Health Services Research
PV QA 3 - Poster Viewing Q&A 3
Purpose/Objective(s): Mammogram screening has led to a significant decrease in the mortality rate, and a shift in the diagnosis of earlier stage disease for breast cancer (BC). Conversely, lower mammogram screening rates may lead to an increase in more advanced stage disease with subsequent increases in mortality. In this study, we examined temporal trends in NV compared to its neighbor CA and the US to gain a better understanding of purported associations between screening and mortality for BC.
Materials/Methods: Mortality data were obtained from the Institute for Health Metrics and Evaluation, Global Health Data Exchange (IHME) and mammography screening data were obtained from the CDC’s Behavioral Risk Factor Surveillance System (BRFSS) for 1995-2014. A chi-square test for trend was used to examine temporal rates in screening; mortality rate curves were compared using the Komolgorov-Smirnov test and by examining overlap of 95% confidence intervals.
Results: Mammogram screening rates in NV are less than both the US and CA rates through time (mean NV: 68.9%; mean CA: 76.3%; median US: 73.8%), with NV falling routinely in the lowest statistical quartiles in every year since 2002. Screening rates in CA have increased slightly (X2=4.02, p=.045), whereas rates in NV have declined since 2002 (X2=6.96, p=.008). Breast cancer mortality rates have generally declined through time, with NV consistently higher than the US since 1995 and consistently higher than CA since 2002. The NV breast cancer mortality temporal rate curve was significantly higher than CA (KMZ=1.74, p=.005), though confidence bands did narrowly overlap for these states. In general, mortality rates/100k decreased from 1995-2014 as follows: NV: 34.06 to 28.16; CA: 35.27 to 24.59; and US: 34.04 to 25.88; this represented an approximate decreases in mortality from BC of 20.9% for NV, 43.4% for CA, and 31.53% for the US.
Conclusion: Large state and national data sets allow an analysis of population-based behaviors and their impact on mortality despite the lack of individual pairwise patient data related to screening and stage of BC. During the last 2 decades, overall mortality rates from BC have decreased for NV, CA and the US, which can be partially attributed to wide spread mammogram screening including the improved radiographic imaging capabilities that have shifted the diagnosis to earlier stage disease with better survival outcomes. However, Nevada’s decrease in mortality rates from BC is only about two-thirds of the US’s mortality reduction, and less than half as for CA. Nevada’s lower mammogram screening rates in comparison to the US and CA may partially explain the lower reduction in mortality rates from BC during the last 2 decades. Our study highlights the potential impact of population-based trend data for mammogram screening on BC mortality rates. Various population-based approaches such as improving access and/or behavioral modification may need to be developed to improve mammogram screening rates to further reduce breast cancer mortality in NV.
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