Seasonal illnesses like influenza and respiratory syncytial virus (RSV) are an increasingly common part of medical practice. The consequences of inaction are shocking: approximately 500,000 people die of flu complications each year. All this puts increased pressure on doctors to diagnose and manage patients more effectively. Traditionally, hospitals relied on enzyme immunoassays (EIAs) to diagnose patients, but this method can be unreliable as they are not sensitive enough to be accurate.
However, there is an innovative alternative available: rapid real time RT-PCR (reverse transcriptase PCR) testing. This methadology is a molecular method recognised as a highly sensitive and specific alternative for the detection of respiratory RNA viruses. This is good news for physicians and patients alike, explains Dr Stanley Leung Wai-ming, the laboratory director at Hong Kong Adventist Hospital – Tseun Wan. “Influenza has become an epidemic in Hong Kong,” he says. “We have a lot of casualties, causing a lot of admissions and deaths, particularly of younger children and elderly patients. Influenza A, Influenza B and RSV detection is really critical to us.”
Initially, doctors diagnose patients purely based on physical signs. “We usually notice if a patient has particular symptoms, like coughing, fever, nasal discharge or even pneumonia,” explains Leung. This can cause problems though. As influenza and RSV patients share many of the same symptoms, it can often be a challenge to know exactly what patients are suffering from.
With a sensitivity rate of around 94% and a specificity rate of over 94%, RT-PCR tests can distinguish between illnesses far more precisely than EIAs. “[We prefer these tests] because of [their] accuracy and sensitivity,” Leung says. “They have a high degree of specificity compared with enzymatic testing, which only has about 70% sensitivity. We miss a lot of cases if there’s an infection.”
While EIAs are quick to perform, they suffer from other limitations. Notably, they can be complicated to set up, and reading the results can be challenging, even for scientists. For their part, molecular tests like RT-PCRs are simple and easy to use. Leung explains: “You just add the sample to the cartridge. Then you put the cartridge in a machine, and it automatically performs the tests.” Doctors can process samples in under a minute, and full test results are ready in under half an hour.
At the same time, Leung uses molecular testing that send results directly back to his hospital’s laboratory information systems, sparing staff the task of manual data entry. This automated approach also precludes human error, something that can’t be guaranteed when he uses EIAs. “The major difference [with RT-PCRs] is that [our] enzymatic testing machines lack computer links with our laboratory information system. So we need to manually enter all the information into our system. In that scenario, there might be an input error.”
All this undoubtedly helps doctors. More importantly, though, molecular testing is saving lives, especially among vulnerable groups. “If we can accurately identify the influenza patients, we can prescribe the right medication to them as soon as possible,” says Leung. “This is particularly helpful to elderly patients, especially if they have critical symptoms like pneumonia.”
Moreover, molecular testing can stop the spread of infection in hospitals. “We really need to ensure that someone definitely has influenza,” Leung continues. “For critically ill patients, when we’re picking where in a hospital they’ll be admitted, we want to put [influenza] patients into a single room to reduce local infections to other patients. This is really good for patient management.”
Overall, Leung is confident that molecular tests provide better quality of care than the alternatives. “We have a hard time explaining the [limitations] of EIA tests to clinicians and patients,” he admits. “But with the advantages of molecular testing, we can be more confident about providing a good service to our clients.”
