Factors associated with one-year mortality in patients with hyponatremia hospitalized in a cardiology department: An exploratory retrospective cohort study

Q: What is the clinical evidence from this study?

Study design: Cohort. Population: Hypotonic hyponatremia in hospitalized cardiac patients (n=119). Intervention: Stage II chronic heart failure, minimum plasma sodium, and peak CK-MB activity vs. No chronic heart failure / reference biomarker levels. Primary outcome: All-cause death within 1 year (HR 8.86, 95% CI 1.81-43.39, p=0.007).

Q: What does this research mean for the field?

In hospitalized cardiology patients with hyponatremia, stage II chronic heart failure and peak CK-MB activity are more robustly associated with one-year mortality than minimum serum sodium levels. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Kristina Gennadievna Pereverzeva; Sergey S Yakushin; Yulia O Cherkasova; Tatiana A Korchagina; Dmitry A Kuznetsov

doi:10.4330/wjc.125738

November 2, 2026World Journal of CardiologyOpen Access

Factors associated with one-year mortality in patients with hyponatremia hospitalized in a cardiology department: An exploratory retrospective cohort study

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Why the study?

Real-world data on factors associated with one-year mortality in hospitalized cardiac patients with hyponatremia are limited, and the temporal relationship between in-hospital predictors and long-term outcomes remains uncertain.

Key Points

To identify factors associated with one-year mortality in hospitalized cardiac patients with hyponatremia and test the robustness of these relationships using sensitivity analyses.
Retrospective single-center cohort study of 119 patients (mean age 71.2 ± 12.7 years, 48.7% female) hospitalized in a cardiology department with hypotonic hyponatremia, excluding those with acute coronary syndrome or myocardial infarction.
The primary endpoint was all-cause mortality within 1 year, tracked via a regional electronic death registry and analyzed using multivariable Cox proportional hazards regression.
Sensitivity analyses were conducted by excluding in-hospital deaths (n = 100) and applying Firth's penalized Cox regression (n = 98).
All-cause mortality at one year was 44.5% (53/119).
In the primary multivariable Cox model, stage II chronic heart failure (HR 8.86; 95%CI: 1.81-43.39; P = 0.007), minimum sodium (HR 0.94; 95%CI: 0.89-1.00; P = 0.040), and peak creatine kinase-MB (HR 1.02; 95%CI: 1.00-1.04; P = 0.002) were significantly associated with one-year mortality.
In sensitivity analyses excluding in-hospital deaths, these associations were no longer statistically significant, while in Firth's penalized model, stage II chronic heart failure (HR 6.60; 95%CI: 1.67-33.37; P = 0.007) and peak creatine kinase-MB (HR 1.02; 95%CI: 1.01-1.04; P = 0.007) remained significant but minimum sodium did not (P = 0.117).

Study Design

Type

Cohort (n=119)

Multicenter

No

Structured PICO

P

Population

119 adult cardiology inpatients (mean age 71.2 years, 48.7% female) with hypotonic hyponatremia, excluding acute coronary syndrome or myocardial infarction, followed for 1 year.

O

Outcome

All-cause death within 1 year of hospital admission, ascertained through the regional electronic death registry.hard clinical

Main Result

Hazard Ratio: 8.86 (95% CI 1.81–43.39)

