Adding new experimental arms to randomised clinical trials: Impact on error rates.

BACKGROUND: Experimental treatments pass through various stages of development. If a treatment passes through early-phase experiments, the investigators may want to assess it in a late-phase randomised controlled trial. An efficient way to do this is adding it as a new research arm to an ongoing trial while the existing research arms continue, a so-called multi-arm platform trial. The familywise type I error rate is often a key quantity of interest in any multi-arm platform trial. We set out to clarify how it should be calculated when new arms are added to a trial some time after it has started. METHODS: We show how the familywise type I error rate, any-pair and all-pairs powers can be calculated when a new arm is added to a platform trial. We extend the Dunnett probability and derive analytical formulae for the correlation between the test statistics of the existing pairwise comparison and that of the newly added arm. We also verify our analytical derivation via simulations. RESULTS: Our results indicate that the familywise type I error rate depends on the shared control arm information (i.e. individuals in continuous and binary outcomes and primary outcome events in time-to-event outcomes) from the common control arm patients and the allocation ratio. The familywise type I error rate is driven more by the number of pairwise comparisons and the corresponding (pairwise) type I error rates than by the timing of the addition of the new arms. The familywise type I error rate can be estimated using Sidák's correction if the correlation between the test statistics of pairwise comparisons is less than 0.30. CONCLUSIONS: The findings we present in this article can be used to design trials with pre-planned deferred arms or to add new pairwise comparisons within an ongoing platform trial where control of the pairwise error rate or familywise type I error rate (for a subset of pairwise comparisons) is required.

Anti-IL-5 treatments in patients with severe asthma by blood eosinophil thresholds: Indirect treatment comparison.

BACKGROUND: Three anti-IL-5 pathway-directed therapies are approved for use in patients with severe eosinophilic asthma (SEA); however, no head-to-head comparison data are available. OBJECTIVE: We sought to compare the efficacy of licensed doses of mepolizumab, benralizumab, and reslizumab in patients with SEA, according to baseline blood eosinophil counts. METHODS: This indirect treatment comparison (ITC) used data from a Cochrane review and independent searches. Eligible studies were randomized controlled trials in patients aged 12 years or greater with SEA. End points included annualized rate of clinically significant exacerbations and change from baseline in Asthma Control Questionnaire score and FEV1. An ITC was performed in patients with Asthma Control Questionnaire scores of 1.5 or greater and stratified by baseline blood eosinophil count. RESULTS: Eleven studies were included. All treatments significantly reduced the rate of clinically significant exacerbations and improved asthma control versus placebo in all blood eosinophil count subgroups. Mepolizumab reduced clinically significant exacerbations by 34% to 45% versus benralizumab across subgroups (rate ratio ≥400 cells/µL: 0.55 [95% CI, 0.35-0.87]; ≥300 cells/µL: 0.61 [95% CI, 0.37-0.99]; and ≥150 cells/µL: 0.66 [95% CI, 0.49-0.89]; all P < .05) and by 45% versus reslizumab in the 400 cells/µL or greater subgroup (rate ratio, 0.55 [95% CI, 0.36-0.85]; P = .007). Asthma control was significantly improved with mepolizumab versus benralizumab (all subgroups: P < .05) and versus reslizumab in the 400 cells/µL or greater subgroup (P = .004). Benralizumab significantly improved lung function versus reslizumab in the 400 cells/µL or greater subgroup (P = .025). CONCLUSIONS: This ITC of the licensed doses suggests that mepolizumab was associated with significantly greater improvements in clinically significant exacerbations and asthma control compared with reslizumab or benralizumab in patients with similar blood eosinophil counts.

Mepolizumab reduces exacerbations in patients with severe eosinophilic asthma, irrespective of body weight/body mass index: meta-analysis of MENSA and MUSCA.

