Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis [Research]

Background:

Conflicting recommendations exist related to which facial protection should be used by health care workers to prevent transmission of acute respiratory infections, including pandemic influenza. We performed a systematic review of both clinical and surrogate exposure data comparing N95 respirators and surgical masks for the prevention of transmissible acute respiratory infections.

Methods:

We searched various electronic databases and the grey literature for relevant studies published from January 1990 to December 2014. Randomized controlled trials (RCTs), cohort studies and case–control studies that included data on health care workers wearing N95 respirators and surgical masks to prevent acute respiratory infections were included in the meta-analysis. Surrogate exposure studies comparing N95 respirators and surgical masks using manikins or adult volunteers under simulated conditions were summarized separately. Outcomes from clinical studies were laboratory-confirmed respiratory infection, influenza-like illness and workplace absenteeism. Outcomes from surrogate exposure studies were filter penetration, face-seal leakage and total inward leakage.

Results:

We identified 6 clinical studies (3 RCTs, 1 cohort study and 2 case–control studies) and 23 surrogate exposure studies. In the meta-analysis of the clinical studies, we found no significant difference between N95 respirators and surgical masks in associated risk of (a) laboratory-confirmed respiratory infection (RCTs: odds ratio [OR] 0.89, 95% confidence interval [CI] 0.64–1.24; cohort study: OR 0.43, 95% CI 0.03–6.41; case–control studies: OR 0.91, 95% CI 0.25–3.36); (b) influenza-like illness (RCTs: OR 0.51, 95% CI 0.19–1.41); or (c) reported workplace absenteeism (RCT: OR 0.92, 95% CI 0.57–1.50). In the surrogate exposure studies, N95 respirators were associated with less filter penetration, less face-seal leakage and less total inward leakage under laboratory experimental conditions, compared with surgical masks.

Interpretation:

Although N95 respirators appeared to have a protective advantage over surgical masks in laboratory settings, our meta-analysis showed that there were insufficient data to determine definitively whether N95 respirators are superior to surgical masks in protecting health care workers against transmissible acute respiratory infections in clinical settings.

[Comment] Respiratory medicine: a call for papers

The Lancet and The Lancet Respiratory Medicine would like to hear from authors of research papers in any area of clinical research related to respiratory medicine and critical care as the two journals are once again planning special issues timed to coincide with the 2016 European Respiratory Society (ERS) International Congress, in London, UK, on Sept 3–7. We welcome high-quality submissions from this thriving research community, particularly clinical trials and research that will change clinical practice or current thinking.

INTEGRATING CARE FOR PATIENTS WITH SERIOUS AND CONTINUING ILLNESS

Rising numbers of patients with serious and continuing illness are set to change the way we provide medical care. They need care that like their ailments, is both serious and continuing.

This is not a new insight. We have known about the increasing load of chronic illness for decades. We know its pattern has changed. We know that while it mainly afflicts older people; children and adolescents who would have died decades ago live on now. They, too, need continuing care. Middle-aged people with cancer or heart disease or mental illness saved from death from an acute illness now likewise need continuing care.

This changing pattern of illness means that hospital and out-of-hospital care must, be better joined up because neither form of care is at its best when managing independent episodes in a long-running story. It means that the way we provide care in future should be built around what is best for the patient, namely, continuous and linked. We have known all this, too – but now the pressure to do better is coming from the community itself.

When the community becomes concerned, politicians respond. The prime minister, Malcolm Turnbull, has committed $38 million this year to trying out ways of linking care for patients with chronic problems, placing the general practitioner in the driving seat.

Meet George Henderson – lets give him that name. I saw him at home several years ago when I was working at the Respiratory Ambulatory Care Service (RACS) at Blacktown Hospital. Two of the nurses who do most of the work of the clinic took me to see him. They had a panel of over 100 patients who had been through the their six week program and were living at home.

George lived in a community-services house. His principal carer was his former wife who had come back for this purpose as their children threatened not to speak to her again unless she did!

We arrived at 10am. He came slowly to the door in pyjamas, trailing a long cord to an oxygen concentrator in his kitchen. He was exhausted when we got him to bed. It was a tiny, lonely room. There was a bedside torch, copious bottles of tablets and on the shelves several small and intricate balsa boat models that he made as his hobby.

The nurses chatted, examined his chest, measured his blood pressure and oxygen saturation. How did he bathe? I asked. He had to clamber over the edge of a bath. There were no handrails. Could we get them installed? One nurse told me this would require authorisation from the hospital social worker. When can she come? I asked. ‘Oh!,’ the nurse laughed. ‘To this suburb? Four weeks! To [an up market neighbouring suburb] one week!’ If he slipped and survived with a broken femur who would be to blame? We would all pay.

