Point-of-Care CD4 Testing in Resource-Limited Settings

Is CD4 Testing Outside of the Laboratory Ready for Prime Time?

Shahin Lockman, MD, MS


October 03, 2012

In This Article

Is Point-of-Care CD4 Testing Ready for Prime Time?

Accumulating data generally show good agreement between CD4 results obtained by point-of-care testing and those from conventional laboratory methods, including in-field conditions in resource-limited settings,[9,10,11,12,13,14,15,16,17] although not all studies have demonstrated such good performance.[18] The sensitivity and specificity of the point-of-care CD4 testing platforms that have been tested seem to be around 90%-98% for establishing a CD4 count below the current treatment eligibility thresholds in resource-limited settings (< 350 cells/µL or < 250 cells/µL).[13,15] Some studies,[13,14] but not others,[10] suggest that results are more accurate with blood samples obtained by venipuncture. The World Health Organization "prequalified" the Pima™ point-of-care CD4 test (Alere Technologies GmbH; Jena, Germany) in December 2011,[19] and other point-of-care CD4 testing platforms are being tested or developed.

Undoubtedly, numerous challenges will arise with widespread implementation of point-of-care CD4 testing. Trevor Peter, PhD, Scientific Director of Diagnostics Services at the Clinton Health Access Initiative, commented:

Point-of-care CD4 testing can significantly improve access to ART-related services and should be considered as a potential intervention to reduce pre-ART loss-to-follow-up in many settings. However, it is important to note that implementing point-of-care CD4 testing alone is not sufficient. Loss to follow-up is still significant despite point-of-care CD4 testing, and initiatives are needed to address this. In addition, with point-of-care CD4 testing, the number of test sites will increase dramatically; systems to manage quality, supply chain, training, and data management will be needed in order to ensure that the service remains reliable.

Nevertheless, although data on the accuracy of different point-of-care CD4 testing platforms are still emerging and such issues as interuser variability and quality assurance are likely to pose challenges as this testing is rolled out, the potential benefits of access to point-of-care CD4 (specifically, enhancing linkage to care and ART and shortening time to ART initiation) will probably outweigh the downsides.

Pre-ART CD4 testing may become a less critical roadblock if programs move toward supporting universal ART initiation in all HIV-infected persons regardless of CD4 count.[20] However, CD4 testing will remain useful for clinical staging. In addition, the lessons that we learn from testing and implementing point-of-care CD4 testing may prove useful with potential future point-of-care assays for persons living with HIV in resource-limited settings, such as HIV-1 RNA testing to assess treatment response.