HIV and AIDS, Understanding the Disease and Documentation Requirements

Spring has finally arrived across most of the country. The landscape is taking on the colors of blooming flowers and trees. This time of year signals new opportunities so let’s revisit one of the diagnoses that can be confusing to coders –  HIV and AIDS.  We will endeavor to better understand the disease process and requirements for documentation.  In turn, as coders, we will be better prepared to analyze record documentation, assign the accurate code and identify when a query is needed.

Human Immunodeficiency Virus (HIV), is a retrovirus that destroys the immune system, disabling the body’s ability to fight infections causing some lymphomas, other malignancies and opportunistic infections to grow.  The Official Coding Guidelines that we followed for coding HIV/ Acquired Immune Deficiency Syndrome (AIDS) in ICD-9-CM have not changed for ICD-10-CM. The only difference is that the codes have changed:

  • B20 – AIDS (previously 042)
  • Z21 – asymptomatic HIV status, HIV + (previously V08)

Regardless of whether a patient is newly diagnosed or has had previous admissions/encounters for HIV conditions, is irrelevant to the sequencing decisions.

  • Code only confirmed cases of HIV infection/illness – Inpatient & Outpatient
  • Chart documentation with qualified diagnoses such as “possible”, “probably”, “rule out”, “suspected” or “suspicion of” are never reported as AIDS (B20) – Inpatient or Outpatient

This is an exception to the rule on the Inpatient side!

  • In this context, “confirmation” does not require documentation of positive serology or culture for HIV; the provider’s diagnostic statement that the patient is HIV positive, or has an HIM-related illness is sufficient.

HIV Positive:  Code Z21

Used when the patient has never been diagnosed with AIDS or an AIDS-defining condition.  Also called “asymptomatic HIV” in ICD-10-CM.

  • Documentation coded as Z21 (not AIDS) – HIV positive, HIV +, HIV Infection, asymptomatic HIV, known HIV, HIV test positive. Do not use if the term “AIDS” is documented for the patient or the patient has any HIM-related illness or has a history of any HIV-related conditions.
  • A diagnosis of HIV + (Z21) is not the same as a diagnosis of HIV infection, symptomatic HIV/AIDS and AIDS (B20)

Diagnostic Criteria

For adults, adolescents and children >18 months of age, the CDC defines AIDS as an HIV-positive patient with any one of the following:

  • Current or prior diagnosis of an AIDS-defining condition


  • Current or prior CD4+ T-Lymphocyte count <200
  • The CD4 Count is a clinical indicator, however the provider MUST document AIDS, HIV related illness, etc., or a query is necessary.

Coding for HIV

For inpatient coding, the physician must state the diagnosis, and if not clearly documented, there is an opportunity to query for clarification.  For outpatient coding, it is often challenging for coders to determine if the patient is just HIV + (Z21) or if the patient has ever had an HIV-related illness (B20).  As of now, most outpatient coders do not have the capability to query for OP coding.  If the coder is unable to determine which the patient has based on the documentation provided, we should default to asymptomatic, rather than assigning the patient a diagnosis of AIDS.

Opportunistic Infections (OIs)

Healthy immune systems can be exposed to certain viruses, bacteria, or parasites and have no reaction to them.  However, people living with HIV/AIDS may have serious health threats from what are known as “opportunistic infections (OIs)”.  These infections attack the weakened immune system and can be life-threatening.  OIs are signs of a declining immune system.  Most life-threatening OIs occur when the CD4 count falls below 200 cells/mm3.  The CDC developed a list of more than 20 OIs that are considered AIDS-defining conditions. Patients having laboratory confirmed HIV infections and one or more of these OIs, will be diagnosed with AIDS regardless of the CD4 count.

Acquired Immunodeficiency Syndrome (AIDS)

AIDS is the final stage of human immunodeficiency virus (HIV) infection, stage 4 by the World Health Organization (WHO) criteria (2007) and stage 3 by Centers for Disease Control and Prevention (CDC) (2008) criteria or clinical categories B or C (CDC). AIDS code (B20) applies if AIDS has ever been previously diagnosed.  B20 must always be coded on every single subsequent encounter and never again code Z21 once AIDS is assigned.

  • Documentation coded as B20 –AIDS: HIC illness, HIV disease, ARC (AIDS – related complex), HIV symptomatic (any current AIDS-defining condition), HIV currently being treated for an HIV-related illness or is described as having any condition resulting from HIV + status, Acquired immune deficiency syndrome.
  • Once a patient has any HIV-related illness (OI0, every subsequent encounter should be coded as AIDS (B20)
  • Asymptomatic HIV (Z21) and inclusive HIV R75) are never reported once a patient has a confirmed diagnosis of AIDS.

Major AIDS-Related Conditions

Therapeutic Treatment

  • Antiretroviral treatment: (HAART) combination of drugs recommended
  • Pre-Exposure Prophylaxis (PrEP)
  • Post-Exposure Prophylaxis treatment for occupational exposure (PEP)

-Zidovudine (Retrovir, ZDZ,AZT) and Lamivudine (Epivir, 3TC) = Combivir

-Lamivudine (Epivir, 3TC) and Stavudine (Zerit, d4T)

-Didanosine (Videx, Videx EC, ddl) and Stavudine (Zerit,d4T)

  • Fulyzag for treatment of antiretroviral treatment induced diarrhea

A lot of information is included that I trust will clarify the assignment of HIV and AIDS as well as opportunities for query.   Take time to enjoy the Spring!


