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      Performance of point-of-care CD4 testing technologies in resource-constrained settings: a systematic review and meta-analysis

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          Abstract

          Background

          Point-of-care (POC) CD4 testing increases patient accessibility to assessment of antiretroviral therapy eligibility. This review evaluates field performance in low and middle-income countries (LMICs) of currently available POC CD4 technologies.

          Methods

          Eight electronic databases were searched for field studies published between January 2005 and January 2015 of six POC CD4 platforms: PointCare NOW™, Alere Pima™ CD4, Daktari™ CD4 Counter, CyFlow® CD4 miniPOC, BD FACSPresto™, and MyT4™ CD4. Due to limited data availability, meta-analysis was conducted only for diagnostic performance of Pima at a threshold of 350 cells/μl, applying a bivariate multi-level random-effects modelling approach. A covariate extended model was also explored to test for difference in diagnostic performance between capillary and venous blood.

          Results

          Twenty seven studies were included. Published field study results were found for three of the six POC CD4 tests, 24 of which used Pima. For Pima, test failure rates varied from 2 to 23 % across study settings. Pooled sensitivity and specificity were 0.92 (95 % CI = 0.88–0.95) and 0.87 (95 % CI = 0.85–0.88) respectively. Diagnostic performance by blood sample type (venous vs. capillary) revealed non-significant differences in sensitivity (0.94 vs 0.89) and specificity (0.86 vs 0.87), respectively in the extended model (Wald χ 2(2) = 4.77, p = 0.09).

          Conclusions

          POC CD4 testing can provides reliable results for making treatment decision under field conditions in low-resource settings. The Pima test shows a good diagnostic performance at CD4 cut-off of 350 cells/μl. More data are required to evaluate performance of POC CD4 testing using venous versus capillary blood in LMICs which might otherwise influence clinical practice.

          Electronic supplementary material

          The online version of this article (doi:10.1186/s12879-016-1931-2) contains supplementary material, which is available to authorized users.

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          Most cited references40

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          Towards complete and accurate reporting of studies of diagnostic accuracy: The STARD Initiative.

          To comprehend the results of diagnostic accuracy studies, readers must understand the design, conduct, analysis, and results of such studies. That goal can be achieved only through complete transparency from authors. To improve the accuracy and completeness of reporting of studies of diagnostic accuracy in order to allow readers to assess the potential for bias in the study and to evaluate its generalizability. The Standards for Reporting of Diagnostic Accuracy (STARD) steering committee searched the literature to identify publications on the appropriate conduct and reporting of diagnostic studies and extracted potential items into an extensive list. Researchers, editors, methodologists and statisticians, and members of professional organizations shortened this list during a 2-day consensus meeting with the goal of developing a checklist and a generic flow diagram for studies of diagnostic accuracy. The search for published guidelines on diagnostic research yielded 33 previously published checklists, from which we extracted a list of 75 potential items. The consensus meeting shortened the list to 25 items, using evidence on bias whenever available. A prototypical flow diagram provides information about the method of patient recruitment, the order of test execution, and the numbers of patients undergoing the test under evaluation, the reference standard, or both. Evaluation of research depends on complete and accurate reporting. If medical journals adopt the checklist and the flow diagram, the quality of reporting of studies of diagnostic accuracy should improve to the advantage of the clinicians, researchers, reviewers, journals, and the public.
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            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.

            Loss to follow-up of HIV-positive patients before initiation of antiretroviral therapy can exceed 50% in low-income settings and is a challenge to the scale-up of treatment. We implemented point-of-care counting of CD4 cells in Mozambique and assessed the effect on loss to follow-up before immunological staging and treatment initiation. In this observational cohort study, data for enrolment into HIV management and initiation of antiretroviral therapy were extracted retrospectively from patients' records at four primary health clinics providing HIV treatment and point-of-care CD4 services. Loss to follow-up and the duration of each preparatory step before treatment initiation were measured and compared with baseline data from before the introduction of point-of-care CD4 testing. After the introduction of point-of-care CD4 the proportion of patients lost to follow-up before completion of CD4 staging dropped from 57% (278 of 492) to 21% (92 of 437) (adjusted odds ratio [OR] 0·2, 95% CI 0·15-0·27). Total loss to follow-up before initiation of antiretroviral treatment fell from 64% (314 of 492) to 33% (142 of 437) (OR 0·27, 95% CI 0·21-0·36) and the proportion of enrolled patients initiating antiretroviral therapy increased from 12% (57 of 492) to 22% (94 of 437) (OR 2·05, 95% CI 1·42-2·96). The median time from enrolment to antiretroviral therapy initiation reduced from 48 days to 20 days (p<0·0001), primarily because of a reduction in the median time taken to complete CD4 staging, which decreased from 32 days to 3 days (p<0·0001). Loss to follow-up between staging and antiretroviral therapy initiation did not change significantly (OR 0·84, 95% CI 0·49-1·45). Point-of-care CD4 testing enabled clinics to stage patients rapidly on-site after enrolment, which reduced opportunities for pretreatment loss to follow-up. As a result, more patients were identified as eligible for and initiated antiretroviral treatment. Point-of-care testing might therefore be an effective intervention to reduce pretreatment loss to follow-up. Absolute Return for Kids and UNITAID. Copyright © 2011 Elsevier Ltd. All rights reserved.
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              High HIV testing uptake and linkage to care in a novel program of home-based HIV counseling and testing with facilitated referral in KwaZulu-Natal, South Africa.

