Background:

Oral rehydration solution (ORS) is the primary treatment for diarrhea. The traditional glucose-based ORS, with an osmolarity of 311 mmol/L, was standard until the early 2000s. Due to concerns about sodium levels and hypernatremia cases, a low-osmolarity ORS solution (LORS) with an osmolarity of 245 or less was introduced. We conducted a systematic review of randomized controlled trials (RCTs) to evaluate LORS effectiveness versus standard ORS for acute and persistent diarrhea.

Methods:

We searched PubMed, CINAHL, Wiley Cochrane Library, ClinicalTrials.gov, WHO-ICTRP, and Scopus until July 20, 2023. Studies were included if published after 1990 and focused on LORS in acute and persistent diarrhea in children younger than age 10. Meta-analysis was done using Review Manager version 5.4.1. Log approximation, ROB 2 for bias assessment, and the GRADE approach for evidence quality was applied. The World Health Organization (WHO) commissioned this review for guideline revision.

Results:

For the comparison of LORS with standard ORS in acute diarrhea, the review suggested a comparable effect of LORS on the number of patients cured within 5 days (risk ratio [RR] = 0.95; 95% CI = 0.61-1.49; low-certainty evidence), treatment failure (RR = 0.13; 95% CI = 0.02-1.00; low-certainty evidence), and frequency of unscheduled intravenous therapy (RR = 0.77; 95% CI = 0.72-9.38; very low-certainty evidence). However, a significant reduction was observed in the duration of diarrhea (mean difference [MD] = -0.28 hours; 95% CI = -0.41 to -0.15; low-certainty evidence), stool output (MD = -0.25 g/kg; 95% CI = -0.35 to -0.16; low-certainty evidence), and ORS intake (MD = -0.18 mL/kg; 95% CI = -0.28 to -0.07; moderate-certainty evidence) in the LORS group. In persistent diarrhea, the effect was comparable for the number of patients cured (RR = 1.08; 95% CI = 0.91-1.28; low-certainty evidence) whereas the duration of diarrhea (MD = -30.60 hours; 95% CI = -48.95 to -12.25; low-certainty evidence), stool output (MD = -14.00 g/kg; 95% CI = -26.63 to -1.37; low-certainty evidence), and ORS intake (MD = -21.40 mL/kg; 95% CI = -41.01 to -1.79; low-certainty evidence) were all significantly reduced with LORS.

Conclusion:

LORS should remain recommended for children younger than age 10 with acute watery or persistent diarrhea, supporting current World Health Organization guidelines.