Association between hyperkalemia at critical care initiation and mortality

Renal Division, Brigham and Women's Hospital, 75 Francis Street, MRB 418, Boston, MA, 02115, USA.
Intensive Care Medicine (Impact Factor: 7.21). 07/2012; 38(11):1834-42. DOI: 10.1007/s00134-012-2636-7
Source: PubMed


To investigate the association between potassium concentration at the initiation of critical care and all-cause mortality.
We performed a retrospective observational study on 39,705 patients, age ≥18 years, who received critical care between 1997 and 2007 in two tertiary care hospitals in Boston, Massachusetts. The exposure of interest was the highest potassium concentration on the day of critical care initiation and categorized a priori as 4.0-4.5, 4.5-5.0, 5.0-5.5, 5.5-6.0, 6.0-6.5, or ≥6.5 mEq/l. Logistic regression examined death by days 30, 90, and 365 post-critical care initiation, and in-hospital mortality. Adjusted odds ratios were estimated by multivariable logistic regression models.
The potassium concentration was a strong predictor of all-cause mortality 30 days following critical care initiation with a significant risk gradient across potassium groups following multivariable adjustment: K = 4.5-5.0 mEq/l OR 1.25 (95 % CI, 1.16-1.35; P < 0.0001); K = 5.0-5.5 mEq/l OR 1.42 (95 % CI, 1.29-1.56; P < 0.0001); K = 5.5-6.0 mEq/l OR 1.67 (95 % CI, 1.47-1.89; P < 0.0001); K = 6.0-6.5 mEq/l OR 1.63 (95 % CI, 1.36-1.95; P < 0.0001); K > 6.5 mEq/l OR 1.72 (95 % CI, 1.49-1.99; P < 0.0001); all relative to patients with K = 4.0-4.5 mEq/l. Similar significant associations post multivariable adjustments are seen with in-hospital mortality and death by days 90 and 365 post-critical care initiation. In patients whose hyperkalemia decreases ≥1 mEq/l in 48 h post-critical care initiation, the association between high potassium levels and mortality is no longer significant.
Our study demonstrates that a patient's potassium level at critical care initiation is robustly associated with the risk of death even at moderate increases above normal.

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Available from: Kenneth B. Christopher, Jan 20, 2015
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    • "The association between hyperkalemia (> 5.1 mEq/l) secondary to potassium supplementation and higher in-hospital mortality is an important result of our study. Previous studies have shown conflicting results [2, 29]. McMahon et al. found that in patients with serum potassium > 5.5 mEq/l, potassium supplementation was associated with increased mortality [2]. "
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    ABSTRACT: Introduction The aim of the study was to investigate predictors of mortality in patients hospitalized with hyperkalemia. Material and methods Data among hospitalized patients with hyperkalemia (serum potassium ≥ 5.1 mEq/l) were collected. Patients with end-stage renal disease on dialysis were excluded. Results Of 15,608 hospitalizations, 451 (2.9%) episodes of hyperkalemia occurred in 408 patients. In patients with hyperkalemia, chronic kidney disease, hypertension, diabetes, coronary artery disease and heart failure were common comorbidities. Acute kidney injury (AKI) and metabolic acidosis were common metabolic abnormalities, and 359 patients (88%) were on at least one drug associated with hyperkalemia. Mean duration to resolution of hyperkalemia was 12 ±9.9 h. Nonsteroidal anti-inflammatory drugs (HR = 1.59), highest potassium level (HR = 0.61), tissue necrosis (HR = 0.61), metabolic acidosis (HR = 0.77), and AKI (HR = 0.77) were significant independent determinants of duration prior to hyperkalemia resolution. Tissue necrosis (OR = 4.55), potassium supplementation (OR = 5.46), metabolic acidosis (OR = 4.84), use of calcium gluconate for treatment of hyperkalemia (OR = 4.62), AKI (OR = 3.89), and prolonged duration of hyperkalemia (OR = 1.06) were significant independent predictors of in-hospital mortality. Conclusions Tissue necrosis, potassium supplementation, metabolic acidosis, calcium gluconate for treatment of hyperkalemia, AKI and prolonged duration of hyperkalemia are independent predictors of in-hospital mortality.
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    • "In our cohort, the patients with a non-English primary language spoken have a significantly decreased age and significantly less sepsis, acute organ failure, inotropes/vasopressor use, and mechanical ventilation compared with patients who speak English as a primary language. Severity of illness is estimated in our study using an acute organ failure score that strongly correlates with mortality (Table 3) and is used in prior studies but not previously compared against Acute Physiology and Chronic Health Evaluation II [15] [16] [17] [36]. Despite adjustment for age and sepsis, using acute organ score as an adjustor for severity of illness, and despite not finding confounding of the primary language spoken–mortality relationship related to mechanical ventilation or vasopressors/intropes, insufficient adjustment for severity of illness may have accounted for our observed results. "
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    ABSTRACT: The study objective was to investigate the association between primary language spoken and all-cause mortality in critically ill patients. We performed a cohort study on 48 581 patients 18 years or older who received critical care between 1997 and 2007 in 2 Boston hospitals. The exposure of interest was primary language spoken determined by the patient or family members who interacted with administrative staff during hospital registration. The primary outcome was 30-day mortality. Associations between language and mortality were estimated by bivariable and multivariable logistic regression models with inclusion of covariate terms thought to plausibly interact with both language and mortality. Adjustment included age, race, sex, Deyo-Charlson index, patient type (medical vs surgical), sepsis, creatinine, hematocrit, white blood count, and number of organs with acute failure. Validation showed that primary language spoken was highly accurate for a statement in the medical record noting the language spoken that matched the assigned language. Patients whose primary language spoken was not English had improved outcomes (odds ratio 30-day mortality, 0.69 [95% confidence interval, 0.60-0.81; P < .001), relative to patients with English as the primary language spoken, fully adjusted. Similar significant associations are seen with death by days 90 and 365 as well as in-hospital mortality. The improved survival in patients with a non-English primary language spoken is not confounded by indicators of severity of disease and is independent of the specific language spoken and neighborhood poverty rate, a proxy for socioeconomic status. There are significant limitations inherent to large database studies that we have acknowledged and addressed with controlling for measured confounding and evaluation of effect modification. In a regional cohort, not speaking English as a primary language is associated with improved outcomes after critical care. Our observations may have clinical relevance and illustrate the intersection of several factors in critical illness outcome including severity of illness, comorbidity, and social and economic factors.
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