Effects of ascent to high altitude on human antimycobacterial immunity.

BACKGROUND: Tuberculosis infection, disease and mortality are all less common at high than low altitude and ascent to high altitude was historically recommended for treatment. The immunological and mycobacterial mechanisms underlying the association between altitude and tuberculosis are unclear. We studied the effects of altitude on mycobacteria and antimycobacterial immunity. METHODS: Antimycobacterial immunity was assayed in 15 healthy adults residing at low altitude before and after they ascended to 3400 meters; and in 47 long-term high-altitude residents. Antimycobacterial immunity was assessed as the extent to which participants' whole blood supported or restricted growth of genetically modified luminescent Bacille Calmette-Guérin (BCG) mycobacteria during 96 hours incubation. We developed a simplified whole blood assay that could be used by a technician in a low-technology setting. We used this to compare mycobacterial growth in participants' whole blood versus positive-control culture broth and versus negative-control plasma. RESULTS: Measurements of mycobacterial luminescence predicted the number of mycobacterial colonies cultured six weeks later. At low altitude, mycobacteria grew in blood at similar rates to positive-control culture broth whereas ascent to high altitude was associated with restriction (p ≤ 0.002) of mycobacterial growth to be 4-times less than in culture broth. At low altitude, mycobacteria grew in blood 25-times more than negative-control plasma whereas ascent to high altitude was associated with restriction (p ≤ 0.01) of mycobacterial growth to be only 6-times more than in plasma. There was no evidence of differences in antimycobacterial immunity at high altitude between people who had recently ascended to high altitude versus long-term high-altitude residents. CONCLUSIONS: An assay of luminescent mycobacterial growth in whole blood was adapted and found to be feasible in low-resource settings. This demonstrated that ascent to or residence at high altitude was associated with decreased mycobacterial growth in whole blood relative to controls, consistent with altitude-related augmentation of antimycobacterial cellular immunity.

Reduction of regulated medical waste using lean sigma results in financial gains for hospital.

This article describes how anesthesiologists can lead innovation and process improvement focused on regulated medical waste reduction and cost savings using a process improvement methodology known as Lean Sigma.

Utilizing audit and feedback to improve hospitalists' performance in tobacco dependence counseling.

INTRODUCTION: Hospitalized smokers benefit from smoking cessation counseling and nicotine replacement therapy (NRT). However, inpatient providers who care for hospitalized patients carry out these preventive measures inconsistently. METHODS: We designed a peer-led audit and feedback intervention to improve (a) the frequency of smoking cessation counseling and (b) the appropriateness of the prescribing of NRT by hospitalist practitioners in our hospital. Documentation of tobacco cessation counseling in progress notes and discharge summaries and the ordering and dosing of NRT were assessed for 30 hospitalists before and after an intervention. This intervention included specific feedback on their counseling and prescribing practices as well as education and was delivered as part of a one-on-one academic detailing session. RESULTS: Five hundred and forty five and 1,119 patient-days were considered for this analysis in the pre- and postperiods, respectively. Documentation of tobacco dependence counseling in progress notes increased from 36% to 44% (p = .002) and from 7.5% to 46.8% in discharge summaries (p < .0001) following the intervention. The appropriateness of NRT dosing increased from 26% (before) to 64% (after) the intervention (p < .0001). DISCUSSION: A peer-led audit and feedback intervention for hospitalists significantly increases the frequency of smoking cessation counseling and the adequacy of NRT prescribing for hospitalized smokers.

Analytic validity of genetic tests to identify factor V Leiden and prothrombin G20210A.

