Substantial Discrepancy Between Fluid and Weight Loss During Acute Decompensated Heart Failure Treatment

Net fluid and weight loss are used ubiquitously to monitor diuretic response in acute decompensated heart failure research and patient care. However, the performance of these metrics has never been evaluated critically. The weight and volume of aqueous fluids such as urine should be correlated nearly perfectly and with very good agreement. As a result, significant discrepancy between fluid and weight loss during the treatment of acute decompensated heart failure would indicate measurement error in 1 or both of the parameters.

The correlation and agreement (Bland-Altman method) between diuretic-induced fluid and weight loss were examined in 3 acute decompensated heart failure trials and cohorts: (1) Diuretic Optimization Strategies Evaluation (DOSE) (n = 254); (2) Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) (n = 348); and (3) Penn (n = 486).

The correlation between fluid and weight loss was modest (DOSE r = 0.55; ESCAPE r = 0.48; Penn r = 0.51; P < .001 for all), and the 95% limits of agreement were wide (DOSE -7.9 to 6.4 kg-L; ESCAPE -11.6 to 7.5 kg-L; Penn -14.5 to 11.3 kg-L). The median relative disagreement ranged from ±47.0% to 63.5%. A bias toward greater fluid than weight loss was found across populations (-0.74 to -2.1 kg-L, P ≤ .002). A consistent pattern of baseline characteristics or in-hospital treatment parameters that could identify patients at risk of discordant fluid and weight loss was not found.

Considerable discrepancy between fluid balance and weight loss is common in patients treated for acute decompensated heart failure. Awareness of the limitations inherent to these commonly used metrics and efforts to develop more reliable measures of diuresis are critical for both patient care and research in acute decompensated heart failure.