Investigating the relationship between mortality from respiratory diseases and childhood acute lymphoblastic leukaemia in Hungary.

Our aim was to investigate the ecological association between death from infectious disease of the respiratory system and the risk of acute lymphoid leukaemia (ALL) in children aged less than 7 years. Poisson regression analyses were carried out using overall data and gender-specific models. The study included 176 cases (92(52.3 %) boys and 84 (47.7 %) girls) of ALL in those aged 0-6 years in South Hungary. Eight cases were diagnosed before the age of 1 year. A significant risk of ALL disease was observed with higher levels of mortality from the chronic respiratory diseases (p = 0.035) and pneumonia (p = 0.010) among children aged 2-5 years (Odds Ratio for trend was 1.001 and 95%CI [1.000-1.002] and Odds ratio for trend was 1.013 and 95%CI [1.003-1.023], respectively). Significantly increased risk of childhood ALL was detected among children under 1 year of age residing in areas around birth with higher levels of mortality from influenza (Odds Ratio (OR) for trend was 1.05; 95%CI [1.01-1.09]; p = 0.012). This risk was also detected in girls (p < 0.001), but not in boys (p = 0.43). Our findings provide new evidence that will help to understand the different pattern of female and male childhood ALL occurrence , but further studies are needed using detailed individual medical history to clarify the role of influenza and other infectious diseases in the etiology of childhood ALL and to explain gender-specific effects.