Table A4.

30-Day Readmission Outcomes: First Stage, OLS and 2SLS Estimates, by Risk-Standardized 90D Hospital Spending Measure

		90D Inpatient Spending		90D Non-Inpatient Spending
		(1)	(2)	(3)	(4)
Panel A. First Stage
	Ambulance Average 90D Inpatient Spending	0.250 (0.0052)	0.251 (0.0052)
	Ambulance Average 90D Non-Inpatient Spending			0.136 (0.0045)	0.137 (0.0045)
Panel B. OLS
	90D Inpatient Spending	0.002 (0.0016)	−0.003 (0.0015)
	90D Non-Inpatient Spending			0.003 (0.0017)	0.002 (0.0016)
Panel C. 2SLS
	90D Inpatient Spending	−0.021 (0.0063)	−0.030 (0.0063)
	90D Non-Inpatient Spending			0.021 (0.0092)	0.009 (0.0090)
	Sample Size	1,575,273
	Outcome Mean	0.426
	Patient Controls	No	Yes	No	Yes

Notes: Each column reports model results based on hospital measures of total spending over 90 days after the index admission. All spending measures are trimmed of outliers and then risk-standardized by age, race and gender. Risk-standardized spending measures have been demeaned and scaled by 2 standard deviations. Thus, the reported coefficients reflect a difference of ±1 standard deviations from the mean (i.e., “low” vs. “high” spending). Means (SDs) for spending variables: 90D Inpatient Total = $15,876 (3,113); 90D Non-Inpatient Total = $10,557 (1,585). Models without patient controls include ZIP × patient origin fixed effects, as well as year and principal diagnosis controls (see Table A1 for a full list); models with patient controls adds all patient and ambulance controls as listed in Table 1, with age controls in 5-year bins. Standard errors, clustered at the Health Service Area (HSA) level, are reported in parentheses.

Source: 2002–2012 Medicare Part A and B Data