  1. Reference: Optum: Guide to Clinical Validation, Documentation and Coding (2014) p.34
  2. References: 2016 CDI Pocket Guide by R. D. Pinson, MD, FACP, CCS & C. L. Tang, RHIA, CCS. p.87, 88.
  3. Reference: Optum: Guide to Clinical Validation, Documentation and Coding (2014) p.30.
  4. Reference: U.S. Department of Health and Human Services. Potential Health Related Problems: Opportunistic Infections.  (2016).
  5. References: ICD-10-CM Official Guidelines and Reporting 2017 1.a.1.2


About the Author

Marie Thomas holds a Masters Healthcare Administration from Pfeiffer University, Charlotte, NC, and a Bachelor of Science in Healthcare Administration from Pfeiffer University. Marie has furthered her career education by becoming an AHIMA-Approved ICD-10-CM/PCS Trainer and Ambassador as well as earning the RHIT, CCS, CCDS, and CPC-H credentials. For more information please comment below.


Beginning the New Year revisiting HIV/AIDS


“Think like a wise man but communicate in the language of the people.”

– William Butler Yeats – Irish poet


Just as cleansing snowfalls, cooler breezes and overcast skies accompany January into the New Year, revenue cycle change is sure to follow.   All of us play a valuable role in the success of increasing quality while decreasing cost as we analyze documentation and assign appropriate codes. Centers for Medicare and Medicaid Services (CMS) have provided the healthcare road map.  It is up to us to understand, communicate and carry out the plan.

As we march forward together, clear, concise, crisp, timely, communication is necessary.  The tasks are requiring more detail and the skills are becoming more defined.  We seek 100% accuracy and learn daily from feedback to be the best we can be.   Resolve in 2017 to thrive with the flow of information and ideas that catapult us into new revenue cycle horizons as we collaborate and communicate together.

Beginning the New Year revisiting HIV/AIDS:

  • Human immunodeficiency virus (HIV) is a virus transmitted through contact with bodily fluids (blood, semen, vaginal secretions, breast milk) containing infected plasma or cells. Being HIV positive from a blood test showing HIV antibodies is not the same as having human immunodeficiency virus disease (AIDS).  “Do not use [code Z21] Asymptomatic human immunodeficiency virus infection status if the term ‘AIDS’ is used or if the patient is treated for any HIV-related illness or is described as having any condition(s) resulting from his/her HIV-positive status; use [code B20] human immunodeficiency virus disease in these cases.”
  • “When and OB patient is identified as having any HIV infection a [code from subcategory O98.7] is assigned with [code B20] assigned as an additional code. If an OB patient tests positive for HIV but has no symptoms and no history of an HIV infection, [codes O98.7- and Z21] are assigned rather than [code B20].”
  • 4 encounter for screening for HIV
  • 7 HIV counseling
  • 89 other problems related to lifestyle (high risk group for HIV infection)
  • 6 contact with and suspected to HIV
  • [Code B20] is NOT assigned when the diagnostic statement indicates that the infection is “suspected,” “possible,” “likely,” or “questionable”. This is an EXCEPTION to the general guideline that directs the coder to assign a code for a diagnosis qualified to ‘suspected” or “possible” as if it were established.  Confirmation in this case does not require documentation of a positive serology or culture for HIV, the provider’s diagnostic statement that the patient is HIV-positive or has an HIV-related illness is sufficient.  The provider should be asked to state the diagnosis in positive terms.
  • Once the patient is diagnosed as AIDS, HIV related disease [code B20], the patient is always reported as AIDS, HIV [code B20] related disease; not returned to the HIV status [code Z21]. “Patients with any known prior diagnosis of an HIV-related illness should be [coded to B20].  Once a patient has developed and HIV-related illness, the patient should always be assigned [code B20] on every subsequent admission/encounter.”

Additional Information:

  • Q: A patient with AIDS was treated in this hospital last year for AIDS-related histoplasmosis.  He is now admitted for acute nephritis.  In the record there is no clear statement that the nephritis is due to his AIDS.  What is the PDX?
  • A: Assign [N00.9] nephritis NOS as the PDX as there is no clear statement that the nephritis is an HIV-related disease.  The coder should not make such assumptions without clear indications within the record.  [Code B20] should be listed as an additional diagnosis. Coding Clinic 4Q 1994 p.35
  • Q: An AIDS patient is admitted for treatment of severe diarrhea and dehydration.  He is diagnosed to have Cryptosporidiosis with dehydration.  How should this be sequenced?
  • A: Assign [B20], [A07.2], [E86.0].  Coding Clinic 4Q 1997 p. 30,31
  • When documentation is unclear or conflicting, the provider must be queried for clarification.

I look forward to working alongside each of you, researching and supporting all the efforts that go into fulfilling a valued and respected profession, coder.  Greet each day with a smile of exhilaration and passion.

About the Author

Marie Thomas holds a Masters Healthcare Administration from Pfeiffer University, Charlotte, NC, and a Bachelor of Science in Healthcare Administration from Pfeiffer University. Marie has furthered her career education by becoming an AHIMA-Approved ICD-10-CM/PCS Trainer and Ambassador as well as earning the RHIT, CCS, CCDS, and CPC-H credentials. For more information please email us at