Statistical analysis of factors associated with duration of exclusive breast feeding in Ethiopia: a comparison of cox ph and shared frailty models

Abstract

Exclusive breastfeeding during the early months of life reduce infant morbidity and mortality. Current recommendation in Ethiopia is to continue exclusive breastfeeding up to six months of age. Objective: The main objective of this paper was to model duration of exclusive breastfeeding by using Cox PH and shared frailty models. Methods: The data was obtained from the EDHS, 2011.The study sample (n = 1371) was based on infants (0–6 months old) during the survey period; extracted from the women data base. The analysis was done by using ordinary Cox's PH model, Cox PH with gamma frailty and Gaussian frailty models with the help of R statistical package. These models were compared by using AIC. Results: Two-thirds (63.96%) of children were introduced with liquid and solid food supplements and breast feeding becomes partial before and at six months of age. The estimated median time for infants to introduce breast milk substitute is five months with 95% CI (4, 5.3) months. The variance of the frailty term for Cox PH with gamma frailty model was 0.281 which was significant. Conclusion: The cox proportional hazard with gamma frailty model provides a suitable choice for modeling duration of exclusive breastfeeding. Place of residence, economic status (wealth index), contraceptive use, education level have significant influence on duration exclusive breastfeeding. There is regional variation in duration of exclusive breast feeding. Key words: Breast feeding, Cox PH, EBF, hazard ratio, frailty, Time-to-event analysis.