Pathology/Lab Coding Alert

Question: Please explain modifier QW and when we should use it in our lab.

Codify Subscriber

Answer: Modifier QW (CLIA waived test) is an informational HCPCS modifier that you should append to lab service codes that are on the list of tests with waived status under the Clinical Laboratory Improvement Amendments (CLIA). If your lab operates with a certificate of waiver, you must use this modifier, and you can perform only tests that are on the CLIA-waived list. You should not report modifier QW if your lab has a different CLIA certification level.

Here are some points to remember about the modifier:

• Modifier QW does not change your reimbursement.
• It does attest that the practice recognizes that it can only perform tests with the "waived" designation, and that the kit used to test the specimen was FDA classified as CLIA waived.
• Not all payers require modifier QW, but Medicare will deny claims without it if you're a CLIA waived lab.