Patients with heart failure (HF) with both the lowest prognostic nutritional index (PNI) quartiles and hyponatremia are at an increased risk for all-cause mortality. The combination of serum sodium level and PNI category enhanced the predictive value for all-cause death in patients who are hospitalized for HF. These findings were published in the journal Nutrition, Metabolism & Cardiovascular Diseases.
A single-center, retrospective, observational study was conducted among patients admitted to the HF care unit of Fuwai Hospital in Beijing, China, between 2008 and 2018. The researchers sought to evaluate the interrelationship of nutritional status and hyponatremia (defined as a serum sodium level of <135 mmol/L) in prediction for mortality risk in patients with HF. A total of 2882 patients with HF were enrolled in the study. Participants were mean aged 56.64±15.96 years. Overall, 71.3% of the patients were men. Participants’ nutritional status was evaluated with the use of PNI, which was calculated as serum albumin (g/L) + 5 × total lymphocyte count (109/L). Lower PNI levels were indicative of worse nutritional status.
All of the participants were divided into 8 groups, according to baseline PNI quartiles (Q1: <43.60; Q2: 43.60-48.55; Q3: 48.55-63.25; Q4: >63.25) and sodium level (normal sodium level and hyponatremia). Following adjustment, participants in PNI Q1 that were associated with hyponatremia experienced a 2.12-fold higher risk for all-cause mortality (95% CI, 1.67-2.70) compared with those in PNI Q4 with normal sodium levels.
A refinement in prediction for risk was reported after adding PNI quartile and serum sodium category to the original model (ΔC-statistic=0.018, 95% CI, 0.007-0.025; net reclassification index=0.459, 95% CI, 0.371 to 0.548; integrated discrimination improvement=0.025; 95% CI, 0.018-0.032).
Limitations of the study include its single-center, retrospective, observational design, which might result in some unmeasured variables having influenced the findings. Further, since this study enrolled a wide range of patients with HF, it is unclear whether the conclusions are applicable to specific HF subpopulations.
“HF patients with the lowest PNI quartiles and hyponatremia are at higher risk of all-cause death,” the study authors wrote. “The combination of serum sodium level and PNI category enhanced the predictive value for all-cause mortality in patients hospitalized for HF.”
Disclosure: None of the study authors has declared affiliations with biotech, pharmaceutical, and/or device companies.
Zhao L, Zhao X, Tian P, et al. Prognostic utility of the prognostic nutritional index combined with serum sodium level in patients with heart failure. Nutr Metab Cardiovasc Dis. Published online April 13, 2022. doi:10.1016/j.numecd.2022.04.004