Response to “Strengthening Causal Interpretation: Home Blood Pressure Phenotypes and Cardiovascular Remodeling in Hemodialysis”

We thank Li and Dong 1 for their thoughtful letter, "Strengthening Causal Interpretation: Home Blood Pressure Phenotypes and Cardiovascular Remodeling in Hemodialysis," regarding our article, "Home Blood Pressure Phenotypes and Cardiovascular Remodeling in Hemodialysis." 2 They raise important issues regarding causal inference, environmental stressors, genetic heterogeneity, and dialysis treatment factors.We agree that our cross-sectional design precludes determination of temporal sequence or causality.Our aim was not to prove that specific blood pressure phenotypes cause cardiovascular remodeling, but to determine whether home blood pressure-based phenotyping identifies clinically meaningful differences in structural cardiovascular burden.The use of standardized 7-day home blood pressure monitoring, objective echocardiographic and vascular assessments, and consistent findings across alternative blood pressure thresholds support the robustness of our central observation-dialysis-unit blood pressure alone may misclassify blood pressure burden, whereas home blood pressure phenotypes identify distinct remodeling patterns.We also agree that seasonality, hydration status, and thermal response may influence blood pressure and cardiovascular risk in hemodialysis.3 We attempted to reduce unstable volume-related confounding by excluding patients with poorly controlled fluid volume status, recent dry-weight or antihypertensive medication changes, symptomatic heart failure, or recent hospitalization.Interdialytic weight gain and dialysis-related covariates were also considered.