p-value: p=0.007

Limitations

Single-center retrospective design with small sample size and low events-per-variable ratio (7.2 to 8.8)
Data-driven variable selection for multivariable model without external validation
Missing data not at random, particularly for CK-MB (17.6% missing) and troponin I (43.7% missing)
Potential reverse causation due to lack of laboratory timestamps and inclusion of 19 in-hospital deaths
Unstable hazard ratio for Stage II CHF due to very small subgroup size (8 patients, 6 deaths)
Small number of HFpEF patients (n=40) precluded separate subgroup analysis
Retrospective single-center design with elements of prospective follow-up does not exclude unmeasured confounding factors.
Exclusion of patients admitted with acute coronary syndrome and/or acute myocardial infarction limits generalizability.
Inability to verify the volume status type of hyponatremia (hypovolemic, euvolemic, or hypervolemic) due to lack of standardized protocols in medical records.
Dates of individual laboratory measurements were not available, preventing time-dependent analysis and raising the possibility of reverse causation (especially given 19 of 53 deaths occurred in-hospital).
Small number of events and small sample size (e.g., only 8 patients in stage II CHF; low events-per-variable ratio of 8.8 in primary model and 7.2 in complete-case model), leading to sparse-data bias and inability to perform subgroup analysis in HFpEF (n=40).
Missing data not at random for key biomarkers (CK-MB missing in 17.6%, troponin I in 43.7%).

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Implication

In hospitalized cardiology patients with hypotonic hyponatremia, one-year mortality is high (44.5%), with severe chronic heart failure (stage II) and subclinical myocardial injury (elevated CK-MB) serving as more robust predictors of death than the severity of hyponatremia itself.

Abstract

BACKGROUNDHyponatremia is a common electrolyte disorder in hospitalized cardiac patients and is associated with increased mortality.However, data on factors associated with one-year mortality in patients with hyponatremia in real-world clinical practice are limited, and the temporal relationship between in-hospital predictors and long-term outcomes remains uncertain. AIMTo explore factors associated with one-year mortality in cardiac inpatients with hyponatremia and assess the robustness of these associations in sensitivity analyses. METHODSThis retrospective single-center cohort study included 119 patients (mean age 71.2 ± 12.7 years, 48.7% female) hospitalized in a cardiology department with hypotonic hyponatremia.Patients with acute coronary syndrome and/or myocardial infarction were excluded.The primary endpoint was all-cause death within 1 year, ascertained through the regional electronic death registry.Cox regression was used.Sensitivity analyses excluding in-hospital deaths and Firth's penalized Cox regression were performed. RESULTSThe one-year mortality rate was 44.5% (53/119).In the primary multivariable Cox model, stage II chronic heart failure (CHF) [hazard ratio (HR) 8.86; 95% confidence interval (CI):1.81-43.39;P = 0.007], minimum sodium (HR 0.94; 95%CI: 0.89-1.00;P = 0.040), and peak creatine kinase-MB (CK-MB) (HR 1.02; 95%CI: 1.00-1.04;P = 0.002) were associated with one-year mortality.However, in a sensitivity analysis excluding in-hospital deaths, these associations were no longer statistically significant.In Firth's penalized model, CK-MB 4 / 35 (HR 1.02; 95%CI: 1.01-1.04;P = 0.007) and stage II CHF (HR 6.60; 95%CI: 1.67-33.37;P = 0.007) remained significant, whereas minimum sodium did not (P = 0.117).Non-linearity was not detected for sodium (P = 0.459) or CK-MB (P = 0.182). CONCLUSIONIn this exploratory analysis, CK-MB and stage II CHF were more robustly associated with one-year mortality than hyponatremia.The sodium association was not confirmed in sensitivity analyses.These findings are hypothesis-generating and require prospective validation.

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Cite This Study

Pereverzeva et al. (2026) conducted a cohort in Hypotonic hyponatremia in hospitalized cardiac patients (n=119). Stage II chronic heart failure, minimum plasma sodium, and peak CK-MB activity vs. No chronic heart failure / reference biomarker levels was evaluated on All-cause death within 1 year (HR 8.86, 95% CI 1.81-43.39, p=0.007).

synapsesocial.com/papers/6aea772189a8acbed9c87ac3 https://doi.org/10.4330/wjc.125738

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Factors associated with one-year mortality in patients with hyponatremia hospitalized in a cardiology department: An exploratory retrospective cohort study

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Factors associated with one-year mortality in patients with hyponatremia hospitalized in a cardiology department: An exploratory retrospective cohort study

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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