Do outpatient or secondary ICD-9 codes reliably identify acute venous thromboembolism?
Outpatient and secondary ICD-9 codes for VTE are insufficiently reliable to identify acute VTE for research or policy purposes.
ICD-9 codes for VTE obtained from outpatient encounters or from secondary diagnosis codes do not reliably reflect acute VTE. More accurate ways of identifying VTE in outpatients are needed before these codes can be adopted for research or policy purposes.
Fang et al. (Fri,) studied this question.