Clinical performance validation of the STANDARD G6PD test: A multi-country pooled analysis.

INTRODUCTION: Screening for G6PD deficiency can inform disease management including malaria. Treatment with the antimalarial drugs primaquine and tafenoquine can be guided by point-of-care testing for G6PD deficiency. METHODS AND FINDINGS: Data from similar clinical studies evaluating the performance of the STANDARD G6PD Test (SD Biosensor, South Korea) conducted in Bangladesh, Brazil, Ethiopia, India, Thailand, the United Kingdom, and the United States were pooled. Test performance was assessed in a retrospective analysis on capillary and venous specimens. All study sites used spectrophotometry for reference G6PD testing, and either the HemoCue or complete blood count for reference hemoglobin measurement. The sensitivity of the STANDARD G6PD Test using the manufacturer thresholds for G6PD deficient and intermediate cases in capillary specimens from 4212 study participants was 100% (95% Confidence Interval (CI): 97.5%-100%) for G6PD deficient cases with <30% activity and 77% (95% CI 66.8%-85.4%) for females with intermediate activity between 30%-70%. Specificity was 98.1% (95% CI 97.6%-98.5%) and 92.8% (95% CI 91.6%-93.9%) for G6PD deficient individuals and intermediate females, respectively. Out of 20 G6PD intermediate females with false normal results, 12 had activity levels >60% on the reference assay. The negative predictive value for females with G6PD activity >60% was 99.6% (95% CI 99.1%-99.8%) on capillary specimens. Sensitivity among 396 P. vivax malaria cases was 100% (69.2%-100.0%) for both deficient and intermediate cases. Across the full dataset, 37% of those classified as G6PD deficient or intermediate resulted from true normal cases. Despite this, over 95% of cases would receive correct treatment with primaquine, over 87% of cases would receive correct treatment with tafenoquine, and no true G6PD deficient cases would be treated inappropriately based on the result of the STANDARD G6PD Test. CONCLUSIONS: The STANDARD G6PD Test enables safe access to drugs which are contraindicated for individuals with G6PD deficiency. Operational considerations will inform test uptake in specific settings.

Antigen concentration, viral load, and test performance for SARS-CoV-2 in multiple specimen types.

The relationship between N-antigen concentration and viral load within and across different specimens guides the clinical performance of rapid diagnostic tests (RDT) in different uses. A prospective study was conducted in Porto Velho, Brazil, to investigate RDT performance in different specimen types as a function of the correlation between antigen concentration and viral load. The study included 214 close contacts with recent exposures to confirmed cases, aged 12 years and older and with various levels of vaccination. Antigen concentration was measured in nasopharyngeal swab (NPS), anterior nares swab (ANS), and saliva specimens. Reverse transcriptase (RT)-PCR was conducted on the NPS and saliva specimens, and two RDTs were conducted on ANS and one RDT on saliva. Antigen concentration correlated well with viral load when measured in the same specimen type but not across specimen types. Antigen levels were higher in symptomatic cases compared to asymptomatic/oligosymptomatic cases and lower in saliva compared to NPS and ANS samples. Discordant results between the RDTs conducted on ANS and the RT-PCR on NPS were resolved by antigen concentration values. The analytical limit-of-detection of RDTs can be used to predict the performance of the tests in populations for which the antigen concentration is known. The antigen dynamics across different sample types observed in SARS-CoV-2 disease progression support use of RDTs with nasal samples. Given lower antigen concentrations in saliva, rapid testing using saliva is expected to require improved RDT analytical sensitivity to achieve clinical sensitivity similar to rapid testing of nasal samples.

Multiplexed micronutrient, inflammation, and malarial antigenemia assessment using a plasma fractionation device.

Processing and storing blood samples for future analysis of biomarkers can be challenging in resource limited environments. The preparation of dried blood spots (DBS) from finger-stick collection of whole blood is a widely used and established method as DBS are biosafe, and allow simpler field processing, storage, and transport protocols than serum or plasma. Therefore, DBS are commonly used in population surveys to assess infectious disease and/or micronutrient status. Recently, we reported that DBS can be used with the Q-plex™ Human Micronutrient 7-plex Array (MN 7-plex), a multiplexed immunoassay. This tool can simultaneously quantify seven protein biomarkers related to micronutrient deficiencies (iodine, iron and vitamin A), inflammation, and malarial antigenemia using plasma or serum. Serum ferritin, an iron biomarker, cannot be measured from DBS due to red blood cell (RBC) ferritin content confounding the results. In this study, we assess a simple blood fractionation tool that passively separates plasma from other blood components via diffusion through a membrane into a plasma collection disc (PCD). We evaluated the concordance of MN 7-plex analyte concentrations from matched panels of eighty-eight samples of PCD, DBS, and wet plasma prepared from anticoagulated venous whole blood. The results showed good correlations of >0.93 between the eluates from PCD and DBS for each analyte except ferritin; while correlations seen for plasma/PCD were weaker. However, the recovery rate of the analytes from the PCD were better than those from DBS. The serum ferritin measures from the PCD were highly correlated to wet plasma samples (0.85). This suggests that surveillance for iron status in low resource settings can be improved over the current methods restricted to only measuring sTfR in DBS. When used in combination with the MN 7-plex, all seven biomarkers can be simultaneously measured using eluates from the PCDs.

