The efficacy and safety of low dialysate sodium levels for patients with maintenance haemodialysis: A systematic review and meta-analysis.

BACKGROUND & AIM: Fluid overload and hypertension frequently results in cardiovascular disease, which is one of the leading causes of death in dialysis patients. It is plausible that low dialysate [Na+] may decrease total body sodium content, thereby reducing fluid overload and hypertension, and ultimately reducing cardiovascular disease morbidity and mortality. This meta-analysis was designed to evaluate the efficacy and safety of using a low (<138 mM) dialysate [Na+] for maintenance haemodialysis (HD) patients.

METHODS

We searched the Cochrane Library, PubMed, EMBASE, Web of Science up to August 22, 2019. Randomised controlled trials (RCTs), both parallel and cross-over, of low (<138 mM) versus neutral (138-140 mM) or high (>140 mM) dialysate [Na+] for maintenance HD patients were included. Mean difference (MD), risk ratio (RR) and 95% confidence interval (CI) values were estimated to compare the outcomes. Two reviewers extracted data and assessed trial quality independently. All statistical analyses were performed using the standard statistical procedures of RevMan 5.2.

RESULTS

12 Randomised controlled trials with 390 patients were included in this meta-analysis. Of these studies, three studies were parallel group, and the remaining nine were crossover. Compared to neutral or high dialysate [Na+], low dialysate [Na+] reduced dialysis mean arterial pressure (MAP) with a pooled MD of -3.38 mmHg (95% CI -4.57 to -2.19; P < 0.00001), reduced interdialytic weight gain with a pooled MD of -0.35 kg (95% CI -0.51 to -0.18; P < 0.0001), reduced predialysis serum [Na+] with a pooled MD of -2.62 mM (95% CI -3.59 to -1.66; P < 0.00001). In contrast, low dialysate [Na+] increased intradialytic hypotension events with a pooled RR of 1.54 (95% CI 1.16 to 2.05; P = 0.003), increased the incidence of intradialytic cramps with a pooled RR of 1.77 (95% CI 1.15 to 2.73; P = 0.01). However, no difference was found between lower and higher dialysate [Na+] in systolic blood pressure and diastolic blood pressure.

CONCLUSIONS

Though our pooled result indicated that low dialysate [Na+] reduced MAP, interdialytic weight gain and predialysis serum [Na+] significantly, it also indicated that low dialysate [Na+] could increase the incidence of intradialytic hypotension and intradialytic cramps events. Considering the contradiction in efficacy and safety of low dialysate [Na+] in our analysis, future larger and up-to-date definitive studies are needed to evaluate the medium to long-term effects of low sodium levels in dialysis fluid, and better inform clinical practice.