How Patient-Records Methodology Can Help Overcome Shortcomings of ATU and Syndicated Data (PDF)
Your claims data may have errors or omissions. Patients with the same condition may be listed under any number of diagnosis codes, and you may not find all of them through claims data.
In this de-identified example from a Clarity study, for more than 4 of 5 patients (83%), ICD-9 xx.1 was used. Surgeons were significantly more likely to use this code than were physicians in any other specialty bucket. An ICD code was never submitted for about 1 patient in 10.
The learning curve associated with the advent of ICD-10 makes this even more critical.