Roshan Hussain

Diagnostic Value of Repeated Enzyme Immunoassays in Clostridium difficile Infection

OBJECTIVES:There has been a significant increase in the prevalence, severity, and mortality of Clostridium difficile infection (CDI), with an estimated three million new cases per year in the United States. Yet diagnosing CDI remains problematic. The most commonly used test is stool enzyme immunoassay (EIA) detecting toxin A and/or B, but there are no clear guidelines specifying the optimal number of tests to be ordered in the diagnostic workup, although multiple tests are frequently ordered. Thus, we designed a study with the primary objective of evaluating the diagnostic utility of repeat second and third tests of stool EIA detecting both toxins A and B (EIA (A&B)) in cases with negative initial samples, and sought to describe the physicians’ patterns of ordering this test in the workup of suspected CDI.METHODS:A retrospective study was carried out using a database of all stool EIA (A&B) tests ordered for a presumptive diagnosis of CDI. All patients were adults admitted to a major teaching hospital over a three-and-a-half-year period (tests completed within 5 days of ordering the first test were grouped into a single episode, and only the first three samples per episode were analyzed). Age, gender, and results of stool EIA were tabulated. In addition, physicians’ ordering patterns and proportion of positive stools relative to the number of tests ordered were also analyzed. A single positive EIA result was interpreted as evidence for the clinical presence of CDI.RESULTS:A total of 3,712 patients contributed to 5,865 separate diarrhea episodes (total stool EIA (A&B)=9,178), and 1,165 (19.9%) of these episodes were positive for CDI. Of the positive patients, 73.2% were over the age of 65 years and 54.2% of them were females. The most frequent ordering pattern for presumptive CDI was a single stool test (60.1%), followed by two more tests (23.2%). Three tests were still ordered in 16.6% of the cases. Of the 1,165 positive cases, 1,046 (89.8%) were diagnosed in the very first test, 95 (8.2%) in the second, and only 24 (2.0%) in the third test. In 1,934 instances, a second test was ordered after an initial negative result, of which 95 (4.91%) became positive. In 793 episodes, a third test was ordered after two negative samples, of which only 24 (3.03%) became positive.CONCLUSIONS:This study highlights the low diagnostic yield of repeat stool EIA (A&B) testing. Findings strongly support the utility of limiting the workup of suspected CDI to a single stool test with only one repeat test in cases of high clinical suspicion, and avoiding the routine ordering of multiple stool samples. As Clostridium difficile is becoming an endemic health-care problem resulting in major financial burdens for the US health-care system, clear guidelines specifying the optimal number of stool EIA (A&B) tests to be ordered in the diagnostic workup of suspected CDI must be established to assist physicians in the practice of evidence-based medicine.

Hand hygiene in long-term care facilities: a multicenter study of knowledge, attitudes, practices, and barriers.

An anonymous survey of 1143 employees in 17 nursing facilities assessed knowledge of, attitudes about, self-perceived compliance with, and barriers to implementing the 2002 Centers for Disease Control and Prevention hand hygiene guidelines. Overall, employees reported positive attitudes toward the guidelines but differed with regard to knowledge, compliance, and perceived barriers. These findings provide guidance for practice improvement programs in long-term care settings.

