Alere Pima™ CD4
Independent Clinical Studies
Alere Pima™ CD4
Below are summaries of a number of independent clinical studies featuring the Alere Pima™ CD4 test. For more studies and links to papers please visit our Studies and Implementations map.
Evaluation of Pima point-of-care CD4 testing in a large UK HIV service.
Sophie Herbert*, Simon Edwards, Gina Carrick, Andrew Copas, Christopher Sandford, Marc Amphlett, Paul Benn.
Sex Transm Infect. 2012 Apr 27. Epub ahead of print, DOI 10.1136/sextrans-2012-050507
*Central and North West London NHS Foundation Trust, London, UK.
This study was conducted between December 2010 and July 2011 at the United Kingdom's largest HIV outpatient service which serves a cohort of approximately 3,900 clients. The aims of this study were to assess the performance of the Alere Pima™ CD4 test used on capillary blood against the standard of care flow cytometry reference method (Beckman Coulter) used at the study site. Patients' acceptability of the new test as well as the impact of point-of-care CD4 testing on patient flow were also assessed.
A total of 254 patients with paired results from the Alere Pima™ CD4 test and the flow cytometry reference method were evaluated in this study. The authors observed that Alere Pima™ CD4 correlated well with the reference method and concluded that for treatment initiation decisions at the typical threshold of 350 cells/?l, the assay yielded high sensitivity and specificity.
To assess patient acceptability of point-of-care CD4 testing all patients undergoing Alere Pima™ CD4 testing were asked to complete a questionnaire on their testing experience; 235 patients completed the survey. The majority of participants reported favourable experience with point-of-care testing and fingerstick sample collection compared to conventional CD4 testing from venous blood. For example 87% of the participants were happy to wait 20 minutes for the result and 82% found it helpful to receive the CD4 test result on the same day of sampling. Only a minority experienced the point-of-care testing scenario as stressful (12%) and would rather have an additional doctor's appointment to receive the result (16%). Interestingly, almost half of the participants (49%), especially those with chronic stable infection, would be happy to have the CD4 testing being performed at the point-of-care by their general practitioner.
Another observation highlighted by Herbert et al. was that access to point-of-care CD4 testing was particularly beneficial for newly diagnosed patients, of whom there were 47 during the study period. Despite having relatively good access to conventional CD4 testing, in which results are typically returned to the clinic within 48 hours, and a well developed triaging algorithm driven by medical need, the availability of CD4 test results at the time of diagnosis allowed for more rapid interventions to be taken with a reduced number of follow up visits being required. While more tailored intervention strategies could be immediately initiated without undue delay in symptomatic patients, asymptomatic patients with CD4 counts less than 350 cells/?l (45%) were able to be fast tracked to follow up visits within one week whereas those with CD4 counts more than 350 cells/?l were offered a standard appointment within two and four weeks.
Overall the authors conclude that the Alere Pima™ CD4 test correlates well with the reference method, is well received by the majority of patients and provides significant benefits for clinical management even in well resourced settings with good access to laboratory services.
The reliability of point-of-care CD4 testing in identifying HIV-infected pregnant women eligible for antiretroviral therapy.
Coceka Mnyani*, James McIntyre, Landon Myer.
JAIDS. 2012. Epub ahead of print, DOI: 10.1097/QAI.0b013e318256b651
*Anova Health Institute, Johannesburg, South Africa.
Antiretroviral therapy for pregnant women living with HIV is a proven cornerstone in the prevention of mother to child transmission. Most HIV programs in resource limited settings rely on immunological and/or clinical staging in order to decide whether and when to initiate ART for these women. Unfortunately clinical staging has proven unreliable with one recent study demonstrating that this method only identified 23% of ART eligible women while CD4 testing identified 94% (Carter 2010). This finding highlights the fact that timely immunological staging for pregnant women would be a critical component for successful PMTCT programs. Given the potential for improved access to CD4 results offered by the Alere Pima™ CD4 test Mnyani et al. sought to determine the accuracy of the test compared to standard of care flow cytometry reference method (Beckman Coulter) specifically within the context of pregnancy and HIV.