Evaluation of a protein-to-creatinine dipstick diagnostic test for proteinuria screening in selected antenatal care clinics in three Districts in the Bono-East Region of Ghana.

BACKGROUND: Preeclampsia and eclampsia contribute significantly to maternal and newborn deaths worldwide. Early and accurate identification of pregnant women at risk can avert these deaths, but the necessary diagnostics are not widely available. A protein and creatinine ratio, rather than a measurement of protein alone, may provide better identification of proteinuria. The objective of this study was to assess the operational and performance characteristics of the LifeAssay Diagnostics (LAD) Test-it™ protein-to-creatinine ratio (PrCr) urinalysis dipstick test in a representative antenatal care setting (ANC). METHODS: Mixed methods were used to assess the operational and performance characteristics of the PrCr test, including a usability study with 25 participants, a prospective cross-sectional diagnostic accuracy study (N = 1483), and a targeted reassessment of discordant frozen samples (N = 200). Several other commonly used proteinuria tests were included for comparison. RESULTS: The test demonstrated improved clinical performance for detection of proteinuria over the current standard-of-care tests widely used in Ghana. The LAD PrCr test showed a sensitivity of 50.7% and specificity of 69.2% when run at the point of care. In contrast, the standard-of-care Accu-Tell® protein dipstick test was found to have a sensitivity of 32.4% and a specificity of 82.2%. The LAD test shows minor improvement over the tests currently used in Ghana to detect proteinuria. CONCLUSIONS: The PrCr test offers the potential for improved detection of proteinuria over the standard-of-care tests used in ANC. However, this test and the others evaluated for this study demonstrate limited performance, particularly among samples with a low level of proteinuria. Additional exploration in other clinical use cases, such as triage among high-risk populations, is warranted. The LAD test can also be considered a transition product, as health systems consider adopting next-generation biomarker tests when more readily available.

Screening for Severe Acute Respiratory Syndrome Coronavirus 2 in Close Contacts of Individuals With Confirmed Infection: Performance and Operational Considerations.

BACKGROUND: Point-of-care and decentralized testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is critical to inform public health responses. Performance evaluations in priority use cases such as contact tracing can highlight trade-offs in test selection and testing strategies. METHODS: A prospective diagnostic accuracy study was conducted among close contacts of coronavirus disease 2019 (COVID-19) cases in Brazil. Two anterior nares swabs (ANS), a nasopharyngeal swab (NPS), and saliva were collected at all visits. Vaccination history and symptoms were assessed. Household contacts were followed longitudinally. Three rapid antigen tests and 1 molecular method were evaluated for usability and performance against reference reverse-transcription polymerase chain reaction (RT-PCR) on nasopharyngeal swab specimens. RESULTS: Fifty index cases and 214 contacts (64 household) were enrolled. Sixty-five contacts were RT-PCR positive during ≥1 visit. Vaccination did not influence viral load. Gamma variants were most prevalent; Delta variants emerged increasingly during implementation. The overall sensitivity of evaluated tests ranged from 33% to 76%. Performance was higher among symptomatic cases and those with cycle threshold (Ct) values <34 and lower among oligosymptomatic or asymptomatic cases. Assuming a 24-hour time to results for RT-PCR, the cumulative sensitivity of an anterior nares swab rapid antigen test was >70% and almost 90% after 4 days. CONCLUSIONS: The near-immediate time to results for antigen tests significantly offsets lower analytical sensitivity in settings where RT-PCR results are delayed or unavailable.

A multicenter analytical performance evaluation of a multiplexed immunoarray for the simultaneous measurement of biomarkers of micronutrient deficiency, inflammation and malarial antigenemia.

