shack) and floor (dirt floor), no independent kitchen.