Survival Analysis of Recurrent Events: an Application to Diabetes Mellitus Patients in The Case of Menellik li Referral Hospital
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Date
2016-06
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Addis Abeba university
Abstract
Diabetes mellitus is a group of metabolic diseases characterized by elevated blood glucose
levels (hyperglycemia) resulting from defects in insulin discharge, insulin action or both.
Recovery to normal blood sugar level in DM patients often is recurrent and correlation between
events needs to be taken into account during analysis of such data. The main objectives of this
research were to analysis time to recovery of DM patients and make a comparison between
standard Cox-proportional Hazard (PH) and Frailty models. To achieve the objectives of the study,
a retrospective data were obtained from Menellik II Referral Hospital chronic patient’s clinic. All
diabetes patients of over 15 years of age and who were under treatment between 2009 and 2015
were included in the study. Unmeasured shared similarities due to the impact of multiple events
were modeled using a random effect (Frailty) term. The Likelihood Cross Validation (LCV)
criteria were used for comparison between the Standard Cox PH and Frailty model. Shared Log-
Normal Frailty model had a minimum value of LCV than the Cox PH and shared Gamma Frailty
models. Hence, the shared log-normal Frailty model was chosen for analysis of the recurrent event
of time to recovery of DM patients in Menellik II Referral Hospital. The median recovery time of
DM patients was 32 weeks. The patient’s sex and Regimen groups at baseline were significantly
associated with recurrent event of time to recovery of DM patients.
Key Words: Recurrent events, Frailty, Gamma, Log-normal, LCV, Penalized Marginal
Likelihood
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Keywords
Recurrent Events, Frailty, Gamma, Log-Normal, LCV, Penalized Marginal Likelihood