The objective of this study is to systematically review methods for detecting Factor V Leiden or prothrombin G20210A. English-language literature from MEDLINE, EMBASE, The Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature, PsycInfo(c), 2000-December 2008. Studies assessed methods for detection of these mutations in at least 10 human blood samples and reported concordance, discordance, or reproducibility. Two investigators abstracted data on the sample selection criteria, test operators, DNA extraction, experimental test, reference standard, commercial instruments, concordance rates, explanation of any discordance, and whether discordance resolved after repetition. We assessed strength of the evidence using the GRADE criteria. We reviewed 7,777 titles and included 66 articles. The majority of the reviewed studies used PCR-RFLP or AS-PCR as the reference standard. The studies demonstrated that commercially available and precommercial tests have high analytic validity with all having greater than 99% concordance with the reference standard. With a few exceptions, discordance resolved with repetition of the test, suggesting operator or administrative errors were responsible for the discordant results. In the quality assurance studies, greater than 98% of laboratories demonstrated high, even perfect, accuracy when asked to diagnose a sample with a known mutation. The majority of errors came from a limited number of laboratories. Although not all methods may be accurate, there is high-grade evidence that genetic tests for the detection of FVL and prothrombin G20210A have excellent analytic validity. There is high-grade evidence that most, but not all, clinical laboratories test for FVL and prothrombin G20210A accurately.

Predictive value of factor V Leiden and prothrombin G20210A in adults with venous thromboembolism and in family members of those with a mutation: a systematic review.

CONTEXT: Testing for genetic risks for venous thromboembolism (VTE) is common, but the safety and utility of such testing need review. OBJECTIVES: To define rates of recurrent VTE among adults with VTE with a factor V Leiden (FVL) or prothrombin G20210A mutation compared with those without such mutations; to define rates of VTE among family members of adults with a FVL or prothrombin G20210A mutation according to presence or absence of a mutation; and to assess whether testing adults with VTE for FVL or prothrombin G20210A improves outcomes. DATA SOURCES: We searched MEDLINE, EMBASE, the Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature, and PsycInfo through December 2008. STUDY SELECTION: Studies were included if they assessed rates of VTE in individuals with a history of VTE who were tested for FVL or prothrombin G20210A or in family members of individuals with these mutations. Studies assessing the harms and benefits associated with testing were also included. DATA EXTRACTION: Two investigators abstracted data and assessed study quality. We pooled the odds of VTE associated with the mutations using random-effects models. We assessed the strength of the evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. RESULTS: We reviewed 7777 titles and included 46 articles. Heterozygosity (odds ratio [OR], 1.56; 95% confidence interval [CI], 1.14-2.12) and homozygosity (OR, 2.65; 95% CI, 1.2-6.0) for FVL in probands are predictive of recurrent VTE compared with individuals without FVL. Heterozygosity for FVL predicts VTE in family members (OR, 3.5; 95% CI, 2.5-5.0), as does homozygosity for FVL (OR, 18; 95% CI, 7.8-40) compared with family members of adults without FVL. Heterozygosity for prothrombin G20210A is not predictive of recurrent VTE in probands compared with individuals without prothrombin G20210A (OR, 1.45; 95% CI, 0.96-2.2). Evidence is insufficient regarding the predictive value of prothrombin G20210A homozygosity for recurrent VTE and the risk of VTE in family members of individuals with prothrombin G20210A. High-grade evidence supports that anticoagulation reduces recurrent VTE events in probands with either mutation. Low-grade evidence supports that this risk reduction is similar to that in individuals with a history of VTE and without mutations. CONCLUSIONS: Patients with FVL are at increased risk of recurrent VTE compared with patients with VTE without this mutation. However, it is unknown whether testing for FVL or prothrombin G20210A improves outcomes in adults with VTE or in family members of those with a mutation.

Outcomes of genetic testing in adults with a history of venous thromboembolism.

