The International Pulsar Timing Array: First data release

International audienceThe highly stable spin of neutron stars can be exploited for a variety of (astro)physical investigations. In particular, arrays of pulsars with rotational periods of the order of milliseconds can be used to detect correlated signals such as those caused by gravitational waves. Three such 'pulsar timing arrays' (PTAs) have been set up around the world over the past decades and collectively form the 'International' PTA (IPTA). In this paper, we describe the first joint analysis of the data from the three regional PTAs, i.e. of the first IPTA data set. We describe the available PTA data, the approach presently followed for its combination and suggest improvements for future PTA research. Particular attention is paid to subtle details (such as underestimation of measurement uncertainty and long-period noise) that have often been ignored but which become important in this unprecedentedly large and inhomogeneous data set. We identify and describe in detail several factors that complicate IPTA research and provide recommendations for future pulsar timing efforts. The first IPTA data release presented here (and available on-line) is used to demonstrate the IPTA's potential of improving upon gravitational-wave limit

Post-traumatic stress and future substance use outcomes: leveraging antecedent factors to stratify risk

Background: Post-traumatic stress disorder (PTSD) and substance use (tobacco, alcohol, and cannabis) are highly comorbid. Many factors affect this relationship, including sociodemographic and psychosocial characteristics, other prior traumas, and physical health. However, few prior studies have investigated this prospectively, examining new substance use and the extent to which a wide range of factors may modify the relationship to PTSD. Methods: The Advancing Understanding of RecOvery afteR traumA (AURORA) study is a prospective cohort of adults presenting at emergency departments (N = 2,943). Participants self-reported PTSD symptoms and the frequency and quantity of tobacco, alcohol, and cannabis use at six total timepoints. We assessed the associations of PTSD and future substance use, lagged by one timepoint, using the Poisson generalized estimating equations. We also stratified by incident and prevalent substance use and generated causal forests to identify the most important effect modifiers of this relationship out of 128 potential variables. Results: At baseline, 37.3% (N = 1,099) of participants reported likely PTSD. PTSD was associated with tobacco frequency (incidence rate ratio (IRR): 1.003, 95% CI: 1.00, 1.01, p = 0.02) and quantity (IRR: 1.01, 95% CI: 1.001, 1.01, p = 0.01), and alcohol frequency (IRR: 1.002, 95% CI: 1.00, 1.004, p = 0.03) and quantity (IRR: 1.003, 95% CI: 1.001, 1.01, p = 0.001), but not with cannabis use. There were slight differences in incident compared to prevalent tobacco frequency and quantity of use; prevalent tobacco frequency and quantity were associated with PTSD symptoms, while incident tobacco frequency and quantity were not. Using causal forests, lifetime worst use of cigarettes, overall self-rated physical health, and prior childhood trauma were major moderators of the relationship between PTSD symptoms and the three substances investigated. Conclusion: PTSD symptoms were highly associated with tobacco and alcohol use, while the association with prospective cannabis use is not clear. Findings suggest that understanding the different risk stratification that occurs can aid in tailoring interventions to populations at greatest risk to best mitigate the comorbidity between PTSD symptoms and future substance use outcomes. We demonstrate that this is particularly salient for tobacco use and, to some extent, alcohol use, while cannabis is less likely to be impacted by PTSD symptoms across the strata

Predicting at-risk opioid use three months after ed visit for trauma: Results from the AURORA study

OBJECTIVE: Whether short-term, low-potency opioid prescriptions for acute pain lead to future at-risk opioid use remains controversial and inadequately characterized. Our objective was to measure the association between emergency department (ED) opioid analgesic exposure after a physical, trauma-related event and subsequent opioid use. We hypothesized ED opioid analgesic exposure is associated with subsequent at-risk opioid use. METHODS: Participants were enrolled in AURORA, a prospective cohort study of adult patients in 29 U.S., urban EDs receiving care for a traumatic event. Exclusion criteria were hospital admission, persons reporting any non-medical opioid use (e.g., opioids without prescription or taking more than prescribed for euphoria) in the 30 days before enrollment, and missing or incomplete data regarding opioid exposure or pain. We used multivariable logistic regression to assess the relationship between ED opioid exposure and at-risk opioid use, defined as any self-reported non-medical opioid use after initial ED encounter or prescription opioid use at 3-months. RESULTS: Of 1441 subjects completing 3-month follow-up, 872 participants were included for analysis. At-risk opioid use occurred within 3 months in 33/620 (5.3%, CI: 3.7,7.4) participants without ED opioid analgesic exposure; 4/16 (25.0%, CI: 8.3, 52.6) with ED opioid prescription only; 17/146 (11.6%, CI: 7.1, 18.3) with ED opioid administration only; 12/90 (13.3%, CI: 7.4, 22.5) with both. Controlling for clinical factors, adjusted odds ratios (aORs) for at-risk opioid use after ED opioid exposure were: ED prescription only: 4.9 (95% CI 1.4, 17.4); ED administration for analgesia only: 2.0 (CI 1.0, 3.8); both: 2.8 (CI 1.2, 6.5). CONCLUSIONS: ED opioids were associated with subsequent at-risk opioid use within three months in a geographically diverse cohort of adult trauma patients. This supports need for prospective studies focused on the long-term consequences of ED opioid analgesic exposure to estimate individual risk and guide therapeutic decision-making

Delay in Arrival is Primary Reason Patients With Large Vessel Stroke Do Not Receive Thrombolysis

Background and Objectives: Intravenous thrombolysis (IVT) is the recommended treatment for acute ischemic stroke (AIS) patients presenting within 4.5 h of stroke onset. In large vessel occlusion stroke (LVOS), IVT appears to have a synergistic effect with endovascular therapy (EVT) resulting in better outcomes than EVT alone. The most cited reasons that patients do not receive IVT are time from stroke onset to hospital arrival \u3e4.5 h and minor/ improving symptoms. Data are lacking about why IVT is not administered in patients with LVOS as these patients usually have clear and significant neurologic deficits. This investigation explores why IVT was not administered to a cohort of patients with LVOS undergoing EVT. Methods: This is an analysis of the Optimizing Prehospital Stroke Systems of Care-Reacting to Changing paradigms (OPUS-REACH) registry. The OPUS-REACH registry contains patients from eight U.S. health systems (nine endovascular stroke centers [ESCs]) who underwent EVT for LVOS. We excluded patients who had their stroke after hospital arrival or who arrived at the hospital by mobile stroke unit. Statistical analysis was done with simple statistics and compared using T-tests to calculate a p-value. Results: 2010 patients were included our analysis. 39% of patients received IVT. Patients who received IVT were younger (69.4 years v. 71.6 years) and had higher mean National Institutes of Health Stroke Scores (16.6 vs. 15.6). Patients who arrived by ambulance were more likely to receive IVT than those who arrived by private vehicle (40.5% vs. 26.3%). When examining patients who did not receive IVT, 58.7% of patients did not receive IVT because of stroke onset to hospital arrival of \u3e4.5 h. The second most common reason was active anticoagulant use (16.0%). Patients were less likely to receive IVT at primary stroke centers (PSC) than ESCs (34.3% vs. 41.1%). On multivariable analysis, younger age, higher NIHSS, treatment at an ESC, and arrival by ambulance were all associated with increased likelihood of receiving IVT. Conclusion: In this large U.S. study examining why LVOS patients do not receive IVT, the most frequent reason for exclusion continues to be stroke onset to hospital arrival of \u3e4.5 h. The second most common reason was active anticoagulation. As IVT plus EVT improves good functional outcomes in LVOS over EVT alone, efforts must be made to increase public awareness of time-sensitive nature of stroke