Inadequate dried blood spot samples for Early Infant Diagnosis, how common and what are the reasons for rejection in Zimbabwe?

Abstract

Background Early infant diagnosis (EID) of HIV in infants provides an opportunity for early detection of the infection and early access to Antiretroviral treatment (ART). Dried Blood Spot (DBS) samples are used for EID of HIV-exposed infants, born from HIV positive mothers. However, DBS rejection rates have been exceeding in Zimbabwe the target of less than 2% per month set by the National Microbiology Reference Laboratory (NMRL). The aim of this study was to determine the DBS samples rejection rate, the reasons for rejection and the possible associations between rejection and level of health facility where the sample was collected.

Methods Analytic cross-sectional study using routine DBS samples data from the NMRL in Harare, Zimbabwe, between January and December 2017.

Results A total of 34.950 DBS samples were received at the NMRL. Of these, 1291(4%) were rejected and reasons for rejections were: insufficient specimen volume (72%), missing request form (11%), missing sample (6%), cross contamination (6%), mismatch information (4%) and clotted sample (1%). Samples collected from clinics/rural health facilities had five times likelihood to be rejected compared to those from a central hospital.

Conclusion Rejection rates were above the set target of 2%. The reasons for rejection were ‘pre-analytical’ errors including labeling errors, sample damage, missing or inconsistent data, and insufficient volume. Samples collected at primary healthcare facilities had higher rejection rates.