A lack of comparative data across laboratories is often a barrier to the uptake and adoption of new technologies. Furthermore, data generated by different immunoassay methods may be incomparable due to a lack of harmonization. In this multicenter study, we describe validation experiments conducted in a single lab and cross-lab comparisons of assay results to assess the performance characteristics of the Q-plex™ 7-plex Human Micronutrient Array (7-plex), an immunoassay that simultaneously quantifies seven biomarkers associated with micronutrient (MN) deficiencies, inflammation and malarial antigenemia using plasma or serum; alpha-1-acid glycoprotein, C-reactive protein, ferritin, histidine-rich protein 2, retinol binding protein 4, soluble transferrin receptor, and thyroglobulin. Validations included repeated testing (n = 20 separately prepared experiments on 10 assay plates) in a single lab to assess precision and linearity. Seven independent laboratories tested 76 identical heparin plasma samples collected from a cohort of pregnant women in Niger using the same 7-plex assay to assess differences in results across laboratories. In the analytical validation experiments, intra- and inter-assay coefficients of variation were acceptable at <6% and <15% respectively and assay linearity was 96% to 99% with the exception of ferritin, which had marginal performance in some tests. Cross-laboratory comparisons showed generally good agreement between laboratories in all analyte results for the panel of 76 plasma specimens, with Lin's concordance correlation coefficient values averaging ≥0.8 for all analytes. Excluding plates that would fail routine quality control (QC) standards, the inter-assay variation was acceptable for all analytes except sTfR, which had an average inter-assay coefficient of variation of ≥20%. This initial cross-laboratory study demonstrates that the 7-plex test protocol can be implemented by users with some experience in immunoassay methods, but familiarity with the multiplexed protocol was not essential.

Reference and point-of-care testing for G6PD deficiency: Blood disorder interference, contrived specimens, and fingerstick equivalence and precision.

Certain clinical indications and treatments such as the use of rasburicase in cancer therapy and 8-aminoquinolines for Plasmodium vivax malaria treatment would benefit from a point-of-care test for glucose-6-phosphate dehydrogenase (G6PD) deficiency. Three studies were conducted to evaluate the performance of one such test: the STANDARD™ G6PD Test (SD BIOSENSOR, South Korea). First, biological interference on the test performance was evaluated in specimens with common blood disorders, including high white blood cell (WBC) counts. Second, the test precision on fingerstick specimens was evaluated against five individuals of each, deficient, intermediate, and normal G6PD activity status. Third, clinical performance of the test was evaluated at three point-of-care settings in the United States. The test performed equivalently to the reference assay in specimens with common blood disorders. High WBC count blood samples resulted in overestimation of G6PD activity in both the reference assay and the STANDARD G6PD Test. The STANDARD G6PD Test showed good precision on multiple fingerstick specimens from the same individual. The same G6PD threshold values (U/g Hb) were applied for a semiquantitative interpretation for fingerstick- and venous-derived results. The sensitivity/specificity values (95% confidence intervals) for the test for G6PD deficiency were 100 (92.3-100.0)/97 (95.2-98.2) and 100 (95.7-100.0)/97.4 (95.7-98.5) for venous and capillary specimens, respectively. The same values for females with intermediate (> 30% to ≤ 70%) G6PD activity were 94.1 (71.3-99.9)/88.2 (83.9-91.7) and 82.4 (56.6-96.2)/87.6(83.3-91.2) for venous and capillary specimens, respectively. The STANDARD G6PD Test enables point-of-care testing for G6PD deficiency.

Evaluation of a point-of-care diagnostic to identify glucose-6-phosphate dehydrogenase deficiency in Brazil.

BACKGROUND: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common enzyme deficiency, prevalent in many malaria-endemic countries. G6PD-deficient individuals are susceptible to hemolysis during oxidative stress, which can occur from exposure to certain medications, including 8-aminoquinolines used to treat Plasmodium vivax malaria. Accordingly, access to point-of-care (POC) G6PD testing in Brazil is critical for safe treatment of P. vivax malaria. METHODOLOGY/PRINCIPAL FINDINGS: This study evaluated the performance of the semi-quantitative, POC STANDARD G6PD Test (SD Biosensor, Republic of Korea). Participants were recruited at clinics and through an enriched sample in Manaus and Porto Velho, Brazil. G6PD and hemoglobin measurements were obtained from capillary samples at the POC using the STANDARD and HemoCue 201+ (HemoCue AB, Sweden) tests. A thick blood slide was prepared for malaria microscopy. At the laboratories, the STANDARD and HemoCue tests were repeated on venous samples and a quantitative spectrophotometric G6PD reference assay was performed (Pointe Scientific, Canton, MI). G6PD was also assessed by fluorescent spot test. In Manaus, a complete blood count was performed. Samples were analyzed from 1,736 participants. In comparison to spectrophotometry, the STANDARD G6PD Test performed equivalently in determining G6PD status in venous and capillary specimens under varied operating temperatures. Using the manufacturer-recommended reference value thresholds, the test's sensitivity at the <30% threshold on both specimen types was 100% (95% confidence interval [CI] venous 93.6%-100.0%; capillary 93.8%-100.0%). Specificity was 98.6% on venous specimens (95% CI 97.9%-99.1%) and 97.8% on capillary (95% CI 97.0%-98.5%). At the 70% threshold, the test's sensitivity was 96.9% on venous specimens (95% CI 83.8%-99.9%) and 94.3% on capillary (95% CI 80.8%-99.3%). Specificity was 96.5% (95% CI 95.0%-97.6%) and 92.3% (95% CI 90.3%-94.0%) on venous and capillary specimens, respectively. CONCLUSION/SIGNIFICANCE: The STANDARD G6PD Test is a promising tool to aid in POC detection of G6PD deficiency in Brazil. TRIAL REGISTRATION: This study was registered with ClinicalTrials.gov (identifier: NCT04033640).

