The era of lateral flow tests
Laura Baker, Marketing Manager at BIOHIT Ltd
I had little experience or knowledge of the scientific or healthcare sectors when I started out in the IVD industry seven years ago, so when I was told that the company I was interviewing for developed lateral flow tests (LFTs), I had to do my research. For the next five and a half years, I got bewildered looks when family and friends asked what I did for work, and I mentioned the words ‘lateral flow’. The only way of explaining was to use the example of a pregnancy test. It seemed unimaginable then that LFTs would become a common household item, a regular topic of conversation and part of everyday vocabulary. But since the global COVID-19 pandemic, it’s made it into song lyrics and often pops up in social media memes, with every event promoting the mantra ‘lateral flow before you go’!
The dawn of a new age
Who would have thought in 2019 that we’d be ordering LFTs for next day delivery through Amazon? I guess many of us in the point-of-care diagnostics industry hoped that would be the future, but we never imagined the explosive speed of adoption that followed the onset of the COVID-19 pandemic in 2020. The whole diagnostics industry beyond LFTs was thrown into the spotlight, and the everyday Joe Bloggs became much more conscious of – and interested in – diagnostics for all kinds of diseases and conditions. The pandemic certainly brought to light the opportunities that point-of-care testing can offer. We’ve seen the likes of Prince Harry advocating point-of-care HIV testing, but the possibilities go far beyond infectious diseases, and even outside of human healthcare. This simple diagnostic tool has potential in food production and veterinary applications, plus much more.
How does a lateral flow test work?
LFTs are based on immunoassay technology, and use coloured nanoparticle ‘labels’ and antibodies to produce results. When a sample is added to the test cassette, it binds to the antibody-conjugated labels and migrates along the absorbent pad. When it reaches the ‘test’ line, the antibody-conjugate-sample complex will be ‘captured’ by a strip of analyte-specific immobilised antibodies if the target analyte is present, forming a coloured line that indicates a positive result. A second strip of immobilised antibodies acts as a ‘control’ line, capturing antibody-conjugate-sample complexes regardless of whether the target analyte is present. The images below show an example of a typical LFT cassette (left) and the test strip contained within.
Could lateral flow technology be the answer to many of the NHS’s burdens?
In the current situation, the use of LFTs in primary care could solve many issues – from long patient waiting lists and backlogs for more invasive and costly diagnostic methods to improved prognostics – by offering a simpler and more convenient testing pathway and, ultimately, cost savings.
GastroPanel® Quick Test is one such example where a routine laboratory test – ELISA – has evolved into a test that is ideal for primary care settings. This simple blood test aids the diagnosis of dyspepsia, and can be used to effectively identify atrophic gastritis and gastric cancer risk, helping to select patients for referral to gastroscopy. A clinical validation study conducted at Oulu University Hospital (OUH)1 looked at a cohort of 522 patients with symptoms of dyspepsia, who had all been referred for diagnostic gastroscopy. GastroPanel identified atrophic gastritis warranting gastroscopy in just 10 per cent of these cases. Each gastroscopy performed in England costs £421* compared to just £30 with GastroPanel so, if 90 per cent of gastroscopy referrals could be avoided, NHS procedural costs could be reduced by £69m.
Then there’s common everyday conditions, such as reflux. A large majority of reflux patients are managed in primary care, and are often prescribed a proton pump inhibitor (PPI) – such as omeprazole – to reduce the amount of stomach acid. The root cause is not always fully investigated unless symptoms persist or are severe, or do not respond to PPIs, yet a differential diagnosis between reflux and ‘silent’ reflux – otherwise known as laryngopharyngeal reflux (LPR) – is key to directing the right treatment or appropriate lifestyle changes. Current diagnostic pathways rely on time-consuming, inconvenient, invasive and costly techniques, including endoscopy, manometry, 24-hour pH monitoring, barium swallow and even biopsy. In contrast, Peptest is a simple, non-invasive LFT that measures pepsin in saliva samples to effectively differentiate between gastro-oesophageal reflux disease (GORD), LPR and other conditions that present as reflux.
Peptest can confirm the presence or absence of pepsin in a patient’s sample within 20 minutes, with tests performed in any standard laboratory. It is convenient, too; samples can be handled in a GP’s surgery, or patients can use a send-away service – in theory, they don’t even need to leave the house! It’s safe, far more comfortable for patients, and avoids any exposure to radiation. It is also less open to operator variability and equipment-related factors than, for example, barium swallows and gastroscopy, and less susceptible to subjective interpretation.
The potential cost savings are significant too. Traditional diagnostic reflux tests frequently involve specialist personnel, facilities and materials, and an overall cost of around £750 to the NHS is not unusual. Peptest, on the other hand, does not need specialised equipment, and costs around £25 per test. And with an estimated 40 per cent of PPI medication currently being prescribed by GPs to treat reflux not completely resolving the issue, a differential diagnosis from Peptest at the primary care level could significantly cut this waste.
Let’s add mobile technology into the mix
The benefits of disease monitoring with lateral flow technology reach a whole new level of convenience when you bring in the added benefit of mobile technology. Let’s consider SmarTest® Calprotectin, a quantitative home test system for the determination of calprotectin in stool samples. SmarTest Calprotectin is designed for self-testing and individual monitoring of disease activity and treatment efficacy for patients with chronic inflammatory bowel disease (IBD). This rapid LFT detects human calprotectin via gold-conjugated anti-calprotectin antibodies. The result is quantified based on the intensity of the test and control lines using a smartphone app, then automatically sent to the patient’s doctor and logged in the Doctor’s Online Portal for the IBD team to monitor remotely. For a patient suffering from an IBD flare up, the symptoms can be debilitating, and the thought of regular trips to the GP or hospital unbearable. The simple use of an LFT from the comfort of your home, with results sent via a mobile phone, overcomes all these concerns. Turnaround times are faster than the routine lab alternative, with results available instantly, enabling patient-initiated follow-up (PIFU) and allowing individuals to take control of their disease.
Does the future of diagnostics lie in the simple technology of a lateral flow test?
While more complex and detailed testing methods, such as PCR, have a vital role to play, LFTs undoubtedly have much to offer. As a first line diagnostic for ruling out disease, monitoring lifelong conditions and helping to speed up diagnosis, lateral flow technology could provide a very cost-effective solution.
References
- Koivurova O-P, et al. Serological biomarker panel in diagnosis of atrophic gastritis and Helicobacter pylori infection in gastroscopy referral patients. Clinical validation of the new generation GastroPanel® test. Anticancer Res. 2021;41(11):5527-5537. DOI: https://doi.org/10.21873/anticanres.15366
* NHS England tariff 2021/2022
