Analysis of Sodium in Inpatients, Outcomes, and Nephrology Engagement (ASIN-ONE): A Study on Nephrology Referral Timing in Hyponatremic Adult Patients at a Tertiary Hospital

Background: Hyponatremia is the most common inpatient electrolyte abnormality. Earlier referral to a nephrologist may shorten hospitalization and improve patient survival. Methods: This was a 6-month retrospective cohort study of nephrology referrals in a tertiary hospital. We analyzed four groups based on days from admission to referral (<1d, 1-<3d, 3-7d, and >7d) for length of stay, in-hospital mortality, and hyponatremia resolution. Kaplan-Meier curves and Cox proportional hazard regression were done. Results: Of the 800 patients analyzed, overall mortality was 31.87%. Those referred <1d from admission had significantly shorter hospitalization (median 8.41 vs. 24.57 days) and significantly lower mortality (26.04% vs. 51.35%) than the >7d group. The 3-7d group had a higher risk of death than the <1d group (HR 2.91, 95% CI, 1.94–4.36). Kaplan-Meier curves revealed decreased survival in patients referred >72 hours from admission. There was no significant difference across groups in terms of normonatremia attainment prior to discharge or mortality. Conclusion: Earlier nephrology referral was associated with decreased hospital stay and mortality. Significant divergence in in-hospital mortality was seen in hyponatremic patients referred more than 72 hours from admission.Cox proportional hazards regression between referral timing and in-hospital mortalityKaplan-Meier survival curve of timing of nephrology referral - Hospital Outcomes Timing of Referral from Admission (Days) <1 Day 1-<3 Days 3-7 Days >7 Days p-value Length of Stay, Days [Median (IQR)] 8.41 (10.15) 10.55 (10.255) 10.27 (12.82) 24.565 (27.62) <0.001 In-hospital Mortality [Frequency (%)] 132 (26.04%) 46 (31.94%) 39 (52.00%) 38 (51.35%) <0.001 Hyponatremia Resolution [Frequency (%)] 215 (42.41%) 64 (44.44%) 39 (52.00%) 39 (52.70%) 0.202