Patient outcomes in historical comparators compared with randomised-controlled trials

Routine low-dose continuous or nocturnal oxygen for people with acute stroke: three-arm Stroke Oxygen Supplementation RCT

BACKGROUND

Stroke is a major cause of death and disability worldwide. Hypoxia is common after stroke and is associated with worse outcomes. Oxygen supplementation could prevent hypoxia and secondary brain damage.

OBJECTIVES

(1) To assess whether or not routine low-dose oxygen supplementation in patients with acute stroke improves outcome compared with no oxygen; and (2) to assess whether or not oxygen given at night only, when oxygen saturation is most likely to be low, is more effective than continuous supplementation.

DESIGN

Multicentre, prospective, randomised, open, blinded-end point trial.

SETTING

Secondary care hospitals with acute stroke wards.

PARTICIPANTS

Adult stroke patients within 24 hours of hospital admission and 48 hours of stroke onset, without definite indications for or contraindications to oxygen or a life-threatening condition other than stroke.

INTERVENTIONS

Allocated by web-based minimised randomisation to: (1) continuous oxygen: oxygen via nasal cannula continuously (day and night) for 72 hours after randomisation at a flow rate of 3 l/minute if baseline oxygen saturation was ≤ 93% or 2 l/minute if > 93%; (2) nocturnal oxygen: oxygen via nasal cannula overnight (21:00-07:00) for three consecutive nights. The flow rate was the same as the continuous oxygen group; and (3) control: no routine oxygen supplementation unless required for reasons other than stroke.

MAIN OUTCOME MEASURES

Primary outcome: disability assessed by the modified Rankin Scale (mRS) at 3 months by postal questionnaire (participant aware, assessor blinded). Secondary outcomes at 7 days: neurological improvement, National Institutes of Health Stroke Scale (NIHSS), mortality, and the highest and lowest oxygen saturations within the first 72 hours. Secondary outcomes at 3, 6, and 12 months: mortality, independence, current living arrangements, Barthel Index, quality of life (European Quality of Life-5 Dimensions, three levels) and Nottingham Extended Activities of Daily Living scale by postal questionnaire.

RESULTS

In total, 8003 patients were recruited between 24 April 2008 and 17 June 2013 from 136 hospitals in the UK [continuous, n = 2668; nocturnal, n = 2667; control, n = 2668; mean age 72 years (standard deviation 13 years); 4398 (55%) males]. All prognostic factors and baseline characteristics were well matched across the groups. Eighty-two per cent had ischaemic strokes. At baseline the median Glasgow Coma Scale score was 15 (interquartile range 15-15) and the mean and median NIHSS scores were 7 and 5 (range 0-34), respectively. The mean oxygen saturation at randomisation was 96.6% in the continuous and nocturnal oxygen groups and 96.7% in the control group. Primary outcome: oxygen supplementation did not reduce disability in either the continuous or the nocturnal oxygen groups. The unadjusted odds ratio for a better outcome (lower mRS) was 0.97 [95% confidence interval (CI) 0.89 to 1.05; p = 0.5] for the combined oxygen groups (both continuous and nocturnal together) (n = 5152) versus the control (n = 2567) and 1.03 (95% CI 0.93 to 1.13; p = 0.6) for continuous versus nocturnal oxygen. Secondary outcomes: oxygen supplementation significantly increased oxygen saturation, but did not affect any of the other secondary outcomes.

LIMITATIONS

Severely hypoxic patients were not included.

CONCLUSIONS

Routine low-dose oxygen supplementation in stroke patients who are not severely hypoxic is safe, but does not improve outcome after stroke.

FUTURE WORK

To investigate the causes of hypoxia and develop methods of prevention.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN52416964 and European Union Drug Regulating Authorities Clinical Trials (EudraCT) number 2006-003479-11.

FUNDING DETAILS

This project was funded by the National Institute for Health Research (NIHR) Research for Patient Benefit and Health Technology Assessment programmes and will be published in full in Health Technology Assessment; Vol. 22, No. 14. See the NIHR Journals Library website for further project information.

Effect of Routine Low-Dose Oxygen Supplementation on Death and Disability in Adults With Acute Stroke: The Stroke Oxygen Study Randomized Clinical Trial

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 PARTICIPANTS

In 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 MEASURES

The 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.

TRIAL REGISTRATION

ISRCTN Identifier: ISRCTN52416964.

Nationwide survey of decompressive hemicraniectomy for malignant middle cerebral artery infarction in Japan

OBJECTIVE

Decompressive hemicraniectomy (DHC) for malignant middle cerebral artery (MCA) infarction has been shown to reduce mortality and improve functional outcomes in young adults; however, there is currently debate regarding how routinely such surgery should be performed in the clinical setting, considering the very high rate of disability and functional dependence among survivors. We herein report the current status of the frequency of and indications for DHC for malignant MCA infarction in Japan.

