Journal watch: recent studies of note

Recent studies about pressure stocking use after stroke, hospital-acquired pneumonia, and other topics.

Pressure stockings offer no DVT protection after stroke

Pressure stockings don't help prevent proximal deep venous thrombosis (DVT) after stroke, a recent study has found.

Researchers randomly assigned 2,518 poststroke patients from 64 institutions in the United Kingdom, Italy and Australia to receive routine care plus thigh-length graduated compression stockings (GCS) or routine care and no stockings (1,256 patients vs. 1,262 patients). All patients underwent compression Doppler ultrasonography of both legs at about 7 to 10 days and again at 25 to 30 days “when practical”; the ultrasound technician was blinded to the study group. The primary outcome was any DVT (symptomatic or asymptomatic) in the popliteal or femoral veins. The study results were published online May 27 by The Lancet.

Overall, 126 patients in the GCS group and 133 patients in the no-GCS group developed DVT (10.0% vs. 10.5%; absolute risk reduction, 0.5% [95% CI, −1.9% to 2.9%]). Patients in the GCS group were significantly more likely to develop adverse effects such as skin breaks, blisters, ulcers and skin necrosis (5% vs. 1%; odds ratio, 4.18 [95% CI, 2.40 to 7.27]). The authors concluded that thigh-high graduated compression stockings are not effective in preventing DVT after stroke and noted that guidelines recommending their use might need to be updated to reflect the trial results. An accompanying editorial went further, saying “GCS do not reduce DVT or overall [venous thromboembolism] in patients with recent stroke; indeed, they damage the skin and might promote limb ischemia. GCS should not be used after stroke and current guidelines will need to be amended.”

The results of a follow-up study comparing below-the-knee GCS and thigh-high GCS should be available by the end of 2009. A related study looking at the efficacy of intermittent pneumatic compression devices is currently under way.

PPIs increase hospital-acquired pneumonia risk

Inpatients who receive acid-suppressive medications are at higher risk for hospital-acquired pneumonia, according to a recent study.

The prospective cohort trial included 63,878 admissions at an academic medical center in Boston between 2004 and 2007. Included patients spent at least three days in the hospital, but were not in the intensive care unit. Researchers compared outcomes between the 52% of patients who were prescribed acid-suppressives and the rest who were not. Patients on the medication had an unadjusted 4.9% rate of hospital-acquired pneumonia, compared to 2% in the unexposed group (odds ratio, 2.6 [95% CI, 2.3 to 2.9]). After multivariable adjustment, the study found that the use of acid-suppressive medication was associated with a significant 30% higher risk of hospital-acquired pneumonia. This association was stronger for aspiration pneumonia than for non-aspiration pneumonia.

The researchers also looked at what type of acid suppression patients were on. While proton-pump inhibitors posed a statistically significant increased risk, the risk from histamine-2 receptor antagonists was not statistically significant at an odds ratio of 1.2 (CI, 0.98 to 1.4). However, the study authors noted that that subset was not adequately powered to detect small differences. The study was published in the May 27 Journal of the American Medical Association.

Extrapolating from the study, researchers said that annually more than 180,000 cases of pneumonia and 33,000 preventable deaths potentially could be attributed to acid- suppressive medication. They noted that these figures do not reflect the potential benefits of the medication. The findings do add to the existing literature indicating a relationship between acid-suppressive medications and pneumonia, and further scrutiny of the medications' use is warranted, the study authors concluded.

Mobilization during “sedation stops” improves outcomes

Interrupting sedation and initiating physical and occupational therapy in the early days of a critical illness resulted in better outcomes at hospital discharge and fewer days on ventilation, a recent study found.

The randomized controlled trial included 104 sedated adults in the ICU at two university hospitals who had been on mechanical ventilation for less than 72 hours, were expected to continue for at least 24 hours, and met criteria for baseline functional independence. Patients in the intervention group underwent exercise and mobilization during daily interruptions of sedation while patients in the control group had daily sedation stops only. The study appeared in the May 30 issue of The Lancet.

Researchers found that 59% of patients in the intervention group returned to premorbid independent functional status at discharge (defined as the ability to perform six activities of daily living and to walk independently) versus 35% in the control group. In addition, patients in the intervention group had a shorter duration of delirium (2 vs. 4 days, P=0.02) and more ventilator-free days (23.5 vs. 21 days, P=0.05) than control group patients during the 28-day follow-up period.

An accompanying editorial noted that the study's findings on delirium deserve further study because of the difficulty of assessing confusion in critically ill patients, almost all of whom would test positive for one or more of the criteria for delirium. Future studies should examine whether delirium is actually reduced or whether physical therapy enhances patients' ability to reach an awakened state, the editorial said.

