Wednesday, 31 July 2013

Influenza vaccination for children - Fluenz


Sorry - not even August and another influenza story but this is a big one.

It has been a busy few days in the world of childhood vaccination.  Fresh on the heels of advice from the Joint Committee on Vaccination and Immunisation (JCVI), the body that advise the Department of Health about vaccination policy not to introduce meningococcal type B vaccine yet, we now have details from the Department of Health about routine influenza vaccination for children over the age of 2 years.
Essentially it is to be offered to all children who are aged 2 and 3 years on the 1st September; and to older children up to the age of 10 years in some pilot areas.  There are a number of things about this that need to be highlighted:
  • Influenza is not always a mild illness, and it can lead to more serious infections.
  • Vaccination has two effects, it protects the individual, but by reducing the risk of them catching the disease it also protects other people.  So if your child doesn’t get the flu then they can’t give it to siblings, grandparents…etc.  This is the same thing that I discussed previously with regards to taking time off work reducing the spread of influenza.  So even if you are not worried about your child, what about their grandparents and other contacts?  What about that child at nursery who has asthma?  I don’t want to lay it on too thick, but there are a lot of people around who can become very ill with the flu.
  • This is not the same as the normal seasonal flu vaccine.  That is an inactivated vaccine (note inactivated – it can’t give you the flu!); this is a cold attenuated live vaccine.  This means that it is alive (as much as viruses can be described as ‘alive’) but has been altered so that it can only grow in cool environments – such as the nose, which is much cooler than the lungs and respiratory tract.  This also raises the interesting prospect of the altered strain circulating in the community, that people could ‘catch’ the vaccine virus and become immune that way (which would be a good thing!)
  • It is not an injection but a squirt up the nose (two squirts actually, one up each nostril).
  • If you or your child is in a risk group, this does not replace the need for annual vaccination, it is an additional layer of protection.  You (or your child) still need to be vaccinated as normal.
  • Finally, immunity is not immediate; you need to give the system a good 2 weeks for immunity to develop.
 There are a few children who should not have it: those under 2 years, those with egg allergy, children who are severely immune suppressed and other children who live in their house, and children with asthma who are wheezy at the time of vaccination.
Although this is a new vaccine to the UK, the Americans have been using it for some time.  For people who are worried about it I would just say this, if you are not convinced of the need for your child to be protected; if you are not convinced by the part that this will play in reducing the spread of flu, and I respect (but disagree with both of these); it can’t be worse than catching the flu anyway – because that is all it is, but in a form that is much, much, much less likely to cause disease.

The advice from the JCVI is here; the guidance that healthcare professionals use (the 'Green Book') is here, always check before use as  it changes quite regularly; and the letter from the Department of Health is here.

Monday, 22 July 2013

Vaccination works!

Perhaps not such a surprising headline; but it is nice to see it demonstrated.

One of the wonderful things about vaccination is that as an intervention it works at multiple levels, most notably at the individual and popluation levels.  What that means is that when you vaccinate an individual, as long as that vaccine has worked they should be protected against infection - that is the individual level protection.  Furthermore, because fewer people are catching or carrying the disease; it does not spread so much within the population, giving some degree of protection to people who are not immune.  This is a concept known as herd immunity, and it is particularly powerful when vaccination coverage is high.  This is based on a number known as R0, which I discuss a little here, in summary to find the crucial proportion needed to achieve herd immunity the calculation is 1-1/R0 (so if the R0 is 10, the cacluation is 1-1/10 or 0.9 or 90%.

So if you are caring for someone who is particularly susceptibe to infectous disease, one of the best things you can do is to ensure that you are fully up-to-date with your vaccines.  This is one of the rationales for vaccinating children against influenza, clearly to protect them, but also to protect grandparents and others at risk of severe influenza illness.

A study from America has looked at this phenomena with regards to hospitalisation with pneumonia (Griffn et al (2013) N Engl J Med 369 155-163).  It looked at three periods: before the introduction of the pneumococcal vaccination into the infant schedule; its early days of introduction; and a latter phase when it was fully embedded.  The findings were stark, among both young and old the numbers of people admitted to hospital with pneumonia was reduced, from period one to three the reduction was 43.2% in those under 2 years of age (who would have had the vaccine) but even more impressively by13% in those aged 75-84 years and by 22.8% in those over the age of 85 years.  Overall the reduction ws 10.5%, in numbers this equated to a reduction of 168 000 hospital admissions in one year.  (When you see percentages or relative risks/odds ratios always look at the actual numbers as well - remember 10.5% of nothing is.....nothing.  These numbers are fairly impressive though).

