DIFFERENTIAL FEATURES OF MOTOR-NEURON DISEASE MORTALITY IN SPAIN

Background. The objective of this study was to describe the temporal a nd spatial patterns of motor neuron disease (MND) in Spain. Methods. W e studied data where MND was stated as the principal cause of death in official statistics from Spain. Time trends were analysed for age-, s ex-specific and age-adjusted rates for the period 1951-1990. Age-adjus ted mortality and relative risk, obtained by Poisson regression adjust ing for age, were calculated for each province from deaths during the period 1975-1988. Maps were constructed using log transformed rates. S tatistical significance of spatial aggregation was assessed using the Ohno et al. test. Results. The 1951-1990 mortality rate, age-and sex-a djusted to the European population, for the population aged greater th an or equal to 40 years was 1.49 per 100 000; 1.90 and 1.21 for males and females respectively, In general, mortality increased with age. Ag e-adjusted rates rose until 1960, dropped by 70% during the 1960s and declined slightly over the 1951-1990 period as a whole. From 1970 onwa rds MND mortality rose evenly, particularly in the 60-69 age group. A North-South gradient was suggested for both sexes with statistically s ignificant clustering in the Northern coastal regions and-for males al one-in the Midwest provinces. Conclusions. Mortality from MND in Spain displayed a magnitude and recently rising temporal trend similar to t hat described in several other countries. Specific traits were: a decr ease during the 1960s, which has been described for Japan only, as wel l as spatial heterogeneity and a predominant recent increase among the 60-69 age group. The determinants of these unusual MND mortality patt erns are unknown.