Modeling time-to-recovery of adult diabetic patients: a comparison of cox-proportional hazard and shared gamma frailty models

Background: The chances of developing diabetic may depend on a mix of genes, lifestyle and environmental factors. The objective of this study is modeling time-to-recovery of adult diabetic patients in a comparison of Cox-proportional hazard and shared gamma frailty models. Methods: A retrospective data was obtained from Jimma University Specialized Hospital diabetic patient clinic. All diabetic patients 18 years of age and who are under treatments in between September 2010 and August 2013 are included in the study. Time of fasting blood sugar level to reach the first normal range, 70-130 mg/dl, of blood since time of treatment or intervention were the response variable. Due to the impact of residential places and unmeasured shared similarities in a cluster, district (Woreda) is used as a random effect (frailty) term in the survival models. In this study, Cox-PH and shared gamma frailty model were used. Results: Types of diabetic, bodyweight at baseline, fasting blood sugar at baseline, sex and age of patients are significantly associated with time to recovery of diabetic patients. These variables are important factors that should be considered during the selection phase a treatment (combination of treatments) for diabetes. Conclusion: The Cox-PH with shared gamma frailty model is the most powerful one in predicting recovery time of diabetic patients when there is significant difference among districts.