Abstract:
Background: Hypertension is a chronic disease that has a major health problem over the centuries
due to its significant contribution to the global health burden. According to World Health
Organization, hypertension is the seventh leading cause of death in Ethiopia and it ranks as one of
the first causes of cardiovascular related mortality.
Objective: The main objective of this study is to explore possible modeling approaches of time-togood control of hypertension using Cox proportional hazard and frailty models, using data from
Bahir-Dar Felege Hiwet Referral Hospital.
Methods: An institutional-based retrospective cohort study was conducted in June 2014. The study
population consists of all hypertensive patients measured repeatedly at least three times with a three
month follow up between1st January, 2009 to last December, 2013. Five hundred patients were
selected using simple random sampling. The data were collected by trained data collectors using
check list. SPSS version 16 and R software were used for data entry and processing of the data,
respectively. First, single covariate analysis was done using Cox proportional hazard and univariate
frailty models. Then all variables that are significant were included in the multi-variable analysis.
Results: The median survival time of hypertensive patients to attain good control is 48 months and
the mean survival time is 43.6 months. Age and systolic blood pressure of patients have a negative
relationship with outcome variable. However, fasting blood sugar has positive relationship with the
outcome the variable. Moreover, the result showed that, the progression of outcome depends on
patient’s baseline socio-demographical characteristic such as age.
Conclusion: Cox proportional hazard based analysis reveled that the major factors that affect good
control of hypertensive patients are age, systolic blood pressure, fasting blood sugar and creatinine.
The result of univariate frailty analysis showed that there is unobserved heterogeneity between
individuals in the study set-up, which indicates, there are unmeasured covariates. the clinicians
should have give an attention to the younger age and lower systolic blood pressure group to
attain good control of hypertension earlier like that of older age and higher systolic blood
pressure groups.
