Relationship between increased interdialytic body weight and left ventricular hypertrophy in maintenance dialysis patients

Interdialytic weight gain (IDWG) has been reported to contribute to cardiovascular mortality in haemodialysis patients. In order to determine the relationship of IDWG to the pre-dialysis blood pressure and left ventricular hypertrophy, 168 patients on maintenance haemodialysis were initially evaluated. The IDWG was estimated as the current pre-dialysis weight minus the preceding post-dialytic weight and expressed as a proportion (%) of the current dry weight. Patients were divided into two groups: group I consisted of patients with a mean IDWG > 5% each month for 6 months and group II consisted of patients with a mean IDWG <5% each month for 6 months. As 51 patients had increased IDWG > 5% on more than one occasion, but fewer than six times, they were not included in the above two groups. Thus, 117 patients (33 men, 84 women) were enrolled in this study. All patients received haemodialysis three times a week, with a duration of 4.6 +/-0.5 h per dialysis session. Pre-dialysis systolic and diastolic blood pressure (SBP, DBP) and left ventricular mass index (LVMI), as determined by echocardiography, were studied regularly. The results demonstrated that the IDWG correlated significantly with age (r=-0.209, P=0.024) and solute removal index (Kt/V) (r=0.254, P=0.006), but did not correlate with pre-dialysis systolic or diastolic blood pressure. In contrast, LVMI correlated with SEP (r=0.816, P<0.001), DBP (r=0.377, P<0.001) and age (r=0.458, P<0.001). Left ventricular hypertrophy presented in 18 group I subjects (81%) and 68 group II subjects (72%) respectively (P<0.001). In conclusion, this study shows that excessive IDWG in patients maintained on haemodialysis does not correlate with pre-dialysis blood pressure, emphasizing that additional factors other than fluid volume may play a role in the control of blood pressure in uraemic patients.