Seasonality of death in a historical population

Mireia Esparza, Universitat de Barcelona
Neus Martínez-Abadías, Universitat Autònoma de Barcelona
Torstein Sjovold, Stockholm University
Rolando González-José, Consejo Nacional de Investigaciones Científicas y Técnicas
Clara E. Garcia-Moro, Universitat de Barcelona
Anais Rivas, Universitat de Barcelona
Miguel Hernández, Universitat de Barcelona

The present work analyzes the 12278 death records of the Catholic parish of Hallstatt, an Austrian village, recorded during three centuries (1603 - 1905), with the aim of testing the seasonality of mortality in this period. Hallstatt, one of the oldest settlements in Austria, is placed about 75 km south-east from Salzburg, in the province of Upper Austria, next to Hallstatt lake. To observe the presence of a seasonal model, Henry coefficients have been obtained and plotted, and results have been tested with a χ2 test, comparing death distribution with a random one. Edwards test has been also used in order to detect a cyclic model of simple harmonic variation. These analyses have been performed with the Estacio software. To detect possible changes in the seasonality pattern along time, the analysis has been also performed after splitting the database in six sub-periods of 50 years. The results obtained show a clear and statistically significant seasonal model (p<0,001), with a maximum of mortality in spring, specifically in April, and a minimum in autumn. This pattern could be related with a high incidence of infectious diseases related with the respiratory system. When the analyses were performed for each sub-period, an attenuation of this seasonal model is observed, especially in the last years (1850-1906), due to the decreasing incidence of this kind of diseases with the epidemiological transition.