Advances in technology, such as in paper microfluidics and microfluidic circuits, have enabled the development of testing kits that allow people to diagnose themselves (or their dependents) in their own homes. These include: finger-prick blood tests for various illnesses such as coeliac disease, diabetes, and kidney disease; urine dipsticks for pregnancy, STDs, and illicit drugs; and home test kits to indicate blood in stools as an early screening test for bowel cancer.
These DIY diagnostic tests are confidential, convenient, often quick and easy to use, and allow increasingly autonomous and resourceful patients to take control of their own health. Some tests cost as little as a cinema ticket but they can save lives by enabling early-stage disease diagnosis and treatment, and are helping to diagnose illnesses in developing countries where many people have little or no access to medical care.
Given the many benefits of home-use tests, it’s no surprise that they are flying off the shelves. The point-of-care diagnostics market is set to stand at US$37 billion by the end of 2021, with a predicted 9.8% CAGR between 2016 and 2021. This growth is mainly due to increasing consumer awareness, as well as the proliferation of new at-home tests through venture funding and government support.
One recently developed at-home test is a hand-held blood count testing kit for chemotherapy patients, which indicates whether they are ready to receive chemotherapy, thus limiting hospital visits and allowing treatments to be tailored to patients’ specific needs. Other home-use tests in development include a saliva test that can accurately tell you if you have cancer in ten minutes, and a microfluidic device the size of a postage stamp containing immobilized bioreceptors that can detect pertinent disease biomarkers in a patient’s blood sample.
Despite their benefits, it is recommended not to rely solely on at-home diagnostic testing kits instead of professional medical help, as they are generally only initial indicators of disease and need a confirmatory test. Regulatory authorities have warned that at-home tests should be used with caution, and should not replace regular visits to the doctor, as they are “best evaluated together with your medical history, a physical exam, and other testing” (US FDA).
Visiting a professional healthcare practice enables diagnostic tests to be conducted in a dedicated clinical laboratory with specialist equipment and trained technicians, to provide more definitive diagnoses as well as richer information (e.g. disease stage) to better inform treatment decisions. Laboratory testing can often be more reliable than at-home diagnostic tests. For example, stool antigen detection kits have been found to be 1,000 to 10,000 times less sensitive than polymerase chain reaction (PCR) testing, and rapid HIV self-testing kits can be less sensitive than clinical laboratory tests, such as enzyme immunoassays, and so can give misleading results.
The increased reliability and richer information output of diagnostic tests in the clinical laboratory, compared to those used at home, is due in large part to the controlled laboratory environment. This includes using a supply of clinical grade ultrapure water, such as for diluting reagents, feeding incubator baths and wash stations, and washing reaction cuvettes.
This is crucial because using impure water could have disastrous effects on a laboratory’s diagnostic data outputs, such as interference of bacterial by-products in immunoassay systems, and sample and reagent probe washing contamination and carryover. As such, using reliable water purification systems like ELGA’s MEDICA® 7/15 and Pro systems, can mean the difference between diagnoses that hinder or help patients’ health.