Evaluation of diagnostic ultrasound use in a breast cancer detection strategy in Northern Peru.

To evaluate the diagnostic impact of point-of-care breast ultrasound by trained primary care physicians (PCPs) as part of a breast cancer detection program using clinical breast exam in an underserved region of Peru. Medical records and breast ultrasound images of symptomatic women presenting to the Breast Cancer Detection Model (BCDM) in Trujillo, Peru were collected from 2017-2018. Performance was measured against final outcomes derived from regional cancer center medical records, fine needle aspiration results, patient follow-up (sensitivity, specificity, positive, and negative predictive values), and by percent agreement with the retrospective, blinded interpretation of images by a fellowship-trained breast radiologist, and a Peruvian breast surgeon. The diagnostic impact of ultrasound, compared to clinical breast exam (CBE), was calculated for actual practice and for potential impact of two alternative reporting systems. Of the 171 women presenting for breast ultrasound, 23 had breast cancer (13.5%). Breast ultrasound used as a triage test (current practice) detected all cancer cases (including four cancers missed on confirmatory CBE). PCPs showed strong agreement with radiologist and surgeon readings regarding the final management of masses (85.4% and 80.4%, respectively). While the triage system yielded a similar number of biopsies as CBE alone, using the condensed and full BI-RADS systems would have reduced biopsies by 60% while identifying 87% of cancers immediately and deferring 13% to six-month follow-up. Point-of-care ultrasound performed by trained PCPs improves diagnostic accuracy for managing symptomatic women over CBE alone and enhances access. Greater use of BI-RADS to guide management would reduce the diagnostic burden substantially.

Health Outcomes at 1 Year After Thermal Ablation for Cervical Precancer Among Human Papillomavirus- and Visual Inspection With Acetic Acid-Positive Women in Honduras.

PURPOSE: This study aims to assess the detection of cervical intraepithelial lesions grades 2 and 3 (CIN2-3) at 1 year after treatment with thermal ablation among human papillomavirus (HPV)-positive and visual inspection with acetic acid (VIA)-positive women. METHODS: All women screened and triaged for cervical cancer at four government health facilities in Honduras who were eligible for ablative treatment were enrolled and treated with thermal ablation. Women with confirmed CIN2-3 and a subset of women with CIN1/normal diagnoses at baseline were evaluated at 12 months. Follow-up procedures included HPV testing (careHPV), VIA, directed biopsy (if VIA-positive), and Papanicolaou test (if HPV positive, VIA negative). Outcomes at 1 year included histologic or cytologic assessment of CIN lesions among those with any abnormal test. RESULTS: Among the 319 women treated with thermal ablation, baseline histologic diagnoses were available for 317. Two (0.6%) had invasive cancer, 36 (11.4%) had CIN3, 40 (12.6%) had CIN2, and 239 (75.4%) had CIN1/normal histology. Among the 127 women eligible for follow-up, 118 (92.9%) completed all study procedures at 1 year. Overall, 98 (83.1%) had no evidence of CIN2-3 or persistent low-grade infection, 13 (11.2%) had CIN1/atypical squamous cells of undetermined significance, six (5.1%) had CIN2/high-grade squamous intraepithelial lesion, and 1 (0.8%) had a persistent CIN3. No adverse events associated with thermal ablation at 1 year were registered. CONCLUSION: A high proportion of women had no evidence of CIN2-3 at 1 year after thermal ablation treatment. Thermal ablation is an alternative to cryotherapy that may facilitate greater treatment coverage and prevent unnecessary deaths from cervical cancer.

Recall Efforts Successfully Increase Follow-Up for Cervical Cancer Screening Among Women With Human Papillomavirus in Honduras.

