Medium chain acyl-CoA dehydrogenase deficiency (MCADD) is a hereditary metabolic disease characterised by decreased ability of the body to use fat as a source of energy during periods of fasting or increased metabolic need. It is due to a deficit of the medium chain acyl-CoA dehydrogenase enzyme and is transmitted through an autosomal recessive mode. Affected individuals may present with hypoketotic hypoglycaemia, which may lead to coma or death. If individuals are detected before a life-threatening episode, the complications of MCADD are, however, preventable by avoiding fasting stress and providing regular feeds in the first years of life.
The prevalence of MCADD at birth among Caucasian populations ranges between 1/10 000 and 1/27 000 [1–8]. In France, while epidemiological studies of a sufficient sample size have not been conducted, it is nevertheless likely that the prevalence lies within the range of the extreme values found in the neighbouring countries.
Universal newborn screening based on a dried blood spot test is a well-established, government-funded programme in France. It is currently organised through a network of 22 regional labs and its coverage is over 99.99%. It includes five diseases – phenylketonuria (PKU), congenital hypothyroidism, congenital adrenal hyperplasia, cystic fibrosis, and, among high-risk populations, sickle cell disease.
The development of tandem mass spectrometry (MS/MS) in the early 1990s led to a substantial increase in the number of potentially detectable hereditary metabolic diseases. This technology is being used to screen newborns for an increasing number of diseases in an increasing number of countries in Europe  and elsewhere.
The French National Authority for Health (HAS) was asked by the Ministry of Health to evaluate options and to produce public health recommendations concerning the expansion of the national newborn screening programme for inborn errors of metabolisms using MS/MS. Based on a preliminary literature review, it was agreed to start by evaluating the expansion of newborn screening to MCADD, a disease for which there is ample evidence to suggest that newborn screening is an effective and cost-effective intervention [10–22]. Cost-effectiveness was considered by the French health authorities to be an important element to inform policy decision even though France has not defined any incremental cost-effectiveness ratio (ICER) threshold for the implementation of new public health interventions.
Several economic analyses of MCADD newborn screening have been performed in Europe [10, 13–15] and North America [18–23], and several reviews of such economic analyses have been published [10, 13, 24, 25]. Estimates of cost-effectiveness of MCADD screening varied widely, depending on the modelling assumptions .
One Canadian study estimated an ICER of 253 161 Canadian dollars (about €200 000) per life year (LY) , assuming systematic lifetime supplementation of carnitine. If, however, it was assumed that supplements were provided up to the age of 5 years only, MCADD screening became cost-saving. In another Canadian study , where no carnitine supplementation was assumed, the ICER was estimated to be 2 676 Canadian dollars (about €2 000) per quality-adjusted life year (QALY). As highlighted in a recent review, more data are needed to reduce the uncertainty surrounding a number of parameters, particularly the proportion of MCADD cases who die in the first few days of life and will thus never be detected by screening, the effectiveness of screening in preventing MCADD deaths, the quality of life attached to the different health states, and the costs of diagnosis and treatment in the absence of screening . Because of health system specificities and limitations in transposing health care costs from one country to another, it was felt important to carry out a cost-effectiveness analysis of MCADD newborn screening, taking into account the French setting and, where available, using local data.