Q&A: Documenting HIV versus HIV-related illness

Q: I have a question about coding human immunodeficiency virus (HIV) and HIV-related illnesses. If a physician documents a patient is HIV positive, should the chart be coded to Z21? What about if they document the patient is HIV positive with an HIV-related illness—would that be coded to B20?

A: You are correct. The ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.1.a.2.f. says that patients who are HIV positive with any known prior diagnosis of an HIV related illness should be coded to code B20. Only confirmed cases are coded using code B20. HIV is one of four conditions that cannot be coded based on the documented terminology, “possible, probable, or suspected,” or any other similar terminology.

It is not required that any form of testing be documented, such as a positive serology test. The physician’s diagnostic statement that the patient is HIV positive with a prior HIV-related condition is all that is necessary for coding. Once a patient is coded to B20, they will always have B20 coded on their record; they will never go back to being coded using the asymptomatic code Z21.

Code Z21 is used for patients who are asymptomatic, meaning they are HIV positive but have never had an HIV-related condition. Once that patient experiences an HIV-related condition, the Z21 code is no longer appropriate. If the physician documentation states only that the patient is HIV positive, has HIV, or an HIV infection, a query could be required for clarification as to whether or not a patient has ever had an HIV related condition.

So, the principal diagnosis will be based on the circumstances of the admission. If the patient is admitted with an HIV related condition, the HIV will be sequenced first, followed by a code for the manifestation, then any other secondary diagnoses they may have. If the patient is admitted for a condition unrelated to the HIV, the unrelated condition would be sequenced first, followed by the code for HIV, which is classified as a CC when it is a secondary diagnosis.

Editor’s Note: Sharme Brodie, RN, CCDS, CCDS-O, CDI education specialist and CDI Boot Camp instructor for HCPro in Middleton, Massachusetts, answered this question. For information, contact her at sbrodie@hcpro.com. For information regarding CDI Boot Camps, click here. This article originally ran in May 2019 and has been updated according to all new coding and documentation guidelines.