Assessing Differences between Early and Later Adopters of Accountable Care Organizations Using Taxonomic Analysis

Objective To compare early and later adopters of the accountable care organization ( ACO ) model, using the taxonomy of larger, integrated system; smaller, physician‐led; and hybrid ACO s. Data sources The National Survey of ACO s, Waves 1 and 2. Study design Cluster analysis using the two‐step clustering approach, validated using discriminant analysis. Wave 2 data analyzed separately to assess differences from Wave 1 and then data pooled across waves. Findings Compared to early ACO s, later adopter ACO s included a greater breadth of provider group types and a greater proportion self‐reported as integrated delivery systems. When data from the two time periods were combined, a three‐cluster solution similar to the original cluster solution emerged. Of the 251 ACO s, 31.1 percent were larger, integrated system ACO s; 45.0 percent were smaller physician‐led ACO s; and 23.9 percent were hybrid ACO s—compared to 40.1 percent, 34.0 percent, and 25.9 percent from Wave 1 clusters, respectively. Conclusions While there are some differences between ACO s formed prior to August 2012 and those formed in the following year, the three‐cluster taxonomy appears to best describe the types of ACO s in existence as of July 2013. The updated taxonomy can be used by researchers, policy makers, and health care organizations to support evaluation and continued development of ACO s.