Error rates for unvalidated medical age assessment procedures

Artikel i vetenskaplig tidskrift, 2019

During 2014–2015, Sweden received asylum applications from more than 240,000 people, of which more than 40,000
were termed unaccompanied minors. In a large number of cases, claims by asylum seekers of being below 18 years
were not trusted by Swedish authorities. To handle the situation, the Swedish national board of forensic medicine
(Rättsmedicinalverket, RMV) was assigned by the government to create a centralized system for medical age assessments. RMV
introduced a procedure including two biological age indicators; x-ray of the third molars and magnetic resonance imaging of
the distal femoral epiphysis. In 2017, a total of 9617 males and 337 females were subjected to this procedure. No validation
study for the procedure was however published, and the observed number of cases with different maturity combinations
in teeth and femur were unexpected given the claims originally made by RMV. We present a general stochastic model
enabling us to study which combinations of age indicator model parameters and age population profiles are consistent with
the observed 2017 data for males. We find that, contrary to some RMV claims, maturity of the femur, as observed by RMV,
appears on average well before maturity of teeth. According to our estimates, approximately 15% of the tested males were
children. These children had an approximate 33% risk of being classified as adults. The corresponding risk for an adult to
be misclassified as a child was approximately 7%. We determine uncertainties and ranges of estimates under reasonable
perturbations of the prior.