Challenges in handling congenital anomalies clusters: a recent mediatic example in France

Abstract

Abstract Issue In 2018 in France, reports of aggregated cases of isolated transverse limb reduction defects, a rare congenital anomaly (1.7 for 10,000 total births) generated a large mediatic interest with environmental factors overtly pointed out. Our aim is to describe the investigations carried out and to share the challenges we met. Description of the response Over a period of 5 years (2010-2015), 3 aggregates were signaled by health professionals in 3 different areas in France. Investigations included case ascertainment, epidemiological analyses, and search for a common exposure. Standardized Incidence Ratios were computed using the 6 French registries’s data as reference. In one area, the local registry performed a concurrent analysis using satscan. Parents filled a questionnaire addressing environmental and occupational exposures. Environmental databases were consulted as well as animal health surveillance data. Results Fourteen cases met the case definition. The excess of cases was ascertained in two aggregates located in a two small towns in the western part of France and comprising respectively 3 children born in 2007-2008 (SIR: 87.8 CI95%:[17-256]) and 4 children born in 2011-2013 (79.8 [2.5-204.2]). The third signal included 7 cases born between 2009 and 2014 residing in 7 towns located above the Alps and did not yield a significant excess when related to expected cases in the administrative subdivision (0.94 [0.38-1.95]). The concurrent analysis found a significant excess, generating a lengthy debate. None of the investigations identified a common cause or notable exposure. Delayed feedback and negative conclusions led to incomprehension among families. Lessons Informing stakeholders timely is crucial but communicating effectively about methods used and negative results can be challenging. Key messages Congenital anomalies clusters are sensitive topics. Cluster investigations involve a scientific and a societal component that must both be taken into account in organizing the public health response.