Hospital costs, length of stay and prevalence of hip and knee arthroplasty in patients with inflammatory bowel disease

AIM: To examined the prevalence of hip and knee arthroplasty in patients with inflammatory bowel disease (IBD) by comparing the diagnostic codes for these procedures in patients with IBD and a control group of patients. METHODS: The National Inpatient Sample database (NIS) is part of the Healthcare Cost and Utilization Project (HCUP), the largest publicly available inpatient healthcare database in the United States. The NIS samples about 20% of discharges from all community hospitals participating in HCUP, representative of more than 95% of the United States population, with approximately 7000000 hospitalizations reported annually. NIS contains data on diagnoses, procedures, demographics, length of stay (LOS), co-morbidities and outcomes. ICD-9-CM diagnostic codes for primary hospitalizations for arthroplasty of the hip or knee with a co-diagnosis of IBD [combining both Crohn’s disease (CD) and ulcerative colitis (UC)] were used to identify study subjects for cost and LOS analysis for NIS from 1999-2012. Statistical analysis: 1: 2 propensity score matching between IBD vs a control group based on following factors: Patient age, gender, race, total co-morbidities, # of procedures, admission type, insurance, income quartiles, and hospital bed size, location and hospital teaching status. Categorical variables were reported as frequency and compared by χ(2) tests or Fisher’s exact tests. Individual 1:3 matching was also performed for patients carrying diagnostic codes for CD and for patients with the diagnostic code for UC. After matching, continuous variables were rcompared with Wilcoxon signed rank or Paired T-tests. Binary outcomes were compared with the McNemar’s test. This process was performed for the diagnosis of hip or knee arthroplasty and IBD (CD and UC combined). Prevalence of the primary or secondary diagnostic codes for these procedures in patients with IBD was determined from NIS 2007. RESULTS: Costs and mortality were similar for patients with IBD and controls, but LOS was significantly longer for hip arthroplasties patients with IBD, (3.85 +/-2.59 d vs 3.68 +/-2.54 d, respectively, P = 0.009). Costs, LOS and survival from the procedures was similar in patients with CD and UC compared to matched controls. These results are shown in Tables 1-10. The prevalence of hip arthroplasty in patients with IBD was 0.5% in 2007, (170/33783 total patients with diagnostic codes for IBD) and was 0.66% in matched controls (P = 0.0012). The prevalence of knee arthroplasty in patients with IBD was 1.36, (292/21202 IBD patients) and was 2.22% in matched controls (P < 0.0001). CONCLUSION: Costs and mortality rates for hip and knee arthroplasties are the same in patients with IBD and the general population, while a statistical but non-relevant increase in LOS is seen for hip arthroplasties in patients with IBD. Compared to the general population, arthroplasties of the hip and knee are less prevalent in hospitalized patients with IBD.