Problem Based Learning Scenario 3: "Mrs Moonshine and MMR"
Problem Based Learning Assessment 1
Candidate: 13027
Community Health Sciences BMedSci
Hand in Date: 09/01/2006
Word Count: 2,998
Problem Based Learning Scenario 3: "Mrs Moonshine and MMR"
"Mrs Moonshine is visiting the paediatric community clinic. She I seen by a practise nurse and discusses the MMR vaccine with him. She is concerned about her child Henry, who is due to receive the vaccine. She has read reports about the vaccine and brings an article about a study which she has read to the clinic and wants to know why the medical community does not respect it. The practice nurse declares that the study was methodologically flawed and lacked internal validity. Later Mrs. Moonshine demands that Henry is given the three vaccines as separate injections. The practise nurse insists that this is dangerous and offers to refer her to the immunisation co-ordinator.
What issues are raised here? Consider the implications for research and practice?" (Community Health Sciences Problem Based Learning booklet 2005)
Objectives derived from above article: Page
. Define Terms - Immunisation Coordinator and Internal Validity. 2
2. Critical Appraisal of the Wakefield et al paper . 4
3. Advantages and disadvantages of MMR (measles, mumps, rubella) combined vaccine and individual vaccines. 7
4. Public perceptions of MMR vaccines and how it affects clinical consultations. 8
5. Medicalisation of Autism. 9
6. 1. Define Terms
Immunisation Coordinator
The amount of health professionals involved in administering vaccines are vast and ranges from doctors to school nurses.1 This factor calls for a regulatory body to provide an efficient method of controlling all health promoting individuals to ensure efficient service is provided to the public. This body was names the District Immunisation Coordinator (DIC) in 1985 and was commissioned by the Department of Health and Social Services through all the relevant health authorities.1
"In 1988 the main objectives of a DIC were highlighted to include:
* Coordinate the work of all those involved with immunisation
* Establish a commitment, with all concerned, to immunisation
* Provide training and updating of all staff involved in immunisation
* Maintain an up to date register of all children in the district
* Give feedback and follow up poor results
* Establish an advisory service
* Take specific action to deal with "difficult families"
* Mount local campaigns
* Ensure immunisation is readily available. " 1,2
The qualities of the DIC must include understanding of current immunisation programmes and the inner workings of the health service. This must be married with the ability to be a part of a team and to lead others, a clinical knowledge is not necessary but it may help in understanding vaccines in depth. Predicting inevitable problems and having the solutions to those problems remain a pivotal required skill as a DIC. 1
District health coordinators remain the main professional individuals when it comes to immunisation. Since their introduction they have made vital changes and guidelines involving childhood immunisation schedule, they have also aided in the introduction of important new immunisation programmes. 1
Internal Validity
All clinical trials aim to answer one underlying question. Usually this question is whether there is a "true" relationship between two variables. Useful studies have made the most effort to determine whether a result is due to chance or due to an actual profound difference between the tested variables.3
Internal validity is involved in the quest for the "truth" and it is a measure of systemic error or bias within a study. It's heavily influenced by bias,
"any process at any stage of inference tending to produce results that differ systematically from the true values."4
There are four main types of bias which include:
Selection bias: involved in the skewed allocation of intervention and control groups.5
Performance bias: the biased allocation of care apart from the treatment under study.6
Detection bias: the unequal recording and analysis of results. 9,11
Attrition bias: the amount of diversion from protocol and not taking into account drop out rates.7
2. Critical Appraisal of the Wakefield et al paper
In the PBL scenario Mrs. Moonshine talks about a paper that has not been accepted by the medical community and for the below article it is assumed that the paper of concern is the controversial paper written by Andrew Wakefield together with twelve other doctors.8 The paper was originally set out to link gastrointestinal pathology to the advent of increased uptake of the MMR vaccine programme but it is the secondary finding of behavioural changes in the eight out of twelve children included in the study that stirred a public and media frenzy.
Critical appraisal is involved in the analysis and digestion of a particular published study. Certain questions must be answered to complete a competent appraisal.8
Firstly, the topic concerned must be relevant to the target readers. The Wakefield et al13 paper was very relevant at the time of publishing; this also explains the media interest in the subject which followed.9 The year 1998 was related with the rise in incidence of Autism and a link between this and the new combined MMR vaccine would be a very interesting factor.9
There seemed to be no similar studies related ...
This is a preview of the whole essay
Critical appraisal is involved in the analysis and digestion of a particular published study. Certain questions must be answered to complete a competent appraisal.8
Firstly, the topic concerned must be relevant to the target readers. The Wakefield et al13 paper was very relevant at the time of publishing; this also explains the media interest in the subject which followed.9 The year 1998 was related with the rise in incidence of Autism and a link between this and the new combined MMR vaccine would be a very interesting factor.9
There seemed to be no similar studies related to the Wakefield et al13 paper which explored links between gastrointestinal abnormalities, MMR and autism in children and hence this study was truly "unique" at that time.
