Abstract:
Background: Multiple longitudinal responses together with time-to-event outcome are common in
biomedical studies. There are several instances where the longitudinal responses are correlated with
each other and at the same time each longitudinal response is associated with the survival outcome. The
primary goal of this study was to present and explore a bivariate joint modeling approach for the
bivariate longitudinal change of blood pressures and time to death of heart failure patients at Felege
Hiwot Referral Hospital.
Methods: A retrospective study design was used to collect relevant data on heart failure patients from the
medical charts of 245 cases. A joint bivariate linear mixed-effects model and Weibull model were used for
longitudinal and survival data respectively, to identify factors that jointly affect blood pressure and time
to death of heart failure patients. The longitudinal model and the survival model were linked by random
intercept and random slope association parameters.
Results: The DBP change was significantly associated with the death of heart failure patients (
; 95% CI: -2.09022, -0.0645; p-value=0.042 and ; 95% CI: -0.1600, -0.0672; p value=0.000). The analysis also showed that patients with 40%< Ejection fraction<50 % ( ;
95% CI: -1.7865, -0.9676; p-value=0.000), Ejection fraction>=50 %( ; 95CI: -0.8995, -
0.5528; p-value=0.000), used spironolactone treatment and high PR were significantly lowering the
death of heart failure patients. Patients with age 46-55, 56-65, 66 and above, dilated cardiomyopathy
( ; 95% CI: 0.7203, 1.1254; p-value=0.000), Anemia, diabetic mellitus, chronic kidney
disease, pneumonia, lower sodium, high Creatinine, New York Heart Association class III and class IV
were significantly increased the death of heart failure patients. Similarly age group 56-65, 66 and above,
sodium, Creatinine, pneumonia, Digoxin, Spironolactone were significantly lowering the DBP of patients
also patients with 40 %< Ejection fraction<50%, hypertensive heart disease and platelets were
significantly increased the DBP of heart failure patients.
Conclusion: from clinical perspective, patients who had older age, less Ejection fraction, dilated
cardiomyopathy, Anemia, diabetic mellitus, chronic kidney disease, pneumonia,, low sodium, high
creatinine, no take spironolactone treatment, New York Heart Association class III, New York Heart
Association class IV and high Pulse rate to experiences the death of heart failure. From methodology
perspective, a joint model approach provides wide range information about the change of bivariate
longitudinal and time to death model to provide dynamics prediction and increasing precise knowledge of
diseases.
Key words: Heart failure, Systolic blood pressure, Diastolic blood pressure, longitudinal analysis,
survival analysis, joint model, MCMC method