Political scientists increasingly recognize that multiple imputation represents a superior strategy for analyzing missing data to the widely used method of listwise deletion. However, there has been ...little systematic investigation of how multiple imputation affects existing empirical knowledge in the discipline. This article presents the first large-scale examination of the empirical effects of substituting multiple imputation for listwise deletion in political science. The examination focuses on research in the major subfield of comparative and international political economy (CIPE) as an illustrative example. Specifically, I use multiple imputation to reanalyze the results of almost every quantitative CIPE study published during a recent five-year period in International Organization and World Politics, two of the leading subfield journals in CIPE. The outcome is striking: in almost half of the studies, key results “disappear” (by conventional statistical standards) when reanalyzed.
High-frequency oscillatory ventilation has been advocated for hypoxemia accompanying the acute respiratory distress syndrome. In this trial comparing HFOV with conventional ventilation, HFOV had no ...significant effect on 30-day mortality.
The acute respiratory distress syndrome (ARDS) is a severe, diffuse inflammatory lung condition caused by a range of acute illnesses. Mortality in affected patients is high,
1
and survivors may have functional limitations for years.
2
,
3
Although mechanical ventilation can initially be lifesaving in patients with ARDS, it can also further injure the patients' lungs and contribute to death.
4
High-frequency oscillatory ventilation (HFOV) was first used experimentally in the 1970s to minimize the hemodynamic effects of mechanical ventilation.
5
Patients' lungs are held inflated to maintain oxygenation, and carbon dioxide is cleared by small volumes of gas moved in and out of . . .
Prevention of falls in older people is important. In this pragmatic, cluster randomized, controlled trial, advice given by mail, screening for risk of falls, and targeted interventions ...(multifactorial fall prevention or exercise) for older people at increased risk for falls did not prevent fractures more than advice by mail alone.
International organizations (IOs) have long been a central focus of scholarship in international relations, yet we know remarkably little about their performance. This article offers an explanation ...for differences in the performance of IOs and tests it using the first quantitative data set on the topic. I argue that the primary obstacle to effective institutional performance is not deviant behavior by IO officials—as conventional “rogue-agency” analyses suggest—but the propensity of states to use IOs to promote narrow national interests rather than broader organizational objectives. IOs that enjoy policy autonomy vis-à-vis states will thus exhibit higher levels of performance. However, in the international context policy autonomy cannot be guaranteed by institutional design. Instead, it is a function of (1) the existence of (certain types of) institutionalized alliances between IOs and actors above and below the state; and (2) the technical complexity of IO activities. I provide empirical evidence for the argument by constructing and analyzing a cross-sectional data set on IO performance—based in part on a new wave of official government evaluations of IOs and in part on an original survey of IO staff—and conducting a comparative case study in the realm of global food security.
Summary Background Mechanical chest compression devices have the potential to help maintain high-quality cardiopulmonary resuscitation (CPR), but despite their increasing use, little evidence exists ...for their effectiveness. We aimed to study whether the introduction of LUCAS-2 mechanical CPR into front-line emergency response vehicles would improve survival from out-of-hospital cardiac arrest. Methods The pre-hospital randomised assessment of a mechanical compression device in cardiac arrest (PARAMEDIC) trial was a pragmatic, cluster-randomised open-label trial including adults with non-traumatic, out-of-hospital cardiac arrest from four UK Ambulance Services (West Midlands, North East England, Wales, South Central). 91 urban and semi-urban ambulance stations were selected for participation. Clusters were ambulance service vehicles, which were randomly assigned (1:2) to LUCAS-2 or manual CPR. Patients received LUCAS-2 mechanical chest compression or manual chest compressions according to the first trial vehicle to arrive on scene. The primary outcome was survival at 30 days following cardiac arrest and was analysed by intention to treat. Ambulance dispatch staff and those collecting the primary outcome were masked to treatment allocation. Masking of the ambulance staff who delivered the interventions and reported initial response to treatment was not possible. The study is registered with Current Controlled Trials, number ISRCTN08233942. Findings We enrolled 4471 eligible patients (1652 assigned to the LUCAS-2 group, 2819 assigned to the control group) between April 15, 2010 and June 10, 2013. 985 (60%) patients in the LUCAS-2 group received mechanical chest compression, and 11 (<1%) patients in the control group received LUCAS-2. In the intention-to-treat analysis, 30 day survival was similar in the LUCAS-2 group (104 6% of 1652 patients) and in the manual CPR group (193 7% of 2819 patients; adjusted odds ratio OR 0·86, 95% CI 0·64–1·15). No serious adverse events were noted. Seven clinical adverse events were reported in the LUCAS-2 group (three patients with chest bruising, two with chest lacerations, and two with blood in mouth). 15 device incidents occurred during operational use. No adverse or serious adverse events were reported in the manual group. Interpretation We noted no evidence of improvement in 30 day survival with LUCAS-2 compared with manual compressions. On the basis of ours and other recent randomised trials, widespread adoption of mechanical CPR devices for routine use does not improve survival. Funding National Institute for Health Research HTA – 07/37/69.