Next, the study hypothesis should be clearly stated. 8,10 The paper concerned did not state a clear research question. There were no case studies or previous studies to back up a hypothesis and no effort seems to have been made to do so.
The study design involved the descriptive account of twelve children who were referred to paediatric gastroenterology clinic with bowel symptoms. Biopsies and blood samples were taken. The samples were investigated to exclude diseases such as thyroid and inherited metabolic syndromes. Out of the many tests performed on each child, some were abnormal but none were constantly erratic in every child. Then it was up to the parents to recall whether their child was given the MMR vaccine and if so when it was given. The developmental delay of eight children, which was said to be "Autism like" was said to have surfaced two weeks post MMR vaccination. In three children this time frame for the onset of developmental delay was said to be fourty-eight hours. 13
The appropriateness of the design is very questionable and at the same time hard to evaluate as there was no research hypothesis stated in this study.11 If the hypothesis was stated as a link between MMR, autism and bowel symptoms then this stuffy lacks the internal validity to do so.
The sample of twelve was very small and a statistical calculation to prove a causal link would be obsolete as the power of a study would be too low. 8,12 Hence smaller the study participants the more likely the link may occur by chance alone. The sample itself was also highly selected. They were specifically selected for their concerned bowel symptoms and autism-like syndrome. Given that these are rare conditions to be occurring together in population, hand picking them and calling them rare is false. 8
Another flaw seems to be that there was no comparable control group. This is basic scientific practice to include a group of individuals who are similar in every aspect apart from the intervention itself, to the study group. 8,13 This is a vital step in ensuring that the relationship between the symptoms identified are just as true for subjects who have not received the MMR vaccine.
Recall bias plays a heavy part in this study with respect to the parents being asked to consider how closely the vaccine time relates with the start of the autism-like behavior. These parents would have just signed a consent form to take part in a study to explore the link between MMR and autism and this title itself would lead the parents into considering there is a link, hence providing skewed information to confirm this.14 Also it is assumed that this delay in development occurs acutely and suddenly when it is known that autism syndromes tend to occur gradually over weeks or months, so the fourty-eight hours or two week intervals between administration of the vaccine and the diagnosis is again implausible. 15
Attrition bias was also present with a short follow up period of days or weeks rather than months or years, no steps were taken to counter this either.8
There was no evidence of blinding of any investigators and the Hawthorne effect would be present in this case.16 The investigators would know that a positive result would be a link between MMR and the symptoms that they were investigating and this would be a finding to warrant publication. It would have been more scientifically accepted if the investigators were unaware of the status of the samples.
Certainly there have been a lot of flaws in the Wakefield et al13 paper as stated above. The practice nurse involved in this pbl scenario was correct to state that this study has lacked internal validity and should have also mentioned it was later retracted as many other studies with better designs have shown to be no link between MMR vaccine and autism-like syndromes. These studies include one from Finland, which followed 1.8 million children prospectively after receiving the MMR vaccine for 14 years and showed no link.17 In 1999 a retrospective study showed 500 cases of autism to have no excess cases in immunised children. The risk of inflammatory bowel disease was also investigated and found to be the same for vaccinated and unvaccinated people. Only one percent of cases of bowel symptoms arose within a year after MMR vaccination and one percent of controls developed bowel symptoms in the same period.18
Therefore the Wakefield et al study was cannot be scientifically validated and included bias at every stage of study procedures. It is surprising that a prestigious journal such as The Lancet would publish such a journal with clear lack of internal validity and this goes to show the extent of the interest in the field.
3. Advantages and disadvantages of MMR (measles, mumps, rubella) combined vaccine and individual vaccines
The whole issue surrounding the link between MMR and Autism has made parents look at alternatives. This inadvertently brought to light other options available to parents such as single vaccines, which in some theories would mean less burden on the immune system compared with the combined vaccine that are said to overload it. 19
To explore this theory a German study found that vaccinated children were immune to those particular diseases but were less likely to be infected with other viruses and bacteria also. Hence a combined vaccine was found to "boost" the immune system rather than weaken it.20 The previous pertussis and single smallpox vaccines contained more antigens than the current MMR and individuals are exposed to hundreds of times as many antigens everyday in the activities we undertake such as eating, breathing and even drinking.21
Also the usage of three separate vaccines could leave children vulnerable between the administration processes. This would perhaps mean that they would acquire other infections prior to receiving the next vaccine. 26,27 The financial burden on the health service would also inevitably increase, in treating these infections and in funding single vaccines which are more costly than a combination and the children will be enduring the trauma of more injections than necessary.
