Joint Modeling of Longitudinal Measurements and Survival Time to Cardiovascular Disease Complication among Hypertensive Outpatients Treated at Debretabor Hospital, Ethiopia

The objective of the study was to identify factors that affect longitudinal outcomes and survival time to cardiovascular disease complications among hypertension outpatients. A retrospective study design was conducted on a cohort of 178 randomly selected hypertensive outpatients at Debre Tabor Hospital under a follow-up period from September 2017 to December 2019. To analyze the data, the study used three different models namely: the bivariate mixed-effects model, cox-proportional hazard model, and bivariate joint model for longitudinal and survival sub-model linked by shared random effects. The bivariate mixed-effects and a cox proportional hazards survival sub-model jointly were preferred based on the minimum Akaike Information Criterion value. The estimated values of the association parameters were 0.0655(p-value = 0.0270), and 0.963(p-value = 0.0387) that the association of systolic blood pressure, and diastolic blood pressure with time to event is guaranteed. The joint bivariate mixed-effects model analysis shows that hypertension outpatients with a family history of hypertension and clinical stage II hypertension have a high chance of developing cardiovascular disease complications and have high average systolic blood pressure and diastolic blood pressure compared to their counter groups. Hypertension outpatients with diabetes have high systolic blood pressure and diastolic blood pressure compared to their counter groups. Generally, systolic blood pressure and diastolic blood pressure became stable over the follow-up time of treatment while adherence for developed cardiovascular disease complications was statistically insignificant. Health professionals and concerned bodies should therefore focus on outpatients with comorbidity, aged and poor adherence patients to control hypertension and cardiovascular disease complications. Paying attention to treatment time to stable progression of systolic blood pressure and diastolic blood pressure of patients is also recommended.