Evaluating Vitamin D levels in Rheumatic Heart Disease patients and matched controls: A case-control study from Nepal

Abstract

Background: Diagnosis and treatment for Rheumatic Heart Disease (RHD) is inaccessible for many of the 33 million people in low and middle income countries living with this disease. More knowledge about risk factors and pathophysiologic mechanisms involved is needed in order to prevent disease and optimize treatment. This study investigated risk factors in a Nepalese population, with a special focus on Vitamin D deficiency because of its immunomodulatory effects.

Methods: Ninety-nine patients with confirmed RHD diagnosis and 97 matched, cardiac-healthy controls selected by echocardiography were recruited from hospitals in the Central and Western region of Nepal. Serum 25(OH)D concentrations were assessed using dried blood spots and anthropometric values measured to evaluate nutritional status. Conditional logistic regression analysis was used to define association between vitamin D deficiency and RHD.

Results: The mean age of RHD patients was 31 years (range 9-70) and for healthy controls 32 years (range 9-65), with a 4:1 female to male ratio. Vitamin D levels were lower than expected in both RDH and controls. RHD patients had lower vitamin D levels than controls with a mean s-25(OH)D concentration of 39 nmol/l (range 8.7-89.4) compared with controls 45 nmol/l (range 14.5-86.7) (p-value = 0.02). People with Vitamin D insufficiency had a higher risk (OR = 2.59; 95% CI: 1.04-6.50) of also having RHD compared to people with Vitamin D concentrations >50 nmol/l. Body mass index was significantly lower in RHD patients (22.6; 95% CI, 21.5-23.2) compared to controls (24.2; 95% CI, 23.3-25.1).

Conclusion: RHD patients in Nepal have lower Vitamin D levels and overall poor nutritional status compared to the non-RHD controls. Longitudinal studies are needed to explore the causality between RHD and vitamin D level. Future research is also recommended among Nepali general population to confirm the low level of vitamin D as reported in our control group.

Fig 1. Flowchart of inclusions and exclusions.

Fig 2. Distribution of s-25 (OH)D concentrations.

(A) Distribution of s-25(OH)D concentrations in cases and controls with mean and standard deviation. (B) Distribution of rheumatic heart disease patients and healthy controls with severe Vitamin D deficiency (<12 nmol/l), Vitamin D deficiency (12–25 nmol/l), Vitamin D insufficiency (25–50 nmol/l) and sufficient (>50 nmol/l) s-25(OH)D levels.