Medical Costs of Abnormal Serum Sodium Levels

Abstract

An abnormal serum sodium level is the most common electrolyte disorder in the United States and can have a significant impact on morbidity and mortality. The direct medical costs of abnormal serum sodium levels are not well understood. The impact of hyponatremia and hypernatremia on 6-mo and 1-yr direct medical costs was examined by analyzing data from the Integrated HealthCare Information Services National Managed Care Benchmark Database. During the period analyzed, there were 1274 patients (0.8%) with hyponatremia (serum sodium Ͻ135 mmol/L), 162,829 (97.3%) with normal serum sodium levels, and 3196 (1.9%) with hypernatremia (Ͼ145 mmol/L). Controlling for age, sex, region, and comorbidities, hyponatremia was a significant independent predictor of costs at 6 mo (41.2% increase in costs; 95% confidence interval, 30.3% to 53.0%) and at 1 yr (45.7% increase; 95% confidence interval, 34.2% to 58.2%). Costs associated with hypernatremia were not significantly different from those incurred by patients with normal serum sodium. In conclusion, hyponatremia is a significant independent predictor of 6-mo and 1-yr direct medical costs. Abnormal serum sodium is the most common electrolyte disorder in the United States. Estimates of the prevalence of hyponatremia range from 1% in general acute care populations 1,2 to 18% among elderly nursing home residents 3 and nearly 30% in intensive care settings. 4 Hypernatremia is less common, ranging from 0.3% to 8.9% in hospitalized adults. 5,6 Mild, chronic hyponatremia is often asymptomatic; neurologic and gastrointestinal symptoms generally increase as the condition worsens. 7 Hypernatremia may also be asymptomatic until it exceeds a certain threshold, at which point central nervous system dysfunction develops. 8 However, hyponatremia and hypernatremia of all severity levels have significant effects on morbidity and mortality.In a cohort of 4123 elderly patients, Terzian et al. 9 studied the relationship between hyponatremia at the time of hospital admission and treatment outcomes. After adjustment for age, sex, length of stay, and several clinical factors, hyponatremia was a significant independent predictor of mortality.Similar results have been found for patients with heart failure and myocardial infarction. In a study of patients with suspected congestive heart failure at admission, serum sodium Յ135 mmol/L was independently associated with major complications during hospitalization, greater length of stay, higher hospital costs, and greater inpatient mortality. 10 In a more recent trial, patients hospitalized for worsening heart failure with hyponatremia at admission (serum sodium Յ135 mmol/L) experienced significantly greater in-hospital and 60-d mortality, compared with patients with normal or high serum sodium. 11 In patients with acute ST-

Clinical management of SIADH

“…Since that time more than 5000 articles have been published analyzing hyponatremia in various ways. It was found that hyponatremia occurs in many different settings, that it has an incidence of between 4% and 15% in hospital patients and that it is the most frequent electrolyte disorder encountered [Anderson et al1985;Goldstein et al 1983;Hoorn et al 2006;Miller et al 1995;Shea et al 2008;Sherlock et al 2009;Upadhyay et al 2006]. Despite this, physicians did not have specific therapy for hyponatremia, until very recently.…”

Hyponatraemia: new associations and new treatments

“…In addition, data from a US healthcare database showed that in over 160 000 patients, hyponatraemia was a significant independent predictor of medical costs at 6 months (41% increase) and 1 year (46% increase) of follow-up (24). The data could not comment on whether treatment of hyponatraemia would lower medical costs.…”

Hyponatremia Etiology and Tolvaptan: Are we Optimally Targeting the Mechanism?

“…In addition, hyponatremia imposes a huge economic burden on the cost of medical care. A recent analysis of 168,000 patients from 39 medical centers revealed that the one-year cost of medical care for patients with normal (>135 mEq/L) serum sodium concentration was $9,257 versus $19,215 for those with hyponatremia [3]. * Restriction of water intake is the usual treatment for asymptomatic hyponatremia.…”