Figure 3.

Variations in the utilization of LDCT and SDMC services and state-level factors according to the three identified clusters. Cluster analysis was conducted on a complete dataset including three utilization variables (numbers of utilizations, Medicare FFS beneficiaries, and unique providers) and four state-level factors (lung cancer mortality rate, prevalence of current smokers aged ≥ 65 years and former smokers, and median household income). All the variables were log transformed and normalized by using z scores; as such, a (positive/negative) z score indicates that a state level factor is z score times (above/below) the overall average. Statistically significant differences were found for all variables across the three clusters (Kruskal-Wallis tests, P < .001). States included in cluster 1 were Alaska, Arizona, California, Colorado, Connecticut, District of Columbia, Delaware, Hawaii, Idaho, Kansas, Massachusetts, Maryland, Maine, Minnesota, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, Nevada, Oregon, South Dakota, Virginia, Vermont, Washington, Wisconsin, and Wyoming; cluster 2, Alabama, Arkansas, Idaho, Indiana, Kansas, Kentucky, Louisiana, Maine, Missouri, Mississippi, North Carolina, New Mexico, Nevada, Ohio, Oklahoma, South Carolina, Tennessee, and West Virginia; and cluster 3, Arizona, California, Colorado, Delaware, Florida, Georgia, Iowa, Idaho, Illinois, Kansas, Massachusetts, Maryland, Maine, Michigan, North Carolina, North Dakota, Nebraska, New Hampshire, New Jersey, New York, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Texas, Virginia, Vermont, Washington, and Wisconsin. (Bolded states were unique states in each cluster.) FFS = fee-for-service. See Figure 1 legend for expansion of other abbreviations.