R Loch Macdonald

Dr. R Loch Macdonald

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Research Focus & Metrics

Academic Career Length

29Years (1998-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 February 2017 in The Lancet
Verified
Journal Article
Closed access
RMR Loch Macdonald
R Loch Macdonald
TSTom A Schweizer
Tom A Schweizer

19 October 2020 in Translational Stroke Research
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Journal Article
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SNSean N. Neifert
Sean N. Neifert
ECEmily K. Chapman
Emily K. Chapman
MMMichael L. Martini
Michael L. Martini
WSWilliam H. Shuman
William H. Shuman
ASAlexander J. Schupper
Alexander J. Schupper
RMR Loch Macdonald
R Loch Macdonald

1 June 2012 in Stroke
Verified
Journal Article
Closed access
RMR Loch Macdonald
R Loch Macdonald
RHRandall T. Higashida
Randall T. Higashida
EKEmanuela Keller
Emanuela Keller
SMStephan A. Mayer
Stephan A. Mayer
AMAndy Molyneux
Andy Molyneux
NKNeal Kassell
Neal Kassell
Background and Purpose—: Clazosentan, an endothelin receptor antagonist, has been shown to reduce vasospasm after aneurysmal subarachnoid hemorrhage (aSAH). CONSCIOUS-3 assessed whether clazosentan reduced vasospasm-related morbidity and all-cause mortality postaSAH secured by endovascular coiling. Methods—: This double-blind, placebo-controlled, phase III trial randomized patients with aSAH secured by endovascular coiling to ≤14 days intravenous clazosentan (5 or 15 mg/h) or placebo. The primary composite end point (all-cause mortality; vasospasm-related new cerebral infarcts or delayed ischemic neurological deficits; rescue therapy for vasospasm) was evaluated 6 weeks postaSAH. The main secondary end point was dichotomized extended Glasgow Outcome Scale (week 12). Results—: CONSCIOUS-3 was halted prematurely following completion of CONSCIOUS-2; 577/1500 of planned patients (38%) were enrolled and 571 were treated (placebo, n=189; clazosentan 5 mg/h, n=194; clazosentan 15 mg/h, n=188). The primary end point occurred in 50/189 of placebo-treated patients (27%), compared with 47/194 patients (24%) treated with clazosentan 5 mg/h (odds ratio [OR], 0.786; 95% CI, 0.479–1.289; P= 0.340), and 28/188 patients (15%) treated with clazosentan 15 mg/h (OR, 0.474; 95% CI, 0.275–0.818; P= 0.007). Poor outcome (extended Glasgow Outcome Scale score ≤4) occurred in 24% of patients with placebo, 25% of patients with clazosentan 5 mg/h (OR, 0.918; 95% CI, 0.546–1.544; P= 0.748), and 28% of patients with clazosentan 15 mg/h (OR, 1.337; 95% CI, 0.802–2.227; P= 0.266). Pulmonary complications, anemia, and hypotension were more common in patients who received clazosentan than in those who received placebo. At week 12, mortality was 6%, 4%, and 6% with placebo, clazosentan 5 mg/h, and clazosentan 15 mg/h, respectively. Conclusions—: Clazosentan 15 mg/h significantly reduced postaSAH vasospasm-related morbidity/all-cause mortality; however, neither dose improved outcome (extended Glasgow Outcome Scale). Clinical Trial Registration—: URL: http://clinicaltrials.gov . Unique identifier: NCT00940095.

