Prevalence of multiple congenital contractures including arthrogryposis multiplex congenita in Alberta, Canada, and a strategy for classification and coding.

BACKGROUND: The population prevalence of multiple congenital contractures, many of which have either arthrogryposis multiplex congenita or amyoplasia congenita, ranges from 1/3300 to 1/56,000. Three other studies report a range of 1/4500 to 1/12,500. Classification and coding of these disorders in the International Classification of Diseases, tenth edition, (ICD-10) is less than satisfactory, even when augmented by the Royal College of Pediatrics and Child Health (RCPCH). expansion.
METHODS: The database of the Alberta Congenital Anomalies Surveillance System (ACASS) was used to review all cases (1980-2007) of the previously named disorders with special emphasis on the 1997-2007 cohort. The latter period was chosen because more complete ascertainment was likely due to the addition of terminations of pregnancy data beginning in 1997. This cohort was further analyzed into the three practical groups: I, limb only; II, limb plus non-central nervous system anomalies; and III, limb plus lethality, central nervous system anomalies, or both, with further syndrome identification in groups II and III. The ICD-10-RCPCH classification and codes were reviewed.
RESULTS: The prevalence for multiple congenital contractures in Alberta is 1/8700 for 1980-1996 and 1/4300 for 1997-2007. Rates for the three groups were calculated. Specific diagnostic categories were found in groups II and III of 43% and 65%, respectively. Mortality is high, especially in the first month of life (45% total losses). New classification and coding systems are proposed.