[Interobserver variation in the classification of diseases]

The aim of this study was to describe the variation between observers in classification of diseases, with special regard to pregnancy, birth and maternity. Four observers A, B, C and D classified 150 random cases of pregnancy, birth and maternity. The rate of agreement between the observers and their use of diagnosis was evaluated. The total agreement-rate was 58% concerning diagnoses of pregnancy, 82% concerning maternity and 13% concerning delivery; with variation between the observers at 71-85%, 86-96% and 26-54%. The diagnostic spectrum of the observers and their criteria for the use of diagnoses were variable. In conclusion, great variation was found between observers in classifying diseases, due to different diagnostic criteria being used by the observers, and due to misunderstanding of the Classification of Diseases. The setting-up of committees of branch-specialists is recommended, if we in the future want to use a public diagnostic register as a tool for research. These committees must achieve consensus concerning the need for classification within each specialty, define criteria of diagnosis and effect recommendation or education in the system of classification.