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Table 1 Sample characteristics*

From: Sensitivity of International Classification of Diseases codes for hyponatremia among commercially insured outpatients in the United States

Characteristic

Laboratory Claims Indicating Hyponatremia†

p||

 

All Claims (n = 40,668)

Negative Test‡ (n = 39,261)

Positive Test§(n = 1407)

 

Age, mean (SD), y

59 (15.7)

59 (15.7)

67 (12.3)

< 0.001

Female sex

24,694 (60.7)

23,769 (60.5)

925 (65.7)

< 0.001

Underlying conditions and comorbidities

    

   Cerebrovascular disease

1874 (4.6)

1721 (4.4)

153 (10.9)

< 0.001

   Chronic obstructive pulmonary disease

4279 (10.5)

4020 (10.2)

259 (18.4)

< 0.001

   Congestive heart failure

2742 (6.7)

2605 (6.6)

137 (9.7)

< 0.001

   Coronary heart disease

5857 (14.4)

5560 (14.2)

297 (21.1)

< 0.001

   Dementia

164 (4.0)

141 (3.5)

23 (1.6)

< 0.001

   Diabetes mellitus

8342 (20.5)

8102 (20.6)

240 (17.1)

0.001

   Hypertension

14,825 (36.5)

13,997 (35.7)

828 (58.8)

< 0.001

   Kidney disease

1491 (3.7)

1405 (3.6)

86 (6.1)

< 0.001

   Liver cirrhosis

26 (0.1)

24 (0.1)

2 (0.1)

0.24

   Metastatic carcinoma

2325 (5.7)

2246 (5.7)

79 (5.6)

0.87

   Nephritis, nephrotic syndrome, and nephrosis

1918 (4.7)

1800 (4.6)

118 (8.4)

< 0.001

   Peripheral vascular disease

1613 (4.0)

1546 (3.9)

67 (4.8)

0.12

   Rheumatic disease

1291 (3.2)

1254 (3.2)

37 (2.6)

0.24

   Syndrome of inappropriate antidiuretic hormone

157 (3.9)

91 (2.3)

66 (4.7)

< 0.001

Medications known to cause hyponatremia

10,492 (25.8)

10,144 (25.8)

348 (24.7)

0.35

  1. * Values are expressed as number (percentage) unless otherwise indicated.
  2. † Hyponatremia was defined as serum sodium < 136 mmol/L.
  3. ‡ 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.
  4. § A positive test was defined as the presence of an outpatient professional claim with a primary or secondary ICD-9-CM diagnosis code of hyponatremia observed within 15 days before or after the laboratory claim indicating hyponatremia.
  5. || p-Values for the comparison between the positive and negative test groups.