What risk factors contribute to C difficile diarrhea?
The number of antibiotics is a factor
The number of antibiotics used also may influence the risk of CDAD. A retrospective cohort of 2859 patients from a community hospital found that an increased number of antibiotics was a risk factor for CDAD (OR=1.49; 95% CI, 1.23-1.81; NNH=44).4 Another retrospective cohort study of 1187 inpatients at a Montreal hospital found 3 or more antibiotics increased the risk (adjusted OR=2.1; 95% CI, 1.3-3.4; NNH=20).5
Hospital risks: Proximity to an infected patient, length of stay
A prospective cohort of 252 patients and a retrospective cohort of 1187 patients show that recent hospitalization puts patients at risk for CDAD (TABLE 2).5,6 Several retrospective cohort studies have shown that patients in close proximity to a C difficile-positive patient in the hospital (roommate, neighbor, or subsequent tenant) are at risk for CDAD.4,7
Length of hospitalization is also a risk factor.2 A retrospective cohort study of 2859 patients found that patients with CDAD had spent more time in the hospital—a mean of 19 days compared with 8 days for patients without diarrhea (P<.001).4 A prospective cohort study of 101,796 admissions reported that the mean length of stay was 15 days (range=8.0-26.0) for CDAD patients compared with 5 days (range=3.0-8.0) for patients without CDAD (P<.001).3
TABLE 2
Hospital risk factors for C difficile diarrhea
| Hospital factor | Reported ratio* (95% CI) | NNH† |
|---|---|---|
| Length of stay 4-7 vs 1-3 days2 | HR=4.69 (2.14-10.28) | 6 |
| Length of stay 8-14 vs 1-3 days2 | HR=5.11 (2.34-11.18) | 6 |
| Length of stay >15 vs 1-3 days2 | HR=3.55 (1.53-7.24) | 10 |
| Any proximity to CDAD-positive patients4 | RR=3.34 (2.00-5.57) | 10 |
| Admission within previous 3 months5 | OR=3.0 (1.5-6.0) | 11 |
| Admission within previous 30 days6 | OR= 2.6 (1.13-5.7) | 14 |
| CDAD-positive patient in adjacent bed7 | OR=2.34 (1.56-3.51) | 17 |
| Occupying bed of previous CDAD-positive patient7 | OR-2.33 (1.54-3.52) | 17 |
| CDAD, Clostridium difficile-associated diarrhea; CI, confidence interval; HR, hazard ratio; NNH, number needed to harm; OR, odds ratio; RR, relative risk. *Because the incidence of C difficile diarrhea is low, each reported hazard ratio or risk ratio is approximately equal to the odds ratio, which was used to calculate number needed to harm. †Assuming an event rate of 5%. | ||
Patient risk factors: Age and comorbid disease
Two cohort studies found that CDAD patients were about 10 years older than patients without CDAD.3,8 Among 535 patients in Jerusalem, patients positive for C difficile toxin had a mean age of 76±20 years compared with 66±26 years in toxin-negative patients (P<.001).8 In the previously mentioned study of 101,796 patients, the average age for patients with CDAD was 65.4±16.9 years compared with 56.5±19.9 years for patients without CDAD (P<.001).3
The patients in this study also showed significant associations between CDAD and comorbid conditions, including myocardial infarction, heart failure, chronic pulmonary disease, peripheral vascular disease, complicated diabetes, fluid and electrolyte disorders, chronic renal failure, cancer, coagulopathy, and methicillin-resistant Staphylococcus aureus infection.3
