Grading the strength of recommendations and the quality of underlying evidence enhances the usefulness of clinical practice guidelines. Professional societies and other organizations, including the American Thoracic Society (ATS), should reach consensus about whether they will use one common grading system and which of the numerous grading systems they would apply across all guidelines. The profusion of guideline grading systems confuses consumers of guidelines, and undermines the value of the grading exercise in conveying a transparent message. In response to this dilemma, the international GRADE working group has developed an approach that is useful for many guideline contexts, and that several national and international organizations have adopted. The GRADE system classifies recommendations as strong or weak, according to the balance of the benefits and downsides (harms, burden, and cost) after considering the quality of evidence. The quality of evidence reflects the confidence in estimates of the true effects of an intervention, and the system classifies quality of evidence as high, moderate, low, or very low according to factors that include the study methodology, the consistency and precision of the results, and the directness of the evidence. On recommendation of the ATS Documents Development and Implementation Committee, the ATS adopted the GRADE approach for its guidelines in line with many other organizations that have recently chosen the GRADE approach. This article informs ATS guideline developers, investigators, and those interpreting future ATS guidelines that follow the GRADE approach about the methodology and applicability of ATS guidelines and recommendations.

Background High blood pressure is common in acute stroke and is a predictor of poor outcome; however, large trials of lowering blood pressure have given variable results, and the management of high blood pressure in ultra-acute stroke remains unclear. We investigated whether transdermal glyceryl trinitrate (GTN; also known as nitroglycerin), a nitric oxide donor, might improve outcome when administered very early after stroke onset. Methods We did a multicentre, paramedic-delivered, ambulance-based, prospective, randomised, sham-controlled, blinded-endpoint, phase 3 trial in adults with presumed stroke within 4 h of onset, face-arm-speech-time score of 2 or 3, and systolic blood pressure 120 mm Hg or higher. Participants were randomly assigned (1:1) to receive transdermal GTN (5 mg once daily for 4 days; the GTN group) or a similar sham dressing (the sham group) in UKbased ambulances by paramedics, with treatment continued in hospital. Paramedics were unmasked to treatment, whereas participants were masked. The primary outcome was the 7-level modified Rankin Scale (mRS; a measure of functional outcome) at 90 days, assessed by central telephone follow-up with masking to treatment. Analysis was hierarchical, first in participants with a confirmed stroke or transient ischaemic attack (cohort 1), and then in all participants who were randomly assigned (intention to treat, cohort 2) according to the statistical analysis plan. This trial is registered with ISRCTN, number ISRCTN26986053.

Summary Background Antiplatelet therapy reduces the risk of major vascular events for people with occlusive vascular disease, although it might increase the risk of intracranial haemorrhage. Patients surviving the commonest subtype of intracranial haemorrhage, intracerebral haemorrhage, are at risk of both haemorrhagic and occlusive vascular events, but whether antiplatelet therapy can be used safely is unclear. We aimed to estimate the relative and absolute effects of antiplatelet therapy on recurrent intracerebral haemorrhage and whether this risk might exceed any reduction of occlusive vascular events. Methods The REstart or STop Antithrombotics Randomised Trial (RESTART) was a prospective, randomised, open-label, blinded endpoint, parallel-group trial at 122 hospitals in the UK. We recruited adults (≥18 years) who were taking antithrombotic (antiplatelet or anticoagulant) therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage, discontinued antithrombotic therapy, and survived for 24 h. Computerised randomisation incorporating minimisation allocated participants (1:1) to start or avoid antiplatelet therapy. We followed participants for the primary outcome (recurrent symptomatic intracerebral haemorrhage) for up to 5 years. We analysed data from all randomised participants using Cox proportional hazards regression, adjusted for minimisation covariates. This trial is registered with ISRCTN (number ISRCTN71907627). Findings Between May 22, 2013, and May 31, 2018, 537 participants were recruited a median of 76 days (IQR 29–146) after intracerebral haemorrhage onset: 268 were assigned to start and 269 (one withdrew) to avoid antiplatelet therapy. Participants were followed for a median of 2·0 years (IQR [1·0– 3·0]; completeness 99·3%). 12 (4%) of 268 participants allocated to antiplatelet therapy had recurrence of intracerebral haemorrhage compared with 23 (9%) of 268 participants allocated to avoid antiplatelet therapy (adjusted hazard ratio 0·51 [95% CI 0·25–1·03]; p=0·060). 18 (7%) participants allocated to antiplatelet therapy experienced major haemorrhagic events compared with 25 (9%) participants allocated to avoid antiplatelet therapy (0·71 [0·39–1·30]; p=0·27), and 39 [15%] participants allocated to antiplatelet therapy had major occlusive vascular events compared with 38 [14%] allocated to avoid antiplatelet therapy (1·02 [0·65–1·60]; p=0·92). Interpretation These results exclude all but a very modest increase in the risk of recurrent intracerebral haemorrhage with antiplatelet therapy for patients on antithrombotic therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage. The risk of recurrent intracerebral haemorrhage is probably too small to exceed the established benefits of antiplatelet therapy for secondary prevention. Funding British Heart Foundation.

The genome sequence strain 104 of the opportunistic pathogen Mycobacterium avium was isolated from an adult AIDS patient in Southern California in 1983. Isolates of non-paratuberculosis M. avium from 207 other patients in Southern California and elsewhere were examined for genotypic identity to strain 104. This process was facilitated by the use of a novel two-step approach. In the first step, all 208 strains in the sample were subjected to a high-throughput, large sequence polymorphism (LSP)-based genotyping test, in which DNA from each strain was tested by PCR for the presence or absence of 4 hypervariable genomic regions. Nineteen isolates exhibited an LSP type that resembled that of strain 104. This subset of 19 isolates was then subjected to high-resolution repetitive sequence-based PCR typing, which identified 10 isolates within the subset that were genotypically identical to strain 104. These isolates came from 10 different patients at 5 clinical sites in the western United States, and they were isolated over a 17-year time span. Therefore, the sequenced genome of M. avium strain 104 has been associated with disease in multiple patients in the western United States. Although M. avium is known for its genetic plasticity, these observations also show that strains of the pathogen can be genotypically stable over extended time periods.The Mycobacterium avium complex (MAC) includes the most clinically significant of the environmental mycobacteria that opportunistically infect susceptible humans. Sequencing of the genome of M. avium strain 104 is nearing completion by The Institute for Genomic Research (TIGR). Strain 104 was isolated in the mid-1980s from an adult patient with AIDS in Southern California. Like many genome sequence strains, its laboratory characteristics are amenable to genetic analysis, but there is little clinical or epidemiologic information regarding its incidence in human MAC disease. The draft sequence of strain 104 has 4,480 predicted open reading frames (ORFs). Annotation of the strain 104 genome identified genes that are shared with other virulent mycobacteria as well as genes that are unique to MAC (23). Whole-genome DNA microarray and PCR evaluation of 43 clinical isolates of M. avium relative to strain 104 revealed a 13.5% polymorphism rate between isolates (23). In comparison to M. tuberculosis, this represents an eightfold-greater strain-to-strain variability on the genomic level. In view of this genomic heterogeneity, the extent to which strain 104 is representative of virulent MAC isolates is an open question.To assess the clinical incidence of infections involving strain 104, we examined a sample of clinical isolates of M. avium from Southern California and elsewhere for genotypic identity with the genome sequence strain. Although these isolates were initially classified as M. avium subsp. avium, new data suggest that true M. avium subsp. avium strains infect a narrow spectrum of avian hosts and are described genotypically by a characteristic restriction fragment length polymorp...

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