Why are diagnoses of pneumonia increasing? This is the question that our Research Statistician, Phuong Quan, (and other scientists from MMM), set out to answer in a paper published this week.
We looked at the hospital database of all people admitted to hospital, and found that admissions for pneumonia had almost tripled over the space of 15 years, an alarming increase. We started investigating what was going on.
Was it because we are now diagnosing pneumonia differently?
When a patient comes to hospital with symptoms of a chest infection, there are lots of things we can call it. ‘Pneumonia’ means that there is irritation and infection in the lungs, to the point where we can see it on a chest xray. Like this:
If the patient has all the symptoms of an chest infection (such as cough, fever, and increased amounts sputum) but has a clear chest on the xray and on listening, we call this a ‘lower respiratory tract infection’ or LRTI. We can also call it ‘bronchitis’. This means the airways (the small tubes that carry air to the lungs) may be infected and irritated, but the lungs themselves are ok. If someone already has a condition known as Chronic Obstructive Pulmonary Disease (COPD), or they have asthma, then we tend to call these chest infections, ‘exacerbations of COPD’ or ‘exacerbations of asthma’.
We wondered whether Doctors had started diagnosing more pneumonia, where 10 years ago it would have been called bronchitis, or LRTI. If this were the case, we’d expect a decrease in other diagnoses to correspond with the increase in pneumonia. However we found that admissions for all respiratory infections were going up. Whilst we couldn’t rule out some changes in diagnosis, this clearly wasn’t the sole cause.
Was it because GPs were just referring more patients to hospital?
There has been a lot of focus in recent years on an increasing reliance on hospital care. There is a perception that GPs are referring more people to hospital who might have otherwise have been treated at home. Others are concerned that the NHS 111 system means that more people are advised to go to hospital. If this were happening, we’d expect more, relatively well, people to be coming to hospital.
We looked how unwell people were when they came to hospital with pneumonia. Using the results of blood tests to look at the immune response, and other markers such as kidney function, actually we found very little change over the years. It didn’t look like the increase in pneumonia was just due to an increase in less-sick patients either.
What else could it be?
We know that over the years, due to advances in living conditions, healthcare and lifestyles, we have an increasingly ageing population, and it is older adults who are at most risk of pneumonia. We know that we’ve seen a large increase in overall number of people come to hospital as well. However when we looked, we couldn’t attribute this three-fold increase in pneumonia admissions to these.
Are the bugs changing?
We did notice that the bugs causing pneumonia appeared to be changing. Whilst the percentage of cases of pneumonia due to bacteria like Streptococcus stayed much the same, pneumonia due to the ‘Enterobacteriaceae’ family (E. coli, Klebsiella and Enterobacter for instance) was steadily increasing. This wasn’t enough to explain the total increase, but it does raise the question of whether these bacteria are becoming more able to cause infections in humans, or whether something else is happening. We have researchers looking into this now. This is concerning because the Enterobacteriaceae family are more difficult to treat than Streptococci, as they are resistant to more antibiotics. If we are seeing more difficult to treat infections, we may be forced to use stronger antibiotics, and patients may not do as well.
In summary, it was apparent that there wasn’t a simple explanation for the increase in pneumonia. It’s not just changing names, it’s not just risk-averse GPs, and it’s not just an ageing population. It appears there is a genuine increase in pneumonia in our region. This has been reported before, but never with this level of detailed investigation.
Whilst we’ll continue looking to find out the cause, the main take home message of the paper is that pneumonia is likely to continue to increase. More patients with pneumonia means more demands on hospital services, more antibiotics being given out, and more patients needing time off, or social care support, as they recover. We, and the healthcare service as a whole, needs to prepare for this.
The original paper is available on open access here: http://thorax.bmj.com/content/early/2016/02/17/thoraxjnl-2015-207688.short?rss=1
This research has been possible with use of the Infections in Oxford Research Database (IORD) – you can read more about it here.
Images: pixabay and pneumonia xray- wikipedia