Direct Costs and Resource Utilization for Inpatient Diverticulitis Admissions

Abstract

Purpose: The incidence of diverticular diseases, including resource-intensive diverticulitis (DV), has increased in lockstep with the aging population. Although DV attacks are common, little is known about resource utilization of inpatient DV admissions, including cost variations between initial vs. subsequent attacks and clinical predictors of resource utilization. As new medical therapies are developed for prevention of DV attacks, it will be important to understand the economic burden of DV admissions; this will inform costeffectiveness analyses of emerging pharmacotherapies and contribute more broadly to knowledge about DV burden of illness. Methods: We performed detailed chart reviews to measure resource utilization in a random sample of prevalent DV admissions to a University-based VA medical center from 1996-2010. We measured clinical variables along with individual resource counts, including surgical and GI consults, CTs, labs, interventional radiology (IR) procedures, surgeries, medications, ICU, monitored, and ward days, and overall length of stay (LOS). Using a third-party payer perspective, we performed resource micro-costing based on 2010 CPT fees and the Red Book. We compared aggregate costs between initial vs. subsequent attacks, and performed multivariable regression analysis to identify cost predictors. Results: There were 109 patients (age=65.8; 98% male) with 136 DV admissions. Mean maximum temperature (Tmax) and WBC max during admission were 99.6F and 14.9K, respectively. The average LOS per admission was 8.3 days (median=6; IQR=3-9.75), with a mean of 1.3, 1.8, and 4.4 days in ICU, monitored, and ward beds, respectively. Clinicians ordered a median of 1 abdominal CT per stay, along with 5 CBCs and 1 LFT. Surgery and IR were performed in 31% and 12%, respectively. The median cost was $3795 per admission (IQR = $2355 to $8427); there was a trend towards cost escalation when comparing median costs for first ($3197 per stay) vs. subsequent ($5076 per stay) attacks (p=0.09). In multivariable regression, cost was independently associated with increasing age (p=0.03) and higher Tmax (p=0.003) after adjustment for surgery, IR, admitting service, and attack number (R2=47%). Conclusion: Detailed micro-costing of DV admissions yields a median cost of $3795 per inpatient stay. There is a trend towards higher direct costs as multiple DV attacks accumulate. Higher Tmax and advancing age are independently associated with increased cost of care. These data further define DV economic burden and identify potential clinical factors associated with higher resource utilization; future studies should evaluate if these benchmarks hold in other and/or larger populations. This research was supported by an industry grant from Shire Pharmaceuticals.