OBJECTIVE: To address whether Factor V Leiden (FVL) testing alone, or in combination with prothrombin G20210A testing, leads to improved clinical outcomes in adults with a personal history of venous thromboembolism (VTE) or to improved clinical outcomes in adult family members of mutation-positive individuals. DATA SOURCES: Searches of MEDLINE, EMBASE, The Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature, and PsycInfo through December 2008. REVIEW METHODS: We focused on the analytic validity, clinical validity, and clinical utility of these tests. Each included article underwent double review for data abstraction and assessment of study quality. We pooled the results of studies addressing the clinical validity of these tests when there were sufficient data. Other evidence was summarized in evidence tables. We graded the evidence by adapting a scheme recommended by the Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group by assessing the limitations affecting individual study quality, the certainty regarding the directness of the observed effects in the studies, the precision and strength of the findings, and the availability (or lack) of data to answer the relevant key question. Evidence for each sub-question was graded as high, moderate, or low. RESULTS: We reviewed 7,777 titles and included 124 articles. No direct evidence addressed the primary objective. However, high-grade evidence supported the conclusion that tests for the detection of FVL and prothrombin G20210A have excellent analytic validity. Most clinical laboratories test for these mutations accurately. Heterozygosity [odds ratio (OR) =1.56 (95 percent confidence interval (CI) 1.14 to 2.12)] and homozygosity [OR=2.65 (95 percent C.I. 1.2 to 6.0)] for FVL in probands are predictive of recurrent VTE. Heterozygosity for FVL predicts VTE in family members [OR=3.5 (95 percent C.I. 2.5 to 5.0)] as does homozygosity for FVL [OR=18 (95 percent C.I. 7.8 to 40)]. Heterozygosity for prothrombin G20210A is not predictive of recurrence in probands [OR=1.45 (95 percent C.I. 0.96-2.2)]. Evidence is insufficient about heterozygosity for prothrombin G20210A in family members and insufficient about homozygosity for prothrombin G20210A. A single study supported the hypothesis that clinicians might change management based on test results. There was high-grade evidence that anticoagulation reduces recurrent events in probands with FVL or prothrombin G20210A, however, there was low-grade evidence that the relative reduction with treatment is comparable to that seen in individuals without mutations. There was moderate evidence to support the conclusion that neither harms nor benefits of testing have been demonstrated conclusively. Decision-analysis models suggest that testing may be cost-effective in select individuals. CONCLUSIONS: There is no direct evidence that testing for these mutations leads to improved clinical outcomes in adults with a history of VTE or their adult family members. The literature supports the conclusion that while these assays have high analytic validity, the test results have variable clinical validity for predicting VTE in these populations and have only weak clinical utility.

Comparison of statistical parametric mapping and SPECT difference imaging in patients with temporal lobe epilepsy.

PURPOSE: Statistical parametric mapping (SPM) is an image-analysis tool that assesses the statistical significance of cerebral blood flow (CBF) changes on a voxel-by-voxel basis, thereby removing the subjectivity inherent in conventional region-of-interest (ROI) analysis. Our platform of single-photon emission computed tomography (SPECT) ictal-interictal difference imaging in clinical epilepsy has been validated for localizing seizure onset. We extend the tools of SPM by further applying statistical measures for the significance of perfusion changes in individual patients to localize epileptogenic foci in patients with defined temporal lobe epilepsy by using paired scans in this preliminary study. METHODS: Twelve patients with pairs of periictal and interictal SPECT scans were analyzed in this comparison study between SPECT difference imaging and SPM difference analysis by using a reference database of paired normal healthy images. These 12 patients possessed seizure foci localized to the mesial temporal lobe as confirmed by surgical outcome and by hippocampal sclerosis on pathology. SPM was used to identify clusters of increased or decreased CBF in each patient in contrast to our control group. RESULTS: The regions having the most significant increased or decreased CBF by SPM analysis were in agreement with regions identified by conventional difference imaging and visual analysis by viewers blinded to the results of the SPM analysis. Differentiated further by time of radiopharmaceutical injection, six of seven patients injected within 100 s of seizure onset displayed hyperperfusion changes localized to the corresponding epileptogenic temporal lobe by both techniques. Among patients receiving injections after 100 s, both techniques showed primarily regions of hypoperfusion, which again were similar between these two methods. CONCLUSIONS: The results provide strong evidence supporting SPM difference analysis in assessing regions of significant CBF change from baseline in concordance with our current clinically used technique of SPECT ictal--interictal difference imaging in epilepsy patients. Difference analysis using SPM could serve as a useful diagnostic tool in the evaluation of seizure focus in temporal lobe epilepsy.