title: Multisite evaluation of point of care CD4 testing in Papua New Guinea.
abstract: Laboratory-based CD4 monitoring of HIV patients presents challenges in resource limited settings (RLS) including frequent machine breakdown, poor engineering support and limited cold chain and specimen transport logistics. This study assessed the performance of two CD4 tests designed for use in RLS; the Dynal assay and the Alere PIMA test (PIMA). Accuracy of Dynal and PIMA using venous blood was assessed in a centralised laboratory by comparison to BD FACSCount (BD FACS). Dynal had a mean bias of -50.35 cells/µl (r(2) = 0.973, p<0.0001, n = 101) and PIMA -22.43 cells/µl (r(2)= 0.964, p<0.0001, n = 139) compared to BD FACS. Similar results were observed for PIMA operated by clinicians in one urban (n = 117) and two rural clinics (n = 98). Using internal control beads, PIMA precision was 10.34% CV (low bead mean 214.24 cells/µl) and 8.29% (high bead mean 920.73 cells/µl) and similar %CV results were observed external quality assurance (EQA) and replicate patient samples. Dynal did not perform using EQA and no internal controls are supplied by the manufacturer, however duplicate testing of samples resulted in r(2) = 0.961, p<0.0001, mean bias =  -1.44 cells/µl. Using the cut-off of 350 cells/µl compared to BD FACS, PIMA had a sensitivity of 88.85% and specificity of 98.71% and Dynal 88.61% and 100%. A total of 0.44% (2/452) of patient samples were misclassified as "no treat" and 7.30% (33/452) "treat" using PIMA whereas with Dynal 8.91% (9/101) as "treat" and 0% as "no treat". In our setting PIMA was found to be accurate, precise and user-friendly in both laboratory and clinic settings. Dynal performed well in initial centralized laboratory evaluation, however lacks requisite quality control measures, and was technically more difficult to use, making it less suitable for use at lower tiered laboratories.
authors.affiliation: Clinton Health Access Initiative, Port Moresby, Papua New Guinea.
authors.forename: Malin
authors.initials: M
authors.lastname: Malagun
authors.affiliation: National Department of Health, HIV Division, Port Moresby, Papua New Guinea.
authors.forename: Gideon
authors.initials: G
authors.lastname: Nano
authors.affiliation: Clinton Health Access Initiative, Port Moresby, Papua New Guinea.
authors.forename: Caroline
authors.initials: C
authors.lastname: Chevallier
authors.affiliation: Heduru Clinic, Port Moresby General Hospital, Papua New Guinea.
authors.forename: Ragagalo
authors.initials: R
authors.lastname: Opina
authors.affiliation: Heduru Clinic, Port Moresby General Hospital, Papua New Guinea.
authors.forename: Gola
authors.initials: G
authors.lastname: Sawiya
authors.affiliation: Central Public Health Laboratory, HIV Section, Port Moresby, Papua New Guinea.
authors.forename: Joseph
authors.initials: J
authors.lastname: Kivavia
authors.affiliation: Pathology Department, Port Moresby General Hospital, Port Moresby, Papua New Guinea.
authors.forename: Albina
authors.initials: A
authors.lastname: Kalinoe
authors.affiliation: Pathology Department, Port Moresby General Hospital, Port Moresby, Papua New Guinea.
authors.forename: Kathalina
authors.initials: K
authors.lastname: Nathaniel
authors.affiliation: Central Public Health Laboratory, Quality Assurance Section, Port Moresby, Papua New Guinea.
authors.forename: Oscillah
authors.initials: O
authors.lastname: Kaminiel
authors.affiliation: National Department of Health, Port Moresby, Papua New Guinea.
authors.forename: John
authors.initials: J
authors.lastname: Millan
authors.affiliation: Clinton Health Access Initiative, Goroka, Papua New Guinea.
authors.forename: Andrea
authors.initials: A
authors.lastname: Carmone
authors.affiliation: Pathology Department, Goroka General Hospital, Papua New Guinea.
authors.forename: Mary
authors.initials: M
authors.lastname: Dini
authors.affiliation: Pathology Department, Goroka General Hospital, Papua New Guinea.
authors.forename: Theresa
authors.initials: T
authors.lastname: Palou
authors.affiliation: Asaro District Health Centre, Eastern Highlands Province, Papua New Guinea.
authors.forename: Kum
authors.initials: K
authors.lastname: Topma
authors.affiliation: Central Public Health Laboratory, Papua New Guinea.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Lavu
authors.affiliation: Clinton Health Access Initiative, Goroka, Papua New Guinea.
authors.forename: Jessica
authors.initials: J
authors.lastname: Markby
mesh_terms: D000328:Adult; D018791:CD4 Lymphocyte Count / Q000191:economics / Q000295:instrumentation / Q000592:standards*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology* / Q000821:virology; D003906:Developing Countries; D005260:Female; D015658:HIV Infections / Q000175:diagnosis* / Q000191:economics / Q000276:immunology / Q000821:virology; D006405:Hematology; D006801:Humans; D007753:Laboratories; D008297:Male; D010219:Papua New Guinea; D019095:Point-of-Care Systems / Q000191:economics / Q000592:standards*; D011786:Quality Control; D012680:Sensitivity and Specificity