Th objectives of this study are: * To determine the performance of G6PD tests in detecting G6PD activity and hemoglobin (Hb) compared to a reference assay * To assess the comprehension of the G6PD test packaging and labelling among intended users * To assess the usability of G6PD test result outputs among intended users
This is a cross-sectional diagnostic accuracy study that includes both participants and health worker participants. The participant population will be recruited at clinics and through a household survey using an enriched sample of a population with known G6PD status, established through previous epidemiological studies. Clinic staff will take capillary blood samples and conduct two point of care (POC) tests: 1) HemoCue® hemoglobin test, and 2) the investigational Standard Diagnostics (SD) Biosensor STANDARD POC test for glucose-6-phosphate dehydrogenase (G6PD) deficiency. Venous blood will be collected and transferred to a laboratory where reference assays will be performed on venous samples using the Pointe Scientific G6PD Analyzer and hemoglobin tests. The health worker participants will include trained intended users of the G6PD tests. Trained health workers will be surveyed to assess product usability through a questionnaire to assess label and packing comprehension as well as results interpretation.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
OTHER
Masking
NONE
Enrollment
1,754
The SD Biosensor G6PD Analyzer is designed to measure the quantitative determination of total hemoglobin concentration and G6PD enzymatic activity in fresh human whole blood specimens based on reflectometry assays in a point-of-care (POC) setting. The test is intended to aid in the identification of people with G6PD deficiency. The test is currently not licensed for use in Brazil and is considered an investigational product.
The Pointe Scientific test kit will serve as the reference assay to assess G6PD activity. Its intended use is for the quantitative, kinetic determination of G6PD in blood at 340 nm.
Tropical Medicine Foundation Doctor Heitor Vieira Dourado
Manaus, Amazonas, Brazil
Centro de Pesquisa em Medicina Tropical de Rondônia
Porto Velho, Rondônia, Brazil
Sensitivity of SD Biosensor STANDARD G6PD Test for Identifying G6PD Deficient Individuals
For the purposes of this study, an individual was considered G6PD deficient if they tested positive in the Pointe Scientific assay. A true positive was defined as a participant with ≤ 30% of normal G6PD activity in circulating venous blood determined by the Pointe Scientific test. Diagnostic sensitivity of the SD Biosensor STANDARD G6PD test is defined as the percentage of participants who tested positive for G6PD deficiency on the reference test who were identified by the test assay as positive, calculated as: Number of participants who were both test and true positive / (Number of participants who were test and true positive + Number of participants who were test negative but true positive \[ie false negative\]) \* 100%. Sensitivity of the SD Biosensor STANDARD G6PD test was calculated from both venous and capillary blood samples.
Time frame: All samples were collected on study day 1
Sensitivity of SD Biosensor STANDARD G6PD Test for Identifying Women With Intermediate G6PD Activity
To investigate the performance of the SD Biosensor STANDARD G6PD test to distinguish females with intermediate G6PD activity from females with normal activity, assay sensitivity was determined at a G6PD activity threshold of 70%. A true positive for intermediate G6PD activity in females was defined as G6PD activity between 30 and 70% of normal in circulating venous blood as determined by the Pointe Scientific test. Sensitivity of the SD Biosensor STANDARD G6PD test is the percentage of women who tested positive for intermediate G6PD activity on the reference test who were identified by the test assay as positive, calculated as: Number of women who were both test and true positive / (Number of women who were test and true positive + Number of women who were test negative but true positive \[ie false negative\]) \* 100%. Sensitivity of the SD Biosensor STANDARD G6PD test for identifying females with intermediate G6PD activity was calculated from both venous and capillary blood samples.
Time frame: All samples were collected on study day 1
Specificity of SD Biosensor STANDARD G6PD Test for Identifying G6PD Deficient Individuals
For the purposes of this study, an individual was considered G6PD deficient if they tested positive by the Pointe Scientific assay. A true negative was defined as \> 30% of normal G6PD activity in circulating venous blood as determined by the Pointe Scientific test. Specificity is the percentage of participants who tested negative for G6PD deficiency on the reference test who were identified as negative using the test assay, calculated as: Number of participants who were both test and true negative / (Number of participants who were test and true negative + Number of participants who were test positive but true negative \[ie false positive\]) \* 100%. Specificity of the SD Biosensor STANDARD G6PD test was calculated from both venous and capillary blood samples.
