In the Literature: HM-Related Research You Need to Know

Study design: Patient-level meta-analysis.

Setting: Pooled patient-level data from seven prospective studies.

Synopsis: Patient-level data were obtained for all patients enrolled using post-treatment D-dimer measurement to predict recurrent VTE in patients with a first unprovoked VTE who had completed at least three months of anticoagulation therapy. The mean length of follow-up was 30 months. Patients with a positive D-dimer had recurrent VTE at a rate of 8.8 per 100 patient-years while those with a negative D-dimer had a rate of 3.7 per 100 patient-years.

Univariate analysis revealed an HR of 2.59 for patients with a positive versus a negative test result. The analysis also showed that the timing of the test, the age of the patient, and the actual cut points used for the various D-dimer tests did not affect the analysis significantly.

These studies’ strength is their large sample sizes and the use of prospective studies. The weaknesses include a mostly white patient population and incomplete data on all patients.

Bottom line: D-dimer testing is useful in predicting VTE recurrence after treatment for a first unprovoked event regardless of patient age, post-treatment timing, or the assay cut point used.

Citation: Douketis J, Tosetto A, Marcucci M, et al. Patient-level meta-analysis: effect of measurement timing, threshold, and patient age on ability of D-dimer testing to assess recurrence risk after unprovoked venous thromboembolism. Ann Intern Med. 2010;153(8): 523-531.

Thigh-High Stockings Are Better than Knee-High Stockings for Post-Stroke DVT Prophylaxis

Clinical question: Are thigh-high compression stockings better then knee-high stockings in immobilized acute-stroke patients?

Background: DVT is common in hospitalized stroke patients with immobility. Graduated compression stockings are often used for DVT prophylaxis, but the CLOTS-1 trial recently found that thigh-high stockings were ineffective after acute stroke. It is unclear if the more commonly used knee-high stockings are more effective than thigh-high stockings.

Study design: Parallel-group trial (the CLOTS-2 trial).

Setting: One hundred twelve hospitals in nine countries.

Synopsis: More than 3,100 patients with acute stroke and immobilization were recruited from January 2002 to May 2009. Patients were randomized to receive thigh-high or knee-high stockings. Patients also received usual care, including anticoagulants and a screening ultrasound for asymptomatic proximal DVT at seven to 10 days. Approximately 640 patients in each group also underwent ultrasound at 25-30 days.

Overall, 6.3% of patients in the thigh-high group had DVT, compared with 8.8% in the knee-high group (P=0.007). There were no significant differences in the secondary outcomes of pulmonary embolism or death. The thigh-high stockings had a higher number of adverse skin events. Enrollment was stopped early when the CLOTS-1 trial showed no difference in DVT rates between thigh-high stockings and no stockings.

Bottom line: Knee-high graduated compression stockings lead to worse outcomes than thigh-high stockings for DVT prophylaxis in immobilized acute-stroke patients.

Citation: CLOTS (Clots in Legs Or sTockings after Stroke) Trial Collaboration. Thigh-length versus below-knee stockings for deep venous thrombosis prophylaxis after stroke: a randomized trial. Ann Intern Med. 2010;153(9):553-562. TH

Pediatric HM Literature

Co-Infection with Pertussis in Infants Hospitalized for Bronchiolitis

Reviewed by Pediatric Editor Mark Shen, MD, medical director of hospital medicine at Dell Children’s Medical Center, Austin, Texas.

Clinical question: How often are infants admitted with bronchiolitis co-infected with Bordatella pertussis?

Background: Infants admitted for bronchiolitis have previously been reported to have co-infection with B. pertussis. Given the nonspecific symptoms associated with early B. pertussis infection, as well as the epidemiology of ongoing outbreaks, it might be useful to better define the risk of co-infection in the seasonal surge of acute bronchiolitis.

Study design: Retrospective cohort study.

Setting: One university hospital in Finland.

Synopsis: A prior study had generated nasopharyngeal aspirate samples for viral antigen detection from 205 healthy, full-term infants younger than 6 months hospitalized for bronchiolitis from 2001 to 2004. Of these samples, 142 (69%) were of quality sufficient for B. pertussis PCR testing in 2009.

Twelve (8.5%) of the 142 infants admitted with bronchiolitis were found to have B. pertussis. Eleven of the 12 infants were co-infected with at least one other virus (RSV in eight of them). Infants who tested positive for pertussis were more often found to have coughing spells (41.7% vs. 14.6% in those who tested negative).

The reported rate of co-infection in this study is higher than other recent reports from the U.S., likely due to the fact that samples were collected during a time period when the incidence of pertussis was relatively high in Finland.

Nevertheless, given the magnitude of a recent pertussis outbreak in California, it might be useful to consider co-infection in young infants admitted for bronchiolitis in areas with a relatively higher incidence of pertussis.

Although the retrospective nature of this study and the lack of a reported definition of coughing spells make further conclusions difficult to draw, cough might deserve further scrutiny during bronchiolitis season.

Bottom line: Consider co-infection with pertussis in young infants admitted with bronchiolitis.

Citation: Nuolivirta K, Koponen P, He Q, et al. Bordatella pertussis infection is common in nonvaccinated infants admitted for bronchiolitis. Pediatr Infect Dis J. 2010;29(11):1013-1015.