Background
Influenza viruses is a leading cause of acute respiratory infection. It is responsible for a large burden of disease, including serious complications in patients with risk factors such as pregnancy, young children, elderly, or those with underlying medical conditions [
1,
2]. Studies have shown respiratory viruses are detectable in 40–50% of hospitalised adults with acute respiratory illness [
3,
4]. The case fatality rate of influenza in hospitalised patients is quoted at 3–8% [
3,
5]. Influenza viruses are highly transmissible within both community and healthcare settings, and places a significant burden on healthcare [
1‐
3]. Nosocomial influenza virus outbreaks lead to increased bed occupancy and closed wards during winter months, with significant financial implications [
6]. Prevention of influenza virus transmission within healthcare facilities requires a multipronged approach, including general precautions such as correct hand hygiene, respiratory etiquette, patient specific contact/droplet precautions, vaccination of patients and staff, antiviral treatment or chemoprophylaxis and surveillance of cases [
7,
8]. Rapid detection and implementation of chemoprophylaxis within hospitals has been identified as one of the most important interventions to contain an influenza virus outbreak [
9].
Influenza virus testing in the UK is based on clinical suspicion and the use of laboratory-based PCR tests [
10,
11]. In the UK, laboratory-based PCR turnaround times range at 24–48 h [
10,
12]. One of the mainstays of controlling influenza in healthcare is around timely diagnosis [
10]. Point of care tests (POCT) can be non-molecular or molecular-based [
13]. POCT for influenza viruses have been previously antigen-based, however lack sensitivity [
13]. More recently, rapid molecular tests are available and broadly equivalent to laboratory-based PCR [
13]. A major benefit of POCT is the rapidity of results, which is important to guide clinical management [
13]. They can also guide infection control measures to optimise patient allocation and bed utilisation within the hospital, reduce nosocomial transmission of respiratory viruses and provide an earlier diagnosis of viral respiratory tract infections [
13]. An influenza virus POCT, specifically a Cepheid GeneXpert, was used in the acute medical unit (AMU) at Queen Elizabeth Hospital Birmingham (QEHB), part of University Hospitals Birmingham (UHB) NHS Foundation Trust, during the 2017/18 influenza season. After the end of the influenza season, a service evaluation was conducted to assess the impact of the POCT on patient care and infection control. The results were compared to the previous influenza season (2016/17), when no POCT was used. Outcomes included rates of healthcare-associated influenza virus, utilisation of oseltamivir, length of stay and achievement of respiratory isolation.
Discussion
Influenza virus is highly transmissible in a healthcare setting. As such it is recommended that patients clinically suspected of having influenza are isolated and offered empirical antiviral treatment [
1,
2]. Rapid influenza virus detection and implementation of chemoprophylaxis within hospitals has been identified as one of the most important interventions to contain an outbreak [
1]. Recently, Young et al.
, (2018) discussed the impact of a POCT for influenza virus in an emergency department [
3]. The POCT was associated with reduced nosocomial transmission of influenza virus and improved patient flow [
3]. A recent randomised clinical trial showed similar effects and suggested use of a POCT was associated with a reduced length of stay as well as improved influenza virus detection and antiviral use [
10]. Here, we report our experience of using a POCT in an AMU looking primarily at four outcomes: length of stay, oseltamivir utilisation, time to isolation and in-hospital cases of influenza virus.
At QEHB, healthcare associated influenza virus cases of 49% (period 1) were reported in 2016/17 compared to 9% (period 2) in 2017/18. There was strong statistical evidence that the mean number of healthcare associated influenza virus cases differed between period 2 where the POCT was used, compared to period 1 where it was not used. Young et al.
, (2018) recently demonstrated a similar result where the rate of healthcare-associated infection per day was lower after the implementation of a POCT in an emergency department [
3]. The number of healthcare associated influenza virus cases in period 2 when the POCT was introduced in our setting could be in part due to the POCT. Young et al.
, (2018) demonstrates that a POCT enables influenza virus cases to be identified earlier, thereby allowing for appropriate infection control precautions such as isolation and antiviral treatment [
3]. In addition, patients presenting with influenza could be discharged home more quickly, thereby prevented delayed diagnosis within the healthcare setting and the opportunity for transmission [
3,
10]. Similarly in a recent RCT by Brendish et al.
, (2017) comparing the use of a POCT vs an in-house laboratory method, a reduction in length of stay was observed in patients testing positive for respiratory viruses [
10]. Brendish et al.
