Predicting the Risk of Clostridium difficile Infection upon Admission: A Score to Identify Patients for Antimicrobial Stewardship Efforts

INTRODUCTION

Increasing morbidity and health care costs related to Clostridium difficile infection (CDI) have heightened interest in methods to identify patients who would most benefit from interventions to mitigate the likelihood of CDI.

OBJECTIVE

To develop a risk score that can be calculated upon hospital admission and used by antimicrobial stewards, including pharmacists and clinicians, to identify patients at risk for CDI who would benefit from enhanced antibiotic review and patient education.

METHODS

We assembled a cohort of Kaiser Permanente Northwest patients with a hospital admission from July 1, 2005, through December 30, 2012, and identified CDI in the six months following hospital admission. Using Cox regression, we constructed a score to identify patients at high risk for CDI on the basis of preadmission characteristics. We calculated and plotted the observed six-month CDI risk for each decile of predicted risk.

RESULTS

We identified 721 CDIs following 54,186 hospital admissions-a 6-month incidence of 13.3 CDIs/1000 patient admissions. Patients with the highest predicted risk of CDI had an observed incidence of 53 CDIs/1000 patient admissions. The score differentiated between patients who do and do not develop CDI, with values for the extended C-statistic of 0.75. Predicted risk for CDI agreed closely with observed risk.

CONCLUSION

Our risk score accurately predicted six-month risk for CDI using preadmission characteristics. Accurate predictions among the highest-risk patient subgroups allow for the identification of patients who could be targeted for and who would likely benefit from review of inpatient antibiotic use or enhanced educational efforts at the time of discharge planning.

Clostridium difficile infection, Colorado and the northwestern United States, 2007

To determine the incidence of Clostridium difficile infection during 2007, we examined infection in adult inpatient and outpatient members of a managed-care organization. Incidence was 14.9 C. difficile infections per 10,000 patient-years. Extrapolating this rate to US adults, we estimate that 284,875 C. difficile infections occurred during 2007.

Epidemiology and healthcare costs of incident Clostridium difficile infections identified in the outpatient healthcare setting

OBJECTIVE

To describe the epidemiology and healthcare costs of Clostridium difficile infection (CDI) identified in the outpatient setting.

DESIGN

Population-based, retrospective cohort study.

PATIENTS

Kaiser Permanente Colorado and Kaiser Permanente Northwest members between June 1, 2005, and September 30, 2008.

METHODS

We identified persons with incident CDI and classified CDI by whether it was identified in the outpatient or inpatient healthcare setting. We collected information about baseline variables and follow-up healthcare utilization, costs, and outcomes among patients with CDI. We compared characteristics of patients with CDI identified in the outpatient versus inpatient setting.

RESULTS

We identified 3,067 incident CDIs; 56% were identified in the outpatient setting. Few strong, independent predictors of diagnostic setting were identified, although a previous stay in a nonacute healthcare institution (odds ratio [OR], 1.45 [95% confidence interval (CI), 1.13-1.86]) was statistically associated with outpatient-identified CDI, as was age from 50 to 59 years (OR, 1.64 [95% CI, 1.18-2.29]), 60 to 69 years (OR, 1.37 [95% CI, 1.03-1.82]), and 70 to 79 years (OR, 1.36 [95% CI, 1.06-1.74]), when compared with persons aged 80-89 years.

CONCLUSIONS

We found that more than one-half of incident CDIs in this population were identified in the outpatient setting. Patients with outpatient-identified CDI were younger with fewer comorbidities, although they frequently had previous exposure to healthcare. These data suggest that practitioners should be aware of CDI and obtain appropriate diagnostic testing on outpatients with CDI symptoms.

Case report: vitamin D-mediated hypercalcemia in fungal infections

Hypercalcemia has been well described in a variety of neoplastic and granulomatous diseases. One mechanism for this hypercalcemia is via the excess production of 1,25-dihydroxyvitamin D from extra-renal sources. The authors describe an AIDS patient infected with Cryptococcus neoformans who had suggestive evidence of vitamin D-mediated hypercalcemia. He had an elevated serum 1,25-dihydroxyvitamin D value, a normal 25-hydroxyvitamin D value, and low values for parathyroid hormone and parathyroid hormone-related peptide. Most previously reported cases of hypercalcemia associated with fungal infections did not include sufficient evidence to implicate a role for excess 1,25-dihydroxyvitamin D production, except for two case reports involving patients with hypercalcemia with infections due to Pneumocystis carinii and Candida albicans. The authors' patient's hypercalcemia resolved during treatment of his underlying infection. Patients with hypercalcemia or in whom hypercalcemia develops during a disseminated fungal infection should have vitamin D metabolites measured as part of their work-up.

Infections caused by Staphylococcus aureus in a Veterans' Affairs nursing home care unit: a 5-year experience

OBJECTIVES

To describe the frequency and patterns of infection caused by methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S aureus (MRSA) infections in a single nursing home population and to determine the effect of MRSA's entry into the facility on subsequent experience with both MSSA and MRSA infections.

DESIGN

Observational and descriptive. Surveillance data on nursing home-acquired infections were reviewed to identify all patients with MSSA and MRSA infections occurring during the 5-year period from 1987 to 1991. The medical records of these patients were reviewed retrospectively to collect additional information about the patients and their infections.

SETTING AND PATIENTS

A 120-bed Veterans' Affairs nursing home care unit (NHCU) whose residents predominantly were elderly men with severe underlying diseases and functional impairments.

RESULTS

During the 5-year study period, 40 MSSA and 28 MRSA infections were acquired by NHCU residents. Twelve to 19 S aureus infections occurred each year. S aureus accounted for 13% to 17% of all NHCU-acquired infections during the years of study, occurring with a frequency of 0.29 to 0.47 infections per 1,000 resident-care days. MRSA infections, first detected in 1988, accounted for an increasing percentage of S aureus infections in subsequent years, but this increase had little effect on the facility's overall infection rates, the composite S aureus infection rates, or the types of infections observed. MSSA and MRSA infections acquired in the NHCU were comparable. Both affected patients with severe underlying diseases and functional impairments. Pneumonia, urinary tract infections, skin and soft tissue infections, and conjunctivitis were the types of infections observed most frequently, accounting for 28%, 25%, 22%, and 15% of all S aureus infections, respectively. Four bacteremic infections occurred in the MSSA group, and five in the MRSA group (P = .47). Four of the MSSA and three of the MRSA infections resulted in death (P = 1.0). Nine of the MSSA and 12 of the MRSA infections resulted in the patient's transfer to the associated acute care hospital for additional care (P = .13).

CONCLUSIONS

In the NHCU setting, MSSA and MRSA infections were similar in terms of the types of residents affected, the sites involved, and the frequency of adverse outcomes. The entry of MRSA into the facility appeared to have no effect on the subsequent experience with NHCU-acquired infections caused by S aureus.