Purpose
To compare the effectiveness of the intravenous (IV) and intraosseous (IO) routes for drug administration in adults with a cardiac arrest enrolled in the Pre-Hospital Assessment of the Role ...of Adrenaline: Measuring the Effectiveness of Drug Administration in Cardiac Arrest (PARAMEDIC2) randomised, controlled trial.
Methods
Patients were recruited from five National Health Service Ambulance Services in England and Wales from December 2014 through October 2017. Patients with an out-of-hospital cardiac arrest who were unresponsive to initial resuscitation attempts were randomly assigned to 1 mg adrenaline or matching placebo. Intravascular access was established as soon as possible, and IO access was considered if IV access was not possible after two attempts.
Results
Among patients with out-of-hospital cardiac arrest, 3631 received adrenaline and 3686 received placebo. Amongst these, 1116 (30.1%) and 1121 (30.4%) received the study drug via the IO route. The odds ratios were similar in the IV and IO groups for return of spontaneous circulation (ROSC) at hospital handover adjusted odds ratio (aOR) 4.07 (95% CI 3.42–4.85) and (aOR 3.98 (95% CI 2.86–5.53),
P
value for interaction 0.90; survival to 30 days aOR 1.67 (1.18–2.35) versus 0.9 (0.4–2.05),
P
= 0.18; and favourable neurological outcome aOR 1.39 (0.93–2.06) versus 0.62 (0.23–1.67),
P
= 0.14.
Conclusion
There was no significant difference in treatment effect (adrenaline versus placebo) on ROSC at hospital handover between drugs administered by the intraosseous route or by the intravenous route. We could not detect any difference in the treatment effect between the IV and IO routes on the longer term outcomes of 30-day survival or favourable neurological outcome at discharge (ISRCTN73485024).
Purpose
To examine the time to drug administration in patients with a witnessed cardiac arrest enrolled in the Pre-Hospital Assessment of the Role of Adrenaline: Measuring the Effectiveness of Drug ...Administration in Cardiac Arrest (PARAMEDIC2) randomised controlled trial.
Methods
The PARAMEDIC2 trial was undertaken across 5 NHS ambulance services in England and Wales with randomisation between December 2014 and October 2017. Patients with an out-of-hospital cardiac arrest who were unresponsive to initial resuscitation attempts were randomly assigned to 1 mg intravenous adrenaline or matching placebo according to treatment packs that were identical apart from treatment number. Participants and study staff were masked to treatment allocation.
Results
8016 patients were enrolled, 4902 sustained a witnessed cardiac arrest of whom 2437 received placebo and 2465 received adrenaline. The odds of return of spontaneous circulation decreased in both groups over time but at a greater rate in the placebo arm odds ratio (OR) 0.93 (95% CI 0.92–0.95) compared with the adrenaline arm OR 0.96 (95% CI 0.95–0.97); interaction OR: 1.03, 95% CI 1.01–1.05,
p
= 0.005. By contrast, although the rate of survival and favourable neurological outcome decreased as time to treatment increased, the rates did not differ between the adrenaline and placebo groups.
Conclusion
The rate of return of spontaneous circulation, survival and favourable neurological outcomes decrease over time. As time to drug treatment increases, adrenaline increases the chances of return of spontaneous circulation. Longer term outcomes were not affected by the time to adrenaline administration. (ISRCTN73485024).
