Prevalence estimation of anorectal malformations using German diagnosis related groups system.

Without major registries, true prevalence of rare congenital diseases is not known. Estimations for occurrence of anorectal malformation (ARM) are based on monitoring centers and epidemiological studies. The new German economical system for payment of inpatient care (G-DRG) obligates the report of each hospitalization, including diagnoses and procedures. These codes and classifications originally developed for morbidity statistics are now misused for economical purposes. Is there an epidemiological use? We present a new method to estimate national wide prevalence rate of congenital malformations exemplarily for imperforated anus. Due to the new German DRG-system, treatment data collections of the years 2002-2005 are freely accessible. This method is applicable if a life saving surgery is mandatory for newborns and has to be ciphered by specific codes. Overall, in German hospitals 1,012 children below 1 year of age are surgically treated with a reconstructive anorectal surgery during the period of 4 years. In the same time 2,817,388 babies are born in Germany. Hence the national wide prevalence rate is about 3.6 (95% CI: 3.4-3.8) per 10,000 or 1:2,784 for all different types of anal atresia requiring surgery. Main ICD-10 diagnosis Q42 was given twice this rate, probably due to at least two hospitalizations in the newborn period. The economic data of the G-DRG system can be used to estimate yearly prevalence of some rare congenital diseases in Germany, in case of specific surgical procedures. It may be a useful supplement to smaller regional registries because of larger size. Further calculations for other epidemiological questions have to be faced.