Post-hospitalization discharge economic burden of Clostridium-difficile associated diarrhea among high-risk patient sub-groups in a managed care setting

Purpose: To evaluate the short- and long-term incremental economic burden following CDAD hospitalization among the following sub-populations: immunocompromised (IC), prior CDAD, concurrent antibiotic users (cABx), renally impaired (RI), inflammatory bowel disease (IBD) and elderly (≥65).

Methods: Patients with an inpatient CDI diagnosis (ICD-9-CM: 008.45), aged ≥18 years and ≥12 months of prior health plan eligibility between 01/01/2005-10/31/2010 were identified from the HealthCore Integrated Research Database (HIRD^SM). Within each sub-population, cases were directly matched to controls- patients hospitalized without a CDI diagnosis. Matching criteria included sub-population defining condition(s), gender, age±10 years, and baseline/in-hospital comorbidities. Follow-up was the period between hospital discharge and earliest occurrence of end of continuous health plan eligibility or available data stream, or death. Incremental(Δ) post-discharge resource and health plan costs between cases and controls were assessed using multivariate GLMs with Poisson and Gamma distributions, respectively, adjusting for significant post-match characteristics. Short-term burden was evaluated for the post-discharge 30-day period. Long-term cost burden was assessed over the available follow-up period on a PMPM basis.

Results: Post-match case-to-control ratios ranged from 1:1 to 1:3 in each sub-population (IC: n=3,586; prior CDAD: n=933; cABx: n=4,429; RI: n=5,533; IBD: n=1,206; elderly: n=10,933 cases respectively). Cases incurred a significantly (p<0.0001) greater number of hospitalizations and overall health plan costs relative to controls during the 30-day (see table) post-discharge duration. Cases also had significantly greater ΔPMPM burden with medical expenditures representing the majority of costs.

Subgroup	30-day Post-discharge Mean ΔBurden*		ΔPMPM($)*
	# Inpatient/Medical encounters Per 100 Patients	Inpatient/Medical Costs($)	Overall
IC	6/3	2,318/3,908	3,033
Prior CDAD	7/47	6,649/4,868	4,513
cABx	7/-5	2,320/2,574	1,831
RI	9/-12	4,410/5,013	3,851
IBD	4/-30	529/557	704
Elderly	9/-43	4,149/3,982	3,258

*Δ= CDAD/non-CDAD difference

Conclusion: CDAD patients in each sub-population incurred substantial incremental PMPM and post-discharge economic burden to the health plan; they appear to be driven by a higher number of hospitalizations.