The impact of ICD-9-CM code rank order on the estimated prevalence of Clostridium difficile infections

Colectomy Rates Are Increasing Among Inpatients With Concomitant Ulcerative Colitis and Clostridioides difficile

BACKGROUND

Clostridioides difficile infection (CDI) is an important cause of inflammatory bowel disease (IBD) exacerbation and is associated with increased risk of hospitalization, colectomy, and mortality. Previous analysis have reported an increasing rate of CDI and associated mortality in IBD patients. We examined the trends in CDI-associated outcomes in hospitalized patients with Crohn's disease (CD) and ulcerative colitis (UC) over the last decade.

MATERIALS AND METHODS

We used data from the National Inpatient Sample to identify patients hospitalized with both CDI and IBD from 2006 to 2014. Outcomes included in-hospital mortality, partial/total colectomy, hospital length of stay, and charges. Analysis included univariate and multivariate regression analysis.

RESULTS

Between 2006 and 2014, CDI-related hospitalizations increased in both CD (1.6% to 3.2%; P<0.001) and UC (4.9% to 8.6%; P<0.001). CDI-associated mortality in CD and UC patients decreased from 2.4% to 1.2% (P<0.001) and 11.3% to 9.7% (P<0.001), respectively. CDI-associated colectomy rate increased from 4.3% to 8.8% (P<0.001) in UC but decreased from 4.5% to 2.8% (P<0.001) in CD. In multivariable analysis, compared with 2006, there was a nonsignificant decrease in mortality in 2014 in both CD [adjusted odds ratio (AOR) 0.56, 95% confidence interval (CI) 0.25-1.24] and UC (AOR 0.81, 95% CI 0.61-1.07), but a significant increase in colectomy in 2014 only in UC (AOR 2.12, 95% CI 1.46-3.06).

CONCLUSIONS

CDI rates have increased in CD and UC over the last decade. Although there has been a significant increase in colectomies in UC, CDI-associated mortality in CD and UC has not increased over this time.

Antibiotic Prescribing Choices and Their Comparative C. Difficile Infection Risks: A Longitudinal Case-Cohort Study

BACKGROUND

Antibiotic use is the strongest modifiable risk factor for the development of Clostridioides difficile infection, but prescribers lack quantitative information on comparative risks of specific antibiotic courses. Our objective was to estimate risks of C. difficile infection associated with receipt of specific antibiotic courses.

METHODS

We conducted a longitudinal case-cohort analysis representing over 90% of Ontario nursing home residents, between 2012 and 2017. Our primary exposure was days of antibiotic receipt in the prior 90 days. Adjustment covariates included: age, sex, prior emergency department or acute care stay, Charlson comorbidity index, prior C. difficile infection, acid suppressant use, device use, and functional status. We examined incident C. difficile infection, including cases identified within the nursing home, and those identified during subsequent hospital admissions. Adjusted and unadjusted regression models were used to measure risk associated with 5- to 14-day courses of 18 different antibiotics.

RESULTS

We identified 1708 cases of C. difficile infection (1.27 per 100 000 resident-days). Longer antibiotic duration was associated with increased risk: 10- and 14-day courses incurred 12% (adjusted relative risk [ARR] = 1.12, 95% confidence interval [CI]: 1.09, 1.14) and 27% (ARR = 1.27, 95% CI: 1.21,1.30) more risk compared to 7-day courses. Among 7-day courses with similar indications: moxifloxacin resulted in 121% more risk than amoxicillin (ARR = 2.21, 95% CI: 1.67, 3.08), ciprofloxacin engendered 89% more risk than nitrofurantoin (ARR = 1.89, 95% CI: 1.45, 2.68), and clindamycin resulted in 112% (ARR = 2.12, 95% CI: 1.32, 3.78) more risk than cloxacillin.

CONCLUSIONS

C. difficile infection risk increases with antibiotic duration, and there are wide disparities in risks associated with antibiotic courses used for similar indications.

Trends in Hospitalizations for Clostridioides difficile Infection in End-Stage Liver Disease, 2005-2014

BACKGROUND

Data on the current estimates of the disease burden of Clostridioides difficile (C. difficile) infection in the setting of end-stage liver disease (ESLD) are emerging.

AIMS

We examined the recent trends and predictors of hospitalizations and in-hospital mortality from C. difficile infection among hospitalizations with ESLD in the USA.

METHODS

We performed a retrospective analysis using the National Inpatient Sample, 2005-2014. We defined ESLD and C. difficile infection using the International Classification of Diseases, Ninth Revision, Clinical Modification. Multivariable logistic regression was used to determine the risk factors that impacted hospitalization and mortality.

RESULTS

The prevalence of coding for C. difficile infection in decompensated cirrhosis increased from 1.3% in 2005 to 2.7% in 2014, with an annual rate of 7.8%. In hospitalizations with hepatocellular carcinoma, C. difficile infection increased steadily from 1.0 to 1.7% with an annual incremental rate of 6.4%. Among hospitalizations with ESLD, each passing 2-year period, increasing age, female, higher Charlson index, accompanying infection, hepatorenal syndrome, and ascites were associated with C. difficile infection. Although C. difficile infection was an independent predictor of in-hospital mortality during hospitalization with decompensated cirrhosis (odds ratio 1.53, 95% confidence interval 1.44-1.63), the proportion of in-hospital mortality during hospitalization with C. difficile infection and decompensated cirrhosis decreased from 15.4% in 2005 to 11.1% in 2014, with an annual rate of - 3.1% (95% CI - 5.7% to - 0.3%).

CONCLUSIONS

While the prevalence of C. difficile infection in hospitalized patients with ESLD increased approximately twofold, the in-hospital mortality decreased significantly during the past decade.

Time trends and predictors of laboratory-confirmed recurrent and severe Clostridioides difficile infections in Manitoba: a population-based study

BACKGROUND

Many previous studies of Clostridioides difficile infection (CDI) epidemiology have used hospital discharge data codes, which can have limited accuracy. We used a data set of laboratory-confirmed cases of CDI in the province of Manitoba, Canada, to describe the epidemiology of CDI over a decade.

METHODS

We conducted a population-based historical cohort study using Manitoba Health's population-wide laboratory-based CDI data set linked to administrative health databases. All individuals living in Manitoba and experiencing a CDI episode between 2005 and 2015 were included (n = 8471) and followed up from CDI diagnosis. We assessed time trends of CDI, incidence and predictors of recurrence and severe outcomes, and health care encounters after CDI diagnosis. CDI episodes were stratified by community versus hospital site of acquiring CDI.