METHODS

We retrospectively studied of cohort cases of DHC for malignant MCA infarction treated at pivotal teaching neurosurgical departments in Japan between January 2011 and December 2011. Information was obtained regarding patient characteristics, radiologic features, and outcomes during follow-up. The end points included 30-day mortality rate and functional outcomes, as measured according to the modified Rankin scale (mRS) score at 3 months.

RESULTS

Three hundred fifty-five patients underwent DHC at 259 neurosurgical departments who replied to the survey, corresponding to a rate of 8.7% of the 4092 candidates with malignant MCA infarction, the latter being equivalent to 8.5% of patients with acute ischemic stroke identified during the same period. Among the patients undergoing DHC, the mean age was 67.0 years, and those ≥60 years of age comprised 80.2% of all DHC patients. The most frequently used modality for vascular imaging was magnetic resonance angiography (77.2%). DHC generally was performed between 24 and 48 hours after onset (38.9%), with 36.9% of patients undergoing surgery at ≥48 hours. At the time of surgery, 26.1% of the patients had a Glasgow Coma Scale score of ≤6. Presurgical midbrain compression was noted in 52.1% of the patients. The 30-day mortality after DHC was 18.6%, and factors affecting death were a Glasgow Coma Scale score of ≤6 (odds ratio [OR] 1.88, 95% confidence interval [95% CI] 1.05-3.32, P = 0.03) and midbrain compression (OR 2.28, 95% CI 1.31-4.09, P = 0.005). According to the multivariate analysis, only midbrain compression was an independent risk factor (OR 2.12, 95% CI 1.16-3.95, P = 0.01) for 30-day mortality. Modified Rankin scale scores at 3 months were available in 175 patients (49.3%), only 5.2% of whom exhibited a favorable functional outcome (mRS score ≤3). Meanwhile, 22.9% of the patients had an mRS score of 4, 26.9% had an mRS score of 5, and 45.1% were found to have died.

CONCLUSIONS

In the present study, less than one-tenth of candidates with malignant MCA infarction in Japan underwent decompressive surgery, and the vast majority of patients were elderly. Age was not found to be an independent factor for immediate mortality in this study, and performing surgery in the elderly may be justified based on additional evidence of functional improvements.

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

BACKGROUND

The Stroke Oxygen Study (SO₂S) is a multi-center randomized controlled trial of oxygen supplementation in patients with acute stroke. The main hypothesis for the trial is that fixed-dose oxygen treatment during the first 3 days after an acute stroke improves outcome. The secondary hypothesis is that restricting oxygen supplementation to night time only is more effective than continuous supplementation. This paper describes the statistical analysis plan for the study.

METHODS AND DESIGN

Patients (n = 8000) are randomized to three groups: (1) continuous oxygen supplementation for 72 hours; (2) nocturnal oxygen supplementation for three nights; and (3) no routine oxygen supplementation. Outcomes are recorded at 7 days, 90 days, 6 months, and 12 months. The primary outcome measure is the modified Rankin scale at 90 days. Data will be analyzed according to the intention-to-treat principle. Methods of statistical analysis are described, including the handling of missing data, the covariates used in adjusted analyses, planned subgroups analyses, and planned sensitivity analyses.

TRIAL REGISTRATION

This trial is registered with the ISRCTN register, number ISRCTN52416964 (30 September 2005).

The Virtual International Stroke Trials Archive (VISTA): Results and Impact on Future Stroke Trials and Management of Stroke Patients

Background

The Virtual International Stroke Trials Archive was established to improve stroke care and trial design through the collation, categorization and potential access to data sets from clinical trials for the treatment of stroke.

Methods

Virtual International Stroke Trials Archive currently provides access to a combined data set of 29 anonymised acute stroke trials and one acute stroke registry with data on >27 500 patients aged between 18 and 103 (mean 71) years.

Results

Virtual International Stroke Trials Archive has facilitated research across a broad canvas. The prognosis was poor in patients with very high blood pressure at the time of admission or with a wide variability of systolic blood pressure during the acute phase. The late occurrence of hyperthermia following an ischaemic stroke worsens the prognosis. Stroke lateralisation is not an important predictor of cardiac adverse events or 90-day mortality. Haemorrhagic transformation is seen frequently in patients with cardio-embolic strokes and is associated with a poor prognosis when occurring after the acute phase. Virtual International Stroke Trials Archive has allowed various prognostic models for patients with ischaemic or haemorrhagic stroke to be established and validated. More direct outcomes such as lesion volume can be useful in phase II clinical trials for determining whether a phase III trial should be undertaken. New outcome measures such as ‘home time’ may also strengthen future trials. On a worldwide level, the prognosis of stroke patients differs considerably between various countries.

Conclusion

Virtual International Stroke Trials Archive provides an excellent opportunity for analysis of natural history data and prognosis. It has the potential to influence clinical trial design and implementation through exploratory data analyses.