Quality Assurance of Rapid Diagnostic Tests for Malaria in Routine Patient Care in Rural Tanzania

Abstract

† In the WHO evaluation, parasite detection rate was defined as the percentage of malaria samples in a test panel giving a positive result by two RDTs per lot at the lower parasite density (200 parasites/µL), and a single RDT per lot at the higher parasite density (2,000 or 5,000 parasites/µL). Thus, it is a combined measure of positivity rate, along with inter-test and inter-lot consistency. Abstract. Histidine-rich protein II (HRP2)-based malaria rapid diagnostic tests (RDTs) have shown high sensitivity and specificity for detecting Plasmodium falciparum malaria in a variety of study settings. However, RDTs are susceptible to heat and humidity and variation in individual performance, which may affect their use in field settings. We evaluated sensitivity and specificity of RDTs during routine use for malaria case management in peripheral health facilities. From December 2007 to October 2008, HRP2-based ParaHIT-f RDTs were introduced in 12 facilities without available microscopy in Rufiji District, Tanzania. Health workers received a single day of instruction on how to perform an RDT and thick blood smear. Job aids, Integrated Management of Childhood Illness guidelines, and national malaria treatment algorithms were reviewed. For quality assurance (QA), thick blood smears for reference microscopy were collected for 2 to 3 days per week from patients receiving RDTs; microscopy was not routinely performed at the health facilities. Slides were stained and read centrally within 72 hours of collection by a reference microscopist. When RDT and blood smear results were discordant, blood smears were read by additional reference microscopists blinded to earlier results. Facilities were supervised monthly by the district laboratory supervisor or a member of the study team. Ten thousand six hundred fifty (10,650) patients were tested with RDTs, and 51.5% (5,488/10,650) had a positive test result. Blood smear results were available for 3,914 patients, of whom 40.1% (1,577/3,914) were positive for P. falciparum malaria. Overall RDT sensitivity was 90.7% (range by facility 85.7-96.5%) and specificity was 73.5% (range 50.0-84.3%). Sensitivity increased with increasing parasite density. Successful implementation of RDTs was achieved in peripheral health facilities with adequate training and supervision. Quality assurance is essential to the adequate performance of any laboratory test. Centralized staining and reading of blood smears provided useful monitoring of RDT performance. However, this level of QA may not be sustainable nationwide.

Prevalence of Malaria among Patients Attending Public Health Facilities in Maputo City, Mozambique

“…28,29 In addition, adequate healthcare worker training and supervision is strongly recommended to achieve and maintain high performance of these tests. 27,30,31 In our study, we found the sensitivity of ICT Malaria P.f. to be comparable to highquality microscopy.…”

“…It is important to remember that our study staff was trained in the use of RDTs and good performance of these tests is highly associated with appropriate training and supervision of healthcare workers and laboratory staff. 30,32 This study has several limitations. First, it was an HF-based survey and, by limiting the information on malaria prevalence to only patients seen at HFs, we may have poorly estimated the true burden of malaria in Maputo City.…”

Prevalence and Factors Associated with Anemia Among Children Under 5 Years of Age—Uganda, 2009

“…29,30 For this analysis, we used the results of the RDT, which are characterized by high sensitivity but lower specificity as the tests detect HRP2 antigen that persists in the bloodstream after clearance of the parasite. 31 Children with a positive RDT were offered treatment with weight-based dosing of Coartem ® artemether/ lumefantrine (Novartis Pharma AG, Basel, Switzerland) at the household according to guidelines from the Uganda NMCP. 32 We analyzed data on Hb levels among children under 60 months and assessed sociodemographic and clinical risk factors associated with anemia using weighted univariate and bivariate analyses.…”

Factoring Quality Laboratory Diagnosis into the Malaria Control Agenda for Sub-Saharan Africa

“…Minimal training is needed to use RDTs, 22,23 and assuming good manufacturing quality accompanied by effective quality assurance systems, several *Address correspondence to Michael Aidoo, Centers for Disease Control and Prevention, 1600 Clifton Road, Mail Stop-A06, Atlanta, GA 30333. E-mail: maidoo@cdc.gov tests will perform well in the field.…”