Scaling up coverage of routine cervical screening in low-resource settings must be accompanied by efforts to retain women throughout the screening cascade and continuum of care, including adequate follow-up of abnormal results. The Scale-Up Project implemented human papillomavirus (HPV) testing for cervical cancer screening within public-sector health facilities in Honduras between 2015 and 2019. Women who were HPV-positive but did not have visually confirmed cervical lesions upon visual inspection with acetic acid (VIA-negative) were instructed to return to the health center after 1 year for repeat HPV testing. The current evaluation assessed the effectiveness of recall strategies to prompt women to return for retesting. Clinic staff placed reminder phone calls and followed up with short message service (SMS) or home visits, if needed. We summarized number of contacts, type of contacts, and time elapsed until return to the clinic, and used log-binomial regression to identify factors associated with return to the clinic. We identified 558 women who were initially HPV-positive VIA-negative from 8 clinics as needing repeat HPV testing 1 year later. Mean age was 43.2 years. Nearly all women (98.6%) were successfully contacted and 75.1% completed repeat HPV testing. The majority of contacts (65.4%) were phone calls, and nearly half of women who returned to the clinic (42.9%) did so after 1 contact. Mean days between contact and presentation at the clinic was 10.7 (standard deviation: 14.7). Women who required 3 or more contacts were 21% less likely to return for repeat HPV testing (prevalence ratio: 0.79; 95% confidence interval=0.69,0.90; P<.001) as compared to women who received only 1 contact. Reminder phone calls were highly successful at recalling women for HPV retesting in Honduras. This low-touch intervention should be included as part of standard follow-up to retain women throughout the continuum of cervical cancer screening and treatment.

Correction: Quantification of glucose-6-phosphate dehydrogenase activity by spectrophotometry: A systematic review and meta-analysis.

[This corrects the article DOI: 10.1371/journal.pmed.1003084.].

Quantification of glucose-6-phosphate dehydrogenase activity by spectrophotometry: A systematic review and meta-analysis.

BACKGROUND: The radical cure of Plasmodium vivax and P. ovale requires treatment with primaquine or tafenoquine to clear dormant liver stages. Either drug can induce haemolysis in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency, necessitating screening. The reference diagnostic method for G6PD activity is ultraviolet (UV) spectrophotometry; however, a universal G6PD activity threshold above which these drugs can be safely administered is not yet defined. Our study aimed to quantify assay-based variation in G6PD spectrophotometry and to explore the diagnostic implications of applying a universal threshold. METHODS AND FINDINGS: Individual-level data were pooled from studies that used G6PD spectrophotometry. Studies were identified via PubMed search (25 April 2018) and unpublished contributions from contacted authors (PROSPERO: CRD42019121414). Studies were excluded if they assessed only individuals with known haematological conditions, were family studies, or had insufficient details. Studies of malaria patients were included but analysed separately. Included studies were assessed for risk of bias using an adapted form of the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Repeatability and intra- and interlaboratory variability in G6PD activity measurements were compared between studies and pooled across the dataset. A universal threshold for G6PD deficiency was derived, and its diagnostic performance was compared to site-specific thresholds. Study participants (n = 15,811) were aged between 0 and 86 years, and 44.4% (7,083) were women. Median (range) activity of G6PD normal (G6PDn) control samples was 10.0 U/g Hb (6.3-14.0) for the Trinity assay and 8.3 U/g Hb (6.8-15.6) for the Randox assay. G6PD activity distributions varied significantly between studies. For the 13 studies that used the Trinity assay, the adjusted male median (AMM; a standardised metric of 100% G6PD activity) varied from 5.7 to 12.6 U/g Hb (p < 0.001). Assay precision varied between laboratories, as assessed by variance in control measurements (from 0.1 to 1.5 U/g Hb; p < 0.001) and study-wise mean coefficient of variation (CV) of replicate measures (from 1.6% to 14.9%; p < 0.001). A universal threshold of 100% G6PD activity was defined as 9.4 U/g Hb, yielding diagnostic thresholds of 6.6 U/g Hb (70% activity) and 2.8 U/g Hb (30% activity). These thresholds diagnosed individuals with less than 30% G6PD activity with study-wise sensitivity from 89% (95% CI: 81%-94%) to 100% (95% CI: 96%-100%) and specificity from 96% (95% CI: 89%-99%) to 100% (100%-100%). However, when considering intermediate deficiency (<70% G6PD activity), sensitivity fell to a minimum of 64% (95% CI: 52%-75%) and specificity to 35% (95% CI: 24%-46%). Our ability to identify underlying factors associated with study-level heterogeneity was limited by the lack of availability of covariate data and diverse study contexts and methodologies. CONCLUSIONS: Our findings indicate that there is substantial variation in G6PD measurements by spectrophotometry between sites. This is likely due to variability in laboratory methods, with possible contribution of unmeasured population factors. While an assay-specific, universal quantitative threshold offers robust diagnosis at the 30% level, inter-study variability impedes performance of universal thresholds at the 70% level. Caution is advised in comparing findings based on absolute G6PD activity measurements across studies. Novel handheld quantitative G6PD diagnostics may allow greater standardisation in the future.