RESULTS

Between 2005 and 2009, overall CDI diagnoses decreased by an average of 12.6% per year (95% confidence interval [CI] -4.4 to -20.0), with no statistically significant change from 2010 to 2015. In stratified analysis, incident and recurrent CDI had a similar decrease in the initial study time period and then stabilized. The proportion of community-associated CDI cases increased by an average of 4.8% per year (95% CI 2.8 to 6.8) during the study period. CDI acquired in a health care facility had a higher recurrence rate and more severe outcomes. Recurrence of CDI increased the likelihood of admission to hospital.

INTERPRETATION

Between 2005 and 2015, the rates of overall laboratory-confirmed CDI, incident CDI, recurrent CDI and severe outcomes following CDI initially decreased before stabilizing, and an increasing proportion of CDI cases were community-associated. There is an increasing need to test for CDI among outpatients with diarrhea and to increase efforts to prevent recurrent CDI.

Outcomes of C difficile infection in solid-organ transplant recipients: The National Inpatient Sample (NIS) 2015-2016

BACKGROUND

Clostridioides (formerly Clostridium) difficile infection (CDI) is one of the leading causes of morbidity and mortality worldwide. Solid organ transplant (SOT) recipients are at an increased risk for CDI. A recent study showed an overall improvement in mortality amongst hospitalized individuals with CDI, but it is unclear if this benefit extends to SOT recipients.

METHODS

We scrutinized the 2015 and 2016 National Inpatient Sample (NIS), the largest all-payer inpatient database in the United States for CDI data in patients with SOT. SOT was defined as any recipient who had received a heart, lung, liver, intestinal, kidney, pancreas, or combined thoracic and/or abdominal organ transplantation. Baseline characteristics, comorbidities, and concomitant diagnosis of pneumonia or urinary tract infection were adjusted for in our analysis. Primary outcomes included inpatient mortality, hospital length of stay and total hospital charges.

RESULTS

A total of 105 780 hospital discharges of SOT recipients were included. The incidence of CDI was 3554 (3.36%) among SOTs. CDI was associated with a higher inpatient mortality (OR 1.85, 95% CI 1.56-2.20, P < .01), longer length of hospital stay (mean difference 5.07 days, 95% CI 4.43-5.71, P < .01) and higher total hospital charges (mean difference 43 958 US dollars, P < .01).

CONCLUSION

Our study found that CDI is associated with poorer overall outcomes among hospitalized SOT recipients. However, there was a possible improving trend of the outcomes when compare to previous studies.

Evaluating the impact of expanding the number of diagnosis codes reported in inpatient discharge databases on the counts and rates of birth defects

Objective

Public health surveillance programs worldwide implement a variety of case-finding strategies, and many rely at least in part on International Classification of Diseases (ICD)-based diagnostic codes in administrative and clinical databases. Over time, state- and national-level hospital discharge databases have been expanding the number of reported diagnosis code fields. This study aimed to evaluate the impact of these expansions on frequencies and rates of major birth defects, and the classification of birth defects as isolated vs multiple.

Methods

We used state-level 2006-2013 Florida Birth Defects Registry data and 2009-2012 data from a nationally representative database (Kids' Inpatient Database). We generated data under different scenarios by varying the number of diagnosis code fields available, and comparing counts and rates of major birth defects generated under each scenario.

Results

The expansion from 10 to 31 diagnosis code fields improved ascertainment by preventing the loss of 1 in every 40 birth defect cases with defect-related diagnoses appearing only in code positions 11 to 31. Although there was variation by birth defect, the largest impact of the expansion tended to occur for less severe birth defects diagnosed in sicker infants. When restricting to fewer codes, not only were fewer cases diagnosed, but more were classified as being isolated due to the inability to capture co-occurring defects.

Conclusion

Our findings encourage additional research for other health outcomes in patients of all ages. Other disease registries rely at least in part on diagnostic codes documented by healthcare providers in their case-finding activities, irrespective of ascertainment protocols, making routine investigation of these databases essential.

Direct cost of health care for individuals with community associated Clostridium difficile infections: A population-based cohort study

Background

Even though the incidence of community-acquired Clostridium difficile infection (CDI) is reported to be increasing, few studies have reported on the healthcare costs of community-acquired CDI. We estimated cost of care for individuals with community-associated CDI and compared with that for matched controls without CDI in the time period of six months before to one year after CDI.

Methods

All individuals in the province of Manitoba, diagnosed with CDI between July 2005 and March 2015 were matched up to 4 individuals without CDI. Health care utilization and direct costs resulting from hospitalizations, physician reimbursement claims and prescriptions were determined from the population based provincial databases. Quantile regressions were performed to determine predictors of cost of individuals with community associated CDI.

Results

Of all CDIs, 30–40% in each period of the study had community-associated CDI; of which 12% were recurrent CDIs. The incremental median and 90^th percentile cost of care for individuals with community-associated CDI was $800 and $16,000 respectively in the six months after CDI diagnosis. After adjustment for age, co-morbidities, sex, socioeconomic status and magnitude of health care utilization prior to CDI, the median incremental cost for recurrent CDI was $1,812 and that for a subsequent episode of CDI was $3,139 compared to those with a single community-associated CDI episode. The median cost for a prescription of Vancomycin was $316 (IQR 209–489).

Conclusions

Health care costs of an episode of community-associated CDI have been much more than the cost of antibiotic treatment. Our study provides population-based data for formal cost effectiveness analysis for use of newer treatments for community-associated CDI.

The Impact of Bariatric Surgery on Short Term Risk of Clostridium Difficile Admissions

BACKGROUND AND AIMS

Clostridium difficile infection (CDI) is major health care concern with reports linking it to obesity. Our aim was to investigate the little known impact of the two most common bariatric surgeries, Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG), on risk of CDI admissions.

METHODS

This is a retrospective cohort study using the 2013 Nationwide Readmission Database. We examined inpatient CDI rates within 120 days after RYGB (n = 40,059) and VSG (n = 45,394). In a time to event analysis we also evaluated inpatient CDI rates up to 11 months post-surgery. We chose morbidly obese patients that underwent non-emergent ventral hernia repair (VHR) as additional surgical controls (n = 9673).

