A Cochrane review [Abstract] 1 included seven studies on reduced osmolarity oral rehydration solution (ORS) compared with standard ORS for treating diarrhea due to cholera, with a total of 718 subjects. Reduced osmolarity formulations are generally considered safe and more effective than standard ORS for treating non-cholera diarrhea.
Biochemical hyponatremia (serum sodium< 130 mmol/l) was more common with glucose-based reduced osmolarity ORS (RR 1.67, CI 1.09 to 2.57; 465 participants, 4 trials); for severe biochemical hyponatremia (serum sodium < 125 mmol/l) this was not significant (RR 1.58, CI 0.62 to 4.04; 465 participants, 4 trials). No trials reported symptomatic hyponatremia or death. There was no statistically significant difference in the need for unscheduled intravenous infusion. Analyses separating children and adults showed no obvious trends. Two trials also examined rice-based ORS. In the reduced osmolarity group, duration of diarrhea was shorter (WMD -16.85 hours, CI -21.22 to -12.48; 102 participants, 2 trials).
Comment: The quality of evidence is downgraded by imprecise results (limited study size for each comparison) and by limitations in study quality (unclear allocation concealment, inadequate reporting).
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