Epidemiology and outcomes of hyponatremia in patients with COVID-19-A territory-wide study in Hong Kong

Gordon Chun Kau Chan; Chun Ka Wong; Benjamin Y F So; Jack Kit Chung Ng; Grace Chung Yan Lui; Cheuk Chun Szeto; Ivan Fan Ngai Hung; Hung Fat Tse; Sydney C W Tang; Tak Mao Chan; Kai Ming Chow; Desmond Y H Yap

doi:10.3389/fmed.2022.1096165

Epidemiology and outcomes of hyponatremia in patients with COVID-19-A territory-wide study in Hong Kong

Front Med (Lausanne). 2023 Jan 11:9:1096165. doi: 10.3389/fmed.2022.1096165. eCollection 2022.

Affiliations

¹ Division of Nephrology, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
² Division of Cardiology, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
³ Division of Nephrology, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
⁴ Division of Infectious Diseases, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
⁵ Division of Infectious Diseases, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.

Abstract

Background: Hyponatremia is common in COVID-19, but its epidemiology and impact on clinical outcomes in relation to different variants, especially the Omicron variant, requires further clarification.

Methods: This was a territory-wide retrospective study to investigate the epidemiology and outcomes of COVID-19 patients with hyponatremia from January 1, 2020 to March 31, 2022 in Hong Kong. The primary outcome was 30-day mortality of patients with COVID-19 and hyponatremia at presentation. Secondary outcomes included rate of hospitalization, intensive care unit (ICU) hospitalization, overall duration of hospitalization, and duration of ICU hospitalization.

Results: A total of 53,415 COVID-19 patients were included for analysis, of which 14,545 (27.2%) had hyponatremia at presentation. 9813 (67.5%), 2821 (19.4%), and 1911 (13.1%) had mild (130 to <135 mmol/L), moderate (125 to <130 mmol/L), and severe hyponatremia (<125 mmol/L) at presentation respectively. Age, male sex, diabetes, active malignancy, white cell count, serum creatinine, hypoalbuminemia, C-reactive protein, and viral loads were independent predictors for hyponatremia in COVID-19 patients (P < 0.001, for all). Hyponatremic patients had increased 30-day mortality (9.7 vs. 5.7%, P < 0.001), prolonged hospitalization (11.9 ± 15.1 days vs. 11.5 ± 12.1 days, P < 0.001), and more ICU admissions (7.0% vs. 3.3%, P < 0.001). Patients diagnosed during the "fifth wave" Omicron BA.2 outbreak had 2.29-fold risk (95% CI 2.02-2.59, P < 0.001) of presenting with hyponatremia compared to other waves.

Conclusion: Hyponatremia is common among COVID-19 patients, and may serve as a prognostic indicator for unfavorable outcomes and increased healthcare utilization in the evolving COVID-19 outbreak.

Keywords: COVID-19; epidemiology; hyponatremia; outcomes; sodium.

Grants and funding

DY received research donations from the Wai Im Charitable Foundation and the Chan Sui Kau Family Benefits and Charitable Foundation. DY, ST, and TC received research funding support from the Mr. and Mrs. Tam Wing Fun Edmund Renal Research Fund. TC received research funding support from the Wai Hung Charitable Foundation and Mr. S. Ho.