RESULT

CDI rates were higher after RYGB than VSG in the first 30 days (odds ratio [OR] = 2.10; 95% confidence interval [CI], 1.05-4.20) with a similar but nonsignificant trend within 31-120 days. CDI rates were also higher after RYGB compared to VHR controls within 31-120 days after surgery (OR = 3.22, 95%CI: 1.31, 7.88, p = 0.01). In a time to event analysis with up to 11 months follow up, RYGB led to higher CDI compared to VSG (hazard ratio [HR] = 1.87; 95% CI, 1.12-3.13) with a trend towards higher CDI compared to VHR (HR = 1.95; 95% CI, 0.94-4.06). Similar CDI rates occurred after VSG vs VHR.

CONCLUSIONS

RYGB may increase the risk of CDI hospitalization when compared to VSG and VHR controls. This data suggest VSG may be a better bariatric choice when post-surgical CDI risk is a concern.

Trends and Predictors of Clostridium difficile Infection among Children: A Canadian Population-Based Study

OBJECTIVE

To assess time trends in Clostridium difficile infection (CDI) rates, and predictors of CDIs, including recurrent CDIs, in children.

STUDY DESIGN

Data were extracted from Manitoba Health Provider Claims, and other population registry datasets from 2005 to 2015. CDI was identified from the Manitoba Health Public Health Branch Epidemiology and Surveillance population-based laboratory-confirmed CDI dataset. Children aged 2-17 years with CDI were matched by age, sex, area of residence, and duration of residence in Manitoba with children without CDI. The rates and time trends of CDIs using previously recommended definitions were determined. Predictors of CDI subtypes were determined using multivariable logistic regression models. Cox regression analysis was used to assess for the potential predictors of recurrent CDI.

RESULTS

Children with and without CDI were followed for 828 and 2753 persons-years, respectively. The overall CDI rate during the study period was 7.8 per 100 000 person-years. There was no significant change in CDI rates over the observation period. Comorbid conditions, more prevalent among children with CDI than matched controls, included Hirschsprung disease (P < .001) and inflammatory bowel disease (P < .0001). Recurrent CDIs (>2 occurrences) were responsible for 10% of CDI episodes (range, 2-6 infections). Predictors of recurrence included malignancy (hazard ratio, 3.0, 95% CI, 1.1-8.8), diabetes (hazard ratio, 4.8; 95% CI, 1.1-21.4), and neurodegenerative diseases (hazard ratio, 8.4; 95% CI, 1.9-37.5).

CONCLUSIONS

The incidence of CDI is stable among children in Manitoba. Children with Hirschsprung disease and inflammatory bowel disease are more susceptible to CDI, and those with malignancy, diabetes. and neurodegenerative disorders are more likely to develop recurrent CDI.

Acute kidney injury impact on inpatient mortality in Clostridium difficile infection: A national propensity-matched study

BACKGROUND AND AIM

Acute kidney injury (AKI) is used as a marker of severity in Clostridium difficile infection (CDI) patients. We estimated the true effect of AKI in inpatient mortality of CDI patients, as there are no large-scale, population-based, propensity-matched studies evaluating AKI's effect in this patient cohort.

METHODS

A retrospective observational study utilizing the National Inpatient Sample from years 2003 to 2012, including all adults with CDI, excluding cases missing data on age, inpatient mortality or gender. Trends and CDI-related complications as mortality predictors were assessed using survey-weighted multivariable regression. We estimated AKI's independent effect by propensity-matching, post-stratifying by chronic kidney disease status, allowing for multiple comorbidity adjustment.

RESULTS

A total of 2 859 599 patients with CDI were included, of which 896 122 (31.3%) had principal diagnosis of CDI. AKI prevalence was 22%. Mortality rate was 8.4%, while among AKI patients was higher (18.2%). In multivariable regression, AKI was associated with higher mortality (odds ratio [OR] = 3.16, 95% confidence interval [CI]: 3.02-3.30; P < 0.001), while after propensity matching, AKI increased mortality by 86% (OR = 1.86, 95% CI: 1.79-1.94; P < 0.001). CDI incidence increased by 1.8, together with the rate of AKI (12.6% in 2003 to 28.8% in 2012, P-trend < 0.001). Despite increasing hospitalizations, mortality over the study period decreased to 7.2% (2012) from 9.0% (2003); P-trend < 0.001.

CONCLUSION

Hospital admissions of patients with CDI and concomitant AKI are increasing, but their inpatient mortality has improved over the study period. AKI is a significant contributor to mortality, independently of other comorbidities, complications, and hospital characteristics, emphasizing the need for early diagnosis and aggressive management in such patients.

Higher Incidence of Clostridium difficile Infection Among Individuals With Inflammatory Bowel Disease

BACKGROUND & AIMS

Studies of Clostridium difficile infections (CDIs) among individuals with inflammatory bowel disease (IBD) have used data from single centers or CDI administrative data codes of limited diagnostic accuracy. We determined the incidence, risk factors, and outcomes after CDI in a population-based cohort of patients with IBD and laboratory confirmation diagnoses of CDI.

METHODS

We searched the University of Manitoba IBD Epidemiology Database and Manitoba Health CDI databases to identify individuals with CDI, with or without IBD, from July 1, 2005 through March 31, 2014. Time trends of incidence were assessed using joinpoint regression. Multivariable Cox regression analyses were performed to assess differences in CDI incidence rates and mortality after CDI between individuals with and without IBD. Conditional logistic regression was performed to determine predictors of CDI among individuals with IBD.

RESULTS

Individuals with IBD had a 4.8-fold increase in risk of CDI than individuals without IBD; we found no difference between individuals with ulcerative colitis vs Crohn's disease. There was no increase in CDI incidence over the study time period in either group. Among individuals with IBD, exposure to corticosteroids, infliximab or adalimumab, metronidazole, hospitalizations, higher ambulatory care visits, shorter duration of IBD, and higher comorbidities were associated with an increased risk of CDI. Although CDI increased mortality among individuals with and without IBD, there was lower mortality after CDI among individuals with IBD than without IBD (hazard ratio, 0.65; 95% confidence interval, 0.44-0.96).

CONCLUSIONS

CDI incidence is no longer increasing among individuals with IBD. We identified unique risk factors for CDI in patients with IBD. CDI is associated with a greater increase in mortality among individuals without IBD than with IBD.

