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ACP HospitalistWeekly 7-22-09

Highlights

• Abdominal CT helps with prognosis for C. difficile patients

Cardiology

• Study suggests optimal intensity of anticoagulation for some cardiac patients
• Low preoperative hemoglobin level predicts post-CABG mortality

FDA update

• Recalls on ventilators, acetaminophen drops, sodium injections
• Approvals of blood thinner, cancer drug, one-dose contraceptive
• Updated labels for drugs used to help prevent rejection of kidney transplants

Cartoon caption contest

• Put words in our mouth

Physician editor: A. Scott Keller, FACP

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Highlights

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Abdominal CT helps with prognosis for C. difficile patients

Abdominal computed tomography (CT) provides additional prognostic information for Clostridium difficile patients compared to that which can be obtained through clinical or laboratory means alone, a new study has found.

In their retrospective cohort study of 1,189 adult patients with newly diagnosed C. difficile infection (CDI), researchers found 165 patients who had undergone abdominal CT within 72 hours of diagnosis by positive stool sample. These CT patients were younger, were more likely to have a fever, had a higher peak white blood cell count, and had a higher serum creatinine level than patients who didn’t have CT. The study was published online July 10 in Clinical Infectious Diseases.

The two groups didn’t differ in outcomes, and there was no difference in CT findings before and after the emergence of the BI/NAP1/027 hypervirulent strain of C. diff. Pleural effusion (adjusted odds ratio [AOR], 2.6; 95% CI, 1.1-6.6), colonic wall thickness >15 mm (AOR, 6.0; 95% CI, 1.1-33.9), peak white blood cell count >30 × 10⁹ cells/L (AOR, 4.8; 95% CI, 1.4-16.4), albumin level <20 g/L (AOR, 6.9; 95% CI, 2.4-20.1), and immunosuppression (AOR, 4.7; 95% CI, 1.5-15.3) were independently associated with complicated CDI.

Study weaknesses include an inherent selection bias, in that CT is more likely to be done on patients with more severe disease or atypical presentation. The most important findings were that the presence of pleural effusion, as well as the maximal thickness of the colonic wall, was independently associated with a higher risk of developing complicated CDI, the authors said. Maximal colonic wall thickness must reflect the severity of the inflammatory process in a way that peripheral leukocytosis doesn’t entirely capture, they noted. It’s not yet known whether the additional information that CT provides can lead to better treatment or outcomes, they added.

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Cardiology

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Study suggests optimal intensity of anticoagulation for some cardiac patients

Anticoagulation in patients with certain cardiac conditions is most effective and least risky at specific international normalized ratios (INRs), according to a new study.

Dutch researchers examined data from patients with mechanical heart valve prostheses (n=483), atrial fibrillation (n=2,111) and myocardial infarction (MI, n=1,608) who presented to an anticoagulation clinic between 1994 and 1998. The researchers calculated incidence rates of untoward events, defined as major thromboembolism and major hemorrhage, according to intensity of anticoagulation, as measured by INRs. Optimal intensity was defined as "the INR level that provides the lowest overall incidence of untoward events." The study results appear in the July 13 Archives of Internal Medicine.

A total of 4,202 patients (7,788 patient-years) and 3,226 hospital admissions were included in the study. Three hundred six hospital admissions were due to untoward events. Rates of untoward events were similar for the three patient groups: 4.3% (95% CI, 3.1%-5.6%) in patients with mechanical heart valve prostheses, 4.3% (95% CI, 3.7%-5.1%) for patients with atrial fibrillation and 3.6% (95% CI, 3.0%-4.4%) for patients with MI. The authors used the medical record to determine patients' INRs on the day of the untoward event in 278 cases and within eight days of the untoward event in 10 cases. INRs were not available in 18 cases. After calculating INR-specific incidence rates, the authors determined that the optimal intensity of anticoagulation was an INR of 2.5 to 2.9 in patients with mechanical heart valve prostheses, an INR of 3.0 to 3.4 in patients with atrial fibrillation, and an INR of 3.5 to 3.9 in patients with MI.

The authors noted that their results should be interpreted with caution because the study included few events and did not consider individual patient characteristics. They also pointed out that vitamin K antagonists and antiplatelet agents are rarely used concomitantly in The Netherlands. Also, their national target ranges at the beginning of the study, which were 3.6 to 4.8 for mechanical heart valve prostheses and 3.0 to 4.0 for atrial fibrillation and MI, changed in 1996 to 3.0 to 4.0 for mechanical heart valve prostheses and MI, and 2.5 to 3.5 for atrial fibrillation. However, they concluded that an INR of 3.0 is an appropriate target for patients with mechanical heart prostheses and those with atrial fibrillation, while an INR of 3.5 is appropriate after MI. Future studies should be done to test these ranges and "provide us with a final answer as to which INR level is safest for patients at high risk of arterial thromboembolism," they wrote.

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Low preoperative hemoglobin level predicts post-CABG mortality

A low preoperative hemoglobin level, both as a continuous variable and as a dichotomous variable ("anemic," defined as a hemoglobin of <13 g/dL in men and <12 g/dL in women, or “not anemic”) is an independent predictor of mortality in patients undergoing coronary artery bypass grafting (CABG), a new study has found.

