Rare Diseases in Spain: a nationwide registry-based mortality study

Abstract

Background: Rare diseases (RD) are still lacking of population-based data and epidemiological indicators. The aim of this study is to assess 15-years’ time trends of mortality attributed to RD in Spain. Methods: Mortality statistics from the Spanish National Statistics Institute provide population-based data [1]. Deaths due to RD were extracted from official annual databases (1999-2013). Only those ICD-10 codes considered as RD by SpainRDR experts were included in this study [2]. Annual sex- and age-specific adjusted mortality rates per 100,000 inhabitants were calculated and time trends were performed by joinpoint regression analysis. Results: RD mortality represents 1.2% of all registered deaths from 1999 to 2013 in Spain. Mortality attributed to RD is higher in males (51.2%) than females (48.8%). Children (<15 years old) account for 15.2% of deceases. Distribution of RD deaths according to main ICD-10 groups is displayed in Fig. 1. Regarding time trends of RD mortality (Fig. 2), there has been a 0.95% decline in the annual age-adjusted death rates due to all RD (-0.95%, p<0.001). In addition: Decrease trends were also observed in the following subgroups: RD of the blood and blood-forming organs and certain rare disorders involving the immune mechanism (-2.06%, p<0.001), RD of the circulatory system (-3.90%, p<0.01), and rare congenital malformations, deformations and chromosomal abnormalities (-5.39%, p<0.01). Increase trends of annual age-adjusted death rates were detected for RD of the nervous system (1.85%, p<0.01), RD of the respiratory system (2.39%, p<0.01), RD of the digestive system (1.83%, p<0.05) and those RD affecting the genitourinary system (9.38% p<0.05). Other RD groups have not showed any significant change in this period. Conclusion: Official mortality statistics share criteria for analysing uniform and robust time series, which is useful for studying low-prevalence diseases. Assessed RD mortality trends are valuable information for the health authorities in Spain.