Survey of Clostridium difficile infection surveillance systems in Europe, 2011

To develop a European surveillance protocol for Clostridium difficile infection (CDI), existing national CDI surveillance systems were assessed in 2011. A web-based electronic form was provided for all national coordinators of the European CDI Surveillance Network (ECDIS-Net). Of 35 national coordinators approached, 33 from 31 European countries replied. Surveillance of CDI was in place in 14 of the 31 countries, comprising 18 different nationwide systems. Three of 14 countries with CDI surveillance used public health notification of cases as the route of reporting, and in another three, reporting was limited to public health notification of cases of severe CDI. The CDI definitions published by the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) and the European Centre for Disease Prevention and Control (ECDC) were widely used, but there were differing definitions to distinguish between community- and healthcare-associated cases. All CDI surveillance systems except one reported annual national CDI rates (calculated as number of cases per patient-days). Only four surveillance systems regularly integrated microbiological data (typing and susceptibility testing results). Surveillance methods varied considerably between countries, which emphasises the need for a harmonised European protocol to allow consistent monitoring of the CDI epidemiology at European level. The results of this survey were used to develop a harmonised EU-wide hospital-based CDI surveillance protocol.

Hospital discharge abstracts have limited accuracy in identifying occurrence of Clostridium difficile infections among hospitalized individuals with inflammatory bowel disease: A population-based study

BACKGROUND

Hospital discharge databases are used to study the epidemiology of Clostridium difficile infections (CDI) among hospitalized patients with inflammatory bowel disease (IBD). CDI in IBD is increasingly important and accurately estimating its occurrence is critical in understanding its comorbidity. There are limited data on the reliability of the International Classification of Diseases 10th revision (ICD-10) (now widely used in North America) CDI code in determining occurrence of CDI among hospitalized patients. We compared the performance of ICD-10 CDI coding to laboratory confirmed CDI diagnoses.

METHODS

The University of Manitoba IBD Epidemiology Database was used to identify individuals with and without IBD discharged with CDI diagnoses between 07/01/2005 and 3/31/2014. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of ICD-10 CDI code was compared to laboratory CDI diagnoses recorded in a province wide CDI dataset. Multivariable logistic regression models were performed to test the predictors of diagnostic inaccuracy of ICD-10 CDI code.

RESULTS

There were 273 episodes of laboratory confirmed CDI (hospitalized and non-hospitalized) among 7396 individuals with IBD and 536 among 66,297 matched controls. The sensitivity, specificity, PPV and NPV of ICD-10 CDI code in discharge abstracts was 72.8%, 99.6%, 64.1% and 99.7% among those with IBD and 70.8%, 99.9%, 79.0% and 99.9% among those without IBD. Predictors of diagnostic inaccuracy included IBD, older age, increased co-morbidity and earlier years of hospitalization.

CONCLUSIONS

Identification of CDI using ICD-10 CDI code in hospital discharge abstracts may not identify up to 30% of CDI cases, with worse performance among those with IBD.

Incidence and Outcomes Associated With Infections Caused by Vancomycin-Resistant Enterococci in the United States: Systematic Literature Review and Meta-Analysis

BACKGROUND

Information about the health and economic impact of infections caused by vancomycin-resistant enterococci (VRE) can inform investments in infection prevention and development of novel therapeutics.

OBJECTIVE

To systematically review the incidence of VRE infection in the United States and the clinical and economic outcomes.

METHODS

We searched various databases for US studies published from January 1, 2000, through June 8, 2015, that evaluated incidence, mortality, length of stay, discharge to a long-term care facility, readmission, recurrence, or costs attributable to VRE infections. We included multicenter studies that evaluated incidence and single-center and multicenter studies that evaluated outcomes. We kept studies that did not have a denominator or uninfected controls only if they assessed postinfection length of stay, costs, or recurrence. We performed meta-analysis to pool the mortality data.

RESULTS

Five studies provided incidence data and 13 studies evaluated outcomes or costs. The incidence of VRE infections increased in Atlanta and Detroit but did not increase in national samples. Compared with uninfected controls, VRE infection was associated with increased mortality (pooled odds ratio, 2.55), longer length of stay (3-4.6 days longer or 1.4 times longer), increased risk of discharge to a long-term care facility (2.8- to 6.5-fold) or readmission (2.9-fold), and higher costs ($9,949 higher or 1.6-fold more).

CONCLUSIONS

VRE infection is associated with large attributable burdens, including excess mortality, prolonged in-hospital stay, and increased treatment costs. Multicenter studies that use suitable controls and adjust for time at risk or confounders are needed to estimate the burden of VRE infections.

Infect Control Hosp Epidemiol. 2017;38:203–215

Epidemiology, outcomes, and predictors of mortality in hospitalized adults with Clostridium difficile infection

Studies have demonstrated an increasing Clostridium difficile infection (CDI) incidence in hospitals and the community, with increasing morbidity and mortality. In this study, we analyzed data from the National Hospital Discharge Survey (NHDS) to evaluate CDI epidemiology, outcomes, and predictors of mortality in hospitalized adults. We identified cases of CDI (and associated comorbid conditions) from NHDS data from 2005 through 2009 using ICD-9 codes. Weighted univariate and multivariate analyses were performed to ascertain CDI incidence, associations between CDI and outcomes [length of stay (LOS), colectomy, all-cause in-hospital mortality, and discharge to a care facility], and predictors of all-cause in-hospital mortality. Of an estimated 162 million adult inpatients, 1.26 million (0.8 %) had CDI. The overall CDI incidence is 77.8/10,000 hospitalizations, with no statistically significant change over the study period. On multivariate analysis, after adjusting for age, gender, and comorbid conditions, CDI is an independent predictor of longer LOS (mean difference, 2.35 days), all-cause mortality [odds ratio (OR) 1.45], colectomy (OR 1.41), and discharge to a care facility (OR 2.12) (all P < 0.001). Elderly patients have a higher CDI incidence and worse outcomes than younger adults. The strongest predictors of all-cause mortality in patients with CDI include age 65 years or older, colectomy, and coagulation abnormalities. Despite stable CDI incidence and advances in management, CDI is associated with increased LOS, colectomy, all-cause in-hospital mortality, and discharge to a care facility in hospitalized, especially elderly, adults. Age older than 65 years should be added to the severity criteria for CDI.

The burden of clostridium difficile infection: estimates of the incidence of CDI from U.S. Administrative databases

Background

Many administrative data sources are available to study the epidemiology of infectious diseases, including Clostridium difficile infection (CDI), but few publications have compared CDI event rates across databases using similar methodology. We used comparable methods with multiple administrative databases to compare the incidence of CDI in older and younger persons in the United States.

Methods

We performed a retrospective study using three longitudinal data sources (Medicare, OptumInsight LabRx, and Healthcare Cost and Utilization Project State Inpatient Database (SID)), and two hospital encounter-level data sources (Nationwide Inpatient Sample (NIS) and Premier Perspective database) to identify CDI in adults aged 18 and older with calculation of CDI incidence rates/100,000 person-years of observation (pyo) and CDI categorization (onset and association).

