Value of bioimpedance analysis estimated "dry weight" in maintenance dialysis patients: a systematic review and meta-analysis

Background Volume overload is a common complication in patients with end-stage kidney disease who undergo maintenance dialysis therapy and associated with hypertension, left ventricular hypertrophy and mortality in this population. Although bioimpedance analysis (BIA), an objective method to assess overhydration, is associated with poor outcomes in observational studies, in randomized controlled trials (RCTs) the results were conflicting. We have examined the role of BIA for assessing the "dry weight" and fluid status in order to improve fluid overload in comparison with a control or clinical-based prescription in patients with ESKD receiving haemodialysis or peritoneal dialysis. Methods All RCTs and quasi-RCTs in which BIA was used to improve fluid overload and assess the effect on all-cause mortality, cardiovascular morbidity, systolic blood pressure and volume control and arterial stiffness were included. Results Seven RCTs with 1312 patients could be included in this review. In low-to-medium quality of the evidence, the use of BIA did not reduce all-cause mortality (relative risk 0.87, 95% CI 0.54-1.39) and had small to no effect on body change, but it improved systolic blood pressure control (mean difference (MD) -2.73 mmHg, 95% CI -5.00 to -0.46 mmHg) and reduce overhydration, as measured by BIA, with 0.43 L [(MD), 95% CI 0.71-0.15 L]. Conclusion In ESKD patients, BIA-based interventions for correction of overhydration have little to no effect on all-cause mortality, whereas BIA improved systolic blood pressure control. Our results should be interpreted with caution as the size and power of the included studies are low. Further studies, larger or with a longer follow-up period, should be performed to better describe the effect of BIA-based strategies on survival.