Prevalence and risk factors for hypertensive retinopathy at Moi Teaching and Referral Hospital, Eldoret, Kenya

Abstract

Background: Hypertensive retinopathy (HTNR) is a recognized complication of hypertension. Early diagnosis is crucial for the mitigation of more severe complications such as retinal detachment and loss of vision by the timely institution of appropriate management strategies. In addition, HTNR findings are a useful risk stratification tool for acute coronary events and strokes, two leading causes of disability adjusted life years (DALYs) worldwide. Paucity of data exists on the prevalence and associated risk factors for HTNR in Sub Saharan Africa. Objectives: To determine the prevalence and associated risk factors for HTNR at Moi Teaching and Referral Hospital (MTRH). Methods: This was a cross-sectional study conducted among patients with hypertension attending the medical out-patient clinic at MTRH between January and April 2018. The study population included 640 patients on follow up for hypertension in this duration. Systematic random sampling was used to select 240 participants. Structured interviewer administered questionnaires were utilized to collect sociodemographic, anthropometric, clinical and laboratory data. Low density lipoproteinscholesterol (LDL-C) measurement was performed using enzymatic colorimetric method and fundoscopic examination performed using an ophthalmoscope, with all measurements taken on the same visit. Grading of HTNR was done using Mitchell- Wong classification. STATA version 15 was used for analysis and appropriate statistics used to analyse various variables in line with the study objectives. Categorical variables were summarized in frequency tables, percentages and bar graphs. Continuous variables were summarized using means, standard deviations, frequencies, medians and interquartile ranges (IQR). Medians were compared using Wilcoxon-rank sum test. Univariate and multivariate logistic regression models were used to assess associations of the variables with HTNR. Results: The median age was 59 years (IQR:52,69). The prevalence of HTNR was 23.3% (95%CI: 18.13-29.20) representing 54 participants. Of those with HTNR, 84% (47) had Grade 1, 13% (7) had Grade 2 and 3% (2) had Grade 3. Chi square p values for age (p=0.001), blood pressure control (p=0.004) and duration of hypertension (p=0.017) showed association with the occurrence of HTNR. On multiple logistic regression, age had an Odds Ratio (OR) of 1.3 (95% CI: 1.026-1.086), Stage 2 HTN had OR 3.66 (95%CI: 1.40-9.50) and duration of HTN of more than 15 years had OR 3.69 (95%CI: 1.10-12.28). Body mass index and LDL-C measurements did not show any association with HTNR. Conclusion: HTNR is a common finding in this population with its mild form (Grade 1) predominating. Longer duration after diagnosis, advanced age and uncontrolled BP were strongly associated with the occurrence of HTNR. Recommendation: Routine screening of HTNR should be part of the evaluation of patients on follow up for HTN, especially those with other additional risk factors. Prospective studies are required to further evaluate how elevated BP and risk factor control impacts prognosis of both vision and other vascular complications.