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Accuracy of ICD-9 codes for identifying children with cerebral sinovenous thrombosis
Meredith R Golomb1, Bhuwan P Garg, Linda S Williams
1Division of Pediatric Neurology, Indiana University School of Medicine, Indianapolis 46202, USA. mgolomb@iupui.edu
Insights
International Classification of Diseases, ninth revision (ICD-9), code 325 can identify children with sinovenous thrombosis. However, this code is not precise for differentiating pyogenic cases and has diagnostic uncertainties.
Area of Science:
- Pediatric Neurology
- Medical Informatics
Background:
- Childhood sinovenous thrombosis is a rare condition, posing challenges for research.
- Utilizing International Classification of Diseases, ninth revision (ICD-9) codes across multiple institutions could facilitate larger studies.
- The accuracy of ICD-9 codes for identifying childhood sinovenous thrombosis requires validation.
Purpose of the Study:
- To evaluate the accuracy of specific ICD-9 codes in identifying childhood sinovenous thrombosis.
- To assess the utility of ICD-9 codes in differentiating pyogenic and nonpyogenic cases.
- To determine the optimal search strategy for identifying cases using ICD-9 codes.
Main Methods:
- Retrospective search of hospital admission records (January 1999–June 2005).
- Utilized ICD-9 codes 325, 437.6, and 671.5 for identifying cerebral sinovenous thrombosis.
- Analyzed identified cases for diagnosis confirmation, pyogenic origin, and positional code usage.
Main Results:
- ICD-9 code 325 identified 56 children with possible, probable, or definite sinovenous thrombosis (92.9% of identified cases).
- Only 76.9% of these cases were classified as probable or definite sinovenous thrombosis.
- Code 325 was ineffective in differentiating pyogenic from nonpyogenic cases; searching codes in any position identified more cases than primary position searches.
Conclusions:
- ICD-9 code 325 is valuable for identifying potential childhood sinovenous thrombosis cases but lacks specificity.
- Diagnostic uncertainty and limitations in imaging interpretation impact accuracy.
- Searching ICD-9 codes in any position is crucial for comprehensive case identification.
Abstract:
Childhood sinovenous thrombosis is rare, making it difficult to study; International Classification of Diseases, ninth revision (ICD-9), code searches across multiple hospitals would permit the identification of large numbers of children with sinovenous thrombosis. However, the accuracy of these codes for identifying childhood sinovenous thrombosis has not been established. We performed a retrospective search of admissions records for Riley Hospital for Children in Indianapolis, Indiana, from January 1999 to June 2005 using ICD-9 codes 325 (cerebral sinovenous thrombosis, excluding nonpyogenic cases and cases associated with pregnancy and the puerperium), 437.6 (cerebral venous thrombosis of nonpyogenic origin), and 671.5 (cerebral venous thrombosis in pregnancy or the puerperium) in any position. During this period, there were 47042 admissions. ICD-9 code 325 identified 61 admissions on 56 children. Only 13% were of pyogenic origin. Fifty-two (92.9%) had "possible, probable, or definite" sinovenous thrombosis, but only 76.9% of those had "probable or definite" sinovenous thrombosis. Uncertainty in diagnoses stemmed from limitations in imaging and disagreement over interpretation of imaging studies. ICD-9 code 325 in the primary position identified 7 children; all had possible (n = 1), probable (n = 1), or definite (n = 5) sinovenous thrombosis. ICD-9 code 437.6 identified a single admission on a single case of probable cerebral venous thrombosis; it was unclear whether this case was "nonpyogenic." ICD-9 code 671.5 did not identify any children. ICD-9 code 325 is useful for identifying children likely to have sinovenous thrombosis, but it is not useful for differentiating pyogenic and nonpyogenic cases, and uncertainty in clinical diagnosis makes it difficult to gauge the true accuracy. Furthermore, it is important to search for the code in any position as limiting searches to the primary position misses most cases.
