Highlights from ACP Journal Club
MODS assay better at detecting TB but poses challenges in developing countries
The microscopic-observation drug-susceptibility (MODS) assay proved a faster and more accurate way of detecting tuberculosis (TB) in a recent study of almost 2,000 patients.
In the study by Moore and colleagues, which was reported in the Oct. 12, 2006, issue of The New England Journal of Medicine, 1,980 patients 18 years or older presenting at hospitals and clinics in Lima, Peru, provided two sputum samples each. The samples were analyzed using the MODS assay, the automated mycobacterial culture or the Lowenstein-Jensen culture.
Overall, 10.7% of the samples tested positive for TB. The MODS assay had a sensitivity of 97.8%, compared with 89% for automated mycobacterial culture and 84% for Lowenstein-Jensen culture. In addition, the MODS assay was faster in identifying drug-resistant strains (7 days to positive test compared with 13 and 26 days, respectively).
Currently, sputum microscopy is the primary method for diagnosing TB in developing countries, where 95% of cases occur, said ACP Journal Club reviewer Oommen John, MD, of the Leprosy Mission Trust India in New Delhi. However, this method is slower than MODS assay and detects only half of the cases.
While the MODS assay has the potential to reduce transmission, there are some concerns, said Dr. John. Developing countries often cannot afford the sophisticated labs needed to safely perform MODS culture. These countries also often do not have adequate infection control and biohazardous waste disposal methods, which are particularly important with MODS because the potential exposure time for health care workers is greater than with other methods that do not use microscopic culture techniques.
Further research is needed on using the MODS assay in resource-limited countries, said Dr. John, because physicians in these areas often rely on empirical treatment rather than lab diagnosis.
Star ratings: IM/Referred Care/Hospitalists, 6/7 stars.
Etoricoxib poses similar risks as diclofenac in arthritis
A recent study found that the cyclooxygenase-2 (COX-2) inhibitor etoricoxib did not increase the incidence of major cardiovascular events compared with using the nonsteroidal anti-inflammatory drug (NSAID) diclofenac in patients with osteoarthritis or rheumatoid arthritis.
In the trial by Cannon and colleagues, which was reported in the Nov. 18, 2006, issue of Lancet, 34,701 patients with osteoarthritis or rheumatoid arthritis received either 60 or 90 mg of etoricoxib daily, 75 mg of diclofenac twice daily or 50 mg of diclofenac three times per day. The cardiovascular event rate per 100 patient-years was similar in all groups. The incidence of major gastrointestinal problems was higher in the diclofenac group.
COX-2 inhibitors were initially thought of as superior to traditional NSAIDs because they were less likely to cause gastrointestinal bleeding, noted ACP Journal Club reviewer Michael Denman, MD, of Northwick Park Hospital in Harrow, England. However, some studies subsequently showed that patients who received COX-2 inhibitors had higher incidences of myocardial infarction and cerebral thrombosis.
This study suggests that COX-2 inhibitors are as safe as NSAIDs. However, Dr. Denman advised against changing practice because the study compared a single COX-2 inhibitor with a single NSAID, and outcomes might vary among drugs in both classes. In addition, the study did not account for the fact that rheumatoid arthritis is a risk factor for cardiovascular disease and that some patients in the study were taking corticosteroids.
As a result, physicians should continue to assess patients on an individual basis, said Dr. Denman. Future research should look at risk factors in susceptible patients rather than large heterogeneous groups, he suggested.
Star ratings: IM/Referred Care/Hospitalists, 6/7 stars.
Ultrasonography superior to landmark technique for central vein catheter insertions
A study comparing techniques for central vein catheter (CVC) insertion in the emergency department (ED) found that real-time ultrasonographically guided insertion was more successful and produced fewer complications than the traditional landmark technique.
The study by Leung and colleagues, which was reported in the November 2006 issue of Annals of Emergency Medicine, included 130 ED patients who required central venous access, excluding trauma patients in whom the cervical spine could not be cleared and patients with uncorrected severe coagulopathy. Insertion of the internal jugular vein catheter was performed using the SonoSite 180 ultrasonographic system or the landmark technique with a central, anterior or posterior approach. Insertion was successful in 94% of the ultrasonographic group versus 78% of the landmark group, a relative benefit increase of 20% (number needed to treat = 7).
This study differs from other similar studies because it was limited to the internal jugular approach, used randomization with concealed allocation and had a sample size large enough to show important differences, said ACP Journal Club reviewer Stephen R. Pitts, MD, MPH, of Emory University School of Medicine in Atlanta. A weakness is that it used few operators for a large number of procedures.
It is difficult to apply the results to practice because other issues often affect what goes on in the ED, said Dr. Pitts. For example, it might not be possible to mobilize an ultrasonography machine in a sudden emergency; thus, landmark techniques should continue to be taught.
This study provides good news that ultrasonography improves outcomes for CVC placement, said Dr. Pitts. Future research might focus on whether the internal jugular approach leads to fewer mechanical complications than the subclavian approach in the era of ED ultrasonography.
Star ratings: IM/Referred Care/Hospitalists, 5/7 stars.
Reinserting stylet improves lumbar puncture
A review of lumbar puncture trials found that reinserting the stylet before removing the needle can reduce post-procedure headache.
A meta-analysis of 15 randomized, controlled trials and six diagnostic studies evaluated interventions to reduce headaches in patients having a diagnostic lumbar puncture. The authors also reviewed studies to determine the accuracy of cerebrospinal fluid (CSF) analysis for diagnosis of bacterial meningitis. Straus and colleagues' study appeared in the Oct. 25, 2006, issue of JAMA.
The review found fewer headaches when smaller needles or atraumatic needles were used and when the stylet was reinserted before removal of the needle. Although only one study compared small-gauge with standard-gauge needles, and a nonsignificant trend was found in the use of atraumatic needles, both interventions are probably efficacious because they mirror findings in anesthesia literature, said ACP Journal Club reviewer Micelle J. Haydel, MD, of Louisiana State University Health Sciences Center in New Orleans. The review also found a nonsignificant decrease in headaches in patients who were mobilized, indicating that bed rest is not necessary, Dr. Haydel said.
On the accuracy of CSF analysis, the review found that the CSF gram stain, leukocyte count, lactate level and blood–glucose ratios were sufficiently accurate in ruling in meningitis, but were not able to rule it out. The findings show that CSF analysis remains a useful tool in identifying patients with meningitis, but the patient's clinical presentation must also be considered, noted Dr. Haydel.
Star ratings: IM/Referred Care/Hospitalists, 6/7 stars.
The March–April 2007 issue of ACP Journal Club is online at www.acpjc.org. View more about ACP Journal Club's star rating system here.
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