Validation of diagnosis of aplastic anaemia in La Rioja (Spain) by International Classification of Diseases codes for case ascertainment for the Spanish National Rare Diseases Registry.

OBJECTIVE: To analyse the validity of diagnosis of aplastic anaemia (AA) by International Classification of Diseases codes in hospital discharge data (MBDS) and the mortality registry (MR) of La Rioja to detect cases to be included in the Spanish National Rare Diseases Registry. METHODS: International Classification of Diseases (ICD) codes were used to detect AA cases during the period 2007-2012 from two administrative databases: the MBDS and the MR of La Rioja (Spain). Medical records of population selected by merging both databases were used to confirm true AA cases. The annual mean incidence rate of AA was calculated using confirmed incident cases. RESULTS: By merging both databases, 62 hypothetical AA incident patients were detected during the period 2007-2012. The medical records of the 89% of them could be revised, and they confirmed that only the 15% of the patients actually suffered AA. The annual mean AA incidence in La Rioja was 4.17 per million inhabitants (6.23 per million, males; 2.10 per million, females). CONCLUSIONS: The MBDS and the MR are not in themselves sufficient to ascertain AA cases in La Rioja and medical records should be reviewed to confirm true AA cases to be included in the Spanish National Rare Diseases Registry.