Results

The incidence of CDI ranged from 66/100,000 in persons under 65 years (LabRx), 383/100,000 in elderly persons (SID), and 677/100,000 in elderly persons (Medicare). Ninety percent of CDI episodes in the LabRx population were characterized as community-onset compared to 41 % in the Medicare population. The majority of CDI episodes in the Medicare and LabRx databases were identified based on only a CDI diagnosis, whereas almost ¾ of encounters coded for CDI in the Premier hospital data were confirmed with a positive test result plus treatment with metronidazole or oral vancomycin. Using only the Medicare inpatient data to calculate encounter-level CDI events resulted in 553 CDI events/100,000 persons, virtually the same as the encounter proportion calculated using the NIS (544/100,000 persons).

Conclusions

We found that the incidence of CDI was 35 % higher in the Medicare data and fewer episodes were attributed to hospital acquisition when all medical claims were used to identify CDI, compared to only inpatient data lacking information on diagnosis and treatment in the outpatient setting. The incidence of CDI was 10-fold lower and the proportion of community-onset CDI was much higher in the privately insured younger LabRx population compared to the elderly Medicare population. The methods we developed to identify incident CDI can be used by other investigators to study the incidence of other infectious diseases and adverse events using large generalizable administrative datasets.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1501-7) contains supplementary material, which is available to authorized users.

Clostridium difficile associated risk of death score (CARDS): a novel severity score to predict mortality among hospitalised patients with C. difficile infection

BACKGROUND

Clostridium difficile infection (CDI) is a public health threat and associated with significant mortality. However, there is a paucity of objectively derived CDI severity scoring systems to predict mortality.

AIM

To develop a novel CDI risk score to predict mortality entitled: Clostridium difficile associated risk of death score (CARDS).

METHODS

We obtained data from the United States 2011 Nationwide Inpatient Sample (NIS) database. All CDI-associated hospitalisations were identified using discharge codes (ICD-9-CM, 008.45). Multivariate logistic regression was utilised to identify independent predictors of mortality. Clostridium difficile associated risk of death score was calculated by assigning a numeric weight to each parameter based on their odds ratio in the final logistic model. Predictive properties of model discrimination were assessed using the c-statistic and validated in an independent sample using the 2010 NIS database.

RESULTS

We identified 77 776 hospitalisations, yielding an estimate of 374 747 cases with an associated diagnosis of CDI in the US, 8% of whom died in the hospital. The eight severity score predictors were identified on multivariate analysis: age, cardiopulmonary disease, malignancy, diabetes, inflammatory bowel disease, acute renal failure, liver disease and ICU admission, with weights ranging from -1 (for diabetes) to 5 (for ICU admission). The overall risk score in the cohort ranged from 0 to 18. Mortality increased significantly as CARDS increased. CDI-associated mortality was 1.2% with a CARDS of 0 compared to 100% with CARDS of 18. The model performed equally well in our validation cohort.

CONCLUSION

Clostridium difficile associated risk of death score is a promising simple severity score to predict mortality among those hospitalised with C. difficile infection.

Obesity is independently associated with infection in hospitalised patients with end-stage liver disease

BACKGROUND

Infection is the most common cause of mortality in end-stage liver disease (ESLD). The impact of obesity on infection risk in ESLD is not established.

AIM

To characterise the impact of obesity on infection risk in ESLD.

METHODS

We evaluated the association between infection and obesity in patients with ESLD. Patients grouped as non-obese, obesity class I-II and obesity class III were studied using the Nationwide Inpatient Sample. Validated diagnostic code based algorithms were utilised to determine weight category and infections, including bacteraemia, skin/soft tissue infection, urinary tract infection (UTI), pneumonia/respiratory infection, Clostridium difficile infection (CDI) and spontaneous bacterial peritonitis (SBP). Risk factors for infection and mortality were assessed using multivariable logistic regression analysis.

RESULTS

Of 115 465 patients identified, 100 957 (87.5%) were non-obese and 14 508 (12.5%) were obese, with 9489 (8.2%) as obesity class I-II and 5019 (4.3%) as obesity class III. 37 117 patients (32.1%) had an infection diagnosis. Infection was most prevalent among obesity class III (44.0%), followed by obesity class I-II (38.9%) and then non-obese (31.9%). In multivariable modelling, class III obesity (OR = 1.41; 95% CI 1.32-1.51; P < 0.001), and class I-II obesity (OR = 1.08; 95% CI 1.01-1.15; P = 0.026) were associated with infection. Compared to non-obese patients, obese individuals had greater prevalence of bacteraemia, UTI, and skin/soft tissue infection as compared to non-obese patients.

CONCLUSIONS

Obesity is newly identified to be independently associated with infection in end-stage liver disease. The distribution of infection sites varies based on weight category.

LORD: a phenotype-genotype semantically integrated biomedical data tool to support rare disease diagnosis coding in health information systems

Characterizing a rare disease diagnosis for a given patient is often made through expert's networks. It is a complex task that could evolve over time depending on the natural history of the disease and the evolution of the scientific knowledge. Most rare diseases have genetic causes and recent improvements of sequencing techniques contribute to the discovery of many new diseases every year. Diagnosis coding in the rare disease field requires data from multiple knowledge bases to be aggregated in order to offer the clinician a global information space from possible diagnosis to clinical signs (phenotypes) and known genetic mutations (genotype). Nowadays, the major barrier to the coding activity is the lack of consolidation of such information scattered in different thesaurus such as Orphanet, OMIM or HPO. The Linking Open data for Rare Diseases (LORD) web portal we developed stands as the first attempt to fill this gap by offering an integrated view of 8,400 rare diseases linked to more than 14,500 signs and 3,270 genes. The application provides a browsing feature to navigate through the relationships between diseases, signs and genes, and some Application Programming Interfaces to help its integration in health information systems in routine.

Emergency Department Visits Related to Inflammatory Bowel Disease: Results From Nationwide Emergency Department Sample

We analyzed a national US database to study the presentation of children with inflammatory bowel disease (IBD) to the emergency department (ED). Our results indicate that from 2006 to 2010, there was a significant increase in the number of ED visits related to children with IBD accompanied by a contemporaneous decline in the rate of hospitalization that followed these ED visits. Earlier published results have highlighted an increased overall rate of hospitalizations in the United States related to children with IBD. In this context, our results support the evidence for an increased prevalence of pediatric IBD in the United States in recent years.