The use of separate vaccines has never been tested for use in this country in a national scale. It is simply the advent of the Autism scare stimulated by the Wakefield et al paper that forced people to consider alternatives to the MMR vaccinations which have been tried at tested much more rigorously for use in the UK.22
Seven international expert groups have reviewed the evidence relating to MMR and ASD. They were all unanimous in their conclusions that the current evidence does not support a link between MMR and ASD.23
4. Public perceptions of MMR vaccines and how it affects clinical consultations
Considering the above evidence, it is rather clear that scientifically MMR has been appraised for its' safety29, however as this pbl scenario suggests to this day the public question its' reliability and in this section the reason for this will be explored.
The level of uptake of MMR vaccinations in the people of Britain from its introduction in 1988 to the "scare" in 1998 has been around 92%.24 As always the mass media play a great part in vital health promotion techniques, in fact the National Health Service is increasingly using these sources to get information through to the public.25 This is even more apparent when it comes to the MMR issue in which the media on the whole escalated the Wakefield et al paper to a highly significant platform. Thereby enabling access to it to a wide array of people in different social contexts and showed the diversity of the MMR uptake drop. This was as example of "mass communication" and how it is interpreted, integrated and digested in different ways by different social groups. Indeed it is highly ironic that in 1988 the introduction of the MMR vaccination brought about the highest uptake in higher social class areas and conversely the lowest uptake following the 1998 MMR "scare" was again seen in the same group.26
The public did take into account the information given to them from the media which resulted in an exaggerated risk of the MMR vaccine. In a focus group study to investigate the influences parents had on accepting or rejecting the MMR vaccination brought to light the following considerations:
"(a) Beliefs about the risks and benefits of MMR compared with contracting the diseases, (b) information from the media and other sources about the safety of MMR, (c) confidence and trust in the advice of health professionals and attitudes towards compliance with this advice, and (d) views on the importance of individual choice within Government policy on immunisation."27
Many individuals often felt pressured to accept the MMR vaccine by health practitioners and were lead to believe this was due to General Practitioners wanting to conform to targets and hence more financially influenced rather than working to the children's best interest.33 This was antagonized further by the chief medical officer's determination not to issue the single vaccinations under the NHS.30,28,29
5. Medicalisation of Autism
Recently Autism has been increasing coverage from media and the general public. The Wakefield et al paper13 has stimulated this growth in interest considerably, together with Dustin Hoffman's role in the true story of a savant in the film Rainman.30
"Autism is a behaviourally defined disorder, characterised by qualitative impairments in social communication, social interaction, and social imagination, with a restricted range of interests and often stereotyped repetitive behaviours and mannerisms."20
Increasingly Autism is being shifted from a behavioural disorder to organic aetiologies. Rubella infection, phenylketonuria (a metabolic disorder) and anticonvulsants taken during pregnancy, tuberous sclerosis (localised lesions) and encephalitis (postnatal infections) have shown to increase the prevalence of autism later in life.31
However 90% of people with autism did not reveal any prenatal insults in their histories.20 Although epilepsy like convulsions are more common among autistic individuals hence leading to the conclusion that autism is a neurological disorder. Twin studies have shown monozygotic twins having a 60% concordance rates, showing that autism is quite genetically orientated and a multi gene disorder, although no precise "candidate" gene has been identified.32,33 Structural brain scans have failed to show comparable diagnostic markers but functional imaging does show abnormalities in the fusiform nucleus. There remains no biological test for autism, as it is a spectrum disorder with varying amount of behaviour and impairments that are present in each individual affected. 20
As parents and clinicians alike become more aware of the diagnosing criteria of autistic spectrum disorders there is indeed an earlier identification of the condition. A successful diagnosis is usually made between two and three years although the accuracy increases as the child develops further.34,35 It is difficult to surveillance or monitor autism36 due to the high diversity of its symptoms together with its treatment as some children perform best in main stream schooling and others better in specialised schools.20
The increasing Medicalisation is a result of the ongoing increase in the practise of risk assessment medicine and as there is no current cure for autism, parents with the backing of the media aim to prevent the condition by decreasing its apparent risk factors as viewed by the public.
6. Personal Conclusions
The future of autism indeed seems to be heading towards its prevention rather than cure. The advent of gene therapy may be the breakthrough clinicians require to achieve this.
As for MMR, it is true that overwhelming science does disprove the link but access and digestion of this information by the public is very limited. However parents use not just facts but family advice, instinct and above all emotions to guide them when deciding what's best for their child. Hence health professionals need to understand the many layers involved in advising parents on these very controversial decisions on vaccinations and must take their time to give up-to-date information in a socially adjusted manner to make parent's verdicts less stressful33 and informed.
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