Abstract
Recent decades have witnessed the adoption of unprecedentedly broad and inclusive accountability mechanisms by many major international institutions, from grievance redress systems to ...transparency policies. What explains the establishment of these mechanisms—and why have only some institutions embraced them? I argue that adoption is more likely when member states, in particular the most powerful, face “bottom‐up” pressures for accountability from dense transnational civil society networks—networks with the capacity to build leverage through agenda setting, coalition building, and advocacy strategies—and when institutions perform governance tasks that are costly to monitor. Analysis of a rich new dataset shows that adoption is positively related to the density of international nongovernmental organizations in an institution's issue area—including only those based in powerful member countries—and that this relationship is stronger when governance tasks entail high monitoring costs. Statistical tests are complemented by qualitative evidence from interviews and other primary sources.
Summary Background Low-back pain is a common and costly problem. We estimated the effectiveness of a group cognitive behavioural intervention in addition to best practice advice in people with ...low-back pain in primary care. Methods In this pragmatic, multicentre, randomised controlled trial with parallel cost-effectiveness analysis undertaken in England, 701 adults with troublesome subacute or chronic low-back pain were recruited from 56 general practices and received an active management advisory consultation. Participants were randomly assigned by computer-generated block randomisation to receive an additional assessment and up to six sessions of a group cognitive behavioural intervention (n=468) or no further intervention (control; n=233). Primary outcomes were the change from baseline in Roland Morris disability questionnaire and modified Von Korff scores at 12 months. Assessment of outcomes was blinded and followed the intention-to-treat principle, including all randomised participants who provided follow-up data. This study is registered, number ISRCTN54717854. Findings 399 (85%) participants in the cognitive behavioural intervention group and 199 (85%) participants in the control group were included in the primary analysis at 12 months. The most frequent reason for participant withdrawal was unwillingness to complete questionnaires. At 12 months, mean change from baseline in the Roland Morris questionnaire score was 1·1 points (95% CI 0·39–1·72) in the control group and 2·4 points (1·89–2·84) in the cognitive behavioural intervention group (difference between groups 1·3 points, 0·56–2·06; p=0·0008). The modified Von Korff disability score changed by 5·4% (1·99–8·90) and 13·8% (11·39–16·28), respectively (difference between groups 8·4%, 4·47–12·32; p<0·0001). The modified Von Korff pain score changed by 6·4% (3·14–9·66) and 13·4% (10·77–15·96), respectively (difference between groups 7·0%, 3·12–10·81; p<0·0001). The additional quality-adjusted life-year (QALY) gained from cognitive behavioural intervention was 0·099; the incremental cost per QALY was £1786, and the probability of cost-effectiveness was greater than 90% at a threshold of £3000 per QALY. There were no serious adverse events attributable to either treatment. Interpretation Over 1 year, the cognitive behavioural intervention had a sustained effect on troublesome subacute and chronic low-back pain at a low cost to the health-care provider. Funding National Institute for Health Research Health Technology Assessment Programme.
Abstract
Background
Fractures are rare events and can occur because of a fall. Fracture counts are distinct from other count data in that these data are positively skewed, inflated by excess zero ...counts, and events can recur over time. Analytical methods used to assess fracture data and account for these characteristics are limited in the literature.
Methods
Commonly used models for count data include Poisson regression, negative binomial regression, hurdle regression, and zero-inflated regression models. In this paper, we compare four alternative statistical models to fit fracture counts using data from a large UK based clinical trial evaluating the clinical and cost-effectiveness of alternative falls prevention interventions in older people (Prevention of Falls Injury Trial; PreFIT).
Results
The values of Akaike information criterion and Bayesian information criterion, the goodness-of-fit statistics, were the lowest for negative binomial model. The likelihood ratio test of no dispersion in the data showed strong evidence of dispersion (chi-square = 225.68,
p
-value < 0.001). This indicates that the negative binomial model fits the data better compared to the Poisson regression model. We also compared the standard negative binomial regression and mixed effects negative binomial models. The LR test showed no gain in fitting the data using mixed effects negative binomial model (chi-square = 1.67,
p
-value = 0.098) compared to standard negative binomial model.
Conclusions
The negative binomial regression model was the most appropriate and optimal fit model for fracture count analyses.
Trial registration
The PreFIT trial was registered as ISRCTN71002650.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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