HPV-based cervical cancer screening in Nicaragua: from testing to treatment.

BACKGROUND: In Nicaragua, cervical cancer is the leading cause of cancer death among women. Human papillomavirus (HPV) testing, primarily using self-sampling, was introduced between 2014 and 2018 in three provinces. We analyzed data from the HPV screening program with the goal of describing key characteristics including reach, HPV prevalence, triage and treatment, and factors associated with follow-up completion. METHODS: We analyzed individual-level data from routinely collected forms for women attending HPV-based cervical cancer screening. HPV-positive women were triaged with Pap or visual inspection with acetic acid (VIA) prior to treatment. Logistic regression was used to identify factors associated with receiving triage and treatment; analyses were adjusted for province, age, and self- vs. provider-collected sampling. RESULTS: Forty-four thousand six hundred thirty-five women were screened with HPV testing; 96.6% of women used self-sampling. Six thousand seven hundred seventy-six women were HPV positive (15.2%), 54.0% of screen-positive women received triage, and 53.1% of triage-positive women were treated, primarily with cryotherapy. If women lost at triage are included, the overall treatment percentage was 27.8%. Province and provider sampling were significantly associated with completing triage. Province and triage type were significantly associated with receiving treatment. The odds of receiving treatment after Pap triage as compared to VIA was significantly lower (aOR: 0.05, 95% CI: 0.04-0.08, p < 0.001), and the relative proportion of women receiving treatment after Pap triage versus VIA was 0.29. CONCLUSIONS: Introduction of HPV testing resulted in a substantial number of women screened, and acceptance of self-sampling was high. Management of screen-positive women remained a challenge, particularly with Pap triage. Our results can inform other developing countries as they work to reach World Health Organization (WHO) elimination targets.

Potential new tool for anemia screening: An evaluation of the performance and usability of the TrueHb Hemometer.

In low- and middle-income countries, many women experience anemia during pregnancy due to insufficient dietary intake of key micronutrients, parasitic infections, hemoglobinopathies, and chronic infections. Maternal anemia increases perinatal risks for both mothers and infants, and slow progress to reduce the prevalence may be due in part to the lack of affordable tools to quantify hemoglobin levels in antenatal care (ANC) clinics. A simple, inexpensive, accurate, and robust diagnostic is needed to measure hemoglobin in ANC. This study evaluated the performance and usability of the TrueHb Hemometer. A cross-sectional diagnostic accuracy study was conducted to compare the accuracy of the TrueHb and the HemoCue® 201+ using capillary samples. Next, analytical performance (precision, coefficient of variation, R2) of the TrueHb was evaluated in varying environmental conditions using linearity panels with serial dilutions of venous blood samples. Lastly, the usability of the TrueHb Hemometer was assessed across three domains (effectiveness, efficiency, and satisfaction) by 20 ANC providers in Ghana. Capillary blood test results were not well correlated (R2 = 0.35) between the TrueHB and HemoCue201+, but 80% of TrueHb measurements were within +/-1.0 g/dl of the HemoCue® 201+ hemoglobin values. Precision tests indicated similar mean values across the three environmental conditions (CV<6%). At 21°C, the TrueHb follows a linear relationship (R2≥0.96) but does not generate accurate readings below 4.0 g/dl. At 30°C and 37°C, the TrueHb follows a linear relationship (R2 > 0.90) but begins to underestimate the hemoglobin concentration below 7.0 g/dl. The usability study identified potential failure modes due to inadequate instructions and device feedback. With some modifications, both to the product and to the instructions for use, the TrueHb may be suitable for use in ANC settings to help fill the diagnostic gap for anemia screening during pregnancy. Further testing is required with anemic populations in LMIC settings.

Acceptability and safety of thermal ablation for the treatment of precancerous cervical lesions in Honduras.

OBJECTIVE: To evaluate the acceptability and safety of thermal ablation (TA) for the treatment of precancerous cervical lesions in women in Honduras. METHODS: Human papillomavirus (HPV) and visual inspection with acetic acid (VIA) screen-positive eligible women received TA. After treatment, women rated the level of pain experienced during treatment using the Wong-Baker FACES® pain-rating scale from 0 to 10. Short-term safety outcomes that could require medical attention were assessed one month after treatment. RESULTS: A total of 319 women received TA treatment. The average pain rating was 2.5 (95% CI: 2.3-2.8), and 85% rated their pain levels as less than 6. No significant differences in low (below 6) or high (6 and above) pain were found by age or number of biopsies performed, but there was a significant difference by the number of TA applications (P < 0.01). When asked if they would recommend this treatment, all women said they would. At the one-month follow-up visit, the most common reported discomforts were bleeding (10%) and cramping (8.4%); 11 women reported severe lower abdominal pain, and none required medical attention. CONCLUSIONS: TA is safe and acceptable to patients as a treatment option for precancerous cervical lesions in low-resource settings.

