Assessing the reach of health reform to outpatient surgery with social network analysis.

Objective: To assess the proportion of outpatient surgery currently delivered in ambulatory surgery centers (ASCs) unconnected to nearby hospitals.

Background: The ASC as a site for outpatient surgery represents one of the fastest growing sectors in health care. Because most are freestanding, ASCs may have little connection to local health systems, possibly placing them outside health reform's reach.

Methods: Using all-payer data from Florida (2005-2009), we identified all ASCs and hospitals active in the state. Using the tools of social network analysis, we then measured each ASC's strength of connection to nearby hospitals on the basis of the number of surgeons shared between facilities. Finally, we determined the proportion of all procedures and charges accounted for by (1) ASCs that are strongly connected to their local health system, (2) those that are weakly connected, and (3) those that are unconnected.

Results: Of the 1.4 million procedures performed in Florida ASCs each year, fewer than 250,000 occur at unconnected and weakly connected ASCs. Put differently, 83% of the $4.3 billion in charges for ASC-based care originate from facilities that have substantial integration with their local health system. Although weakly and strongly connected ASCs are similar from an organizational perspective, unconnected ones tend to focus on a single specialty (P = 0.026) and are staffed by fewer physicians (P = 0.013). Furthermore, there is a trend toward fewer unconnected ASCs over time (P = 0.080).

Conclusions: Most ASCs are strongly connected to their local health system. Thus, efforts to constrain spending should target population-based rates of surgery, not unconnected ASCs.