UNDERDIAGNOSIS OF CHRONIC KIDNEY DISEASE IN THE NURSING HOME POPULATION

To the Editor: Chronic kidney disease (CKD) is present in more than 12% of Americans aged 65 and older. In the guidelines from the National Kidney Foundation (NKF) Kidney Disease Outcome Quality Initiative, age 60 and older is indeed considered to be a major risk factor for CKD. Among various complications, CKD appears to independently predict mortality and cardiovascular disease. 5 Readily available formulas for calculating glomerular filtration rates (GFRs), along with a staging system and CKD stage-dependent therapeutic guidelines, have simplified the ability to identify CKD, categorize its severity, and implement appropriate treatment. Nevertheless, several reports suggest that CKD is underdiagnosed and undertreated. The purpose of this study was to explore how frequently physicians of elderly nursing home residents, who have CKD based on NKF criteria, address this diagnosis. After institutional review board approval was obtained, a retrospective chart review was conducted of all long-term residents in a 672-bed facility aged 60 and older who had resided there for at least 6 months and whose records included at least two serum creatinine levels drawn at least 90 days apart from each other. Each subject’s monthly physician progress notes over the previous 6 months were reviewed to determine whether a diagnosis of CKD was recorded. The Modification of Diet in Renal Disease (MDRD) and Cockcroft-Gault (C-G) formulas were used to estimate subjects’ GFRs, with values less than 60 mL/min per 1.73 m of body surface area regarded as positive screening tests for CKD. Serum creatinine values recommended for identification of CKD ( 1.5 mg/dL for men, 1.3 mg/dL for women) were also used as screening criteria for CKD. Two hundred eighty patients met the criteria. Of those with CKD according to MDRD and C-G criteria, a diagnosis of CKD was not noted in 62% and 82%, respectively, of the charts. Of women with CKD according to MDRD and C-G criteria, 70.4% and 87%, respectively, had no notation of CKD in their charts. A diagnosis of CKD was omitted less often in men with CKD (35.3% and 62.9% when identified according to MDRD and C-G, respectively). A diagnosis of CKD was also frequently omitted from charts of patients with CKD based on aforementioned sex-based serum creatinine values as well. Using logistic regression analysis (P 5.02), when controlling for age, sex was found to significantly affect the likelihood of CKD being recognized. Men had only 0.25 odds of underdiagnosis of CKD when compared with women (P 5.049). When sex was controlled for, there was no significant relationship between age groups and underdiagnosis using the MDRD equation (Table 1). Using patients with CKD according to C-G, a similar effect of sex was observed using logistic regression (P 5.01), but when sex was controlled for, patients who were aged 71 to 80 had only a 0.23 odds of underdiagnosis when compared with those aged 90 and older (P 5.02). Delayed recognition and therapy of CKD may predispose patients to adverse outcomes, and these data suggest that CKD may be substantially underdiagnosed in the elderly nursing home population. Although CKD was addressed in only a minority of patients in whom it was evident using GFR estimations, the presence of CKD was documented more frequently when using the creatinine-based parameters described previously. Although there are a number of potential explanations why such a difference was observed, it may simply be that an overtly high serum creatinine level will be more likely to draw the physician’s attention than a relatively ‘‘normal’’ appearing serum creatinine level that nevertheless corresponds with a diminished GFR that has not been calculated. The NKF guidelines not only recommend use of GFR estimation equations, but also expressly declare use of serum creatinine alone not to be optimal in assessment of kidney function. Although GFR calculations and serum creatinine have limitations, these data nevertheless suggest substantial underdiagnosis of CKD, even with serum creatinine levels above 1.4 mg/dL. In summary, despite well-established criteria for the diagnosis of CKD, including simple methods to estimate GFR, CKD appears to be underdetected within the nursing home setting, potentially placing this community at risk for costly, avoidable outcomes. This study underlines the effect of age and sex on misdiagnosis of CKD. Further studies will

MANDATORY COGNITIVE SCREENING IN HOSPITALIZED ELDERLY PEOPLE: ARE WE MISSING THE DIAGNOSIS?

with resultant massive and potentially life-threatening PE. Although there is no consensus on the thrombolytic therapy protocol, the approved regimen is 100 mg t-PA given during a 2-hour infusion. However, in a few studies, lower doses have been given by prolonged infusions. Although thrombolytic therapy is avoided in elderly patients, there are a few case reports in the literature describing successful use of t-PA in the management of PE in these patients. Because of her age, this patient was considered to be prone to complications of thrombolytic therapy, and it was decided to give a low dose of t-PA using a prolonged infusion. TTE is not only a diagnostic tool for detection of right heart thrombi associated with PE, but also an aid for monitoring the effect of treatment. The close monitoring of right heart thrombus and right ventricular functions using TTE and stopping the thrombolytic therapy when the thrombus has resolved and the patient’s clinical status has improved is suggested to avoid complications of fibrinolytics, especially in the older patients. A successful outcome in a single patient may not prove that the approach used is broadly applicable, but low-dose, slow infusion of t-PA under the guidance of TTE may be a safer treatment protocol, especially in older patients, that needs to be supported by further studies.