Grappling with the grey evidence


A number of recent editorials and commentaries have rehearsed the challenges of researching underlying mechanisms and assessing efficacy of treatments in neurodevelopmental clinical practice. As a result of the many barriers to establishing an evidence base, promising approaches may languish in the limbo of ‘grey evidence’ and with research budgets tightening this may become more so. Many interventions in this field are not only complex but have been adopted into everyday management that makes them expensive and ethically fraught to disentangle. Their adoption may take place in other settings such as education and only impinge on medicine when they are presented as clinical investigations and interventions with attendant requests for health services funding such as personal frequency module systems for ‘auditory processing disorders’.

However, sometimes support for a grey evidence issue develops at such momentum and is accompanied by such strength of feeling that clinicians face significant challenges when grappling with the consequences for their patients and their families. The literature over the last 10 years on the measles, mumps, and rubella (MMR) and autism debacle encapsulates these and charts how clinicians not only vacillate over wherein lies the truth,1 but avoid public debate when this is potentially stifled by the strength of feeling engendered towards supporters of the vaccine.2,3 In addition, work such as that which highlighted the absence of measles antigen in the peripheral leucocytes of children with autism immunized with MMR might only be published in the peer-reviewed specialist journals and therefore not readily enter the public domain.4 In the eyes of the critics, this was then considered not readily accessible to families deliberating on whether or not to immunize their children.

A recent survey of 102 children aged over 9 years affected with autism spectrum disorder in the city of Edinburgh revealed that whilst they had a 97% uptake of their initial MMR vaccination, only 69.2% had received their booster. We do not know the implications yet of inadequate coverage with MMR. Most paediatric neurologists have never cared for a child with measles encephalitis or subacute sclerosing panencephalitis or experienced the death of the one to two per thousand children dying from measles before the advent of protective immunization. Congenital rubella is a rarity in present-day practice. However, all clinicians working with children from universal to specialist services have been exhorted to take responsibility for discussing and encouraging MMR immunization uptake.5

Whilst MMR is perhaps one of the most dramatic examples of grey evidence escalating beyond control there are lessons to be learnt. It is salutary to remember that almost all parents acting on the grey evidence that they read about in the media and the internet do so in good faith. Whilst time-consuming to discuss in the busy clinic, it is reasonable that they should expect their clinicians to give them an informed opinion on the validity of the scientific evidence for investigations and interventions that might be relevant to their child’s care. This is particularly challenging for the clinician working in neurodevelopmental medicine as it arises so often. That is why it is particularly helpful to see Developmental Medicine and Child Neurology publish regular systematic reviews and meta-analyses. Another approach is that adopted by the SIGN 98 guidelines on autism spectrum disorders6 in which all the search questions and terms were appended so that clinicians and other readers could consult them to see whether a putative aetiology or intervention was considered but did not appear in the guideline because of insufficient evidence. This could encompass all the grey evidenced material at the point of drawing up the guidelines, offer transparency to the guideline production and facilitate re-examining the evidence at a future date when further evidence may have emerged, all of which will hopefully provide a useful handle when ‘grappling with the grey evidence’.


LY Yong and L McAlpine for their MMR and Autism Survey 2009.