BACKGROUND: We assessed the efficacy of the licensed mepolizumab dose (100 mg subcutaneously [SC]) in patients with severe eosinophilic asthma according to body weight/body mass index (BMI). METHODS: This was a post hoc individual patient-level meta-analysis of data from the Phase 3 studies MENSA (MEA115588/NCT01691521) and MUSCA (200862/NCT02281318). Patients aged ≥12 years with severe eosinophilic asthma and a history of exacerbations were randomised to 4-weekly placebo, mepolizumab 75 mg intravenously (IV) or 100 mg SC (MENSA) or placebo or mepolizumab 100 mg SC (MUSCA) for 32 (MENSA) or 24 (MUSCA) weeks. The primary endpoint was the annual rate of clinically significant exacerbations; other outcomes included the proportion of patients with no exacerbations, lung function, St George's Respiratory Questionnaire (SGRQ) and Asthma Control Questionnaire-5 (ACQ-5) scores and blood eosinophil counts. Analyses were performed by baseline body weight and BMI (≤60, > 60-75, > 75-90, > 90, < 100, ≥100 kg; ≤25, > 25-30, > 30, < 36, ≥36 kg/m2). RESULTS: Overall, 936 patients received placebo or mepolizumab 100 mg SC. Across all body weight/BMI categories, mepolizumab reduced the rate of clinically significant exacerbations by 49-70% versus placebo. Improvements with mepolizumab versus placebo were also seen in lung function in all body weight/BMI categories except > 90 kg; improvements in SGRQ and ACQ-5 scores were seen across all categories. CONCLUSIONS: Mepolizumab 100 mg SC has consistent clinical benefits in patients with severe eosinophilic asthma across a range of body weights and BMIs. Data show that the fixed-dose regimen of mepolizumab is suitable, without the need for weight-based dosing. TRIAL REGISTRATION: This manuscript is a post hoc meta-analysis of data from the Phase 3 studies MENSA and MUSCA. ClinicalTrials.gov, NCT01691521 (MEA115588; MENSA). Registered September 24, 2012. ClinicalTrials.gov, NCT02281318 (200862; MUSCA). Registered November 3, 2014.

Treatment policy estimands for recurrent event data using data collected after cessation of randomised treatment.

In the past, many clinical trials have withdrawn subjects from the study when they prematurely stopped their randomised treatment and have therefore only collected 'on-treatment' data. Thus, analyses addressing a treatment policy estimand have been restricted to imputing missing data under assumptions drawn from these data only. Many confirmatory trials are now continuing to collect data from subjects in a study even after they have prematurely discontinued study treatment as this event is irrelevant for the purposes of a treatment policy estimand. However, despite efforts to keep subjects in a trial, some will still choose to withdraw. Recent publications for sensitivity analyses of recurrent event data have focused on the reference-based imputation methods commonly applied to continuous outcomes, where imputation for the missing data for one treatment arm is based on the observed outcomes in another arm. However, the existence of data from subjects who have prematurely discontinued treatment but remained in the study has now raised the opportunity to use this 'off-treatment' data to impute the missing data for subjects who withdraw, potentially allowing more plausible assumptions for the missing post-study-withdrawal data than reference-based approaches. In this paper, we introduce a new imputation method for recurrent event data in which the missing post-study-withdrawal event rate for a particular subject is assumed to reflect that observed from subjects during the off-treatment period. The method is illustrated in a trial in chronic obstructive pulmonary disease (COPD) where the primary endpoint was the rate of exacerbations, analysed using a negative binomial model.

Obstructive sleep apnoea and quality of life in Ehlers-Danlos syndrome: a parallel cohort study.

BACKGROUND: Patients with the connective tissue disorder Ehlers-Danlos syndrome (EDS) often suffer from fatigue, excessive daytime sleepiness and impaired quality of life. Obstructive sleep apnoea (OSA) may be an underlying cause for these symptoms but its prevalence in this population is unclear. METHODS: In this prospective parallel-cohort study, we included 100 adult patients with EDS (46% hypermobile-type, 35% classical-type and 19% other), which were one-to-one matched to 100 healthy adult controls according to sex, age, weight and height. Participants underwent structured interviews (including short-form 36) and level-3 respiratory polygraphy. OSA was defined as apnoea-hypopnea index ≥5/hour. Photographic craniofacial phenotyping was conducted in a subgroup. Conditional logistic regression was used to compare the prevalence of OSA. RESULTS: In patients with EDS, OSA prevalence was 32% versus 6% in the matched control group (OR 5.3 (95% CI 2.5 to 11.2); p<0.001). The EDS group reported impaired quality of life in all dimensions (p<0.05) and significantly higher excessive daytime sleepiness measured by the Epworth Sleepiness Scale (median (quartiles) 11 (7-14) vs 7 (5-10); p<0.001). OSA severity was positively associated with daytime sleepiness and lower quality of life in the EDS group. There was no evidence of a difference between the two study groups in terms of craniofacial phenotypes. CONCLUSIONS: The prevalence of OSA is higher in patients with EDS than in a matched control group. This is of clinical relevance as it is associated with fatigue, excessive daytime sleepiness and impaired quality of life. Further studies are needed to assess the clinical benefit of OSA treatment in patients with EDS. TRIAL REGISTRATION NUMBER: NCT02435745.

