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

Abstract

BackgroundHyponatremia 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.MethodsThis 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.ResultsA 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.ConclusionHyponatremia 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.

What is the aetiology of dysnatraemia in COVID-19 and how is this related to outcomes in patients admitted during earlier and later COVID-19 waves? A multicentre, retrospective observational study in 11 Dutch hospitals

“…Patients with hyponatraemia experienced more complications such as aspergillosis pneumonia and physical decline, while those with hypernatraemia were more prone to sepsis and delirium. Similar to previous studies, hyponatraemia and hypernatraemia were more prevalent in men than in women, in elderly patients, those with chronic kidney disease and a lower BMI 9 15 17 26 28–30 38. In contrast to others, we did not find an association between hyponatraemia and diabetes, which possibly relates to the fact that we corrected sodium levels for serum glucose 9 15 17 26 30.…”

“…Similar to previous studies, hyponatraemia and hypernatraemia were more prevalent in men than in women, in elderly patients, those with chronic kidney disease and a lower BMI 9 15 17 26 28–30 38. In contrast to others, we did not find an association between hyponatraemia and diabetes, which possibly relates to the fact that we corrected sodium levels for serum glucose 9 15 17 26 30. Among patients with COVID-19, hyponatraemia appeared to have multiple aetiologies, but hypovolaemic hyponatraemia was found to be predominant.…”

“…Patients presenting with hyponatraemia in this study were significantly older compared with patients with normonatremia, potentially due to age-related tubular atrophy and subsequent decreased urine concentrating capacity and sodium reabsorption 44. The fact that previous studies have identified various other underlying conditions as risk factors for hyponatraemia, including cardiac,17 pulmonary17 and liver diseases17 possibly relates to the older age of patients with hyponatraemia included (median age was 67 years in our study vs a mean age of 74.3 years in Chan et al 17 and a median age of 70 years in Ruiz-Sánchez et al 38…”

“…It has been demonstrated that critically ill patients with COVID-19 more frequently develop hyponatraemia during the first 72 hours of admission 13. Hyponatraemia is also frequently present in other infectious diseases, such as pneumonia, tuberculosis, meningitis, HIV infection, malaria and leishmaniasis and has been linked to negative outcomes in these diseases and in COVID-19 7 8 11 14–17. On the other hand, hypernatraemia is less common, occurring in less than 10% of the general population and in up to 38% of patients in intensive care units (ICUs).…”

“…Previous studies have associated both hyponatraemia and hypernatraemia with worse clinical outcomes in patients with COVID-19 during the early stages of the pandemic 7 8 11 15 17 19. However, most of these studies were conducted before interleukin 6 inhibitors were administered and before the registration of SARS-CoV-2 vaccines 3 7 11 19 26–29.…”