Why count CD4 cells?

 

CD4 T lymphocytes (CD4 cells) are a type of white blood cell in human blood that play a major role in protecting the body from infection. 

Debi Boeras,
CEO of The Global Health Impact Group

Tom Chiller,
Chief of the Mycotic Diseases branch at the Centres for Disease and Control and Prevention

Ben Cheng,
Specialist Consultant working to develop tech to aid treatment and diagnosis of HIV


 

Counting cells is vital

 

Counting the number of CD4 cells in a patient’s blood is the only accurate way of monitoring how well their immune system is working and predicting the progression of HIV. To reinforce this, the World Health Organization (WHO) has issued new guidelines to advise that CD4 cell counting is an essential part of the initial diagnosis and management of advanced HIV disease.

"The longer it takes to link patients with treatment, the more likely they are to fall out of the system completely."

“Up to 30 per cent of patients coming in have advanced HIV disease, which means their CD4 cell count is below 200,” explains Debi Boeras, CEO of The Global Health Impact Group, an organization that helps to integrate diagnostics and care. “These individuals are likely to be really sick and susceptible to cryptococcal meningitis, TB and other infections.”

 

Accurate diagnosis means effective treatment

 

Many patients with advanced HIV disease may look healthy, so accurate and early diagnosis is key to ensure they are put on an advanced package of care, that could prevent potentially fatal outcomes.

"Up to 30% of patients have advanced HIV, which means their CD4 cell count is below 200."

Tom Chiller, Chief of the Mycotic Diseases branch at the Centres for Disease and Control and Prevention, explains “If you put someone on antiretroviral therapy and you don’t know their CD4 count or the degree to which their immune system is compromised, they could develop IRIS – immune reconstitution inflammatory syndrome – from which they can die.”

In response, ministries of health need to coordinate CD4 cell count testing on a national scale. “In South Africa they have about 64 CD4 labs and the samples come in and are processed very quickly. That type of system can work fantastically well, but only if you set it up and have the money to run it and maintain it,” continues Chiller.

 

Improving infrastructure in rural communities

 

The majority of countries still don’t have the infrastructure, transport or technology to effectively manage the blood samples and communicate results back to patients and clinics. Despite advances in the quality and accuracy of diagnostic tests used for near-patient testing, it remains difficult to deliver equipment and supplies to keep the service running in hard to reach communities. Furthermore, with a rapid turnover of healthcare staff, maintaining consistency is an issue too.

“The majority of countries still don’t have the infrastructure, transport or technology to effectively manage the blood samples.”

But change is happening; IT infrastructure that supports remote testing in rural areas is being developed.

“One of the things we’ve been working on is connecting these near-patient technologies up to a central server, so the ministry knows where the devices are, if they’re working and if they’re being used properly,” says Ben Cheng, a specialist consultant who works with a range of partners to develop technologies to aid treatment and diagnosis of HIV.

 

Integrating diagnostics and care

 

The longer it takes to link a patient with treatment, the more likely they are to drop out of the system completely. So, if we are to reduce mortality rates, then the final piece of the jigsaw is to connect patients identified as having advanced HIV disease with the correct package of care as quickly as possible.

“We have four key players: the patient, the clinician, the testing and the treatment,” continues Boeras. “In an ideal world we need to get them all into the same room. Bringing the testing together with the clinical support will help to engage people in the healthcare system.”

New WHO guidelines and technological advancements are all vital, but the health of those with HIV depends on specialists from different disciplines working together with a single focus on patient care.

 

 


*References

For the role of CD4 in HIV analysis and patient management:
WHO (2016): Consolidated guidelines on the use of antiretroviral drugs for treating and preventing HIV
infection: recommendations for a public health approach – 2nd ed.
WHO (2017): Guidelines for managing advanced HIV disease and rapid initiation of antiretroviral therapy.

In addition, WHO published information notes that further define the role of CD4:
WHO (2017): What’s new in treatment monitoring: Viral load and CD4 testing. Information Note WHO/HIV/2017.22.