Evaluation of PIMA point-of-care CD4 testing in a large UK HIV service

To evaluate the performance and patient acceptability of the PIMA point-of-care (POCT) CD4 test.

Parallel POCT and laboratory CD4 testing were performed in newly diagnosed HIV patients and those with chronic infection attending routine or emergency clinics. Demographics, clinical status and time taken for CD4 results to be available were recorded. Patient acceptability was assessed using a five-point Likert scale. POCT and laboratory results were compared.

283 patients underwent POCT and laboratory CD4 testing. Paired laboratory and POCT results were available in 269 patients. After excluding 15 patients tested during the lead-in period, the test comparison was based on 254 results. Most patients were asymptomatic, male and white British reflecting this patient cohort. 236 patients were chronically infected and 47 were newly diagnosed HIV positive. The POCT result was available within 30 min (86%). The laboratory and POCT results were strongly correlated, r=0.93 (p<0.001), but were generally lower for the POCT (201/254 (79%): p<0.001). As a percentage of the laboratory count, the median (95% range) POCT was 87% (57%-126%). The difference between the POCT and laboratory result was greater for those patients attending the emergency clinic. The sensitivity and specificity of the POCT, to identify patients with laboratory CD4 below 350, were 95% (95% CI 88% to 98%) and 88% (95% CI 82% to 93%), respectively. 235 (83%) patients completed the questionnaire and the POCT was highly acceptable.

POCT CD4 was highly correlated with laboratory CD4 testing in this cohort, provided immediate results and was highly acceptable to patients.