Identification of Recurrent Clostridium difficile Infection Using Administrative Codes: Accuracy and Implications for Surveillance

OBJECTIVE

To develop an algorithm using administrative codes, laboratory data, and medication data to identify recurrent Clostridium difficile infection (CDI) and to examine the sensitivity, specificity, positive and negative predictive values, and performance of this algorithm.

METHODS

We identified all patients with 2 or more International Classification of Diseases, Ninth Edition, Clinical Modification (ICD-9-CM) codes for CDI (008.45) from January 1 through December 31, 2013. Information on number of diagnosis codes, stool toxin assays (enzyme immunoassay or polymerase chain reaction), and unique prescriptions for metronidazole and vancomycin was identified. Logistic regression was used to identify independent predictors of recurrent CDI and a predictive model was developed.

RESULTS

A total of 591 patients with at least 2 ICD-9 codes for CDI were included (median age, 66 years). The derivation cohort consisted of 157 patients among whom 43 (27%) had recurrent CDI. Presence of 3 or more ICD-9 codes for CDI (odds ratio, 2.49), 2 or more stool tests (odds ratio, 2.88), and 2 or more prescriptions for vancomycin (odds ratio, 5.87) were independently associated with confirmed recurrent CDI. A classifier incorporating 2 or more prescriptions for vancomycin and either 2 or more stool tests or 3 or more ICD-9-CM codes had a positive predictive value of 41% and negative predictive value of 90%. The area under the receiver operating characteristic curve for this combined classifier was modest (0.69).

CONCLUSION

Identification of recurrent episodes of CDI in administrative data poses challenges. Accurate assessment of burden requires individual case review to confirm diagnosis.

Infect Control Hosp Epidemiol 2015;36(8):893–898

The cost-benefit of federal investment in preventing Clostridium difficile infections through the use of a multifaceted infection control and antimicrobial stewardship program

OBJECTIVE

To determine the potential epidemiologic and economic value of the implementation of a multifaceted Clostridium difficile infection (CDI) control program at US acute care hospitals

DESIGN

Markov model with a 5-year time horizon

PARTICIPANTS

Patients whose data were used in our simulations were limited to hospitalized Medicare beneficiaries ≥65 years old.

BACKGROUND

CDI is an important public health problem with substantial associated morbidity, mortality, and cost. Multifaceted national prevention efforts in the United Kingdom, including antimicrobial stewardship, patient isolation, hand hygiene, environmental cleaning and disinfection, and audit, resulted in a 59% reduction in CDI cases reported from 2008 to 2012.

METHODS

Our analysis was conducted from the federal perspective. The intervention we modeled included the following components: antimicrobial stewardship utilizing the Antimicrobial Use and Resistance module of the National Healthcare Safety Network (NHSN), use of contact precautions, and enhanced environmental cleaning. We parameterized our model using data from CDC surveillance systems, the AHRQ Healthcare Cost and Utilization Project, and literature reviews. To address uncertainty in our parameter estimates, we conducted sensitivity analyses for intervention effectiveness and cost, expenditures by other federal partners, and discount rate. Each simulation represented a cohort of 1,000 hospitalized patients over 1,000 trials. RESULTS In our base case scenario with 50% intervention effectiveness, we estimated that 509,000 CDI cases and 82,000 CDI-attributable deaths would be prevented over a 5-year time horizon. Nationally, the cost savings across all hospitalizations would be $2.5 billion (95% credible interval: $1.2 billion to $4.0 billion).

CONCLUSIONS

The potential benefits of a multifaceted national CDI prevention program are sizeable from the federal perspective.

Emergency department visits related to Clostridium difficile infection: results from the nationwide emergency department sample, 2006 through 2010

OBJECTIVES

The objective was to estimate emergency department (ED) visits for Clostridium difficile infection in the United States for the years 2006 through 2010.

METHODS

Estimates of ED visits for C. difficile infection were calculated in patients 18 years and older using the Nationwide Emergency Department Sample.

RESULTS

During the calendar years 2006 through 2010, there were an estimated total of 491,406,018 ED visits. Of these, 462,160 ED visits were associated with a primary International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis of C. difficile. The C. difficile infection ED visit rate (visits/100,000 census population) increased from 34.1 in 2006 to 42.3 in 2010, an increase of 24% (p < 0.01). There was also a significant overall increased trend in the number of ED visits for C. difficile from 2006 through 2010 (p < 0.01). The highest ED visit rate for C. difficile was observed for patients 65 years and older (163.18 per 100,000), while the lowest visit rate was for patients aged 18 to 24 years (5.10 per 100,000). The greatest increase in C. difficile infection visits occurred in the age group 18 to 24 years.

CONCLUSIONS

These results indicate an increased trend of ED visits for C. difficile in the period 2006 through 2010 with an overall population-adjusted increase of 24%. This represents important complementary data to previous studies reporting an increase in the rate of C. difficile infections in the U.S. hospitalized population.

The National Hospital Discharge Survey and Nationwide Inpatient Sample: the databases used affect results in THA research

BACKGROUND

The National Hospital Discharge Survey (NHDS) and the Nationwide Inpatient Sample (NIS) collect sample data and publish annual estimates of inpatient care in the United States, and both are commonly used in orthopaedic research. However, there are important differences between the databases, and because of these differences, asking these two databases the same question may result in different answers. The degree to which this is true for arthroplasty-related research has, to our knowledge, not been characterized.

QUESTION/PURPOSES

We tested the following null hypotheses: (1) there are no differences between the NHDS and NIS in patient characteristics, comorbidities, and adverse events in patients with hip osteoarthritis treated with THA, and (2) there are no differences between databases in factors associated with inpatient mortality, adverse events, and length of hospital stay after THA.

METHODS

The NHDS and NIS databases use different methods of data collection and weighting to provide data representative of all nonfederal hospital discharges in the United States. In 2006 the NHDS database contained 203,149 patients with hip arthritis treated with hip arthroplasty, and the NIS database included 193,879 patients. Multivariable analyses for factors associated with inpatient mortality, adverse events, and days of care were constructed for each database.

