Validity of ICD Codes for Hyponatremia in Outpatients
Author Information
Author(s): Shea Alisa M, Curtis Lesley H, Szczech Lynda A, Schulman Kevin A
Primary Institution: Duke Clinical Research Institute
Hypothesis
How accurately do ICD-9-CM codes identify hyponatremia in outpatient settings?
Conclusion
ICD-9-CM codes in administrative data are insufficient to identify hyponatremia in an outpatient population.
Supporting Evidence
- Sensitivity for hyponatremia was only 3.5%.
- Specificity was greater than 99% for all cutoff points.
- Positive predictive value was 63%, and negative predictive value was 98%.
- Hyponatremia is often seen in patients with significant comorbidities.
Takeaway
Doctors use special codes to describe diseases, but these codes often miss cases of low sodium levels in patients who visit outpatient clinics.
Methodology
Analyzed outpatient claims and laboratory results for patients aged 18 and older from a national database.
Potential Biases
Potential underrepresentation of elderly patients and reliance on administrative data may lead to inaccurate coding.
Limitations
The study may not be generalizable to older populations and relies on a limited time frame for observing comorbidities.
Participant Demographics
Mean age was 59 years, with 60.7% female.
Statistical Information
P-Value
0.001
Confidence Interval
0.66, 0.74
Statistical Significance
p<0.05
Digital Object Identifier (DOI)
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