Similar to a recent study posted on 11/18, in this multi-center study of 291 patients with chest pain and suspected CAD, patients underwent both coronary CTA and catheterization (abstract). This study found the PPV of CTA (compared to catheterization) was 91% and the NPV was 83% for detecting >50% coronary artery obstruction (in patients with a BMI<40 and a calcium score <600). From this the authors determined that CTA has “reliable accuracy for the diagnosis of obstructive coronary disease” but also argue that it is not appropriate to replace catheterization with CTA, given it is not a perfect test and given the higher radiation exposure with CTA. Since the diagnostic performance of CTA is study/site/reader-specific, it still remains to be seen the best way to utilize this technology.

Norwalk virus is the most frequent cause of epidemic non-bacterial gastroenteritis worldwide (CDC link). It is highly pathogenic and extremely contagious, but symptoms usually only last for about a day. However, in this study, researchers found the fecal shedding of norwalk (in experimentally infected healthy adults) lasted for a median of 1 month, and as long as 2 months in some (abstract). It is important for us to realize the potential prolonged infectivity (even after resolution of diarrhea) of patients with recent Norwalk gastroenteritis.

In this prospective observational cohort, researchers derived and validated a decision rule to predict true bacteremia in 3730 ED patients who had blood cultures drawn (abstract). They determined that patients should get a blood culture if they had at least 1 major or 2 minor criteria (Major criteria were temp>39.5, indwelling vascular catheter, or clinical suspicion of endocarditis; Minor criteria were temp 38.3-39.4, age >65, chills, vomiting, SBP<90, WBC>18, PMN>80%, bands>5%, platelets>150, or creatinine>2). Using these criteria in the validation set, the decision rule had a NPV of 99% (of patients without criteria, <1% actually had bacteremia), indicating its value in identifying those that DO NOT need a blood culture. However, it could not accurately identify those that DO need a blood culture (with a PPV of only 11%, a large number of patients with criteria would not be bacteremic).

The Association for Professionals in Infection Control (APIC) has released a comprehensive prevalence survey on the state of Cdiff in US healthcare facilities (from 648 facilities in 47 states) (link). They found 13 / 1000 inpatients were infected or colonized with Cdiff (94% infected). Over half (54%) were detected in <48 hours of admission (indicating infection at the time of admission), 20% had no history of antibiotic exposure (and 17% only exposed to surgical prophylactic antibiotics), and over half (53%) still had diarrhea after 6 days of treatment. This prevalence survey reminds us to be vigilant for Cdiff in all inpatients with diarrhea (with or without a history of antibiotic use), and to be patient with its treatment course (over half still with symptoms at 6 days).

In the era of cost containment, we are constantly evaluating clinical conditions which can just as effectively, but more efficiently, be cared for in lower cost observation units. Looks like we can add new onset afib to the list. In this single academic center, 153 patients with new (<48 hours) uncomplicated afib were randomized to management in the ED obs unit, or traditional inpatient unit. Short term rate to sinus rhythm was not significantly different, nor was the rate of recurrence or adverse events. However, median length of stay was 10 versus 25 hours. In ED observation units with cardioversion capabilities, management of new afib will likely be as effective and more efficient, than hospital admission (abstract)

Smear negative TB patients are thought to be much less contagious than smear positive patients, but how much so? In this retrospective analysis from the Netherlands using a national DNA fingerprint database, researchers determined 13% of secondary TB cases were attributable to smear negative patients, and that the relative transmission of smear negative, compared to smear positive, patients was 0.24. This study implies that the “no-isolation needed” hospital standard for smear negative TB patients needs to be re-visited, and that the risk of transmission of smear negative patients is less than smear positive, but certainly not insubstantial (abstract)

In patients with chest pain at intermediate risk for CAD, how does non-invasive coronary CTA compare to traditional invasive catheterization? In this multi-center study of patients with chest pain and no known CAD, 230 patients underwent both catheterization and CTA (abstract). Although the positive predictive value for detecting >50% and >70% stenosis was low (64% and 48%), the negative predictive values were 99%. Therefore, this is a good test for ruling out obstructive coronary disease in intermediate risk patients. As an editoralist notes (editorial), this study adds value to the current literature because it was performed at 16 centers (mixed academics and private), and without the traditional CTA patient exclusions (for heart rate >65, high coronary calcium scores, or obesity), providing diagnostic realities. However, the limitations of CTA remain, i.e. that it does not give any prognostic information (unless interpreted with the calcium score, or the severity / complexity of the plaques, of which there is large inter-observer variability) and that it results in a high number of false positive tests.

Although about half of CHF patients have a preserved EF, no meds have been shown to improve patient outcomes. This industry sponsored RCT of >4000 patients, age >60, with CHF and EF > 45% found no difference in mortality or cardiovascular hospitalization between those randomized to irbesartan or placebo (consistent across all measured subgroups) after mean f/u of >4 years. The irbesartan patients were more likely to have at least 1 measured doubling of creatinine. There is no clear role for ARBs in normal EF CHF (abstract).

It is clear that patients with stable PE should not be treated with thrombolytics (ACCP guidelines). However, in those that are “unstable” it is less clear when to administer it. In a past small RCT in patients with submassive PE (defined as R heart dysfunction or pulmonary HTN) (abstract) anteplase+heparin (versus heparin) reduced clinical deterioration of PE patients, but not death or recurrent PE. In this retrospective cohort of over 15,000 patients, thrombolytics were given to only 2.4% of patients. Using propensity scoring, they found higher mortality in those given thrombolytics, but no difference in death in the high-propensity scorers with or without thrombolytics. Although this study was imperfect with residual confounding, it does suggest a few things: we are appropriately stingy in giving thrombolytics (<3%), the risk of bleeding is low (2%), the risk of death is high (10%), and it is still up to us to imperfectly determine which patients are “unstable” and will therefore more likely benefit from thrombolytics  (abstract) (editorial)

This is the largest double-blind randomized controlled trial designed to determine the utility of tylenol and diphenhydramine in reducing the incidence of allergic or febrile non-hemolytic transfusion reactions (abstract). Included patients were those admitted to a leukemia or BMT unit with no prior transfusion reaction, and all transfusions were leukoreduced. They found the incidence of reactions was 1.5/100 transfusions in the placebo group and 1.4/100 transfusions in the intervention group. Based on this (and other smaller and older trials), there is no benefit to pre-meds in cancer patients receiving leukoreduced transfusion products. As an editorialist states, it would be nice to see corroboration in a more general medical population, but for now, routine pre-med use should be discouraged (editorial)