Now there are loads of issues around these findings: just two of the questions are what else might have happended during this period (they discuss reductions in smoking and influnza vaccines for example) and how reliable are the data?  But however cynical one might be, these are impressive results.  The crucial thing to remember though is that herd immunity, which is what is being seen here, relies on high vaccination levels.

Friday, 19 July 2013

It may be sunny but influenza will soon be here..

As the temperature reaches the low 30°Cs it may seem difficult to imagine, but influenza season will soon be upon us.  One of the many dilemmas of flu season is at what point one should go sick or keep a child at home.  A recent study from the United States has looked at this very subject, but from a public health perspective, what is the effect of someone with flu going to work on the wider community? (Kumar et al (2013) Am J Pub Health 103 1406-1411).
This was a study done using agent based modelling, in other words it was a computer simulation.  Probably the most important thing to do when you look at a model such as this is to check the assumptions made in the model, so for example here they had different scenarios: one where not everyone had access to paid sick leave; one where everyone did; and some where employees were able to take either 1 or 2 ‘flu days’ regardless of access to paid sick leave.  In all models it was assumed that 28% stoically went to work even if they had the flu; and that the R0 (the average number of infections caused by each infected person) was 1.4 – pretty typical of seasonal influenza.  However, in some circumstances, such as schools and nurseries it may be much, much higher.
The results of the modelling showed that the attack rate (the proportion of those without immunity who were exposed and caught the flu) was 11.54% in the mixed sick-leave scenario; 10.86% where paid sick leave was universal; only 8.62% where 1 flu day was allowed; and 7.01% where employees were able to take 2 flu days.  In a simulated population of 575 866, this equates to 66 444; 62 538, 49 611; and 40 386 infections respectively.  That is a lot of numbers, but what it is saying is that the 2 flu day scenario reduced the number of infections at work by 26 059 or 39% from the baseline mixed sick-leave scenario.
So the lesson from this is that it may be better for the economy for people to go off sick rather than go to work when they are ill.  Remember that once one has the flu, you can then infect other people who may be in one of the high risk categories for severe disease, so the impact is almost certainly even wider than this study suggests.  This can of course be mitigated by getting vaccinated - and the flu vaccine is gradually being rolled out to all children aged over 2-years (not this is not an injection!); and others in the high risk categories should already be getting it.  More details here (it is a bit wordy - but keep going - it is on page 10!).
 Now major warnings in interpreting these and similar data:
  1. All models are wrong – the trick is to get the model that is least wrong
  2. Look at the assumptions – do they seem sensible?
  3. Does the model allow for ‘random behaviour’?  These are called stochastic models and while they are more lifelike, they are also much more complicated.  The opposite, where people essentially do as they are told or behave the same are called deterministic models.
  4. In epidemiological studies always be clear about the case-definition; how do you know someone has the flu?  This is crucial, because we need to know that we are talking about influenza and not just a bad cold.  The UK case definition and other epidemiological data are here.
Finally reading this paper I learned a new term, which is ‘presenteeism’ – which is going to work or school when ill, something I may have been guilty of in the past...  More about flu to come, in the meantime enjoy the sun!

Sunday, 14 July 2013

So you want to be a children's nurse?


Most Universities will be full for September now, but before you know it they will be interviewing for 2014, so if you want to be a children’s nurse, what might you think about in preparing for your application?  Here are some thoughts; but note I am not an admissions tutor (if I were I would not be able to do this!) and there are no guarantees, these are just some thoughts.  

Before you apply, think about where you want to go to University, but also remember that you will have placements that may start/finish at unsocial hours.  Find out where you will be doing placements and can you get there and home early in the morning and late at night, and at weekends?
Having done this, what about your statement and interview?  The first thing is, and I don’t want to sound patronising, but being a children’s nurse is not like being a nursery nurse, be clear that you know the difference.  I am not going to tell you what these differences are, if you want to be a nurse you should know or find that out, a hint however is that saying ‘I want to be a children’s nurse so that I can look after/because I like children’ is probably not going to be enough.  