18 January 2018 in BMJ
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Journal Article
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BJBlessing N R Jaja
Blessing N R Jaja
GSGustavo Saposnik
Gustavo Saposnik
HLHester F Lingsma
Hester F Lingsma
EMErin Macdonald
Erin Macdonald
KTKevin E Thorpe
Kevin E Thorpe
RMR Loch Macdonald
R Loch Macdonald
Objective To develop and validate a set of practical prediction tools that reliably estimate the outcome of subarachnoid haemorrhage from ruptured intracranial aneurysms (SAH). Design Cohort study with logistic regression analysis to combine predictors and treatment modality. Setting Subarachnoid Haemorrhage International Trialists’ (SAHIT) data repository, including randomised clinical trials, prospective observational studies, and hospital registries. Participants Researchers collaborated to pool datasets of prospective observational studies, hospital registries, and randomised clinical trials of SAH from multiple geographical regions to develop and validate clinical prediction models. Main outcome measure Predicted risk of mortality or functional outcome at three months according to score on the Glasgow outcome scale. Results Clinical prediction models were developed with individual patient data from 10 936 patients and validated with data from 3355 patients after development of the model. In the validation cohort, a core model including patient age, premorbid hypertension, and neurological grade on admission to predict risk of functional outcome had good discrimination, with an area under the receiver operator characteristics curve (AUC) of 0.80 (95% confidence interval 0.78 to 0.82). When the core model was extended to a “neuroimaging model,” with inclusion of clot volume, aneurysm size, and location, the AUC improved to 0.81 (0.79 to 0.84). A full model that extended the neuroimaging model by including treatment modality had AUC of 0.81 (0.79 to 0.83). Discrimination was lower for a similar set of models to predict risk of mortality (AUC for full model 0.76, 0.69 to 0.82). All models showed satisfactory calibration in the validation cohort. Conclusion The prediction models reliably estimate the outcome of patients who were managed in various settings for ruptured intracranial aneurysms that caused subarachnoid haemorrhage. The predictor items are readily derived at hospital admission. The web based SAHIT prognostic calculator (http://sahitscore.com) and the related app could be adjunctive tools to support management of patients.

24 May 2016 in Neurology
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Journal Article
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STShervin Taslimi
Shervin Taslimi
AMAmirhossein Modabbernia
Amirhossein Modabbernia
SASepideh Amin-Hanjani
Sepideh Amin-Hanjani
FBFred G. Barker
Fred G. Barker
RMR Loch Macdonald
R Loch Macdonald
Objective: We pooled the results of studies on natural history of cavernous malformations (CM) to calculate point estimates and investigate main sources of heterogeneity. Methods: We searched MEDLINE, EMBASE, and ISI Web of Science for relevant studies published before May 2015. We used fixed or random effects models and meta-regression to pool the data. Results: Twenty-five studies were entered into the meta-analysis (90–1,295 patients depending on the analysis). Bleeding was defined as symptomatic hemorrhage plus radiologic evidence of hemorrhage. Sources of heterogeneity were identified as mixture of hemorrhage and rehemorrhage, mixture of rehemorrhage before and after 2 years of first bleeding, brainstem vs other locations, and calculation method. The rehemorrhage rate was higher than the hemorrhage rate (incidence rate ratio 16.5, p < 0.001, 95% confidence interval [CI] 9.7–28.0). Rehemorrhage within 2 years of the first hemorrhage was higher than after that (incidence rate ratio 1.8, p = 0.042, 95% CI 1.5–2.0). In two metaregression models, rough estimate of the annual incidence rate of hemorrhage was 0.3% (95% CI 0.1%–0.5%) and 2.8% (2.5%–3.3%) per person year in nonbrainstem and brainstem lesions and rough estimate of annual rehemorrhage rate per person year was 6.3% (3%–13.2%) and 32.3% (19.8%–52.7%) in nonbrainstem and brainstem lesions. Median time to rehemorrhage was 10.5 months. Posthemorrhage full recovery was 38.8%/person-year (28.7%–48.8%). Posthemorrhage full recovery or minimal disability was 79.5%/person-year (74.3%–84.8%). Mortality after bleeding was 2.2%. Conclusions: The incidence of symptomatic hemorrhage or rehemorrhage is higher in brainstem lesions. First symptomatic hemorrhage increases the chance of symptomatic rehemorrhage, which decreases after 2 years.

1 April 2020 in Stroke
Verified
Journal Article
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MMMonica Maher
Monica Maher
TSTom A. Schweizer
Tom A. Schweizer
RMR Loch Macdonald
R Loch Macdonald