Effect of rituximab on pulmonary function in patients with rheumatoid arthritis.

BACKGROUND: Rituximab (RTX), a B-cell depleting monoclonal antibody is increasingly used in several antibody-mediated diseases. It has been reported to cause pulmonary toxicity, though mainly during polychemotherapy of malignant lymphoma. Prospective data on RTX-induced pulmonary complications in patients with rheumatoid arthritis (RA) are lacking. METHODS AND METHODS: Serial spirometries and measurements of diffusion capacity of the lung for carbon monoxide (DLCO) in patients with RA before and 2, 4, 8, and 26 weeks after treatment with RTX were performed. A reduction from baseline of forced vital capacity (FVC) of ≥10%, or ≥15% of DLCO was defined as indicative for pulmonary toxicity. RESULTS: Thirty-three patients (mean (SD) age 59 (12) years, 27% males) were included. Mean (SD) FVC predicted and DLCO predicted at baseline were 108% (18%) and 88% (18%), respectively. In contrast to FVC, DLCO showed a progressive decline during follow-up with a maximum reduction of 6.1% (95%CI 2.5%, 9.7%; p = 0.001) at 26 weeks compared with baseline. After 26 weeks, 22% of the patients had a ≥15% DLCO decline. None of the patients reported increased dyspnea during follow-up. Risk factors for pulmonary function changes after treatment with RTX were cigarette smoking, repeated administration of the drug, and co-medication with Prednisone. CONCLUSION: Although no cases of symptomatic lung injury were observed, the progressive DLCO decline seems to indicate the presence of subclinical RTX-induced pulmonary toxicity.

Target-controlled versus fractionated propofol sedation in flexible bronchoscopy: A randomized noninferiority trial.

BACKGROUND AND OBJECTIVE: Fractionated propofol administration (FPA) in flexible bronchoscopy (FB) may lead to oversedation and an increased risk of adverse events, because a stable plasma concentration of propofol is not maintainable. The purpose of this randomized noninferiority trial was to evaluate whether target-controlled infusion (TCI) of propofol is noninferior to FPA in terms of safety in FB. METHODS: Coprimary outcomes were the mean lowest arterial oxygen saturation (SpO2 ) during FB and the number of propofol dose adjustments in relation to procedure duration. Secondary outcomes were the number of occasions with SpO2 < 90% and/or oxygen desaturations of >4% from baseline, number of occasions with systolic blood pressure < 90 mm Hg, cough frequency, cumulative propofol dose, recovery time, maximum transcutaneous CO2 , mean SpO2 and O2 delivery during FB. RESULTS: Seventy-seven patients were included. TCI was noninferior to FPA in terms of mean (standard deviation) lowest SpO2 during the procedure (88.3% (5.4%) vs 86.9% (7.3%)) and required fewer dose adjustments (0.04/min vs 0.28/min, P < 0.001) but a higher cumulative propofol dose (264 vs 194 mg, P = 0.003). All other secondary outcomes were comparable between the groups. CONCLUSION: We suggest that TCI of propofol is a favourable sedation technique for FB with equal safety issues and fewer dose adjustments compared with FPA.

The Roles of the Charlson Comorbidity Index and Time to First Antibiotic Dose as Predictors of Outcome in Pneumococcal Community-Acquired Pneumonia.

PURPOSE: In this retrospective study, we aimed to investigate the role of comorbidities using the Charlson comorbidity index (CCI) and time to first antibiotic dose (TFAD) in patients with pneumococcal community-acquired pneumonia (PCAP). METHODS: All consecutive ER admissions with PCAP who were hospitalized in the University Hospital, Zurich between 2006 and 2012 were included. The primary outcome was to determine possible determinants of all-cause in-hospital mortality (ACIHM). The second endpoint was to detect risk factors for adverse events (AEs) and determinants of length of stay (LOS). RESULTS: 108 subjects (mean age 57.6 years) were included. The median (IQR) CCI was 4 (1, 8). The median (IQR) TFAD was 210 (150, 280) min. ACIHM was 6.5 % (7/108), and median (IQR) LOS was 9 (6, 14) days. PCAP-related AEs were observed in 57 cases (52.8 %). In the multivariable analysis, neither CCI nor TFAD was associated with the outcome measures. Pneumonia severity index (PSI) was the only statistically significant predictor of ACIHM (HR 1.31/10 point increase, 95 % CI 1.12-1.53, p = 0.001) and AE rate (OR 1.31, 95 % CI 1.15-1.50, p < 0.001). CONCLUSIONS: In this study including comparatively young patients with rather mild disease severity, we found no strong evidence supporting that CCI or TFAD influenced short-term outcome measures of PCAP. Yet, pneumonia severity appears to be the most important factor for the outcome.

