TABLE 3.

OLS Estimates of the Effects of Guideline Changes on Inpatient Diverticulitis Costs, Quarterly

	Costs per Discharge, % Change	95% Confidence Interval	Aggregate Costs, % Change	95% Confidence Interval
Preimplementation period	+1.13%	0.76% to 1.49%	+0.61%	0.28% to 0.94%
Postimplementation period	–0.27%	–0.39% to –0.15%	–0.52%	–0.87% to –0.17%
Total change from pre to postimplementation period	–1.40	–	–1.13	–
	Change in Cost Per Discharge ($)	95% Confidence Interval	Change in Aggregate Costs ($)	95% Confidence Interval (Millions of Dollars)
Preimplementation period*	+$196	$50 to $342	+$3.45 million	$3.43 to $3.48
Postimplementation period†	–$86	–$111 to –$61	–$2.91 million	–$2.94 to –$2.89
Total savings from pre to postimplementation period	–$282	–	–$6.36 million	–

All regressions use robust standard error; standard errors in parenthesis; cost per discharge contains patient, clinical, and hospital variables; aggregate costs generated from a segmented linear regression at the aggregate cost level per discharge quarter from 2004 to 2015. Dollar amounts in 2015 dollars. Unadjusted survey weighted estimates from the NIS; Y left axis is total aggregate costs (in millions of dollars); Y right axis is cost per discharge. All adjusted to 2015 dollars.

*Significant at the 0.05 level.

†Significant at the <0.01 level.

NIS indicates National Inpatient Sample.