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The HemoCue hemoglobin (Hb) 201+ system is designed for quantitative point-of-care whole blood hemoglobin determination in primary care using a specially designed analyzer, the HemoCue Hb 201+ Analyzer, and specially designed microcuvettes, the HemoCue Hb 201+Microcuvettes.
In Manaus, hemoglobin concentration was determined by CBC using an automated hematology analyzer (Sysmex KX-21N).
Time frame: All samples were collected on study day 1
Specificity of SD Biosensor STANDARD G6PD Test for Identifying Women With Intermediate G6PD Activity
To investigate the performance of the SD Biosensor STANDARD G6PD test to distinguish females with intermediate G6PD activity from females with normal activity, the specificity was determined at a G6PD activity threshold of 70%. A true negative for intermediate G6PD activity in females was defined as G6PD activity \> 70% of normal in circulating venous blood as determined by the Pointe Scientific test. Specificity is the percentage of participants who tested negative for G6PD deficiency on the reference test who were identified as negative using the test assay, calculated as: Number of participants who were both test and true negative / (Number of participants who were test and true negative + Number of participants who were test positive but true negative \[ie false positive\]) \* 100%. Specificity of the SD Biosensor STANDARD G6PD test was calculated from both venous and capillary blood samples.
Time frame: All samples were collected on study day 1
Accuracy Between the SD Biosensor STANDARD G6PD Test Assay and the Pointe Scientific Test Kit
Accuracy between the SD Biosensor STANDARD G6PD test assay and the Pointe Scientific G6PD reference assay was calculated as the percent agreement between both G6PD tests, ie, the percentage of participants with the same diagnosis according to both tests (either deficient, intermediate, or normal G6PD levels). Accuracy of the SD Biosensor STANDARD G6PD test was calculated from both venous and capillary blood samples.
Time frame: All samples were collected on study day 1
Accuracy Between the SD Biosensor STANDARD G6PD Test Measure of Hemoglobin and the Reference HemoCue Hemoglobin Test
Accuracy between the SD Biosensor STANDARD G6PD test measure of hemoglobin and the HemoCue hemoglobin reference assay was calculated as the percentage agreement between both tests, ie, the percentage of participants with the same diagnosis according to both tests (either non/mild anemia, moderate anemia or severe anemia).
Time frame: All samples were collected on study day 1
Accuracy Between the SD Biosensor STANDARD G6PD Test Measure of Hemoglobin and the Hemoglobin Measured in a Complete Blood Count
Accuracy between the SD Biosensor STANDARD G6PD test measure of hemoglobin and the hemoglobin result from the complete blood count (CBC) reference assay (using an automated hematology analyzer) was calculated as the percentage agreement between both tests, ie, the percentage of participants with the same diagnosis according to both tests (either non/mild anemia, moderate anemia or severe anemia). Complete blood counts were only conducted for participants enrolled at the site in Manaus.
Time frame: All samples were collected on study day 1
Median G6PD Values Measured by the SD Biosensor STANDARD G6PD Test for Venous and Capillary Blood Samples
Time frame: All samples were collected on study day 1
Number of Participants Who Met Acceptance Criteria for Label Comprehension
After completing training, health worker participants were asked to complete a questionnaire to assess their comprehension of the test label. The questionnaire consisted of 13 multiple-choice questions with mutually exclusive options and a single correct answer focused on aspects of the product label including key warnings, limitations, and restrictions as well as the proper test procedure. Acceptance (success) criterion for label comprehension was defined as at least 85% correct responses (11 out of 13 possible points).
Time frame: Day 1
Number of Participants Who Met Acceptance Criteria for Accurate Results Interpretation
After completing training, health worker participants were asked to complete a questionnaire to assess their ability to interpret the test result outputs. The questionnaire consisted of seven short-answer questions (5 valid results, 2 invalid results) focused on the participant's ability to read the results screen, record the simulated G6PD and hemoglobin quantitative results, and classify the results as normal, intermediate, deficient, or invalid. For each valid result, three points were possible: (one for G6PD result transcription, one for hemoglobin result transcription, and one for result interpretation) and for each invalid result, one point was possible, resulting in a total of 17 possible points. Acceptance (success) criterion for results interpretation was defined as at least 85% correct responses (15 out of 17 possible points).
Time frame: Day 1