A Laboratory in Your Pocket
By Jennifer M Radin, Eric J Topol, Kristian G Andersen, Steven R Steinhubl
Infectious diseases are a leading cause of death, especially among children in low-income and middle-income countries. Rapid, point-of-care (POC) identification of pathogens could help efforts to control and manage infectious diseases. For most infections, specimen collection and testing is limited to formal medical and laboratory settings. Although rapid diagnostic tests exist for some pathogens, such as influenza, group A streptococcus, and HIV, many still lack specificity and sensitivity; thus, specimens must be sent to a trained and equipped laboratory for gold standard testing.
This time taken for diagnosis can worsen outcomes with delays in initiation of treatment or isolation of contagious individuals. Also, therapies can sometimes be started before laboratory confirmation, often unnecessarily, which can increase the potential for the emergence of antibiotic resistant strains.
Until fairly recently, the diagnosis of an infectious pathogen has been dependent upon microscopy and cultures that take several days. But with the development of real-time reverse-transcriptase PCR tests in the mid-1990s, confirmation of specific pathogens and strains became possible within hours. While these techniques are confined to specialized laboratories, new extraction techniques, microfluidic lab-on-a-chip devices, and continued miniaturization of components have enabled the development of mobile POC genomics-based diagnostic tests, which have the potential to provide faster throughput, simplify use, reduce costs, and improve portability.
Although few POC diagnostic tests are commercially available, many are in development. All such tests will need rigorous assessment of their effect on clinical outcomes, diagnostic accuracy, performance in the field, and cost-effectiveness. But if they are shown to be effective then they will have great potential. Soon it might be possible for people to get accurate results almost anywhere, even collecting samples themselves and testing them from their home, as is available now for HIV. The process of home testing is likely to make patients engaged in their diagnosis and owners of their own laboratory data. It could also reduce the anxiety of waiting or the stigma of obtaining results. Results could be digitally transmitted to clinicians or virtual care providers who could then, through digital pathways, provide timely prevention advice and prescriptions back to patients.
The potential for digital connectivity of POC diagnostic tests with smartphones creates an especially useful tool for resource-poor or remote regions. Much of the world does not have access to a local laboratory so specimens are transported to larger, central laboratories—appropriately packaging and labelling specimens while maintaining a cold-chain during shipment can be especially challenging when electrical supply is variable or not available. Getting laboratory results back to patients also poses a challenge in remote areas, where access to clinical care may be far from someone's home. However, POC mobile diagnostic testing could link patients in all regions of the world to laboratory resources and result interpretation, especially with a growing population of smartphone users.
POC tests connected to smartphones will also create an opportunity for real-time infectious disease surveillance tools. Mobile POC results have the potential to be digitally sent to local and national surveillance centers, providing estimates of real-time infectious disease tracking and outbreak identification. Additionally, new POC tests with multiplex assays are in development that could help identify new emerging strains earlier and therefore prevent widespread outbreaks by quick initiation of public health interventions. POC tests could also simultaneously link epidemiological data with the laboratory data, improving our ability to gather data from geographically dispersed regions to answer important research questions and improve outbreak response.
Even though POC diagnostics are promising, they represent only one piece of the puzzle: they must provide both affordable and accurate results, which must be coupled with accessible treatment and prevention efforts to have a large public health impact. POC tests must also maintain proper quality assurance and be safe and easy to use. In addition, while multiplex assays enable testing for multiple pathogens at once, it will still require input from clinicians about selecting appropriate pathogens for testing. In the future, however, faster unbiased real-time metagenomic sequencing of pathogens could eliminate the need for this, by identifying any pathogen and strain based on its unique DNA or RNA sequence. Despite these challenges, quick and accurate mobile POC tests that can be used by non-experts at home or in the community would be a huge jump in democratizing diagnoses.
This article was originally published at http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(16)31813-X/fulltext.
Jennifer M. Radin is working with Biomeme, Inc to develop a grant on rapid assessment of Zika virus complications and on diagnosis of influenza and respiratory syncytial virus in remote settings. The authors are supported by the National Institutes of Health (NIH)/National Center for Advancing Translational Sciences grant UL1TR001114 and a grant from the Qualcomm Foundation.
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