Between January and September 2011 the authors enrolled a total of 296 pregnant women living with HIV, making their first visit to an antenatal clinic in Johannesburg. During that period a total of 1,862 women presented at the clinic for their first visit, yielding an HIV prevalence of 24%. For the 296 women living with HIV a CD4 test was performed on capillary blood using the Alere Pima™ CD4 test and a venous sample was drawn in parallel for evaluation with the reference method.
The authors found good agreement between Alere Pima™ CD4 and the reference method. Using a laboratory threshold of 350 cells/?l, Alere Pima™ CD4 was able to accurately identify 93% of pregnant women as ART eligible. Importantly, neither gestational age nor potential pregnancy-associated haemodilution (arguing for the use of CD4 percentage in pregnant women) had an effect on the performance of the Alere Pima™ CD4 test.
This evaluation provides a compelling case for inclusion of point-of-care CD4 testing in antenatal clinics. Demonstrated excellent performance, improved access to CD4 testing and availability of same day results within a single clinic visit as provided by the Alere Pima™ CD4 test could have a significant role to play in the goal of eliminating MTCT.
Carter, R.J et al (2010) CD4 Cell Count Testing More Effective Than HIV Disease Clinical Staging in Identifying Pregnant and Postpartum Women Eligible for Antiretroviral Therapy in Resource-Limited Settings . JAIDS 2010; 55(3):404-410.
Effect of point-of-care CD4 cell count tests on retention of patients and rates of antiretroviral therapy initiation in primary health clinics: an observational cohort study.
Ilesh Jani*, Madia Sitoe, Eunice Alfai, Patrina Chongo, Jorge Quevedo, Beatriz Rocha, Jonathon Lehe, Trevor Peter.
The Lancet. 2011 Oct 29;378(9802):1572-79.
*Instituto Nacional da Saúde, Maputo, Mozambique.
Losing track of patients after a positive HIV diagnosis is a major problem limiting the ability to provide life saving care in many regions of the world. Studies of the pre-ART loss to follow up issue suggest that the rates can be as high as 80% in some situations. Jani et al. set out to determine the impact of the Alere Pima™ CD4 test on loss to follow up rates at primary health clinics in Mozambique, where HIV diagnosis is provided. The authors introduced Alere Pima™ CD4 tests in the patient care algorithm of four clinics in various settings ranging from peri-urban to rural. To determine the status quo at the participating sites, 492 patients were enrolled before the introduction of point-of-care CD4 and their path within the health care system was analysed. This data served as baseline information to assess the impact of the Alere Pima™ CD4 test. Between March and April 2010, 437 patients participated in the point-of-care CD4 arm of this study.
Introduction of Alere Pima™ CD4 testing at the primary health clinics was associated with a substantial drop in loss to follow up between enrolment and ART initiation from 64% to 33%. This effect seems to be largely due to reduced loss to follow up before immunological staging since this decreased from 57% to 21% following the introduction of Alere Pima™ CD4. Loss to follow up between immunological staging and initiating ART was largely unchanged. While this problem highlights the fact that further work is needed to strengthen health systems and follow up strategies, it also highlights the significant positive impact that on site CD4 testing has on retention in care.
Other interesting observations from this study include that the turn around time for delivering a CD4 result to the patient decreased from a median of 32 to 3 days after introducing Alere Pima™ CD4, in turn reducing median time to initiation of ART from 48 to 20 days and increasing the proportion of enrolled patients commencing ART during the study period from 12% to 21%.
While the longer term loss to follow up rates after initiation of ART still require further investigation and interventions, Jani et al's work provides a compelling argument that Alere Pima™ CD4 placed in the correct setting has a critical role to play in substantially reducing pre-ART initiation loss to follow up.