title: Hyponatremia is a marker of disease severity in HIV-infected patients: a retrospective cohort study.
abstract: Hyponatremia is a frequent electrolyte disorder in HIV-infected patients with a prevalence of up to 56% in the pre-cART era. Several studies have demonstrated that patients with hyponatremia are at an increased risk of death. We aimed to investigate the prevalence of hyponatremia in the recent cART-era and evaluate its association with mortality.
  
  
  
  Single-center retrospective cohort study. A total of 1196 newly diagnosed and cART-naïve HIV patients followed at the AIDS Reference Center, St Pierre University Hospital in Brussels, Belgium, between 1 January 1998 and 31 December 2013 were included. Hyponatremia was defined as a baseline natremia lower than 135 mmol/l. The outcome of interest was the occurrence of death.
  
  
  
  In this study 177 (14.8%) patients had hyponatremia at baseline with a median natremia of 132.0 mmol/l [interquartile range (IQR) 130.0-134.0 mmol/l]. Hyponatremic patients had a lower CD4 cell count (207.5 ± 197.7/μl vs 400.4 ± 277.0/μl; P < 0.0001) and a higher prevalence of AIDS (50.3% vs 12.4%; P < 0.0001) compared to normonatremic patients. A significantly higher proportion of patients with hyponatremia were hospitalized at first contact (72.3% vs 20.0%; P < 0.0001). During the follow-up hyponatremic patients had a shorter median time to a first hospitalization (2.0 IQR [0.0-12.0] months vs 13.0 IQR [2.0-29.0] months; P = 0.001) and an increased incident hospitalization rate (785/1000 patient-years, 95% CI 725-845 vs 370/1000 patient-years, 95% CI 352-388; P < 0.0001]. The incident mortality rate was 28.3/1000 patient-years (95% CI 18.15-42.16) in patients with hyponatremia compared to 9.33/1000 patient-years (95% CI 6.63-12.75) in normonatremic patients (P < 0.0001). Three-year cumulative survival rates were 85.8% ± 3.0% in hyponatremic patients and 96.3% ± 0.7% in normonatremic patients (log-rank P < 0.0001). However, in a multivariate Cox model adjusting for other risk factors such as AIDS, CD4 count < 350/μl and hepatitis C, hyponatremia was no longer a predictor for patient death (hazard ratio: 1.03, 95% CI 0.54-1.97; P = 0.935).
  
  
  
  Hyponatremia is a marker of severity of HIV-disease but not an independent risk factor for mortality. HIV-patients with a low serum sodium at baseline might benefit from a close follow-up to improve outcomes.
authors.affiliation: Department of Infectious Diseases, AIDS Reference Center, Saint-Pierre University Hospital, Université Libre de Bruxelles, Brussels, Belgium. philippe.braconnier@chuv.ch.|Department of Nephrology, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium. philippe.braconnier@chuv.ch.
authors.forename: Philippe
authors.identifier: 0000-0002-1610-9647
authors.initials: P
authors.lastname: Braconnier
authors.affiliation: Department of Infectious Diseases, AIDS Reference Center, Saint-Pierre University Hospital, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Marc
authors.initials: M
authors.lastname: Delforge
authors.affiliation: Department of Infectious Diseases, AIDS Reference Center, Saint-Pierre University Hospital, Université Libre de Bruxelles, Brussels, Belgium.|Department of Nephrology, Centre Hospitalier Universitaire Brugmann, Brussels, Belgium.
authors.forename: Maria
authors.initials: M
authors.lastname: Garjau
authors.affiliation: Department of Nephrology, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium.|Department of Nephrology, Centre Hospitalier Universitaire Brugmann, Brussels, Belgium.
authors.forename: Karl Martin
authors.initials: KM
authors.lastname: Wissing
authors.affiliation: Department of Infectious Diseases, AIDS Reference Center, Saint-Pierre University Hospital, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Stéphane
authors.initials: S
authors.lastname: De Wit
mesh_terms: D000328:Adult; D001530:Belgium / Q000453:epidemiology; D015415:Biomarkers / Q000097:blood*; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000097:blood / Q000150:complications / Q000401:mortality*; D006760:Hospitalization; D006801:Humans; D007010:Hyponatremia / Q000097:blood / Q000150:complications / Q000401:mortality*; D008297:Male; D015995:Prevalence; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D016019:Survival Analysis; D015996:Survival Rate
chemical_list: D015415:Biomarkers
keywords: Acquired immunodeficiency syndrome; Human immunodeficiency virus; Hyponatremia; Mortality; Risk factors