Sedation during bronchoscopy: data from a nationwide sedation and monitoring survey.

BACKGROUND: There is limited knowledge on practice patterns in procedural sedation and analgesia (PSA), the use of propofol, and monitoring during flexible bronchoscopy (FB). The purpose of this study was to assess the current practice patterns of FBs and to focus on the use of propofol, the education of the proceduralist, and the involvement of anaesthesiologists during FB. METHODS: An anonymous questionnaire was sent to 299 pulmonologists. Only respondents who were active physicians in adult respiratory medicine performing FB were subsequently analysed. RESULTS: The response rate was 78 % and 27,149 FB in the previous 12 months were analysed. The overall sedation-related morbidity rate was 0.02 % and mortality was 7/100'000 FB. Sedation was used in 95 % of bronchoscopies. The main drugs used for PSA were propofol (77 %) and midazolam (46 %). In 84 % of PSAs propofol was used without the attendance of an anaesthesiologist. The use of propofol was associated with high volume bronchoscopists (p < 0.010) and career-young pulmonologists (p < 0.001). While monitoring vital parameters has become standard practice, pulmonologists reported a very low rate of systematic basic education and training in the field of PSA (50 %). CONCLUSIONS: In Switzerland, PSA during FB is mostly performed with propofol without the attendance of an anaesthesiologist and the use of this drug is expected to increase in the future. While monitoring standards are very high there is need for policies to improve education, systematic training, and support for pulmonologists for PSA during FB.

The impact of obstructive sleep apnoea on the aorta.

Obstructive sleep apnoea (OSA) has been shown to be a causal factor in the pathogenesis of vascular dysfunction and hypertension, conditions which can promote dilation and subsequent aortic dissection and rupture. The objective of this review is to summarise the current literature on the possible association between OSA and aortic disease and delineate the underlying mechanisms.Relevant studies were found by searching for terms including "obstructive sleep apnoea" in combination with "aortic aneurysm, dissection, and dilation" in the MEDLINE and EMBASE databases.Observational studies consistently reported that OSA is highly prevalent among patients with aortic aneurysms and aortic dissections. Patients with co-occurring OSA and Marfan's syndrome as well as patients at the more severe end of the spectrum of OSA seem to be especially vulnerable to aortic disease.Several mechanisms are discussed concerning the link between OSA and aortic disease: nocturnal negative intrathoracic pressure surges leading to mechanical stretching of the aorta and ultimately aortic distension; arousal-induced reflex sympathetic activation with subsequent hypertension; and intermittent hypoxia associated with autonomic nervous system activation and consequently increased oxidative stress. Further well controlled studies are needed in order to define the exact role of OSA as a risk factor for aortic disease.

CPAP vs Mandibular Advancement Devices and Blood Pressure in Patients With Obstructive Sleep Apnea: A Systematic Review and Meta-analysis.

