For the period of 1961 through 1975, 10 geographic and sociologic variables in each of the 159 counties of Georgia were analyzed to determine how they were correlated with the occurrence of Rocky Mountain spotted fever (RMSF). Combinations of variables were transformed into a smaller number of factors using principal-component analysis. Based upon the relative values of these factors, geographic areas of similarity were delineated by cluster analysis. It was found by use of these analyses that the counties of the State formed four similarity clusters, which we called south, central, lower north and upper north. When the incidence of RMSF was subsequently calculated for each of these regions of similarity, the regions had differing RMSF incidence; low in the south and upper north, moderate in the central, and high in the lower north. The four similarity clusters agreed closely with the incidence of RMSF when both were plotted on a map. Thus, when analyzed simultaneously, the 10 variables selected could be used to predict the occurrence of RMSF. The most important variables were those of climate and geography. Of secondary, but still major importance, were the changes over the 15-year period in variables associated with humans and their environmental alterations. Detailed examination of these factors has permitted quantitative evaluation of the simultaneous impacts of the geographic and sociologic variables on the occurrence of RMSF in Georgia. These analyses could be updated to reflect changes in the relevant variables and tested as a means of identifying new high risk areas for RMSF in the State. More generally, this method might be adapted to clarify our understanding of the relative importance of individual variables in the ecology of other diseases or environmental health problems.
Acute myeloid leukemia (AML) is a severe and fatal form of leukemia that is prevalent in the older population. In this longitudinal retrospective study, we investigated the epidemiology and survival rates of patients diagnosed with de novo acute myeloid leukemia in South Korea from Jan 1, 2011, to Aug 31, 2020. We used real-world data from the Health Insurance Review and Assessment Service database. We observed an increase in the number of acute myeloid leukemia cases, with age-specific incidence rates escalating in older patients. In contrast a long-term decrease from 1.94 to 1.77 per 100,000 individuals was found in the age-standardized incidence rates. Meanwhile, age-standardized prevalence rates ascended from 8.93 to 9.67 per 100,000 individuals, with a remarkable increase in the age-specific prevalence rate for those aged 80 years and above. Survival rates were notably better in younger or treated patients, and in those who underwent Hematopoietic stem cell transplantation. The time of diagnosis did not affect the survival of patients younger than 65 years. However, the most recent survival rates were significantly lower for patients 65 or older, as shown in the unadjusted Cox survival analysis. After adjustments in the analysis, it was found that the overall survival rates of the most recently diagnosed group improved significantly compared with those diagnosed earlier, with a hazard ratio of 0.90 (95% confidence interval, 0.84–0.97). This improvement may potentially be influenced by the enhanced treatment alternatives available for newly diagnosed older patients aged 65 years or older. In conclusion, aging appears to fuel an increase in the number of acute myeloid leukemia cases and mortality. Further studies are warranted to understand the impact of aging on acute myeloid leukemia treatment outcomes and devise efficacious care strategies for older patients.