Background The reliability of mortality data is a critical aspect of epidemiological studies on cancer. The under-registration of deaths, a high proportion of deaths classified as due to unspecified causes,4 and inadequate report of immediate or mediate conditions as the underlying cause of death are the main problems affecting the reliability of mortality data. Several statistical techniques to correct this problem were reported, resulting in a variety of methods for the same purpose. This study aims to discuss the impact on the magnitude and temporal trends of mortality of four different strategies of redistribution that have been used to assess cancer mortality in Brazil.
Methods This study used anonymized georeferenced provided by the Brazilian Ministry of Health. Four different approaches were used to perform the redistribution of ill-defined deaths and garbage codes. Age-standardized mortality rates used the world population as reference. Prais-Winsten autoregression allowed calculating trends for each region, sex and cancer type.
Results Death rates increased considerably in all regions after performing the redistribution. Overall, the Elisabeth B. França and World Health Organization methods had a milder impact on trends and magnitudes of rates when compared to the method used in the Global Burden of Disease 2010 study. This study also observed that when the Brazilian Ministry of Health dealt with the problem of redistributing ill-defined deaths, the results were similar to those obtained by the Global Burden of Disease method. The redistribution methods also influenced the assessment of trends; however, differences in the annual percent change were less pronounced.
Conclusions Given the impossibility of developing a gold standard method for comparison, the matching of global techniques with those that consider the local reality may be an alternative for methodology selection. In the present study, the compatibility of the findings suggests the validity of the Global Burden of Disease method as concerning the Brazilian context. However, caution is needed in this interpretation. Future studies should assess the impact of these methods as applied to the redistribution of deaths to type-specific neoplasms.