Assessing the relative cost of healthcare-associated infections using published studies

Background:   While most studies of the excess patient costs due to healthcare-associated infections (HAI) present the results as absolute dollar amounts, an important measure of the opportunity cost of HAIs (from economic theory) that is rarely reported directly is the relative percent change in costs between infected and non-infected patients. 

 

Objective:   To calculate the relative cost change from published studies and show how this information can be used to provide an estimate of the excess cost of HAIs for a particular hospital.

 

Methods:   The formula to calculate the percent change in patient cost is:

Percent Change in Total Cost =

                                     

where

TotalCost_Infected = average total costs of patients with HAI

TotalCost_Non-infected = average total costs of patients without HAI.

Four previously published studies, containing the needed data for the formula, are used to demonstrate the calculation.

 

Results:   The table below illustrates the calculation of relative cost changes. 

 Table:  Calculation of Relative Percent Change in Patient Cost Due To HAI

Study (year)         (1)	Study Setting           (2)	Organisms Included         (3)	Total Non-infected Patient Costs     (4)	Estimated Excess Patient Cost due to  HAI   (5)	Total Patient Costs (Column 4 plus Column 5) (6)	Relative Percent Change in Total Cost     (7)
Roberts et al. (2003)	Single hospital, hospital-wide excluding Trauma, Burn and Obstetrical units,	All organisms detected using modified CDC criteria	$7,333	$15,275	$22,608	+208%
Warren et al. (2003)	Single center, ICU only	VAP detected using CDC criteria	$21,620	$11,809	$33,429	+55%
Warren et al. (2006)	Single center, ICU only	CLABSI detected using CDC criteria	$23,803	$11,971	$35,774	+50%
Olsen et al. (2008)	Single center	SSI detected in patients undergoing breast surgery using CDC criteria	$9,973	$4,091	$14,064	+41%

VAP=ventilator-associated pneumonia

CLABSI =Central line-associated bloodstream infection

SSI=Surgical Site Infection

Estimated excess costs ranged from +$4,091 to +$15,275.  Relative percent change costs ranged from +41% to +208%.

Conclusions:  

Studies on the cost of HAIs should report non-infected patient costs along with the excess costs of acquiring infection to facilitate the calculation of relative cost change.  Calculating the relative cost change provides a measure of the opportunity costs of the hospital resources used to treat HAI.  These cost increases can be multiplied by the number of infections occurring to estimate a total hospital burden.   These calculations neutralize the effect of other extraneous economic factors on HAI cost estimates like regional price differences and price inflation.   Also, this information is powerful for individual hospital assessments as it only requires the hospital's own total costs of infected patients (for the appropriate specified study population) and the relative change from the literature to solve for the excess cost of HAI.