West Coast Ballroom
The use of segmented regression for evaluation of an interrupted time series study involving complex intervention: The CaPSAI Project Experience (306653)Victoria Boydell, Global Health Centre
Joanna Paula Cordero, The World Health Organization
*Ndema Abu Habib, The World Health Organization
James Kiarie, The World Health Organization
Dela Nai, Population Council
My Huong Nguyen, The World Health Organization
Donat Shamba, Ifakara Health Institute
Petrus S Steyn, The World Health Organization
Soe Soe Thwin, The World Health Organization
Keywords: complex intervention, quasi-experiment, interrupted time series, segmented regression, community-driven intervention, modern contraception uptake.
Interrupted time series with a parallel control group (ITS-CG) design is the most powerful quasi-experimental design for evaluation of effectiveness of community-driven complex public health interventions. Using this design, the effectiveness of a social accountability intervention on increasing uptake of modern contraception was studied. The intervention was rolled-out gradually over time to intervention communities in Ghana and Tanzania; with control communities receiving standard of care. The ITS Poisson segmented model applying a generalized estimating equations (GEE) is proposed for evaluation of the level and rate of uptake of modern contraception. Two approaches are demonstrated to account for the lag in intervention roll-out;(1) through a two-segmented ITS model; and (2) through a three-segmented ITS model. Parameters interpretation and study design strengths and limitations are highlighted. In a well-planned ITS study design with a parallel control group, the segmented regression analysis that applies advanced statistical techniques to ensure the internal validity of the results remains the preferred approach to evaluating the impact of community-based interventions.