IMPORTANCE: Obstructive sleep apnea is associated with higher levels of blood pressure (BP), which can lead to increased cardiovascular risk. OBJECTIVE: To compare the association of continuous positive airway pressure (CPAP), mandibular advancement devices (MADs), and inactive control groups (placebo or no treatment) with changes in systolic BP (SBP) and diastolic BP (DBP) in patients with obstructive sleep apnea. DATA SOURCES: The databases of MEDLINE, EMBASE, and the Cochrane Library were searched up to the end of August 2015 and study bibliographies were reviewed. STUDY SELECTION: Randomized clinical trials comparing the effect of CPAP or MADs (vs each other or an inactive control) on BP in patients with obstructive sleep apnea were selected by consensus. Of 872 studies initially identified, 51 were selected for analysis. DATA EXTRACTION AND SYNTHESIS: Data were extracted by one reviewer and checked by another reviewer. A network meta-analysis using multivariate random-effects meta-regression was used to estimate pooled differences between each intervention. Meta-regression was used to assess the association between trial characteristics and the reported effects of CPAP vs inactive control. MAIN OUTCOMES AND MEASURES: Absolute change in SBP and DBP from baseline to follow-up. RESULTS: Of the 51 studies included in the analysis (4888 patients), 44 compared CPAP with an inactive control, 3 compared MADs with an inactive control, 1 compared CPAP with an MAD, and 3 compared CPAP, MADs, and an inactive control. Compared with an inactive control, CPAP was associated with a reduction in SBP of 2.5 mm Hg (95% CI, 1.5 to 3.5 mm Hg; P < .001) and in DBP of 2.0 mm Hg (95% CI, 1.3 to 2.7 mm Hg; P < .001). A 1-hour-per-night increase in mean CPAP use was associated with an additional reduction in SBP of 1.5 mm Hg (95% CI, 0.8 to 2.3 mm Hg; P < .001) and an additional reduction in DBP of 0.9 mm Hg (95% CI, 0.3 to 1.4 mm Hg; P = .001). Compared with an inactive control, MADs were associated with a reduction in SBP of 2.1 mm Hg (95% CI, 0.8 to 3.4 mm Hg; P = .002) and in DBP of 1.9 mm Hg (95% CI, 0.5 to 3.2 mm Hg; P = .008). There was no significant difference between CPAP and MADs in their association with change in SBP (-0.5 mm Hg [95% CI, -2.0 to 1.0 mm Hg]; P = .55) or in DBP (-0.2 mm Hg [95% CI, -1.6 to 1.3 mm Hg]; P = .82). CONCLUSIONS AND RELEVANCE: Among patients with obstructive sleep apnea, both CPAP and MADs were associated with reductions in BP. Network meta-analysis did not identify a statistically significant difference between the BP outcomes associated with these therapies.

Effect of CPAP on blood pressure in patients with minimally symptomatic obstructive sleep apnoea: a meta-analysis using individual patient data from four randomised controlled trials.

BACKGROUND: CPAP reduces blood pressure (BP) in patients with symptomatic obstructive sleep apnoea (OSA). Whether the same benefit is present in patients with minimally symptomatic OSA is unclear, thus a meta-analysis of existing trial data is required. METHODS: The electronic databases Medline, Embase and trial registries were searched. Trials were eligible if they included patients with minimally symptomatic OSA, had randomised them to receive CPAP or either sham-CPAP or no CPAP, and recorded BP at baseline and follow-up. Individual participant data were obtained. Primary outcomes were absolute change in systolic and diastolic BP. FINDINGS: Five eligible trials were found (1219 patients) from which data from four studies (1206 patients) were obtained. Mean (SD) baseline systolic and diastolic BP across all four studies was 131.2 (15.8) mm Hg and 80.9 (10.4) mm Hg, respectively. There was a slight increase in systolic BP of 1.1 mm Hg (95% CI -0.2 to 2.3, p=0.086) and a slight reduction in diastolic BP of 0.8 mm Hg (95% CI -1.6 to 0.1, p=0.083), although the results were not statistically significant. There was some evidence of an increase in systolic BP in patients using CPAP <4 h/night (1.5 mm Hg, 95% CI -0.0 to 3.1, p=0.052) and reduction in diastolic BP in patients using CPAP >4 h/night (-1.4 mm Hg, 95% CI -2.5 to -0.4, p=0.008). CPAP treatment reduced both subjective sleepiness (p<0.001) and OSA severity (p<0.001). INTERPRETATION: Although CPAP treatment reduces OSA severity and sleepiness, it seems not to have a beneficial effect on BP in patients with minimally symptomatic OSA, except in patients who used CPAP for >4 h/night.

A multi-arm multi-stage clinical trial design for binary outcomes with application to tuberculosis.