              For antiretroviral therapy (ART) to have a population-level HIV prevention impact, high levels of HIV testing and effective linkages to HIV care among HIV-infected persons are required. We piloted home-based counseling and testing (HBCT) with point-of-care CD4 count testing and follow-up visits to facilitate linkage of HIV-infected persons to local HIV clinics and uptake of ART in rural KwaZulu-Natal, South Africa. Lay counselor follow-up visits at months one, three and six evaluated the primary outcome of linkage to care. Plasma viral load was measured at baseline and month six. 671 adults were tested for HIV (91% coverage) and 201 (30%) were HIV-infected, of which 73 (36%) were new diagnoses. By month three, 90% of HIV-infected persons not on ART at baseline had visited an HIV clinic and 80% of those eligible for ART at baseline by South African guidelines (CD4≤200 cells/μL at the time of the study) had initiated ART. Among HIV-infected participants who were eligible for ART at baseline, mean viral load decreased by 3.23 log10 copies/mL (p<0.001) and the proportion with viral load suppression increased from 20% to 80% between baseline and month six. In this pilot of HBCT and linkages to care in KwaZulu-Natal, 91% of adults were tested for HIV. Linkage to care was ∼90% both among newly-identified HIV-infected persons as well as known HIVinfected persons who were not engaged in care. Among those eligible for ART, a high proportion initiated ART and achieved viral suppression, indicating high adherence and reduced infectiousness.
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                Author and article information

                Contributors
                +61 0392822128 , minh.pham@burnet.edu.au
                pagius@burnet.edu.au
                L.romeo@alfred.org.au
                peter.mcglynn@monash.edu
                anderson@burnet.edu.au
                crowe@burnet.edu.au
                sluchters@burnet.edu.au
                Journal
                BMC Infect Dis
                BMC Infect. Dis
                BMC Infectious Diseases
                BioMed Central (London )
                1471-2334
                21 October 2016
                21 October 2016
                2016
                : 16
                : 592
                Affiliations
                [1 ]Burnet Institute, 85 Commercial Road, Melbourne, VIC 3004 Australia
                [2 ]Department of Epidemiology and Preventive Medicine, Faculty of Medicine Nursing and Health Science, Monash University, Melbourne, Australia
                [3 ]The Alfred Hospital, The Ian Potter Library, Melbourne, VIC Australia
                [4 ]Department of Immunology, Faculty of Medicine Nursing and Health Science, Monash University, Melbourne, Australia
                [5 ]Department of Infectious Diseases, The Alfred Hospital and Monash University, Melbourne, Australia
                [6 ]Department of Obstetrics and Gynecology, International Centre for Reproductive Health, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
                Article
                1931
                10.1186/s12879-016-1931-2
                5073828
                27769181
                6fd16b76-871b-4150-8b18-4ae149a9b212
                © The Author(s). 2016

                Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

                History
                : 24 June 2016
                : 13 October 2016
                Funding
                Funded by: National Health and Medical Research Council of Australia
                Award ID: Project grant GNT 1063725, and Career Development Fellowship
                Award Recipient :
                Funded by: NHMRC Principle Research fellowship
                Funded by: International Postgraduate Research Scholarship (IPRS) from the Commonwealth of Australia and the Victorian International Research Scholarship (VIRS) from State Government of Victoria, Australia (VIRS)
                Categories
                Research Article
                Custom metadata
                © The Author(s) 2016

                Infectious disease & Microbiology
                cd4,point of care testing,diagnostic accuracy,systematic review,meta-analysis

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