Statistical analysis plan for the Stroke Oxygen Study (SO2S): a multi-center randomized controlled trial to assess whether routine oxygen supplementation in the first 72 hours after a stroke improves long-term outcome

Sim, Julius; Gray, Richard; Nevatte, Tracy; Howman, Andrew; Ives, Natalie; Roffe, Christine

doi:10.1186/1745-6215-15-229

Cited by 2 publications

(4 citation statements)

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“…This was a multicenter randomized clinical trial of oxygen supplementation with single-blind outcome assessment. The protocol and statistical analysis plan (Supplement 1 and Supplement 2), and data collection forms are published. Fully informed written or witnessed oral consent was given by the participants or, if they did not have capacity to consent, by a legal representative.…”

Section: Methodsmentioning

confidence: 99%

“…The initial recruitment target was 6000 participants, which was estimated to provide 90% power to detect small (0.2 mRS-point [eg, a 1-point improvement among 1 in 5 participants]) differences between oxygen (continuous and night-only groups combined) and no oxygen at a P value of less than or equal to .01 and 90% power at a P value of less than or equal to .05 to detect small differences between continuous oxygen and nocturnal-only oxygen. The study size was subsequently revised to 8000 participants, using ordinal methods, without knowledge of interim results, to increase the number of patients with severe stroke and thereby provide greater power to investigate any differential effectiveness of oxygen vs control within subgroups (defined by severity).…”

Section: Methodsmentioning

confidence: 99%

“…Additional imputations were performed to allow for the possibility that data were missing not at random and were either better or worse than expected; missing values were thereby replaced by either very good (ie, lowest) or very poor (ie, highest) scores on the mRS as appropriate (eTable 3 in Supplement 3). Subgroups, for the mRS only, were analyzed by an interaction term and were predefined in the statistical analysis plan …”

Section: Methodsmentioning

confidence: 99%

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Effect of Routine Low-Dose Oxygen Supplementation on Death and Disability in Adults With Acute Stroke

Roffe

Nevatte

Sim

et al. 2017

JAMA

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160

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IMPORTANCE Hypoxia is common in the first few days after acute stroke, is frequently intermittent, and is often undetected. Oxygen supplementation could prevent hypoxia and secondary neurological deterioration and thus has the potential to improve recovery. OBJECTIVE To assess whether routine prophylactic low-dose oxygen therapy was more effective than control oxygen administration in reducing death and disability at 90 days, and if so, whether oxygen given at night only, when hypoxia is most frequent, and oxygen administration is least likely to interfere with rehabilitation, was more effective than continuous supplementation. DESIGN, SETTING, AND PARTICIPANTSIn this single-blind randomized clinical trial, 8003 adults with acute stroke were enrolled from 136 participating centers in the United Kingdom within 24 hours of hospital admission if they had no clear indications for or contraindications to oxygen treatment (first patient enrolled April 24, 2008; last follow-up January 27, 2015).INTERVENTIONS Participants were randomized 1:1:1 to continuous oxygen for 72 hours (n = 2668), nocturnal oxygen (21:00 to 07:00 hours) for 3 nights (n = 2667), or control (oxygen only if clinically indicated; n = 2668). Oxygen was given via nasal tubes at 3 L/min if baseline oxygen saturation was 93% or less and at 2 L/min if oxygen saturation was greater than 93%. MAIN OUTCOMES AND MEASURESThe primary outcome was reported using the modified Rankin Scale score (disability range, 0 [no symptoms] to 6 [death]; minimum clinically important difference, 1 point), assessed at 90 days by postal questionnaire (participant aware, assessor blinded). The modified Rankin Scale score was analyzed by ordinal logistic regression, which yields a common odds ratio (OR) for a change from one disability level to the next better (lower) level; OR greater than 1.00 indicates improvement.RESULTS A total of 8003 patients (4398 (55%) men; mean [SD] age, 72 [13] years; median National Institutes of Health Stroke Scale score, 5; mean baseline oxygen saturation, 96.6%) were enrolled. The primary outcome was available for 7677 (96%) participants. The unadjusted OR for a better outcome (calculated via ordinal logistic regression) was 0.97 (95% CI, 0.89 to 1.05; P = .47) for oxygen vs control, and the OR was 1.03 (95% CI, 0.93 to 1.13; P = .61) for continuous vs nocturnal oxygen. No subgroup could be identified that benefited from oxygen. At least 1 serious adverse event occurred in 348 (13.0%) participants in the continuous oxygen group, 294 (11.0%) in the nocturnal group, and 322 (12.1%) in the control group. No significant harms were identified.CONCLUSIONS AND RELEVANCE Among nonhypoxic patients with acute stroke, the prophylactic use of low-dose oxygen supplementation did not reduce death or disability at 3 months. These findings do not support low-dose oxygen in this setting.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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