I noticed when I assessed him that his teeth were poor. A dental appointment at a hospital outpatient department would take many months. One nurse told me that when they found an acute and serious dental problem, they would send the patient to hospital ‘with an exacerbation’. That way, the nurse said, his dental problem would be speedily sorted. But getting him to hospital ran the risk of oxygen overdose on the way and ICU on arrival for hypercapnia.

To expect a general practitioner to be the centrepiece of George’s care would require remuneration that matched the cost. The doctor would need allied health professional staff immediately at his or her call – physios, nurses and more. Connection to a specialist would have to be immediately available. To give George a sense of confidence he would need to be able to talk to someone who knew and understood him 24/7.

One of the nurses who was on the RACS 24/7 roster told me how George had called at 2am one day, acutely breathless and anxious. She was able to ‘talk him down’, encourage him to breathe as he had been taught, make a cup of tea. She avoided a hugely disruptive emergency visit to hospital.

There is more to integrating care for patients with serious and continuing illness than can be written in bureaucratic documents and business charts. It is a matter, most fundamentally, of our response to the real, grounded problems of the people we care for, the way we respond to growing human needs. Money matters, but it can be found. As a profession we should consider joining our voices to those of our patients in seeking better ways of caring for those with chronic problems.

E-cigarettes most popular with young people

The use of e-cigarettes in New South Wales is highest in young people, however they are mostly using them less than weekly.

Research published in the Medical Journal of Australia found that 16% of respondents age 18-29 were currently using e-cigarettes.

Unlike older e-cigarette users, these respondents weren’t using the products to help them quit smoking. Instead they said it was because e-cigarettes tasted better and they could smoke them in places where cigarettes were banned.

The study found adults over the age of 55 were the most frequent users of e-cigarettes and those over 30 were more likely to use the products to help them quit tobacco.

Related: E-cigs: a help or a harm?

However researchers expressed concerns about this, saying many users in the sample were smoking both conventional and e-cigarettes.

“For avoiding the risks of smoking-related premature death, however, reducing cigarette numbers is much less effective than quitting, and future research should investigate whether tobacco smokers using e-cigarettes to cut down are doing so as part of a cessation strategy or in the hope of reducing smoking-related harm,” the authors wrote.

According to an accompanying editorial in MJA, there is a lack of evidence that e-cigarettes were any more effective than other unassisted cessation or conventional nicotine replacement therapies.

“A Cochrane review reported the evidence as being of ‘low/very low quality’, and a recent metaanalysis concluded that they, in fact, reduced the probability of quitting,” they wrote.

Recent statistics released by HealthStats NSW certainly seem to back up that evidence. According to new data, the 45-54 year old age bracket has seen tobacco smoking rates jump more than 2% in the last year.

While smoking rates overall have fallen in the last year from 15.6% to 13.5%, the results haven’t been seen in the older age groups.

Anita Dessaix, manager of Cancer Prevention at the Cancer Institute NSW told Fairfax media that older people would find it harder to quit as most took up smoking as teenagers.

“The message particularly for old people is not to despair and keep trying and that there is hope and support and that they can quit smoking,” Ms Dessaix said.

Latest news:

[Series] High-flow oxygen therapy and other inhaled therapies in intensive care units

In this Series paper, we review the current evidence for the use of high-flow oxygen therapy, inhaled gases, and aerosols in the care of critically ill patients. The available evidence supports the use of high-flow nasal cannulae for selected patients with acute hypoxaemic respiratory failure. Heliox might prevent intubation or improve gas flow in mechanically ventilated patients with severe asthma. Additionally, it might improve the delivery of aerosolised bronchodilators in obstructive lung disease in general.

[Series] Clinical challenges in mechanical ventilation

Mechanical ventilation supports gas exchange and alleviates the work of breathing when the respiratory muscles are overwhelmed by an acute pulmonary or systemic insult. Although mechanical ventilation is not generally considered a treatment for acute respiratory failure per se, ventilator management warrants close attention because inappropriate ventilation can result in injury to the lungs or respiratory muscles and worsen morbidity and mortality. Key clinical challenges include averting intubation in patients with respiratory failure with non-invasive techniques for respiratory support; delivering lung-protective ventilation to prevent ventilator-induced lung injury; maintaining adequate gas exchange in severely hypoxaemic patients; avoiding the development of ventilator-induced diaphragm dysfunction; and diagnosing and treating the many pathophysiological mechanisms that impair liberation from mechanical ventilation.

[Comment] Expanding the benefits of HPV vaccination to boys and men

Human papillomavirus (HPV) is the most common sexually transmitted infection. It affects 80% of the population, with the initial infection usually occurring between 15 and 24 years of age. Persistent infection with high-risk oncogenic HPV genotypes, primarily types 16 and 18, is the cause of almost all cervical cancers.1 HPV is also thought to cause about 95% of anal cancers, 75% of oropharyngeal cancers, 75% of vaginal cancers, 70% of vulvar cancers, and 60% of penile cancers.2 Low-risk or non-oncogenic genotypes (eg, types 6 and 11) cause anogenital warts, low-grade cervical disease, and recurrent respiratory papillomatosis.

