Validation of ICD-10 codes shows intracranial venous thrombosis incidence to be higher than previously reported

• Published in: Health Information Management Journal Vol. 49; no. 1; pp. 58 - 61
• Main Authors: Handley, Joel D, Emsley, Hedley CA
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01-01-2020
• Subjects: Admission and discharge; Adult; Aged; Cerebral embolism and thrombosis; Cerebrovascular disease; Diagnosis related groups; England - epidemiology; Female; Hospitals; Humans; Incidence; International Classification of Diseases; Intracranial Thrombosis - classification; Intracranial Thrombosis - epidemiology; Male; Middle Aged; Nosology; Patients; Venous Thrombosis - classification; Venous Thrombosis - epidemiology; England; sinus thrombosis; ICD-10; incidence; clinical coding; cerebral thrombosis; venous thrombosis
• ISSN: 1833-3583; 1322-4913; 1833-3575
• DOI: 10.1177/1833358318819105

Background: Intracranial venous thrombosis (ICVT) accounts for around 0.5% of all stroke cases. There have been no previously published studies of the International Classification of Diseases, Tenth Edition (ICD-10) validation for the identification of ICVT admissions in adults.
Objective: The aims of this study were to validate and quantify the performance of the ICD-10 coding system for identifying cases of ICVT in adults and to derive an estimate of incidence.
Method: Administrative data were collected for all patients admitted to a regional neurosciences centre over a 5-year period. We searched for the following ICD-10 codes at any position: G08.X (intracranial and intraspinal phlebitis and thrombophlebitis), I67.6 (non-pyogenic thrombosis of intracranial venous system), I63.6 (cerebral infarction due to cerebral venous thrombosis, non-pyogenic), O22.5 (cerebral venous thrombosis in pregnancy) and O87.3 (cerebral venous thrombosis in the puerperium).
Results: Sixty-five admissions were identified by at least one of the relevant ICD- 10 codes. The overall positive predictive value (PPV) for confirmed ICVT from all of the admissions combined was 92.3% (60 out of 65) with the results for each code as follows: G08.X 91.5% (54 of 59), O22.5 100% (4 of 4), I67.6 100% (1 of 1), I63.6 100% (1 of 1) and O87.3 100% (1 of 1). There were 40 unique cases of ICVT over a 5-year period giving an annual incidence of ICVT of 5 per million.
Conclusions: All codes gave a high PPV. Implications for practice: As demonstrated in previous studies, the incidence of ICVT may be higher than previously thought.