Diabetes coding requires sophistication

Key Points

Also, diabetic retinopathy has been selected as one of the four ophthalmic conditions eligible for reporting under Medicare's Physician Quality Reporting Initiative. This is the "pay for performance" program that will provide a 1.5% payment bonus for meeting the reporting benchmarks.

Several principles of diagnostic coding are relevant for the diabetic population. Diagnoses should be chosen at the highest level of specificity. Also, multiple codes should be used when present. New ICD-9-CM codes for diabetic retinopathy were added in 2006, and these new codes should be used rather than those from the older manuals.

The importance and complexity of the encounter is diminished from the payers' perspective when nonspecific diagnostic codes are used and when relevant additional diagnostic codes are omitted.

Patients with any ophthalmic manifestation of diabetes mellitus will be coded ICD-9-CM 250.5, with a fifth digit added depending on the type of diabetes (type I versus type II), and whether or not the diabetes is under control. Typically, your encounter has added importance both when the diabetes is type I and when the diabetes is uncontrolled. Make an effort to document these points when present.

Your coder should add additional diagnosis codes to describe the ophthalmic manifestations of diabetes. Those include codes for diabetic blindness, cataract, glaucoma, macular edema, and "retinopathy." There are also separate codes for rubeosis iridis, ischemic optic neuropathy, and other manifestations of the disease.

Retinopathy is subdivided into background (specified as microaneurysms), non-proliferative, and proliferative. Diabetic macular edema can also be coded.

The testing services that are probably most commonly performed in patients with diabetic retinopathy are CPT 92235, Fluorescein angiography; CPT 92250, Fundus photography; and optical coherence tomography (OCT), which is appropriately coded as CPT 92135, Scanning computerized ophthalmic diagnostic imaging.

Medical necessity

For all tests, medical necessity must be demonstrated. Normal eyes (even when the contralateral eye demonstrates pathology) cannot be coded with a diagnosis code reflecting pathology. The test will generally be denied for normal eyes because medical necessity will not be apparent, lacking an appropriate diagnosis code for the test.

Interpretation and reporting is required for all three tests. Simply filing the study in the chart is inadequate. Ideally, the interpretation and report will appear separate from the office visit in the medical record. This is because the testing code is distinct from the office visit code, and separate documentation emphasizes the distinction.

Both fluorescein angiography and OCT are payable per eye. When both eyes demonstrate pathology, each eye is coded with the –RT or –LT modifier, respectively. For Medicare patients, the bilateral modifier –50 may be used.

Fundus photography is a bilateral code. That means payment has been based on both eyes being tested. Report bilateral cases with the base code, CPT 92250. Unilateral cases may be reported with –RT or –LT.

Medicare's National Correct Coding Initiative bundles fundus photography with OCT. Medicare's logic (often challenged) is that the two tests provide overlapping information. For commercial carriers, you may bill for both tests when performed on the same day, but in many cases one of the tests will be denied.