Abstract 21551: Loop Diuretics Impair the Assessment of Sodium Intake in Patients With Heart Failure
Introduction: The measurement of sodium intake in heart failure (HF) patients is necessary in both clinical and research settings. Twenty-four hour urine collections are considered the gold standard for sodium intake assessment. Whether a diagnosis of HF or the use of loop diuretic (LD) therapy for HF compromises the validity of 24-hour urine collections as a surrogate marker for sodium intake is unknown.
Objective: To determine the strength of association and limits of agreement between 24-hour urine collections and food records for sodium intake assessment in non-HF cardiac patients, and in patients with HF stratified by LD usage.
Methods: Patients simultaneously completed weighted food records and 24 hour urine collections for two consecutive days. Correlation coefficients and the Bland-Altman method of agreement were used to describe the relationship between the two assessment techniques.
Results: Cardiac controls (n=96, 65±11 years) and HF patients not taking LD (n=47, 62±11 years) and HF patients taking LD (n=62, 60±11 years) had a reported mean sodium intake of 2721±1180 mg, 2728±1342 mg, 2498±967 mg, respectively. There was a significant correlation between sodium assessed by urine collections and food records for cardiac controls (r=0.624, p<0.001) and for HF patients not taking LD (r=0.678, p<0.001). However, there was no significant association between methods for HF patients taking LD (r=0.132, p=0.312), and compared to the cardiac controls, the mean difference between methods in sodium intake estimation was significantly higher in this group (762±1535 mg, p<0.05). The Bland-Altman 95% limits of agreement were similar between the cardiac controls and the group of HF patients not taking LD, while the limits of agreement for the HF patients taking LD was much wider.
Conclusions: Twenty-four hour urine collections agree well with food records for assessing sodium intake in non-HF patients with cardiovascular disease and in HF patients not taking LD therapy. However, once HF patients are prescribed LD this agreement is lost, suggesting that food records may provide a better estimate of sodium intake in these patients.
- © 2010 by American Heart Association, Inc.