Salim Abdulla|Joanna Schellenberg|Oscar Mukasa|Christian Lengeler
Usefulness of a dispensary-based case-control study for assessing morbidity impact of a treated net programme
Ifakara Health Institute
casecontrol studies proposed appropriate tool health impact evaluation insecticidetreated nets itn programmesa dispensarybased casecontrol study carried one village tanzania case fever parasitaemia child 5 years paired one community one dispensary control without fever parasitaemia cases controls compared regard itn ownership factors assessed questionnaire crosssectional survey factors associated parasitaemia including itn use carried study dispensary attendance rates study children calculated using passive case detection datacases dispensary controls higher dispensary attendance rates compared community controls children nets attended illness events comparison cases community controls showed strong statistically significant association untreated net use case odds ratio 21 95 ci 1334 itn smaller weaker association risk case itn use 14 95 ci 0922 comparison cases dispensary controls showed association untreated treated nets risk case treated nets 09 95 ci 0514 untreated nets 12 95 ci 0720 results contrary crosssectional assessment children itn lower prevalence parasitaemia nets 05 95 ci 0309 also contrary assessments health impact itn populationthe positive association mild malaria net ownership counterintuitive best explained attendance bias since children nets attended frequently curative preventive services dispensary without nets dispensarybased casecontrol studies may appropriate assessing impact treated nets clinical malaria crosssectional surveys might represent attractive alternative