Tackling smoking, childhood obesity and back pain: it’s not for want of trying

Humans are complex beings, and few of even our simplest actions are entirely rational. The more of us there are, the more unpredictable things get. It’s not entirely unexpected then that evidence on how to tackle complex health conditions, particularly at the population level, has been limited and simple solutions elusive. A recent crop of Cochrane reviews shows mixed results.

Let’s start with good news. Reducing exposure to second-hand smoke through legislation banning smoking in public and work places has been commonplace in Australia for many years. It’s reassuring then that a review of 77 studies from 21 countries demonstrated consistent evidence of a positive impact of these laws, especially on improving cardiovascular health outcomes and reducing mortality from smoking-related illnesses. However, the evidence was less consistent for respiratory and perinatal health, and for smoking prevalence and tobacco consumption (doi: 10.1002/14651858.CD005992.pub3).

Tackling childhood obesity is a huge challenge, even more so when many parents struggle with their own weight. Might interventions directed at helping parents change their family’s diet and lifestyle have an impact on their children’s weight? The evidence from a review of 20 wide-ranging studies is not especially encouraging. Diet, physical activity and behavioural treatments delivered to parents only had similar effects compared with parent–child interventions and compared with minimal contact controls (doi: 10.1002/14651858.CD012008).

Chronic low back pain is a common condition for which exercise is a modestly effective treatment. A recent review sought to find out if motor control exercise, a popular form of exercise similar to core strength training, is superior to other forms of exercise in relieving pain and disability. Despite the inclusion of 29 studies, little or no difference was observed in any of the outcomes measured. The effects were the same when motor control exercise was compared with manual therapy (therapy associated with physiotherapists or physical therapists). Only when compared with a minimal intervention was a clinically important effect found, which at least confirms that doing something is better than nothing (doi: 10.1002/14651858.CD012004).

One less talked about consequence of higher antibiotic prescribing rates in children is the increasing likelihood of antibiotic-associated diarrhoea. At least here there is some reason to cheer. A new review of 23 studies involving nearly 4000 children found that probiotics were generally well tolerated and have a protective effect in preventing antibiotic-associated diarrhoea, with a respectable number needed to treat of 10 (doi: 10.1002/14651858.CD004827.pub4).

For more on these and other reviews, visit the Cochrane Library at www.cochranelibrary.com.

[Editorial] The lung: a magnificent organ that needs lifelong attention

When more than 15 000 pulmonologists and other health workers interested in respiratory medicine meet in San Francisco, USA, at the annual American Thoracic Society (ATS) meeting from May 13–18, 2016, the lung will be at the centre of attention. To coincide with the meeting, this issue of The Lancet dedicates content to the lung—a wondrous and neglected organ that provides every cell in the body with vital oxygen and stands at the interface between the environment and the circulation.

Macrolide antibiotics and the risk of ventricular arrhythmia in older adults [Research]

Background:

Many respiratory tract infections are treated with macrolide antibiotics. Regulatory agencies warn that these antibiotics increase the risk of ventricular arrhythmia. We examined the 30-day risk of ventricular arrhythmia and all-cause mortality associated with macrolide antibiotics relative to nonmacrolide antibiotics.

Methods:

We conducted a population-based retrospective cohort study involving older adults (age > 65 yr) with a new prescription for an oral macrolide antibiotic (azithromycin, clarithromycin or erythromycin) in Ontario from 2002 to 2013. Our primary outcome was a hospital encounter with ventricular arrhythmia within 30 days after a new prescription. Our secondary outcome was 30-day all-cause mortality. We matched patients 1:1 using propensity scores to patients prescribed nonmacrolide antibiotics (amoxicillin, cefuroxime or levofloxacin). We used conditional logistic regression to measure the association between macrolide exposure and outcomes, and repeated the analysis in 4 subgroups defined by the presence or absence of chronic kidney disease, congestive heart failure, coronary artery disease and concurrent use of a drug known to prolong the QT interval.

Results:

Compared with nonmacrolide antibiotics, macrolide antibiotics were not associated with a higher risk of ventricular arrhythmia (0.03% v. 0.03%; relative risk [RR] 1.06, 95% confidence interval [CI] 0.83–1.36) and were associated with a lower risk of all-cause mortality (0.62% v. 0.76%; RR 0.82, 95% CI 0.78–0.86). These associations were similar in all subgroups.

Interpretation:

Among older adults, macrolide antibiotics were not associated with a higher 30-day risk of ventricular arrhythmia than nonmacrolide antibiotics. These findings suggest that current warnings from the US Food and Drug Administration may be overstated.