A simple point-of-care testing device for anemia could provide more rapid diagnosis of the common blood disorder and allow inexpensive at-home self-monitoring of persons with chronic forms of the disease.
The disposable self-testing device analyzes a single droplet of blood using a chemical reagent that produces visible color changes corresponding to different levels of anemia. The basic test produces results in about 60 seconds and requires no electrical power. A companion smartphone application can automatically correlate the visual results to specific blood hemoglobin levels. The FDA-funded study describing the device and comparing its sensitivity to gold-standard anemia testing was published in The Journal of Clinical Investigation.
By allowing rapid diagnosis and more convenient monitoring of patients with chronic anemia, the device could help patients receive treatment before the disease becomes severe, potentially heading off emergency room visits and hospitalizations. Anemia, which affects two billion people worldwide, is now diagnosed and monitored using blood tests done with costly test equipment maintained in hospitals, clinics or commercial laboratories.
Because of its simplicity and ability to deliver results without electricity, the device could also be used in resource-poor nations. The goal is to get the device into patients’ hands so they can diagnose and monitor anemia themselves. Patients could use this device in a way that’s very similar to how diabetics use glucose-monitoring devices, but this will be even simpler because this is a visual-based test that doesn’t require an additional electrical device to analyze the results.
The test device was developed in a collaboration of Emory University, Children’s Healthcare of Atlanta and the Georgia Institute of Technology. The test works with a patient sticking a finger with a lance similar to those used by diabetics to produce a droplet of blood. The device’s cap, a small vial, is then touched to the droplet, drawing in a precise amount of blood using capillary action. The cap containing the blood sample is then placed onto the body of the clear plastic test kit, which contains the chemical reagent. After the cap is closed, the device is briefly shaken to mix the blood and reagent.
The capillary is filled with a very precise volume of blood, about five microliters, which is less than a droplet, much less than what is required by other anemia tests.
Blood hemoglobin then serves as a catalyst for a reduction-oxidation reaction that takes place in the device. After about 45 seconds, the reaction is complete and the patient sees a colour ranging from green-blue to red, indicating the degree of anemia.
A label on the device helps with interpretation of the colour, or the device could be photographed with a smartphone running an application written by the team. The app automatically correlates the colour to a specific hemoglobin level, and could one day be used to report the data to a physician.
To evaluate sensitivity and specificity of the device the team studied blood taken from 238 patients. Each blood sample was tested four times using the device, and the results were compared to reports provided by conventional hematology analyzers. The work showed that the results of the one-minute test were consistent with those of the conventional analysis. The smartphone app produced the best results for measuring severe anemia.
About a third of the population is at risk for anemia, which can cause neurocognitive deficits in children, organ failure and less serious effects such as chronic fatigue. Women, children, the elderly and those with chronic conditions such as kidney disease are more likely to suffer from anemia.
The test ultimately will require approval from the FDA. The team plans to study how the test may be applied to specific diseases, such as sickle cell anemia, which is common in Georgia. The device could be on pharmacy shelves sometime in 2016.
Source: Georgia Institute of Technology