Think about the last time you were sick with a cold or a flu. If it was your first visit for this particular ailment, in all likelihood, you were prescribed medicines based on your symptoms rather than on a diagnostic evaluation of what was causing the illness. The reason: collecting a sample, sending it to a diagnostic laboratory, and awaiting results are expensive and time-consuming processes. Achieving diagnostic evaluations are particularly problematic in rural areas and developing countries, where a patient might have to travel several miles to reach the nearest diagnostic center and wait a few hours or return after a day or two to receive the results. The time involved in waiting could also spell casualty for the patient.
This delay in diagnosis, the large costs involved in purchasing and maintaining diagnostic equipment, and hiring trained personnel all highlight the pressing need for better point of care diagnostics (POCD) that are cheap, easy to handle, and provide accurate results. If some estimates are to be believed, better POCD technologies for just four infections (bacterial pneumonia, syphilis, malaria, and tuberculosis) could prevent more than 1.2 million deaths each year in developing countries.
The “point-of-care” in POCD could be a physician’s office, an ambulance, or one’s home. In this article, we particularly highlight technologies that have been developed over the last decade to enable diagnosis at an individual’s home as well as in resource-limited settings, and look at where the future of point of care diagnostics is headed.
Smartphone technologies:
Given that more than 5 billion people in the world possess a mobile phone, over half of which are smartphones, medical technologies are being designed such that the ever-increasing quality of camera lenses and screen resolutions are exploited. A good example is the modern-day otoscope, a simple clip-on peripheral that can be attached to a smartphone that captures images to assess the severity of an ear infection in children and transmits the images to a pediatrician. The developers of this device, a Berkeley-based startup called CellScope, have also invented a mobile phone–based video microscope that captures and analyzes videos of microfilarial motion of the parasite Loa loa in blood.
Testing for L. loa is important because those with the parasite in their blood experience adverse side effects when ivermectin, a drug that combats lymphatic filariasis and onchocerciasis, is mass administered in places such as Central Africa. This microscope would enable people with L. loa to be excluded from mass administration of ivermectin.
Wearable sensors:
Currently, there is an increasing demand for and development of sensors in the form of watches, bracelets, clothing, and skin patches that offer the noninvasive and continuous monitoring of more than a dozen biometric parameters, well beyond the renowned step count and sleep stages. An added advantage is that the biometric data monitored can then also be shared with one’s healthcare providers, emergency services, family, and friends.
One recent innovation is that of wrist-worn sensors to monitor electro-dermal activity (EDA). EDA is an index of activity of the sympathetic nervous system, which is responsible for the fight-or-flight response. Increased sympathetic activity results in sweating; and since sweat is a good conductor of electricity, tracking the change in skin conductance at the surface serves as a good measure of variation in emotional stress and anxiety. Studies are currently underway to facilitate the use of EDA sensors to monitor conditions of autism, epilepsy, and sleep disorders.
MicroPADs:
Microfluidic paper-based analytical devices (microPADs) are emerging as a biocompatible and cost-effective platform for diagnostics. The general mechanism of these devices is that a fluidic sample flows along a strip of paper, reacting with embedded reagents on its way, to produce results in the form of colored signals. A well-known example is that of pregnancy test kits. Current research in the field is aimed at performing multi-step immunoassays without human intervention. The company Diagnostics For All (DFA) has produced a wide range of paper-based diagnostics that monitor liver function and micronutrient levels, along with devices for early infant diagnosis of HIV.
Researchers at Labonachip, another startup company, have developed paper-based circuits where the sample fluid can activate the subsequent flow of reagents in a sequential manner, with a predetermined delay. They believe that the platform can be applied to diagnose several diseases such as Ebola, malaria, and Lyme disease. Cofounder and scientific advisor at the company, Mohammad Faghri, stated, “If someone comes up with a new biomarker for detecting a disease, we can create a test for it using our platform.”
The unsung reward:
While reduced diagnosis time and expenses are clear benefits of point of care diagnostics, one of the biggest advantages is that it is a step in the fight against antibiotic resistance. Knowing whether an infection is caused by a bacteria or a virus would drastically reduce inappropriate diagnoses, and consequently, inappropriate antibiotic usage. POCD techniques that detect antibodies produced as a response to bacteria can help physicians provide more accurate antibiotic treatment and thus prevent inappropriate applications that lead to the increasing resistance to antibiotics.
The road ahead:
The global POCD market is projected to reach US $38.13 billion by 2022. Research and development in the field of POCD is currently witnessing rapid advancement. A key requirement however is commercialization of these technologies and their development into a market-ready form without compromising on the accuracy and reliability of the results provided. Transcending this barrier, point of care diagnostics will place us on the road to saving more lives and making healthcare more accessible to all.
