Absolute interdialytic weight gain is more important than percent weight gain for intradialytic hypotension in heavy patients

AIM: Few published reports have mentioned the difference between absolute interdialytic weight gain (IDWG) and IDWG/DW (IDWG%), and subsequent effects on daily dialysis. The aim of present study was to evaluate the difference between absolute IDWG and IDWG% in new haemodialysis patients. METHOD: We retrospectively reviewed the records of 255 patients who recently received conventional haemodialysis for at least 1 year at the same centre from 1997 to 2008. The first 4 weeks after starting haemodialysis was defined as the pre-study period. Data were collected for 5-56 weeks. RESULTS: IDWG% value remained relatively constant in the first year of haemodialysis despite most patients having certain residual renal function. For haemodialysis outcomes, both absolute IDWG and IDWG% were significantly correlated with intradialytic hypotension (IDH) in men and heavy women. After dividing patients into four strata, which according to the gender and the median dry weight, stepwise multivariate linear regression analysis showed that absolute IDWG, rather than IDWG%, was an independent risk factor for IDH in heavy men (Beta = 0.585, P < 0.001) and heavy women (Beta= 0.458, P < 0.001). CONCLUSIONS: Absolute IDWG, rather than IDWG%, is an independent risk factor for IDH in heavy haemodialysis patients. Therefore, higher absolute IDWG needs to be strictly controlled despite the corresponding IDWG% possibly being relatively small in heavy haemodialysis patients.