How To Diagnose Peripheral Arterial Disease
• polyvascular diseases (e.g., CAD and CVD) such as myocardial infarction (MI) or stroke;
• diabetes, especially if it is of a longstanding and poorly-controlled nature, and with other DM complications (e.g., prior amputations, nephropathy, neuropathy or retinopathy);
• chronic, non-healing wounds longer than four weeks; and/or
• non-specific leg complaints such as cramping, achiness or generalized pain.
CPT codes 93922 (single-level, bilateral extremities) and 93923 (multiple levels, bilateral extremities) are the appropriate CPT codes for the reimbursement of non-invasive vascular testing. One should pair these CPT codes with the appropriate ICD-9 codes that indicate a diagnosis representing PAD or ischemic conditions. For example, one may use the ICD-9 code 440.23 for atherosclerosis of the extremities with ulcer. It is also important to document the medical necessity for these CPT codes, test results and interpretations, and have a hard copy of the diagnostic studies you perform.
Currently, Medicare does not reimburse for these studies when one uses them as screening tools. Accordingly, in order to receive Medicare reimbursement for these studies, a patient must present with ischemic symptoms. Unfortunately, up to 50 percent of patients with PAD are asymptomatic so these patients will be overlooked. Clinicians need to determine whether to provide non-reimbursable screening tests, knowing that PAD is grossly under-diagnosed and under-treated. Future studies should address this topic as a source of possible cost savings to the Centers for Medicare and Medicaid Services (CMS) in the form of limb salvage.
A Closer Look At Non-Invasive Testing Methods For PAD
There are five non-invasive vascular testing methods that are commercially available and widely implemented. They include the ankle brachial index (ABI), the toe-brachial index (TBI), pulse volume recording (PVR), transcutaneous oxygen monitoring (TCOM) and skin perfusion pressure (SPP).
The ankle brachial index is the most well-known, non-invasive vascular testing tool. Clinicians often perform an ABI test with a handheld Doppler probe and a blood pressure cuff. One calculates the ABI by dividing the ankle pressure by the brachial systolic pressure.
Pros. The ABI is a relatively quick and cost-effective test for screening of PAD with known sensitivity and specificity of 90 percent or higher.5 One can perform this test with inexpensive equipment.
Cons. Calcified leg arteries in DM or dialysis patients may yield falsely elevated ABI results. The test is operator dependent (i.e., pulses in ischemic or edematous feet and ankles are difficult to locate).
Interpretation of ABI. An ABI of
However, there are pitfalls of “normal” ABIs with calcified arteries. ABI values have a linear correlation with wound healing potential in lower extremity wounds. As Padberg illustrates, ABI is highly unreliable in patients with diabetes and/or those undergoing dialysis due to chronic renal failure (CRF).8 These patients may have calcified and hardened lower extremity arterial walls that cannot be readily compressed and occluded with blood pressure cuffs. This produces falsely elevated ankle pressure readings that are often in the “normal ABI range” (0.9 to 1.2) or sometimes in the non-physiological range of above 1.3.
Simply put, a low ABI (>0.9) may be misleading and unreliable in the diagnosis or ruling out of PAD, especially in DM and CRF patients.
A Guide To The Toe-Brachial Index
The toe-brachial index is analogous to ABI in that one would calculate TBI by dividing the blood pressure of the great toe by the systolic brachial blood pressure. Clinicians can measure toe pressure by placing a small toe cuff around the great toe and attaching a plethysmography probe at the pulp of great toe tip.