Abstract:
Background: Glaucoma is a neurodegenerative condition that affects the eye and is associated
with increased intraocular pressure (IOP). IOP is the fluid pressure of the eye. IOP is carefully
regulated and disturbance often implicated in the development of pathologies such as glaucoma,
uveitis and retinal detachment. The aim of the present study was identifying factors that have
strong association with the longitudinal IOP and the survival experience (time to blindness) of
glaucoma patients attending ophthalmology clinic at FHSCH, Bahir Dar, Ethiopia using Bayesian
joint model analysis.
Methods: A longitudinal and time-to-event study with data obtained from FHSCH, glaucoma
patients enrolled in ophthalmology clinic, the measurement of IOP change approximately in every
six months and the time of an event occurring were taken. The study subjects were enrolled
between the period 1st January 2016 and 1st January 2020. A total of 328 patients, who fulfill the
inclusion criteria were selected for the study. Data were explored using basic descriptive statistics
and individual and mean profile plots over a period of study time. The censoring status of
categorical covariates was also presented. Bayesian linear mixed model for the longitudinal data
and Kaplan-Meier, Bayesian weibull proportional hazard model for the survival data analysis
were used along with their model comparison, model estimation, model diagnosis and missing
data analysis.
Results: The analysis included 328 individuals with 9 for maximum and 2 for minimum repeated
measurement of IOP change, including the baseline. From the Bayesian linear mixed model
variables like observation time, age, place of residence, gender, cup-disk ratio of patients, type of
medicine (like Pilocarpin, Timolol with Pilocarpin, Timolol with Diamox with Pilocarpin) and
blood pressure of the glaucoma patients were have an association with the IOP change over time.
But type of medicine (Diamox and Timolol with Diamox) were not affect the IOP change over time.
The Bayesian weibull PH model covariates age, blood pressure, diabetic, Pilocarpin, Timolol with
Pilocarpin, Timolol with Diamox, Timolol with Diamox with Pilocarpin, medium treatment
duration, long treatment duration and advanced stage of glaucoma of patients significantly
determines the hazard function. Bayesian weibull PH model is selected the appropriate parametric
model. Bayesian joint analysis answers question that cannot be possible by Bayesian separate
models