ABSTRACT
Current methods for clustering adult obesity prevalence by state focus on creating a single map of obesity prevalence for a given year in the United States. Comparing these maps for different years may limit our understanding of the progression of state and regional obesity prevalence over time for the purpose of developing targeted regional health policies. In this application note, we adopt the non-parametric Dynamic Time Warping method for clustering longitudinal time series of obesity prevalence by state. This method captures the lead and lag relationship between the time series as part of the temporal alignment, allowing us to produce a single map that captures the regional and temporal clusters of obesity prevalence from 1990 to 2019 in the United States. We identify six regions of obesity prevalence in the United States and forecast future estimates of obesity prevalence based on ARIMA models.
ABSTRACT
BACKGROUND: Current practice guidelines for patients with thoracic aortic aneurysms (TAAs) recommend 6 to 12-month intervals for surveillance imaging based on growth estimates of 0.10 to 0.42 cm/y gleaned from limited studies which included patients with thoracoabdominal aneurysms, known acute or chronic aortic dissection, and other syndromic and nonsyndromic high-risk conditions (TAA-HRC) associated with high-risk for adverse aortic events and death. Our objective was to determine TAA growth and event-free survival rates for patients with aortic root or midascending diameters <5.0 cm, and without thoracoabdominal aneurysms, acute or chronic aortic dissection or higher risk syndromic or nonsyndromic conditions (TAA-NoHRC). METHODS: A retrospective review of patient records and imaging studies were done. Aortic diameter measurements were all performed by the lead author. RESULTS: For 197 TAA-NoHRC found incidentally during chest imaging, with 616 chest imaging studies over 868 patient-years, the mean aortic root and midascending aortic growth rates were 0.018 and 0.022 cm/y, respectively. The growth rate was significantly lower for aneurysms initially measured at <4.5 cm versus ≥ 4.5 cm at both the aortic root (0.011 vs. 0.068 cm/y) and midascending aorta (0.013 vs. 0.043 cm/y). Survival free from adverse aortic events (dissection, rupture, and surgery) or death at 5 years was 99.5%. CONCLUSION: Adult TAA-NoHRC patients with initial aortic root and/or ascending aortic diameters <5.0 cm, and particularly <4.5 cm, have very low aortic growth, and adverse event rates which may permit longer intervals between surveillance imaging, up to 3 to 5 years, after initial (6-12 months) stability is documented.
