Portable Diagnostic Bioassays - hot or not? View the infographic here

What are portable diagnostic bioassays (PDBs)? 

Portable diagnostics bioassays (PDBs) are a range of devices used near a person  to diagnose or monitor disease, including at or near the point of patient care (POC). This eliminates the need to move patient samples -such as blood, swabs, saliva, or urine- to a laboratory for analysis and then waiting hours if not days for the results to return. Instead with PDBs, the biological analysis of the sample is performed directly on a compact or ‘hand-held’-style device from which the results are also promptly reported. 

The concept of PDBs is not new. For example modern home pregnancy tests provide results within minutes and on the whole tend to be accurate if used correctly. Various PDBs are already in use in our healthcare systems, including glucose monitoring kits for diabetic patients, blood-gas analysers to assess respiratory disease, and blood coagulation monitors for patients at risk of serious bleeding or stroke. The tests are particularly useful for regular monitoring of chronic conditions as well as diagnosing disease in emergency situations so that decisions on patient care can be taken when and where they are needed. Innovations in mobile phones, DNA sequencers, microfluidics, and microelectronics are further driving developments in the next generation of PDBs. 

Is this the end for laboratory testing? 

No, not quite. Whilst there have been notable developments in the testing capabilities of PDBs over the years, most diagnostic testing still occurs in a laboratory setting. This is partly due to the practical challenge of miniaturising complex tests onto very small devices. But also because in many cases long established laboratory testing offers a level of quality assurance, consistency, and pricing with which PDBs cannot generally currently compete. 

Still, there is scope for much greater PDB use in healthcare, not least because of growing unmet clinical need for rapid near-patient diagnostics, particularly in emergency medicine and infectious disease management. According to the WHO the unavailability of reliable, low-cost, point-of-care tests which allow diagnosis and treatment in a single visit is a major barrier to sexually transmitted infections (STIs) control and prevention. Point-of-care diagnostics are also viewed as a central part of the solution to enormous unnecessary antibiotic use. 

Developments in PDB’s could also expand options for self-management of chronic conditions, as glucose monitors do for diabetic patients. But perhaps the most radical offering arising from remote and continuous monitoring is the possibility of identifying markers of preclinical disease in otherwise presumptively healthy individuals. As with existing ‘screening’ tests, a careful balance will have to be drawn between the benefits of earlier disease detection and risks of over diagnosis.

Fast, affordable, and reliable PDBs – close prospect or a distant pipedream? 

This burgeoning demand for near-patient diagnostics is being met with the significant commercial investment in the field. The projected global market for POC diagnostics is expected to reach US$27.5billion by 2018. So the availability of new PDBs is likely to be a matter of when and not if. Nevertheless, unless proactive action is taken now to address some of the implementation challenges for this group of technologies, our health system will struggle to promptly adopt any new PDBs and put them to the most effective use. These challenges include:  

Demonstrating validity: When it comes to choosing between speed, quality and cost, convention tells us to ‘pick two’. Yet any new PDB test should provide all three; accurate results, within actionable timeframes, and at a price affordable to health systems. A recent scandal surrounding the PDB developer, Theranos, demonstrates that there can be no concessions when it comes to test accuracy and reproducibility. Earlier this year a scathing report by regulators claimed that Theranos’ operations risked serious injury, harm, or even death to patients, and the company now find themselves under criminal investigation. To break into the healthcare market test developers will have to demonstrate high analytic precision and reproducibility in large number of samples and ensure their tests meet the relevant quality benchmarks and pass accreditation processes. 

Closing the evidence gap: There is a dearth of evidence around the cost effectiveness of existing POC testing over traditional laboratory testing - the little evidence that does exist is often conflicting. Whilst economies of scale probably make the unit cost of a laboratory test cheaper than an equivalent PDB test, PDB testing could potentially offer savings at other stages of the patient care pathway. In theory speedier return of results could enable more effective use of resources e.g. through facilitating faster triage, or the need for fewer follow-up consultations. Developing an economic case for investing in PDBs will require evidence to be collected across the entire care pathway as well as an understanding of the financial flows across all the departments involved. 

Rethinking care pathways: Finally, realis ing the benefits of PDBs will be contingent on the ability of care pathways to adjust to incorporate near-patient testing and their agility to respond to more rapid results. This will require a willingness of health system leaders to rethink the design of patient care pathways, and in particular consider the implications of tests results not only being generated remotely, but increasingly in the homes and hands of patients. Furthermore investment in electronic data management systems will be integral to ensuring test data can be transferred quickly to the relevant clinical department and directly from PDB devices to central hospital systems. 

The promise of the next generation of PDBs is huge; democratised diagnostics, faster results, more patient-centric care. How long it takes to get there will depend on the degree of collaboration between the technologies developers and its clinical end-users, not only to generate the necessary evidence of validity and utility, but also to set out the vision for how PDBs can be best deployed in an evolving system of healthcare delivery.