Table 4.

Likelihood of a negative test for claims indicating hyponatremia*

	OR	95% CI
Age in years	0.97	0.96, 0.97
Female	0.75	0.67, 0.85
Underlying conditions and comorbidities
Cerebrovascular disease	0.61	0.50, 0.73
Chronic obstructive pulmonary disease	0.62	0.54, 0.72
Congestive heart failure	1.09	0.89, 1.34
Coronary heart disease	0.98	0.84, 1.14
Dementia	0.44	0.27, 0.70
Diabetes mellitus	1.47	1.27, 1.70
Hypertension	0.53	0.47, 0.59
Kidney disease	1.24	0.84, 1.83
Liver cirrhosis†	0.31	0.07, 1.38
Metastatic carcinoma	1.11	0.87, 1.41
Nephritis, nephrotic syndrome, and nephrosis	0.49	0.35, 0.69
Peripheral vascular disease	1.40	1.08, 1.82
Rheumatic disease	1.27	0.91, 1.77
Syndrome of inappropriate antidiuretic hormone	0.06	0.04, 0.08
Medications known to cause hyponatremia	1.08	0.95, 1.22

* Hyponatremia was defined as serum sodium < 136 mmol/L. A negative test was defined as the presence of an outpatient professional claim with no ICD-9-CM code for hyponatremia or the absence of any outpatient professional claims within 15 days before or after the laboratory claim indicating hyponatremia.

† Indicates that the condition was present in < 1% of the population.

Abbreviations: OR indicates odds ratio; and CI, confidence interval.