Secondly, remember that although a lot of children’s nursing is done in hospital, even more is done out of hospital.  Nurses don’t just work with sick children, but increasingly with well children; trying to prevent disease as well as to treat it.  Even for children who are sick, they are looked after at home as far as possible.  This is where the future really lies, to find out more look up health visiting or community nursing on the search engine of your choice.

Thirdly, have some idea of what is going on both in the world, the nation, and in the NHS.  Look up a few recent reports and have some idea of what they said; for example try the Kennedy Report.   Don’t read the whole thing (unless you want to), when you get reports such as this look for something called the Executive Summary – it is all you need to know in a few pages.

Fourth, if you have trouble with maths, get some help.  You will have to do a maths test at some point – it will usually be at the interview stage, but you will also have to demonstrate your ability to do basic maths throughout the course.  This is crucial for the delivery of safe care; most children’s drugs for example are given according to weight (usually) or surface area, and so you need to be able to calculate these doses.

Fifth, remember children are not ‘little adults’; but developing individuals.  Think about children of different ages, and how they develop both physically and cognitively (how they think and understand the world).  For example, the heart rate of a baby is much higher than an adult; and a rash will seem different to a 3 year-old than to a 14 year-old.

Six, try and think about things from the child and families point of view; what do you think matters to them?  You might get some clues from this blog and other websites - but just think logically, even better, ask some children!

Finally, you need to be competent to practice as a nurse, but you also need to be nice.  Show this side: be assertive, but be polite; be professional, but smile; take part in group exercises, but don’t be too pushy.

Good luck!

Friday, 12 July 2013

Does failure to respond to antipyretic drugs tell you anything useful about how serious an infection is? Answer no

This was a question that we considered when drawing up the NICE Guidelines on the treatment of fever in children; and we concluded the answer is no.  A recent review in Archives of Disease in Childhood has looked at 8 papers which have each answered the same question, and concluded the same thing.

It is always good when other people confirm your opinion, particularly so in this case because this is a real 'old chestnut' - "if the temperature comes down quickly they are likely to be ok".  Because serious infection is rare this appears to be true, most children whose temperature comes down quickly are indeed ok; but then so are most children whose temperature does not come down quickly.  They are all likely to be ok.  The key when reading papers which assess diagnostic tools is not to look at the sensitivity and specificity; but rather the positive and negative predictive values (PPV and NPV respectively).  This is not the time or the place to go into the difference, but essentially the predictive values tell you what you want to know.  For example, the PPV answers the question "if I test positive am I likely to be ill?", where as the sensitivity answers the question "if I am ill am I likely to test positive?"  So take care when you are reading or being given sensitivities and specificities.

Back to this paper.  So response to antipyretics is not useful in identifying serious illness in children.  Another couple of observations: Firstly the papers are old - does this matter?  Not really, apart from the appearance of aspirin and the absence of ibuprofen.  Probably not important, there is no particular reason to think ibuprofen should be different.  Secondly, two of the papers are by the same authors, and crucially use the same patients.  Duplicate publication can be a big problem, and including the same patients in meta-analyses where the studies are combined statistically can lead to erroneous conclusions, one study finding that including duplicated data led to a 23% overestimation of the efficacy of one drug.

The problem when reading reviews is that you often don't know this, in this case the authors noticed it and discussed it.  However, when all you have is a forest plot of results it takes a sharp eye to spot sometimes.

Monday, 8 July 2013

Are children really 'little adults'?


One of the phrases that trips off of the tongue of most paediatric nurses is that ‘children are not little adults’, but a recent review in Archives of Disease in Childhood looking at drug dosing in children suggests that in this regard at least, they may be.  There are two crucial concepts in pharmacology, these being pharmacokinetics (PK), which is what the body does to the drug; and pharmacodynamics (PD), which is what the drug does to the body.  The other important issue of course is the desired effect and how this balances against undesirable effects.

The authors suggest that the per Kg doing method probably results in under-dosing of many children, particularly those in the 1-3 year-old age group who have relatively high drug clearance and metabolic rates. Furthermore the relationship between drug clearance and weight is not linear, which may be problematic particularly among obese children as the role that fat plays in drug distribution and clearance differs between different drugs.  As if that weren’t enough, there is a third method of assessing maturity, while we are used to thinking of age and weight; the passage of time, (defined as the postmenstrual age) may also be useful measure as this takes account of maturation before birth.  All of this leads the authors to conclude that children over the age of 2 years are indeed probably adult-like (yes ‘little adults’) differing only in size; while those under this age, being less mature are immature children.

