The National Health Service (NHS) Newborn Bloodspot Screening Programme screens for certain rare, serious disorders where prompt intervention can prevent severe and often irreversible harm: phenylketonuria, congenital hyperthyroidism, sickle-cell disease, cystic fibrosis and MCADD. It uses a technology called tandom mass-spectrometry to analyse the biochemical composition of the blood and reveal the presence of metabolic and other genetic disorders.
Some countries such as the US have greatly expanded the panel of conditions for which screening is performed, but the UK takes a more conservative approach and only incorporates new indications based on evidence that the expected benefits outweigh the potential harms.
The 2010 PHG Foundation report Expanded newborn screening showed that expanding screening to include some specific additional disorders had the potential ‘to reduce death and severe disability caused by these conditions in a cost-effective manner’ based on a systematic review of the evidence. A one year NHS pilot scheme ran from 2012-13 to trial expanded newborn screening.
The NSC recommendations for this latter group were based on pilot data: the proportion of false-positive results, mild symptoms in some affected children, and babies that developed symptoms so quickly that they were diagnosed (and in three cases also died) before the screening results were received, so technically they did not benefit from screening.
Public health experts at the PHG Foundation point out that drawing statistical conclusions from the very small number of cases identified is not appropriate, given the limited size of the pilot scheme combined with the rarity of the conditions screened for. Larger scale trials in other countries have provided evidence supporting the efficacy (and cost-efficacy) of screening for the conditions in question; the pilots were intended, rather, to assess whether including them in the national scheme was feasible. They showed that the number of screening false positives was modest and manageable without causing excessive parental anxiety, and established the feasibility and operating parameters for an expanded service.
The PHG Foundation response also notes that the international evidence supports the clinical benefit of prompt diagnosis via screening for patients, even those with relatively mild symptoms since they may nevertheless go on to experience medical crises requiring prompt and expert management to prevent serious harm; it concludes that it is ‘illogical to dismiss two of the conditions on the basis of the precise timing and presentation of the very small number of incident cases during the pilot time frame’.
Ultimately, including all the conditions under consideration in the UK newborn screening programme will result in benefit to only small additional numbers of babies each year – but the benefit is likely to be enormous, preventing early avoidable death or severe disability in most cases, and improving outcomes for all.