New scoring system for predicting VAP mortality

A simple five-point scoring system may be as effective as an older tool in evaluating and predicting mortality in patients with ventilator-associated pneumonia (VAP), a recent study concluded.

The new scoring system, called IBMP-10, assigned one point to each of the following: presence of immunodeficiency; blood pressure <90 mm Hg (systolic) or <60 mm Hg (diastolic); multilobar infiltrates noted on a chest radiograph; platelet count <100,000/mm3; and duration of hospitalization before VAP onset of >10 days. Researchers found that the new system worked as well as the Acute Physiology and Chronic Health Evaluation II (APACHE II) score, which is traditionally used to predict mortality in patients with VAP. The results were reported in the July 1 Clinical Infectious Diseases.

Researchers concluded that if future studies validate their results, the IBMP-10 score may represent a simple tool to evaluate VAP severity and predict outcomes.

Tools better than opinion for delirium diagnosis in ICU

Assessment tools are better for detecting delirium in the ICU than physicians' opinions alone, according to a recent study.

Researchers examined the value of three methods for detecting delirium in the ICU: the Confusion Assessment Method for the ICU (CAM-ICU), the Intensive Care Delirium Screening Checklist (ICDSC), and the opinion of the ICU physician. One hundred twenty-six patients from a single mixed medical/surgical ICU were evaluated over an eight-month period. Nurses administered the assessment tools, and the ICU physicians were asked whether they thought patients were delirious. A reference rater—a psychiatrist, geriatrician or neurologist—then used established criteria to diagnose delirium. The study results appeared in the June Critical Care Medicine.

The CAM-ICU had superior sensitivity and negative predictive value compared with the ICDSC (64% vs. 43% and 83% vs. 75%, respectively), while the ICDSC had higher specificity and positive predictive value (95% vs. 88% and 82% vs. 72%, respectively). Physicians' opinion had a sensitivity of just 29% and a specificity of 96% compared with the diagnosis made by the reference rater. However, this poor performance, which was made by a composite of residents, fellows and intensivists, was mostly due to the inaccurate evaluations by the residents. When scored separately, the intensivists and fellows showed much better diagnostic capabilities (sensitivity, 63%; specificity, 100%; positive predictive value, 100%; negative predictive value, 72%).

The authors noted that evaluations of delirium were not always performed at the same time and that some patients were given psychoactive medications between evaluations, which may have affected the results. However, they concluded that formal tools for assessing delirium perform better than physician opinion, highlighting the need for standardized screening in the ICU setting.

New severity score for CAP outcomes outperforms older scores

The newly developed Severe Community-Acquired Pneumonia (SCAP) score is slightly more accurate than other existing scores at predicting adverse outcomes in hospitalized patients with CAP, a recent study found.

Researchers prospectively compared three severity scores in an internal validation cohort of 1,189 patients with CAP from one hospital, and in an external validation cohort of 671 patients from three other hospitals. The scores were the SCAP; the pneumonia severity index (PSI); and the British Thoracic Society CURB-65 rule (confusion, urea >7 mmol/L, respiratory rate ≥30 breaths/minute, blood pressure <90 mm Hg systolic or <60 mm Hg diastolic, age ≥65 years). Major adverse outcomes measured were ICU admission, need for mechanical ventilation, treatment failure and progression to severe sepsis (defined as sepsis associated with organ dysfunction and perfusion abnormalities). The study was published in the June 2009 Chest.

As all three scores increased, so did the rate of adverse outcomes (P<0.001) in the external validation cohort. Patients who were classified as high risk by the SCAP score had higher rates of adverse outcomes than did patients identified as high risk on the PSI and CURB-65. In the external validation cohort, the discriminatory power of the SCAP score, as measured by the area under the curve (AUC), was 0.75 for ICU admission (vs. 0.63 for PSI and 0.61 for CURB-65) and 0.79 for severe sepsis (vs. 0.72 for PSI and 0.66 for CURB-65)—a statistically significant difference between SCAP and the other two scores. There were also significant differences in sensitivity and specificity among the three scores, all favoring SCAP, but the differences were small and of uncertain clinical significance.

Strengths of the study include the use of two large independent cohorts of hospitalized CAP patients, and the use of external validation to support the generalizability and accuracy of the SCAP score, the authors said. Limitations include the possibility that the study sample didn't reflect the full array of adverse outcomes that can occur in CAP. Still, the SCAP performed better than the other two scores, and can be useful in helping identify patients who need more aggressive monitoring and treatment after initial evaluation, the authors concluded.

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