POS-251 THE PREVALENCE, PATTERN AND PREDICTORS OF HYPOVITAMINOSIS D IN PATIENTS WITH CHRONIC KIDNEY DISEASE: A STUDY IN A TERTIARY HOSPITAL IN NIGERIA

Abstract

Hypovitaminosis D is associated with the progression of chronic kidney disease (CKD) and its complications, particularly the cardiovascular events. Studies about the pattern of occurrence of hypovitaminosis D and its relationship with other characteristics among patients with CKD in Nigeria is required to inform optimal care and improve outcomes. In this study, we determined the prevalence of hypovitaminosis D and its relationship with kidney function and markers of cardiovascular disease. This was a hospital-based cross-sectional study of 135 patients with CKD and 135 age- and sex-matched control participants. Clinical history, blood pressure and anthropometric measurements were documented using standard procedures. CKD was defined as estimated glomerular filtration rate (GFR) of < 60 ml/min/1.73m2 and/or persistent albuminuria (urine albumin excretion rate [AER] ≥ 30 mg/24 hours or urinary albumin-creatinine ratio (uACR) of ≥ 30mg/g) for ≥ 3 months. Estimated GFR was calculated using the CKD-EPI equation and patients were stratified into the stages of CKD accordingly. Serum vitamin D was measured and the study participants’ vitamin D status was categorized as; optimal, insufficiency, mild and severe deficiency based on its levels (NKF/KDOQI guidelines). Urinary albumin-creatinine ratio (uACR) and other laboratory parameters were assayed and echocardiography was conducted to document the left ventricular mass index (LVMI) and ejection fraction. We assessed the relationship between vitamin D and socio-demographic, clinical and laboratory parameters by Pearson’s correlation analysis and determined independent predictors of hypovitaminosis D by multivariate linear regression. The prevalence of hypovitaminosis D amongst the patients was 82.2% (48.1% had vitamin D insufficiency, 28.1% mild deficiency and 5.9% with severe deficiency) compared to 45.2% in the control participants (p value < 0.001). Serum vitamin D correlated inversely with LVMI (r= - 0.555, p value < 0.001), uACR (r = -0.367, p value < 0.001) and systolic blood pressure (r = -0.244, p value = 0.004); and positively with eGFR (r = 0.354, p value < 0.001). The major predictors of hypovitaminosis D were; eGFR (strongest), uACR, and the LVMI with an overall coefficient of determination (R2) of 0.391, p = 0.001. Hypovitaminosis D is significantly higher amongst patients with CKD compared with age- and sex-matched control participants in our centre and the predictors were eGFR (strongest), LVMI and uACR. Larger studies are required to determine the role of vitamin D on cardiovascular (CV) outcomes in these patients.