, (2018) also demonstrated rapid turnaround times using a POCT are associated with higher rates of early discharge and early discontinuation of antibiotics compared to longer turnaround times in adults with acute respiratory illness [
17]. Other reasons for the results observed in the current study could include the acuity of the strains of influenza virus, which could potentially have been less virulent. Out of the 666 cases of influenza viruses reported in period 2, 408 cases were influenza B, as compared to period 1, where there were three cases of influenza B. Further work is warranted to observe whether a POCT does in fact reduce transmission rates via more timely identification.
The reduction in healthcare-associated influenza virus cases seen in the current study may result from improvements in respiratory isolation. The ability for respiratory isolation in the first five days of admission when patients are most infectious has been previously shown to reduce rates of transmission of healthcare-associated influenza viruses. Time to isolation in period 2 was significantly quicker compared to period 1 in the current study; the POCT could in part explain these results. Brendish et al.
, (2017) demonstrated side room isolation for confirmed respiratory virus infection was more common when a POCT was used [
10]. Similarly to our study, they demonstrated better use of side rooms when the POCT was used; with reduced time from admission to isolation in confirmed influenza virus cases [
10]. The authors concluded that rapid and appropriate assignment of side rooms for patients with respiratory virus infection is hugely important to reduce the risk of nosocomial transmission to other vulnerable hospitalised patients [
10]. Similar findings would be true at QEHB where patients with transmissible respiratory viral infections are isolated (data not shown). When the infection status is not known, or even considered, patients are not often isolated. Young et al.
, (2018) demonstrated that when a POCT was not used to identify patients with influenza they were not isolated as often as than those patients where a POCT was used to diagnose influenza (21.5% vs 74.8%). Thereby increasing the risk of influenza virus exposure to susceptible patients [
3].
In addition to reductions in healthcare associated influenza virus cases and time to isolation, our study shows that POCT might be associated with a reduction in hospital length of stay. The median length of stay of patients with influenza virus in period 2 was statistically lower compared to period 1. It is possible that the prevalent strain of influenza virus provoked less severe disease in period 2 than period 1, which could in part explain the results seen. Brendish et al.
, (2017) demonstrated a similar finding in patients with exacerbation of airways disease [
10]. The authors concluded that reduced hospital length of stay was due to earlier discharge in patients testing positive for respiratory viruses via a POCT [
10]. The reduction in length of stay reported by Brendish et al.
, (2017) was in the order of 1 day, which equated to around 200,000 bed days saved, with a cost saving of £80 million per year [
10,
18]. In the current study, the reduction in length of stay was in the magnitude of 3 days, with a higher proportion of bed days saved and thus the potential for even greater cost savings. Further work is warranted to explore the cost savings.
In agreement with prior studies, we found that prescription of oseltamivir increased post-introduction of an influenza virus POCT (data not shown) [
19‐
21]. Oseltamivir treatment is recommended by UK Public Health England for all patients hospitalised with influenza [
22]. Our study showed a statistically quicker administration of oseltamivir in period 2, when a POCT was used, as compared to period 1. Increased oseltamivir prescription may have contributed towards a reduction in healthcare-associated influenza viruses seen at QEHB by reducing ongoing transmission. Brendish et al.
, (2017) showed that a POCT for respiratory viruses leads to an increased proportion of influenza-positive patients correctly receiving treatment with neuraminidase inhibitors and suggested a reduced time to administration of the first dose [
10]. There is much debate on the effectiveness of oseltamivir, however the literature details the most effective use is within the first 48 h of symptoms [
23]. The POCT in our setting certainly helped with quicker administration of oseltamivir. Further work is warranted to look at the effect of neuraminidase inhibitors on resolution of symptoms and the effectiveness within the first 48 h of treatment.
Finally unlike Brendish et al.
, (2017) this study used an influenza virus/RSV POCT rather than syndromic multiple for respiratory viruses [
10]. The added value for syndromic multiplex molecular POCT above molecular Influenza virus testing is currently unknown but there are potential clinical benefits to the detection of other non-influenza viruses at the POCT including infection control and early cessation of stopping unnecessary antibiotics, although these would need to be considered against the extra expense of the syndromic panels.
Limitations of the study include the differences in Influenza season in periods 1 and 2. There was a large difference in the amount of Influenza virus seen and a difference in Influenza strains seen. This could have affected the results observed and warrants further analysis in future Influenza seasons. Another factor to explain the results seen is that the acuity of the strains of influenza could potentially have been less virulent in the current study. However, despite the limitations the quality and efficiency of management of influenza-like illness was improved in season 2. To note there were no other interventions during these two periods 1 and 2.
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.