OBJECTIF: Evaluer l'acceptabilité et la sécurité de l'ablation thermique (AT) pour le traitement des lésions cervicales précancéreuses chez les femmes au Honduras. MÉTHODES: Les femmes éligibles, portant le virus du papillome humain (VPH) et avec une inspection visuelle positive au test de dépistage à l'acide acétique (IVA) ont reçu une AT. Après le traitement, les femmes ont estimé le niveau de douleur ressenti au cours du traitement à l'aide de l'échelle d'évaluation de la douleur Wong-Baker FACES® de 0 à 10. Les résultats de sécurité à court terme pouvant nécessiter une attention médicale ont été évalués un mois après le traitement. RÉSULTATS: 319 femmes ont reçu un traitement d'AT. L'estimation moyenne de la douleur était de 2,5 (IC95%: 2,3-2,8) et 85% estimaient que leur niveau de douleur était inférieur à 6. Aucune différence significative dans la douleur faible (moins de 6) ou élevée (6 et plus) n'a été constatée en fonction de l'âge ou du nombre de biopsies réalisées, mais il y avait une différence significative selon le nombre d'applications d'AT (P < 0,01). Lorsqu'on leur a demandé si elles recommanderaient ce traitement, toutes les femmes ont répondu qu'elles le feraient. Lors de la visite de suivi à un mois, les malaises les plus fréquents signalés étaient les saignements (10%) et les crampes (8,4%). Onze femmes ont rapporté des douleurs sévères dans le bas de l'abdomen et aucune n'a nécessité de soins médicaux. CONCLUSIONS: L'AT est sûre et acceptable pour les patientes comme option de traitement pour les lésions cervicales précancéreuses dans les régions à faibles ressources.

Measurement of micronutrient deficiency associated biomarkers in dried blood spots using a multiplexed immunoarray.

Simplifying blood collection is often critical when collecting specimens in remote and/or austere settings. The use of dried blood spots (DBS) offers a practical collection method suitable for a wide variety of analytes. A small volume of whole blood can be obtained rapidly through a minimally invasive heel- or finger-stick using a disposable safety lancet. Once dried, the samples require no further processing, are stable for months or longer, pose minimal risk of disease transmission, and are easy to ship. DBS are often used in demographic health surveys to assess infectious disease status in vulnerable populations. These samples can be used to screen biomarkers of micronutrient deficiency (MND) and inflammation. We recently described a multiplexed immunoarray, the Q-plex human micronutrient array, which can simultaneously quantify seven biomarkers related to MND, inflammation and malarial antigenemia using plasma (alpha-1-acid glycoprotein, C-reactive protein, ferritin, histidine-rich protein 2, retinol binding protein, soluble transferrin receptor, and thyroglobulin). In this work, we present a protocol for preparing eluates from DBS samples and their measurement using a modified protocol for this new tool. We evaluated the concordance of analyte concentrations (excluding ferritin) from a panel ninety samples of DBS prepared from anticoagulated venous blood and paired K2-EDTA plasma. The results show high correlation between DBS eluates and wet plasma for five of the six analytes screened, suggesting the Q-plex human micronutrient array can be used with DBS samples, but also highlighting that anticoagulants can have a negative effects on some test components.

Evaluation of a Novel Quantitative Test for Glucose-6-Phosphate Dehydrogenase Deficiency: Bringing Quantitative Testing for Glucose-6-Phosphate Dehydrogenase Deficiency Closer to the Patient.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, a common genetic blood condition, can result in kernicterus at birth, and later in life as severe hemolysis on exposure to certain infections, foods, and drugs. The unavailability of point-of-care tests for G6PD deficiency is a barrier to routine curative treatment of Plasmodium vivax malaria with 8-aminoquinolines, such as primaquine. Two quantitative reference tests (Trinity Biotech, Bray, Ireland and Pointe Scientific, Canton, MI; Cat No. G7583) and the point-of-care STANDARD™ G6PD test (SD Biosensor, Suwon, South Korea) were evaluated. The STANDARD G6PD test was evaluated at multiple temperatures, in anticoagulated venous and capillary samples, including 79 G6PD-deficient and 66 intermediate samples and across two laboratories, one in the United States and one in Thailand. The STANDARD test performed equivalently to a reference assay for its ability to diagnose G6PD deficiency (< 30% normal) with a sensitivity of 100% (0.95 confidence interval [CI]: 95.7-100) and specificity of 97% (0.95 CI: 94.5-98.5), and could reliably identify females with less than 70% normal G6PD activity with a sensitivity of 95.5% (0.95 CI: 89.7-98.5) and specificity of 97% (0.95 CI: 94.5-98.6). The STANDARD G6PD product represents an opportunity to diagnose G6PD deficiency equally for males and females in basic clinical laboratories in high- and low-resource settings. This quantitative point-of-care diagnostic test for G6PD deficiency can provide equal access to safe radical cure of P. vivax cases in high- and low-resource settings, for males and females and may support malaria elimination, in countries where P. vivax is endemic.