All of this is rather confusing for the clinical nurse, so what should be done.  Firstly there is everyone’s favorite dissertation recommendation – more research.  More immediately it may be possible to individualise doses more, taking into account specific covariates, although this may require computer support to allow for the more complex calculations and decision making processes.  

However, there is something that everyone can do right now, which is to make treatments explicitly outcome-based, taking into account the benefits and risks of treatments.  The authors of the papers give a good example, which is that of opiate analgesia, how specific children may balance the relative importance of pain control and nausea; some might think the first is more important, others might put up with a bit of pain in order not to feel nauseated.  The treatment of fever presents another such challenge, what outcome should be aimed for in the treatment of fever with antipyretics, bearing in mind fever is a symptom not a disease; it does not need treating and may even be helpful?    

Along with ‘children are not little adults’, another phrase I remember from my student days was the four rights right patient, right drug, right dose, right time; maybe we should add a fifth – right outcome?

Sunday, 7 July 2013

Challenging the paediatric ward discharge status-quo

One of the unwritten rules of paediatric medicine is that once a child is admitted to a ward they will stay over-night; and if they are ok they will bed and breakfast and probably go home the next morning.  That is one of the reasons that assessment and observation units were set up.  A recent paper in JAMA Pediatrics by Stephanie Iantorno and Evan Fieldston challenges this assumption, and in particular the idea that morning discharges are necessarily a measure of good practice.  One quote in particular seemed pertinent..."accommodating evening discharges can enhance the patient centeredness of care; families have obligations and barriers, including employment and transportation, that make morning discharges difficult and undesirable."

This seems to be one of the biggest challenges for health systems around the world - not just providing high quality care; but also care that fits in with today's lifestyles and expectations that things should happen when we want them to happen or when we need them to happen.  This is an American paper, and of course the health system there is very different to the UK; but the same challenges exist.  Some of this can be seen in the case of general practice hours - which often don't fit in with the hours of those who work in the day.  Another surprisingly important issue in London is avoiding the rush-hour; 07.00-10.00 and 16.00-19.00 are not good discharge times, particularly if one is relying on public transport!


Consolidated guidelines on the use of antiretroviral drugs for treating and preventing HIV infection

This slightly wordy heading refers to Guidelines issued by the WHO this week on treating HIV.  Although really aimed at low and middle-income countries, they contain some useful ideas for everyone.  Apart from the numerous recommendations - the most significant of which is probably starting therapy earlier than is often the case, my take on it is this.

  1. Firstly the idea of consolidated guidelines - rather than having different guidelines for pregnancy; children; adolescents; adults etc..... put them all together.  This makes the transitional arrangements clearer and may help to reduce the barriers that different professional groups have working with each other.
  2. The same goes for hospital - community care.  This is important because something that more developed health care systems are going to have to get to grips with is the change from HIV being an acute disease ending in sickness and death and with a relatively low prevalence; to a chronic disease with less sickness but higher prevalence as people with HIV survive.  There is probably much that we can learn from middle-income countries about how to provide less intense but equally effective services.
  3. Linked to the above is who and how to provide services - do we actually need highly trained doctors and nurses to do all of this?  Yes some people will require that level of expertise, but taking blood; monitoring blood counts.....could this be done in different ways?  One suggestion is to take the principles of the NICE Guidelines for the treatment of fever in children - devise a 'traffic-light' system of signs and symptoms that are associated with low, intermediate and high risk of serious disease.  This needs to be accompanied by high quality 'safety-net' advice but may allow patients to do more of their own monitoring.
  4. GRADE as a way of developing recommendations.  This is not the time or place to explain GRADE, apart from to say that GRADE stands for the Grading of Recommendations Assessment, Development and Evaluation, and is a way of grading the quality of evidence and strength of recommendations.  For anyone who is having difficulty getting to grips with GRADE this may help their understanding
  5. Which brings me back to the opening point.  Rather than assume as an advanced health system that we know everything; we should learn from how others do things, including countries with fewer resources, because necessity is, as they say, the mother of invention.  If I were to make one major criticism of the UK NHS it is this - sometimes money stifles innovation.