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

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.


INTRODUCTION
Prevention of mother-to-child transmission (PMTCT) of HIV is one of the most an important 53 tool for global elimination of pediatric HIV infection [1,2]. WHO recommends Early Infant 54 Diagnosis (EID) to be performed as part of PMTCT on HIV-exposed infants within four to six 55 weeks of age [1]. in the implementation of PMTCT and ART programs. However, only half (51%) of the HIV-60 exposed infants receive an EID test by the age of six to eight weeks or at earliest possible 61 opportunity [1]. If the EID test is negative at 6-8 weeks and HIV exposure through breast feeding 62 continues, the test must be repeated at weaning. Thereafter, definitive diagnosis after 18 months 63 is done using rapid test [6]. It has been said that if HIV-positive infant is given ART within the 64 first 12 weeks of life, they are 75% less likely to die from an AIDS related illness [4,5]. The laboratory rejects all samples that do not meet the criteria indicated in Box 1.
80 Figure 1 below shows the DBS samples that were being accepted for testing, anything that was 81 not meeting this criteria in terms of volume was being rejected. 84 There is evidence that insufficient specimen volume is one of the major reasons for high 85 proportion of DBS rejections. It is unclear why that is a case, given that the evidence also 86 suggests that the technology used for testing DBS samples can analyse and produce conclusive 87 results from samples with minimum of two full spots [ . The same stuy also showed that DBS collected at primary and 100 secondary health care facilities were two to three times more likely to be rejected than those 101 collected at tertiary healthcare facilities [10].

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In Zimbabwe, it takes up to fourteen days from sample collection before NMRL communicates 103 rejection to the submitting healthcare facility [11]. It takes further few weeks before the 104 healthcare facility informs the mother-baby pair that the sample has been rejected and that 105 therefore there is a need to provide a new DBS sample [10]. This inevitably results in delay in  There have been concerns that there is no laboratory surveillance in Zimbabwe to monitor and 109 track EID related processes from pre-analytical phase of laboratory processes. In addition, there 110 are very few studies that investigate the causes of DBS rejections [6]. The absence of the data on DBS rejection rates means that there is a limited intelligence to act and take appropriate 112 corrective actions to improve the EID program and reduce loss to follow up.

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The aim of this study was to determine the proportion of DBS samples that were sent to the 114 Zimbabwean NMRL and rejected between January 2017 and December 2017 and the reasons for 115 their rejection.

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A cross-sectional study that used routine data from EID laboratory information management

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The country is divided into 8 provinces and 2 metropolitan provinces (Bulawayo and Harare).

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It has four tiered system of health care services, which includes (i) the primary health care      (1) 10 (

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The current study found that large proportion of rejection were due to insufficient blood volume 253 collection. and actions could be taken at district level before sending the samples to the NMRL.

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 Laboratory processes needs to strengthen implementation of quality management system 302 to identify deficiencies in DBS sample management so that corrective actions are taken to 303 continuously reduce sample rejection rates that impacts patient care.

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 NMRL needs to conduct a laboratory validation of "two insufficient spot protocol" 305 against a" one full spot protocol" so that the rejection criteria may be reviewed based on 306 the scientific evidence of the validation.

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This study has shown that DBS rejection rates were above the national target. The major reason 310 for rejection was insufficient volume samples. Clinic/rural health centers have higher rejection 311 rate than central hospitals. Over all, there is need to monitor rejection rates in real time, so that 312 corrective and preventive actions may be taken to reduce or eliminate causes of DBS rejection. 313 on a course developed jointly by the International Union Against Tuberculosis and Lung Disease