{"id":28045,"date":"2015-03-24T09:21:54","date_gmt":"2015-03-24T09:21:54","guid":{"rendered":"http:\/\/i-base.info\/htb\/?p=28045"},"modified":"2015-03-24T11:39:23","modified_gmt":"2015-03-24T11:39:23","slug":"point-of-care-hiv-pcr-test-for-infant-diagnosis-good-performance-but-poorer-results-in-youngest-age-group","status":"publish","type":"post","link":"https:\/\/i-base.info\/htb\/28045","title":{"rendered":"Point of care HIV PCR test for infant diagnosis: good performance but poorer results in youngest age group"},"content":{"rendered":"

Polly Clayden, HIV i-Base<\/strong><\/p>\n

\"CROI<\/p>\n

A point of care (POC) assay performed well in infant diagnosis in a large laboratory study. But its error rate of 6% has implications for implementation and its newborn performance requires further evaluation.<\/strong><\/p>\n

Nei-Yuan Hsiao from the University of Cape Town presented these findings at CROI 2015.<\/p>\n

The study evaluated the Alere q HIV1\/2, a qualitative POC, nucleic acid test for HIV designed for use in the clinic that does not require a laboratory or extensive training. The test is real-time PCR, targeting unspliced HIV RNA, cartridge based, requiring a 25 uL blood sample with turnaround time of approximately 55 minutes.<\/p>\n

Samples were routinely collected from HIV-exposed infants in the Western Cape from December 2013 to August 2014 from: primary care facilities (infants); maternity services (newborns < 7 days) and tertiary hospitals (infants and newborns).<\/p>\n

The performance of the POC assay was compared with the local standard-of-care (SOC), Roche CAP\/CTM HIV-1 V1 qualitative PCR in a laboratory setting and to the final infant HIV status (positive on two different PCR assays or two positive PCR assays on two different samples).<\/p>\n

The investigators tested 1131 samples from 1098 infants with a median age of 47 days (IQR: 42 \u2013117); 90 were newborns. The majority of samples were from primary facilities (74%), the remainder were from tertiary paediatric services (19%) and maternity services (7%).<\/p>\n

There were error results in 60 samples (6%) with the first test of which, 70% were resolved with a repeat test, and >90% were assay or sample related. Errors are more common with newborns.<\/p>\n

Excluding retest or errors, sensitivity of Alere q was 95.5% (95% CI: 91.7 to 97.9) and specificity was 99.8% (95% CI: 99.1 to 100%). See Table 1 for results.<\/p>\n\n\n\n\n\n\n\n\n
Table 1: POC performance against SOC assay<\/caption>\n
Alere q first test<\/th>\nRoche CAP\/CTM HIV-1 PCR<\/th>\n<\/tr>\n
Positive<\/td>\nNegative<\/td>\nTotal<\/td>\n<\/tr>\n
Positive<\/td>\n192<\/td>\n2<\/td>\n194<\/td>\n<\/tr>\n
Negative<\/td>\n9<\/td>\n832<\/td>\n841<\/td>\n<\/tr>\n
Error<\/td>\n11<\/td>\n52<\/td>\n63<\/td>\n<\/tr>\n
Total<\/td>\n212<\/td>\n886<\/td>\n1098<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Dr Hsiao noted that with re-test, sensitivity improved but specificity remained the same.<\/p>\n

False negative samples had a median cycle threshold (CT) value of 33 on the SOC assay, higher than the true positives and errors, both p<0.001. This was possibly due to lower levels of circulating virus during early infection.<\/p>\n

Performance against the final infant HIV test result, excluding indeterminate status and Alere q errors: sensitivity 96.9% (95% CI: 93.4 to 98.9) and specificity 100% (lower 95% CI: 99.6)<\/p>\n

Stratified by age group, the investigators found the performance was worse in younger infants: 6-10 weeks, sensitivity 96%, specificity 100%, error rate, 4%; newborns <7 days, sensitivity 93%, specificity 100%, error rate 10%.<\/p>\n

Reference:<\/p>\n

Hsiao N et al. Evaluation of the Alere q for point-of-care early infant HIV diagnosis in South Africa. CROI 2015. Seattle, Washington. 23-26 February 2015. Oral abstract 34.
\nhttp:\/\/www.croiconference.org\/sessions\/evaluation-alere-q-point-care-early-infant-hiv-diagnosis-south-africa<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Polly Clayden, HIV i-Base A point of care (POC) assay performed well in infant diagnosis in a large laboratory study. But its error rate of 6% has implications for implementation and its newborn performance requires further evaluation. Nei-Yuan Hsiao from …<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,35,32,21],"tags":[203],"class_list":["post-28045","post","type-post","status-publish","format-standard","hentry","category-conference-reports","category-pmtct-and-maternal-health","category-paediatric-care","category-diagnostic","tag-croi-2015"],"_links":{"self":[{"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/posts\/28045","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/comments?post=28045"}],"version-history":[{"count":0,"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/posts\/28045\/revisions"}],"wp:attachment":[{"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/media?parent=28045"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/categories?post=28045"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/tags?post=28045"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}