RESULTS

We found that 26 of 42 of the factors in demographics, comorbidities, and adverse events after THA in the NIS and NHDS databases differed more than 10%. Age and days of care were associated with inpatient mortality with the NHDS and the NIS although the effect rates differ more than 10%. The NIS identified seven other factors not identified by the NHDS: wound complications, congestive heart failure, new mental disorder, chronic pulmonary disease, dementia, geographic region Northeast, acute postoperative anemia, and sex, that were associated with inpatient mortality even after controlling for potentially confounding variables. For inpatient adverse events, atrial fibrillation, osteoporosis, and female sex were associated with the NHDS and the NIS although the effect rates differ more than 10%. There were different directions for sources of payment, dementia, congestive heart failure, and geographic region. For longer length of stay, common factors differing more than 10% in effect rate included chronic pulmonary disease, atrial fibrillation, complication not elsewhere classified, congestive heart failure, transfusion, discharge nonroutine compared with routine, acute postoperative anemia, hypertension, wound adverse events, and diabetes mellitus, whereas discrepant factors included geographic region, payment method, dementia, sex, and iatrogenic hypotension.

CONCLUSIONS

Studies that use large databases intended to be representative of the entire United States population can produce different results, likely related to differences in the databases, such as the number of comorbidities and procedures that can be entered in the database. In other words, analyses of large databases can have limited reliability and should be interpreted with caution.

LEVEL OF EVIDENCE

Level II, prognostic study. See the Instructions for Authors for a complete description of levels of evidence.

Extraintestinal Clostridium difficile infections: a single-center experience

OBJECTIVES

To evaluate the clinical burden of extraintestinal Clostridium difficile infection (CDI) seen at a single institution and to characterize the management and outcomes of these rare infections.

PATIENTS AND METHODS

A retrospective medical record review was conducted to identify patients with isolation of C difficile from extraintestinal sites from January 1, 2004, through December 31, 2013. Medical records were reviewed and data, including demographic characteristics, microbiology, clinical associations, management, and infection outcomes, were abstracted.

RESULTS

Overall, 40 patients with extraintestinal CDI were identified: 25 had abdominopelvic infections, 11 had bloodstream infections, 3 had wound infections, and 1 had pulmonary infection. C difficile was isolated with other organisms in 63% of cases. A total of 85% of infections were nosocomial. Factors associated with extraintestinal CDI included surgical manipulation of the gastrointestinal tract (88%), recent antibiotic exposure (88%), malignant tumors (50%), and proton pump inhibitor use (50%). Diarrhea was present in 18 patients (45%), 12 of whom had C difficile polymerase chain reaction (PCR)-positive stool samples. All isolates tested were susceptible to metronidazole and piperacillin-tazobactam. Management included both antimicrobial therapy and guided drainage or surgical intervention in all but one patient. The infection-associated mortality rate was 25%, with death a median of 16 days (range, 1-61 days) after isolation of C difficile.

CONCLUSION

Extraintestinal CDI is uncommon and often occurs in patients with surgical manipulation of the gastrointestinal tract and well-recognized risk factors for intestinal CDI. Management of extraintestinal CDI includes both antimicrobial and surgical therapies. Extraintestinal CDI is characterized by poor outcome with high mortality.

Analysis of Clostridium difficile infections after cardiac surgery: epidemiologic and economic implications from national data

OBJECTIVES

Clostridium difficile infections (CDIs) have increased during the past 2 decades, especially among cardiac surgical patients, who share many of the comorbidity risk factors for CDI. Our objectives were to use a large national database to identify the regional-, hospital-, patient-, and procedure-level risk factors for CDI; and determine mortality, resource usage, and cost of CDIs in cardiac surgery.

METHODS

Using the Nationwide Inpatient Sample database, we identified 349,122 patients who had undergone coronary artery bypass, valve, or thoracic-aortic surgery from 2004 to 2008. Of these, 2581 (0.75%) had been diagnosed with CDI. Multivariable regression analysis and the propensity method were used for risk adjustment.

RESULTS

Compared with the West, CDIs were more likely to occur in the Northeast (odds ratio [OR], 1.28; 95% confidence interval [CI], 1.12-1.47) and Midwest (OR, 1.27, 95% CI, 1.11-1.46) and less likely in the South (OR, 0.80; 95% CI, 0.70-0.90). Medium-size hospitals (OR, 0.88; 95% CI, 0.78-0.99) had a lower risk of CDI than did large hospitals. Older age (>75 years; OR, 2.59; 95% CI, 1.93-3.49), longer preoperative length of stay (OR, 1.51; 95% CI, 1.43-1.60), Medicare (OR, 1.21; 95% CI, 1.05-1.39) and Medicaid (OR, 1.60; 95% CI, 1.31-1.96) coverage, and more comorbidities were associated with CDI. Among the matched pairs, patients with CDIs had greater mortality (302 [12%] vs 187 [7.2%], P<.001), a longer median length of stay (21 vs 11 days, P<.001), and greater median hospital charges ($193,330 vs $112,245, P<.001). The cumulative incremental cost of CDIs was an estimated $212 million annually.

CONCLUSIONS

Our results have shown that CDI is associated with increased morbidity and resource usage. Additional work is needed to better understand the complex interplay among regional-, hospital-, and patient-level factors.

Multistate point-prevalence survey of health care-associated infections

BACKGROUND

Currently, no single U.S. surveillance system can provide estimates of the burden of all types of health care-associated infections across acute care patient populations. We conducted a prevalence survey in 10 geographically diverse states to determine the prevalence of health care-associated infections in acute care hospitals and generate updated estimates of the national burden of such infections.

METHODS

We defined health care-associated infections with the use of National Healthcare Safety Network criteria. One-day surveys of randomly selected inpatients were performed in participating hospitals. Hospital personnel collected demographic and limited clinical data. Trained data collectors reviewed medical records retrospectively to identify health care-associated infections active at the time of the survey. Survey data and 2010 Nationwide Inpatient Sample data, stratified according to patient age and length of hospital stay, were used to estimate the total numbers of health care-associated infections and of inpatients with such infections in U.S. acute care hospitals in 2011.

RESULTS

Surveys were conducted in 183 hospitals. Of 11,282 patients, 452 had 1 or more health care-associated infections (4.0%; 95% confidence interval, 3.7 to 4.4). Of 504 such infections, the most common types were pneumonia (21.8%), surgical-site infections (21.8%), and gastrointestinal infections (17.1%). Clostridium difficile was the most commonly reported pathogen (causing 12.1% of health care-associated infections). Device-associated infections (i.e., central-catheter-associated bloodstream infection, catheter-associated urinary tract infection, and ventilator-associated pneumonia), which have traditionally been the focus of programs to prevent health care-associated infections, accounted for 25.6% of such infections. We estimated that there were 648,000 patients with 721,800 health care-associated infections in U.S. acute care hospitals in 2011.

