TABLE 3.

Multivariable Differences-In-Differences Model to Determine the Association Between Hospital-level Acquisition of the Surgical Robot and Changes in Proportion of Partial Nephrectomy^*

Hospital Characteristics	Marginal Change in Proportion of Partial Nephrectomy Compared With 2001 (95% CI)	P
Robot acquisition 2001–2004	In 2005: +29.9% (10.7 to 49.1)	< 0.01
	In 2008: +34.9% (14.0 to 55.8)	< 0.01
Robot acquisition 2005–2008	In 2008: +15.5% (1.4 to 29.7)	0.03
Year 2005	+19.8% (14.0 to 25.7)	< 0.01
Year 2008	+25.7% (18.8 to 32.5)	< 0.01
Nephrectomy volume (per 1% increase)	+0.66% (0.58 to 0.71)	< 0.01
Fraction of female hospital inpatients (per 1% increase)	−0.17% (−0.30 to −0.04)	0.01
Mean age of hospital inpatients	−0.6% (−1.1 to −0.1)	0.01
Median Elixhauser Comorbidity Score of hospital inpatients	−5.6% (−8.6 to −2.6)	< 0.01
No. beds	+0.01% (−0.01 to 0.04)	0.16
Teaching	+4.22% (−2.1 to 10.6)	0.19
Urban	−7.5% (−14.3 to −0.8)	0.03
Fraction of privately insured hospital inpatients (per 1% increase)	−0.08% (−0.22 to 0.06)	0.25

Nephrectomy volume: number of all nephrectomies (partial or radical) performed for renal cell carcinoma at a given hospital per year.

Fraction of female patients: the percentage of all patients who were of the female sex at a given hospital.

Median Elixhauser Comorbidity Score of patients: the median Elixhauser Comorbidity Score of all patients at a given hospital.

Fraction of privately insured patients: the percentage of patients at a given hospital who were privately insured.

^*Each hospital characteristic was determined at the hospital level.