BACKGROUND: Randomised controlled trials are becoming increasingly costly and time-consuming. In 2011, Royston and colleagues proposed a particular class of multi-arm multi-stage (MAMS) designs intended to speed up the evaluation of new treatments in phase II and III clinical trials. Their design, which controls the type I error rate and power for each pairwise comparison, discontinues randomisation to poorly performing arms at interim analyses if they fail to show a pre-specified level of benefit over the control arm. Arms in which randomisation is continued to the final stage of the trial are compared against the control on a definitive time-to-event outcome measure. To increase efficiency, interim comparisons can be made on an intermediate time-to-event outcome which is on the causal pathway to the definitive outcome. METHODS: We adapt Royston's MAMS design to binary outcomes observed at the end of a fixed follow-up period and analysed using an absolute difference in proportions. We apply the design to tuberculosis (TB), an area where many new drugs are in development, and demonstrate how it can greatly accelerate the evaluation of new TB regimens. We use simulations to support the extensions to the methodology and to investigate the amount of bias in the estimated treatment effects of arms in which randomisation is ceased at the first interim analysis and arms which continue to the final stage of the trial. RESULTS: The proposed seamless phase II/III TB trial designs are shown to greatly reduce sample size requirements and trial duration compared to conducting separate phase II and III trials. The bias in the estimated treatment effects for the definitive outcome is shown to be small, especially when treatment selection is based on an intermediate outcome or when a reanalysis is performed at the planned end of the trial after all recruited patients have completed follow-up. CONCLUSIONS: The proposed designs are practical and could be used in a variety of disease areas. They hold considerable promise for speeding up the evaluation of new treatments particularly in TB where many new regimens will soon be available for testing in phase II and phase III trials.

Patient-Reported Outcome Measures for Severe Recurrent Bilateral Nasal Polyps: Psychometric Evaluation and Content Validity.

Objective: To date, no patient-reported outcome measures have been specifically developed to assess pharmacological treatment effect in participants with severe chronic rhinosinusitis (CRS) with recurrent bilateral nasal polyps (NP). These studies aimed to assess (1) the psychometric properties and (2) content validity of Visual Analogue Scales (VAS) assessing NP symptom severity. Study Design: (1) Retrospective psychometric validation study using clinical trial data and (2) cross-sectional qualitative patient interview study. Setting: (1) Multicentre trial; (2) real-world. Methods: (1) Psychometric validation was performed using data from a randomized, double-blind, placebo-controlled, Phase II study (NCT01362244) investigating the effect of mepolizumab in 105 participants with severe, recurrent bilateral NP currently needing polypectomy surgery. (2) Content validity was explored through cognitive debriefing interviews in 27 adults with severe CRS with recurrent bilateral NP who had received NP surgery in the past 10 years (NCT03221192). Results: (1) Acceptable reliability, validity, and responsiveness were shown for individual VAS items, although the loss of smell VAS item performed poorly in several analyses, suggesting further evaluation of this item is needed. (2) All individual VAS items were well understood, considered relevant and were consistently interpreted by most participants, providing evidence for their content validity. Conclusion: These findings support the use of symptom VAS measures to evaluate disease experience and treatment effect in clinical trials of participants with severe CRS with recurrent bilateral NP.

Continuous positive airway pressure improves sleepiness but not calculated vascular risk in patients with minimally symptomatic obstructive sleep apnoea: the MOSAIC randomised controlled trial.

BACKGROUND: Continuous positive airway pressure (CPAP) for symptomatic obstructive sleep apnoea (OSA) improves sleepiness and reduces vascular risk, but such treatment for the more prevalent, minimally symptomatic disease is contentious. METHODS: This multicentre, randomised controlled, parallel, hospital-based trial across the UK and Canada, recruited 391 patients with confirmed OSA (oxygen desaturation index >7.5/h) but insufficient symptoms to warrant CPAP therapy. Patients were randomised to 6 months of auto-adjusting CPAP therapy, or standard care. Coprimary endpoints were change in Epworth Sleepiness Score (ESS) and predicted 5-year mortality using a cardiovascular risk score (components: age, sex, height, systolic blood pressure, smoking, diabetes, cholesterol, creatinine, left ventricular hypertrophy, previous myocardial infarction or stroke). Secondary endpoints included some of the individual components of the vascular risk score, objectively measured sleepiness and self-assessed health status. RESULTS: Of 391 patients randomised, 14 withdrew, 347 attended for their follow-up visit at 6 months within the predefined time window, of which 341 had complete ESS data (baseline mean 8.0, SD 4.3) and 310 had complete risk score data. 22% of patients in the CPAP group reported stopping treatment and overall median CPAP use was 2 : 39 h per night. CPAP significantly improved subjective daytime sleepiness (adjusted treatment effect on ESS -2.0 (95% CI -2.6 to -1.4), p<0.0001), objectively measured sleepiness and self-assessed health status. CPAP did not improve the 5-year calculated vascular risk or any of its components. CONCLUSIONS: In patients with minimally symptomatic OSA, CPAP can reduce subjective and objective daytime sleepiness, and improve self-assessed health status, but does not appear to improve calculated vascular risk.