Intraluminal thrombus effect on the progression of abdominal aortic aneurysms by using a multistate continuous-time Markov chain model

Abstract

AbstractObjectiveRecent studies reported the intraluminal thrombus (ILT) among others strongly affects abdominal aortic aneurysms (AAA) expansion rates. Thus, we investigate characteristics of ILT with AAA expansion.MethodsWe applied homogeneous multistate continuous-time Markov chain models to longitudinal data of 26 Korean AAA patients as a retrospective clinical study. We considered four states of AAA and maximal thickness of ILT (maxILT), fraction of wall area covered by ILT (areafrac) and fraction of ILT volume (volfrac) as possible covariates.ResultsBased on likelihood-ratio statistics, areafrac is the most significant biomarker and maxILT is the second most significant. Besides, within AAAs that developed an ILT layer, we found that an AAA expands relatively fast at an early stage but the rate goes slower once AAA reaches in a large size.ConclusionResults recommends surgical intervention when any patient with areafrac more than 60% or maxILT more than 30mm. Although this recommendation should be considered with caution given the limited sample size, one can use the proposed model as a tool to find such recommendations with their own data.