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Urology. 2011 Dec;78(6):1287-91. doi: 10.1016/j.urology.2011.05.070. Epub 2011 Oct 19.

Use of ureteroscopy before and after expansion of lithotripter ownership in Michigan.

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Dow Division of Health Services Research, Department of Urology, University of Michigan, Ann Arbor, Michigan 48109-2800, USA.



To determine whether ureteroscopy (URS) rates decreased following the expansion of lithotripter ownership in Michigan. Historically, Michigan has had limited urologist investment in lithotripters owing to strict Certificate of Need legislation. However, 2 of the nation's largest lithotripsy providers formed Michigan subsidiaries in 2005 and 2006, thereby altering the ownership landscape. Urologists who acquired partnership shares were incentivized to perform shock wave lithotripsy preferentially over URS. Because of ownership expansion, the rates of URS might have decreased.


From the Michigan files of the State Ambulatory Surgery Database, we abstracted the discharges for URS performed at hospital-based outpatient departments. We measured the differences between the patients who underwent URS in the year before (2004) and the year after (2007) ownership expansion. We then calculated the annual rates of URS in Michigan and evaluated for changes over time.


A total of 5857 and 6294 URSs were performed in 2004 and 2007, respectively. Significant differences in age (P < .001), race (P < .001), primary payer (P < .001), and comorbidity status (P < .001) were observed between the patients who underwent URS before and after ownership expansion. However, the rates of URS in Michigan remained relatively flat despite the increased urologist ownership of lithotripters (P = .129 for the temporal trend).


The introduction of physician ownership of lithotripter units in Michigan was not associated with decreased rates of URS but might have influenced treatment selection among certain patient groups.

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