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Validation of an International Classification of Disease, Ninth Revision coding algorithm to identify decompressive
Hormuzdiyar H Dasenbrock1, David J Cote1, Yuri Pompeu1
1Cushing Neurological Outcomes Center, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA.
Insights
A new algorithm using International Classification of Disease, Ninth Revision, Clinical Modification (ICD9-CM) codes accurately identifies patients who had decompressive craniectomy for stroke. This tool enhances administrative claims data analysis for supratentorial infarction cases.
Area of Science:
- Neurosurgery
- Health Informatics
- Stroke Medicine
Background:
- Administrative claims data relies on International Classification of Disease, Ninth Revision, Clinical Modification (ICD9-CM) codes.
- No validated ICD9-CM algorithm exists to identify patients undergoing decompressive craniectomy for space-occupying supratentorial infarction.
Purpose of the Study:
- To develop and validate an ICD9-CM algorithm for identifying patients who underwent decompressive craniectomy for space-occupying supratentorial infarction.
- To assess the accuracy of this algorithm against physician review.
Main Methods:
- Retrospective review of patients who underwent decompressive craniectomy for stroke.
- Extraction of associated ICD9-CM codes from billing data.
- Generation of an ICD9-CM algorithm and comparison with physician review.
Main Results:
- The algorithm included diagnosis codes for cerebral infarction and procedure codes for craniotomy or craniectomy.
- Exclusion criteria targeted conditions mimicking stroke or craniectomy.
- The algorithm demonstrated high sensitivity (97.8%) and specificity (99.9%), with a positive predictive value of 88.2%.
Conclusions:
- An ICD-9-CM algorithm effectively identifies patients undergoing decompressive craniectomy for supratentorial stroke.
- This algorithm can improve the accuracy of administrative claims data analysis for stroke research.
Background:
Although International Classification of Disease, Ninth Revision, Clinical Modification (ICD9-CM) coding is the basis of administrative claims data, no study has validated an ICD9-CM algorithm to identify patients undergoing decompressive craniectomy for space-occupying supratentorial infarction.
Methods:
Patients who underwent decompressive craniectomy for stroke at our institution were retrospectively identified and their associated ICD9-CM codes were extracted from billing data. An ICD9-CM algorithm was generated and its accuracy compared against physician review.
Results:
A total of 10,925 neurosurgical operations were performed from December 2008 to March 2015, of which 46 (0.4%) were decompressive craniectomy for space-occupying stroke. The ICD9-CM procedure code for craniectomy (01.25) was only encoded in 67.4% of patients, while craniotomy (01.24) was used in 19.6% and lobectomy (01.39, 01.53, 01.59) in 13.1%. The ICD-9-CM algorithm included patients with a diagnosis codes for cerebral infarction (433.11, 434.01, 434.11, and 434.91) and a procedure code for craniotomy, craniectomy, or lobectomy. Patients were excluded with an ICD9-CM diagnosis code for brain tumor, intracranial abscess, subarachnoid hemorrhage, vertebrobasilar infarction, intracranial aneurysm, Moyamoya disease, intracranial venous sinus thrombosis, vertebral artery dissection, congenital cerebrovascular anomaly, head trauma or an ICD9-CM procedure code for laminectomy. This algorithm had a sensitivity of 97.8%, specificity of 99.9%, positive predictive value of 88.2%, and negative predictive value of 99.9%. The majority of false-positive results were patients who underwent evacuation of a primary intracerebral hematoma.
Conclusion:
An ICD-9-CM algorithm based on diagnosis and procedure codes can effectively identify patients undergoing decompressive craniectomy for supratentorial stroke.
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