CONCLUSIONS

Results of this multistate prevalence survey of health care-associated infections indicate that public health surveillance and prevention activities should continue to address C. difficile infections. As device- and procedure-associated infections decrease, consideration should be given to expanding surveillance and prevention activities to include other health care-associated infections.

The co-seasonality of pneumonia and influenza with Clostridium difficile infection in the United States, 1993-2008

Seasonal variations in the incidence of pneumonia and influenza are associated with nosocomial Clostridium difficile infection (CDI) incidence, but the reasons why remain unclear. Our objective was to consider the impact of pneumonia and influenza timing and severity on CDI incidence. We conducted a retrospective cohort study using the US National Hospital Discharge Survey sample. Hospitalized patients with a diagnosis of CDI or pneumonia and influenza between 1993 and 2008 were identified from the National Hospital Discharge Survey data set. Poisson regression models of monthly CDI incidence were used to measure 1) the time lag between the annual pneumonia and influenza prevalence peak and the annual CDI incidence peak and 2) the lagged effect of pneumonia and influenza prevalence on CDI incidence. CDI was identified in 18,465 discharges (8.52 per 1,000 discharges). Peak pneumonia prevalence preceded peak CDI incidence by 9.14 weeks (95% confidence interval: 4.61, 13.67). A 1% increase in pneumonia prevalence was associated with a cumulative effect of 11.3% over a 6-month lag period (relative risk = 1.113, 95% confidence interval: 1.073, 1.153). Future research could seek to understand which mediating pathways, including changes in broad-spectrum antibiotic prescribing and hospital crowding, are most responsible for the associated changes in incidence.

Acute kidney injury is an independent marker of severity in Clostridium difficile infection: a nationwide survey

GOALS

To examine clinical outcomes in hospitalized Clostridium difficile infection (CDI) patients with acute kidney injury (AKI) using the National Hospital Discharge Survey for 2005 to 2009.

BACKGROUND

CDI can cause serious complications in hospitalized adults. On the basis of expert opinion, guidelines recommend AKI as a marker of severe CDI, but this has not been extensively validated.

MATERIALS AND METHODS

CDI and AKI patients were identified using International Classification of Diseases 9th edition codes. Weighted data analyses were performed to provide national estimates and compare outcomes in patients with AKI and CDI to CDI patients without AKI.

RESULTS

There were an estimated 1,261,712 patients with CDI identified with a median age of 75 years; 59.2% were female and 17.5% developed AKI. On multiple variable analysis, after adjusting for age, sex, and comorbid conditions, AKI was independently associated with length of hospital stay increase by 1.9 days, risk of colectomy with an odds ratio (OR) of 1.35, all-cause in-hospital mortality (OR, 2.76), and dismissal to a care facility (OR, 1.43), all P<0.0001.

CONCLUSIONS

These data support prior consensus opinion that AKI is an independent marker associated with adverse outcomes in CDI and provides key prognostic information.

Clostridium difficile infection in patients with chronic kidney disease

OBJECTIVE

To examine the rate of Clostridium difficile infection (CDI) and hospital-associated outcomes in a national cohort of hospitalized patients with chronic kidney disease (CKD) and assess the impact of long-term dialysis on outcome in these patients.

PATIENTS AND METHODS

Data for January 1, 2005, through December 31, 2009 were obtained from the National Hospital Discharge Survey, which includes information on patient demographics, diagnoses, procedures, and discharge types. Data collected and analyzed for this study included age, sex, race, admission type (urgent or emergent combined vs elective), any colectomy diagnosis, length of stay, type of discharge, and mortality. International Classification of Diseases, Ninth Revision, Clinical Modification codes were utilized to identify CKD patients and CDI events. Weighted analysis was performed using JMP version 9.

RESULTS

An estimated 162 million adults were hospitalized during 2005-2009, and 8.03 million (5%) had CKD (median age, 71 years). The CDI rate in CKD patients was 1.49% (0.119 million) compared with 0.70% (1.14 million) in patients without CKD (P<.001). Patients with CKD who were undergoing long-term dialysis were more than 2 times as likely to develop CDI than non-CKD patients and 1.33 times more likely than CKD patients not undergoing dialysis (all P<.001). In a weighted multivariate analysis adjusting for sex and comorbidities, patients with CKD and CDI had longer hospitalization, higher colectomy rate (adjusted odds ratio [aOR], 2.30; 95% confidence interval [CI], 2.14-2.47), dismissal to a health care facility (aOR, 2.22; 95% CI, 2.19-2.25), and increased in-hospital mortality (aOR, 1.55; 95% CI, 1.52-1.59; all P<.001) as compared with CKD patients without CDI. Patients with CKD who were undergoing long-term dialysis did not have worse outcomes as compared with CKD patients who were not undergoing long-term dialysis.

CONCLUSION

These data suggest that patients with CKD have a higher risk of CDI and increased hospital-associated morbidity and mortality. Future prospective studies are needed to confirm these findings and to identify effective CDI prevention in CKD patients, who appear to have an increased risk of CDI acquisition.

Clostridium difficile infection in hospitalized liver transplant patients: a nationwide analysis

The incidence of Clostridium difficile infection (CDI) is increasing among hospitalized patients. Liver transplantation (LT) patients are at higher risk for acquiring CDI. Small, single-center studies (but no nationwide analyses) have assessed this association. We used the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project (2004-2008) for this retrospective, cross-sectional study. Patients with any discharge diagnosis of LT composed the study population, and they were identified with International Classification of Diseases, Ninth Revision, Clinical Modification codes. Those with a discharge diagnosis of CDI were considered cases. Our primary outcomes were the prevalence of CDI and the effects of CDI on inpatient mortality. Our secondary outcomes included the length of stay and hospitalization charges. A regression analysis was used to derive odds ratios (ORs) adjusted for potential confounders. There were 193,174 discharges with a diagnosis of LT from 2004 to 2008. The prevalence of CDI was 2.7% in the LT population and 0.9% in the non-LT population (P < 0.001). Most of the LT patients were 50 to 64 years old. LT patients had higher odds of developing CDI [OR = 2.88, 95% confidence interval (CI) = 2.68-3.10]. Increasing age and increasing comorbidity (including inflammatory bowel disease and nasogastric tube placement) were also independent CDI risk factors. CDI was associated with a higher mortality rate: 5.5% for LT patients with CDI versus 3.2% for LT-only patients (adjusted OR = 1.70, 95% CI = 1.29-2.25). In conclusion, the prevalence of CDI is higher for LT patients versus non-LT patients (2.7% versus 0.9%). CDI is an independent risk factor for mortality in the LT population.