Factors Associated with Interdialytic Weight Gain and Its Percentage: Are 2 Metrics Interchangeable?

Background: Interdialytic weight gain (IDWG) is a key indicator of fluid management in hemodialysis patients. Greater IDWG reflects nonadherence to fluid restriction, excessive salt intake, and has been associated with reduced quality of life, increased volume overload, hospitalizations, mortality, and rising healthcare costs. While both absolute IDWG and relative IDWG% are used, this study aims to investigate the factors associated with interdialytic weight gain and its percentage, as well as to assess whether these 2 indicators can be used interchangeably in evaluating fluid management among mainte nance hemodialysis patients. Methods: This prospective observational study included 121 stable maintenance hemodialysis patients from a tertiary hospital. Separate multivariable linear regression analyses were performed for absolute IDWG and IDWG%, using the same set of independent and potentially confounding variables in both models. Results: The only independent factor associated with both IDWG and IDWG% was systolic blood pressure (P = .010 and .026, respectively). Sex (P = .002), age (P = .012), and diabetes mellitus (P = .020) were independently associated with IDWG, whereas dialysis vintage (P = .040), erythropoiesis resistance index (P = .021), and Δ sodium (P = .017) were associated with IDWG%. Conclusion: This study clarifies that absolute IDWG and IDWG% reflect different clinical aspects and may not be completely interchangeable, but rather complementary in the assessment of clinical fluid management. A dual-measure approach may provide a more effective and comprehensive evaluation and avoid misclassification of fluid status in maintenance hemodialysis patients. Cite this article as: Nguyen DM. Factors associated with interdialytic weight gain and its percentage: are 2 metrics interchangeable? Turk J Nephrol. 2026;35(1):55-61.