Association of Serum Vitamin D Levels With the Severity of Chronic Heart Failure: A Retrospective Study.

Background Chronic heart failure (CHF) is a leading cause of morbidity and mortality worldwide. Although vitamin D insufficiency has been implicated in its pathophysiology, its association with CHF severity remains uncertain. Therefore, this study primarily evaluated the association between serum vitamin D levels and CHF severity in hospitalized adults. Secondary analyses assessed the relationship with left ventricular ejection fraction, factors associated with severe CHF, and selected in-hospital outcomes. Methods This retrospective study included 276 patients with chronic heart failure managed at a tertiary care hospital in Pakistan. Demographic, clinical, laboratory, and echocardiographic data were retrieved from patients' medical records. Based on the New York Heart Association (NYHA) functional classification, patients were categorized into severe (Class III-IV) and non-severe (Class I-II) heart failure groups. Statistical analyses were carried out. Continuous variables were compared using the independent-samples t-test, categorical variables using the chi-square test, and the association between serum vitamin D levels and left ventricular ejection fraction (LVEF) was assessed using Pearson correlation analysis. Univariate and multivariable logistic regression analyses were performed to identify independent predictors of severe chronic heart failure. Results Among the 276 patients, 168 (60.86%) had severe CHF and 108 (39.14%) had non-severe CHF. The mean ± standard deviation (SD) age was 63.52 ± 11.24 years, the mean serum vitamin D concentration was 21.16 ± 8.12 ng/mL, and the mean LVEF was 38.54 ± 9.82%. Overall, 208 (75.36%) patients had vitamin D insufficiency. Patients with severe CHF had significantly lower serum vitamin D levels and LVEF than those with non-severe CHF (p<0.001). Serum vitamin D levels demonstrated a moderate positive correlation with LVEF (r=0.48, 95% CI: 0.38-0.57; p<0.001). After multivariable adjustment, vitamin D insufficiency was the strongest independent predictor of severe CHF (adjusted odds ratio [AOR] 3.36, 95% CI: 1.88-6.02; p<0.001), while previous ischemic heart disease (AOR 1.81, 95% CI: 1.01-3.23; p=0.045) and diabetes mellitus (AOR 1.92, 95% CI: 1.08-3.42; p=0.026) also remained significant independent predictors. Patients with vitamin D insufficiency had significantly longer hospital stays, higher coronary care unit admission rates, and greater in-hospital mortality than those with normal vitamin D levels (p<0.05). Conclusions Lower serum vitamin D levels were significantly associated with increased chronic heart failure severity. Vitamin D insufficiency was highly prevalent and emerged as the strongest independent predictor of severe heart failure, while diabetes mellitus and previous ischemic heart disease were also independent predictors. Furthermore, vitamin D insufficiency was associated with poorer in-hospital outcomes. Assessment of vitamin D status may complement conventional clinical and echocardiographic evaluation for risk stratification in patients with chronic heart failure.