Researchers analyzed data for 10,025 patients who underwent isolated CABG from 1998 through 2007, and classified them into four groups. In the “very low” group, hemoglobin was <12 g/dL for men and <11 g/dL for women; in the “low” group it was >12 and <13 g/dL for men and >11 and <12 g/dL for women. These latter two groups were considered anemic. In the “normal” group, the hemoglobin level in men was >13 and <14.5 g/dL and >12 and <13.5 g/dL in women, while the “high normal” group had hemoglobin levels >14.5 g/dL in men and >13.5 g/dL in women. Follow-up data on mortality were obtained primarily from health insurance companies, with early mortality defined as death within the first 30 postoperative days and late mortality defined as death at 31 or more postoperative days.

On multivariate logistic regression analysis, anemia was found to be an independent risk factor for higher early mortality, while Cox analyses found that both low hemoglobin level and anemia predicted higher late mortality. The annual incidence of death was 7.8 per 100 patient-years in the very-low hemoglobin group, 5.3 in the low group, 2.6 in the normal group, and 1.8 in the high-normal group. When compared with a matched general population cohort, patients with the lowest preoperative hemoglobin levels had a worse outcome, and those with the highest levels had a better one. The study appeared in the July 14 Circulation.

It’s difficult to determine if the correlation between hemoglobin level and early mortality is linear because of confounders like diabetes, older age, peripheral vascular disease, renal function impairment and low left ventricular ejection fraction, the authors said. Given the study results, a low hemoglobin level should be considered an independent predictor of higher short- and long-term mortality, they added, and future studies may help establish whether treatment of anemia before surgery can improve outcomes.

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FDA update

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Recalls on ventilators, acetaminophen drops, sodium injections

The following items were recalled in the last week, according to the FDA:

• The BiPAP Focus Non-Invasive Ventilator System, model number PCM120PS18-2315P, due to power supply failures on some ventilators. The product was distributed from August 2006 through April 11, 2008. Customers may contact Respironics U.S. Customer Service at 1-877-387-3377. This is a class I recall.
• Medtronic’s Quick-set infusion sets, used with MiniMed Paradigm insulin pumps, because the sets may not allow the insulin pump to vent air pressure properly. This could result in the device delivering too much or too little insulin and may lead to serious injury or death. Affected infusion sets are reference numbers MMT-396, MMT-397, MMT-398 and MMT-399 with lot numbers starting with the number "8"; patients should discontinue using “Lot 8” sets. This is a voluntary recall by the manufacturer, who will replace the sets for free.
• All lots of Concentrated Acetaminophen Drops (NDC#42192-504-16) in 16-ounce (473-mL) bulk containers, manufactured by Pharmaceutical Associates, Inc. Because the 16-ounce container is comparable in size to the packaging of regular-strength acetaminophen liquid preparations, dosing errors may occur. Overdose of acetaminophen may result in liver toxicity, kidney damage, and blood disorders. This is a voluntary recall by the manufacturer.
• Lot #370-9004 of Mallinckrodt Sodium Chromate Cr-51 Injection, because routine post-market testing found the product to be subpotent. This is a voluntary recall by the manufacturer.

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Approvals of blood thinner, cancer drug, one-dose contraceptive

The FDA last week approved the following drugs:

• Blood thinner prasugrel (Effient), to reduce the risk of blood clots in angioplasty patients. Compared with clopidogrel (Plavix), the fraction of patients with subsequent nonfatal myocardial infarction decreased from 9.2% to 7.0% with prasugrel, a patient trial found. The numbers of deaths and strokes were similar, but patients with a history of stroke had a higher risk of subsequent stroke when taking prasugrel. Also, there was a greater risk of significant bleeding with prasugrel, so the drug’s labeling will include a boxed warning that prasugrel can cause significant, sometimes fatal, bleeding. It shouldn’t be used in patients with active pathological bleeding, a history of transient ischemic attacks or stroke, or urgent need for surgery, including coronary artery bypass graft surgery.
• Fentanyl buccal soluble film (Onsolis), to help cancer patients manage breakthrough pain. The absorbable film, which sticks to the inside of the cheek, is meant for opioid-tolerant patients age 18 years and older who already use opioid pain management continuously. The drug was approved with a boxed warning against use to manage migraines, dental pain, or postoperative pain, or use by patients who take opioids intermittently or on an as-needed basis. The drug will only be available through a restricted distribution program, meaning only prescribers, patients and pharmacies registered with the program, called FOCUS, will be able to prescribe, dispense and receive the drug.
• A one-dose formulation of emergency contraception pill levonorgestrel (Plan B One-Step). The original pill requires two doses. People age 17 years and older will be able to buy Plan B One-Step over the counter; those 16 years of age and under will need a prescription.

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Updated labels for drugs used to help prevent rejection of kidney transplants

The labels of some immunosuppressant drugs used to help prevent rejection of kidney transplants must be updated to reflect an increased risk of infections, the FDA said last week.

The required label changes affect sirolimus (Rapamune), cyclosporine (Sandimmune), cyclosporine modified (Neoral), mycophenolate mofetil (Cellcept) and mycophenolic acid (Myfortic). The changes must reflect a higher risk for opportunistic infections, including activation of latent viral infections such as BK virus-associated nephropathy. These infections may lead to serious outcomes, including kidney graft loss.

Health care providers need to carefully monitor patients who take these drugs for infection, the FDA said, and should consider adjusting immunosuppression therapy for any who develop BK virus-associated nephropathy.

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Cartoon caption contest

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Put words in our mouth

ACP HospitalistWeekly wants readers to create captions for this cartoon and help choose the winner. Pen the winning caption and win a $50 gift certificate good toward any ACP product, program or service.

E-mail all entries by July 23. ACP staff will choose three finalists and post them in the July 29 issue of ACP HospitalistWeekly for an online vote by readers. The winner will appear in the Aug. 5 edition.

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