Malaria case investigation with reactive focal testing and treatment: operational feasibility and lessons learned from low and moderate transmission areas in Amhara Region, Ethiopia.

BACKGROUND: When malaria transmission is very low, investigation of passively detected malaria cases and reactive focal testing and treatment (FTAT) in the case and neighbouring households can identify and contain the source and spread of infections. METHODS: Case investigation with reactive FTAT for malaria was implemented in 10 villages in Amhara Region, Ethiopia during the 2014/2015 malaria transmission season. Intervention villages were purposively selected based on the incidence of passively detected Plasmodium falciparum and mixed infections (P. falciparum and Plasmodium vivax) during the 2013 transmission season. A passively detected P. falciparum or mixed index case triggered an investigation that targeted the index case household and the closest 10 neighbouring households in a 100-m radius. All consenting household members received a rapid diagnostic test (RDT) and RDT-positive individuals received artemether-lumefantrine (P. falciparum, mixed) or chloroquine (P. vivax). RESULTS: From October 2014 to February 2015, 407 P. falciparum or mixed index cases (approximately 6.5 per 1000 population) were passively detected. Of these, 220 (54.1%) were investigated, of which 87.3% were male, 61.8% were age 20-39 years [median age: 27 years (range 1-90)], and 58.6% spent ≥ 1 night away from home in the past month (ranging from 0.0 to 94.1% by village). Among the 4077 residents in the 914 households investigated, 3243 (79.5%) received an RDT and 127 (3.9%) were RDT-positive (2.2% P. falciparum, 0.5% P. vivax, 1.2% mixed). Three epidemiological patterns were found. In six villages, there were almost no cases, with less than 10 index and secondary cases. In three villages, most index cases had a history of travel (> 62%), but there were a small number of secondary cases (< 10). Lastly, in one village none of the index cases had a history of recent travel and there was a large number of secondary cases (n = 105). CONCLUSIONS: Three types of malaria transmission patterns were observed: (1) low importation and low local transmission; (2) high importation and low local transmission; and, (3) low importation and high local transmission. To achieve malaria elimination in Amhara Region, intervention strategies targeting these different patterns of transmission and population movement are required.

Validation of the quantitative point-of-care CareStart biosensor for assessment of G6PD activity in venous blood.

INTRODUCTION: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymopathy in the human population affecting an estimated 8% of the world population, especially those living in areas of past and present malaria endemicity. Decreased G6PD enzymatic activity is associated with drug-induced hemolysis and increased risk of severe neonatal hyperbilirubinemia leading to brain damage. The G6PD gene is on the X chromosome therefore mutations cause enzymatic deficiency in hemizygote males and homozygote females while the majority of heterozygous females have an intermediate activity (between 30-80% of normal) with a large distribution into the range of deficiency and normality. Current G6PD qualitative tests are unable to diagnose G6PD intermediate activities which could hinder wide use of 8-aminoquinolines for Plasmodium vivax elimination. The aim of the study was to assess the diagnostic performances of the new Carestart G6PD quantitative biosensor. METHODS: A total of 150 samples of venous blood with G6PD deficient, intermediate and normal phenotypes were collected among healthy volunteers living along the north-western Thailand-Myanmar border. Samples were analyzed by complete blood count, by gold standard spectrophotometric assay using Trinity kits and by the latest model of Carestart G6PD biosensor which analyzes both G6PD and hemoglobin. RESULTS: Bland-Altman comparison of the CareStart normalized G6PD values to that of the gold standard assay showed a strong bias in values resulting in poor area under-the-curve values for both 30% and 80% thresholds. Performing a receiver operator curve identified threshold values for the CareStart product equivalent to the 30% and 80% gold standard values with good sensitivity and specificity values, 100% and 92% (for 30% G6PD activity) and 92% and 94% (for 80% activity) respectively. CONCLUSION: The Carestart G6PD biosensor represents a significant improvement for quantitative diagnosis of G6PD deficiency over previous versions. Further improvements and validation studies are required to assess its utility for informing radical cure decisions in malaria endemic settings.