Random-effects meta-analysis is commonly performed by first deriving an estimate of the between-study variation, the heterogeneity, and subsequently using this as the basis for combining results, i.e., for estimating the effect, the figure of primary interest. The heterogeneity variance estimate however is commonly associated with substantial uncertainty, especially in contexts where there are only few studies available, such as in small populations and rare diseases. Confidence intervals and tests for the effect may be constructed via a simple normal approximation, or via a Student-t distribution, using the Hartung-Knapp-Sidik-Jonkman (HKSJ) approach, which additionally uses a refined estimator of variance of the effect estimator. The modified Knapp-Hartung method (mKH) applies an ad hoc correction and has been proposed to prevent counterintuitive effects and to yield more conservative inference. We performed a simulation study to investigate the behaviour of the standard HKSJ and modified mKH procedures in a range of circumstances, with a focus on the common case of meta-analysis based on only a few studies. The standard HKSJ procedure works well when the treatment effect estimates to be combined are of comparable precision, but nominal error levels are exceeded when standard errors vary considerably between studies (e.g. due to variations in study size). Application of the modification on the other hand yields more conservative results with error rates closer to the nominal level. Differences are most pronounced in the common case of few studies of varying size or precision. Use of the modified mKH procedure is recommended, especially when only a few studies contribute to the meta-analysis and the involved studies’ precisions (standard errors) vary.

Central pain in multiple sclerosis (MS) is common and often refractory to treatment. We conducted a single-center, 5-week (1-week run-in, 4-week treatment), randomized, double-blind, placebo-controlled, parallel-group trial in 66 patients with MS and central pain states (59 dysesthetic, seven painful spasms) of a whole-plant cannabis-based medicine (CBM), containing delta-9-tetrahydrocannabinol:cannabidiol (THC:CBD) delivered via an oromucosal spray, as adjunctive analgesic treatment. Each spray delivered 2.7 mg of THC and 2.5 of CBD, and patients could gradually self-titrate to a maximum of 48 sprays in 24 hours. Sixty-four patients (97%) completed the trial, 34 received CBM. In week 4, the mean number of daily sprays taken of CBM (n = 32) was 9.6 (range 2 to 25, SD = 6.0) and of placebo (n = 31) was 19.1 (range 1 to 47, SD = 12.9). Pain and sleep disturbance were recorded daily on an 11-point numerical rating scale. CBM was superior to placebo in reducing the mean intensity of pain (CBM mean change -2.7, 95% CI: -3.4 to -2.0, placebo -1.4 95% CI: -2.0 to -0.8, comparison between groups, p = 0.005) and sleep disturbance (CBM mean change -2.5, 95% CI: -3.4 to -1.7, placebo -0.8, 95% CI: -1.5 to -0.1, comparison between groups, p = 0.003). CBM was generally well tolerated, although more patients on CBM than placebo reported dizziness, dry mouth, and somnolence. Cognitive side effects were limited to long-term memory storage. Cannabis-based medicine is effective in reducing pain and sleep disturbance in patients with multiple sclerosis related central neuropathic pain and is mostly well tolerated.

Understanding and measuring mental health and wellbeing amongst teenagers has recently become a priority. The Warwick-Edinburgh Mental Well-being Scale (WEMWBS) is validated for measuring mental wellbeing in populations aged 16 years and over in the UK. We report here a study designed to establish the validity and reliability of WEMWBS in teenagers in the UK.

The aim of this study was to investigate the effect of contact-to-balloon time on mortality in ST-segment elevation myocardial infarction (STEMI) patients with and without haemodynamic instability. Using data from the prospective, multicentre Feedback Intervention and Treatment Times in ST-Elevation Myocardial Infarction (FITT-STEMI) trial, we assessed the prognostic relevance of first medical contact-to-balloon time in n = 12 675 STEMI patients who used emergency medical service transportation and were treated with primary percutaneous coronary intervention (PCI). Patients were stratified by cardiogenic shock (CS) and out-of-hospital cardiac arrest (OHCA). For patients treated within 60 to 180 min from the first medical contact, we found a nearly linear relationship between contact-to-balloon times and mortality in all four STEMI groups. In CS patients with no OHCA, every 10-min treatment delay resulted in 3.31 additional deaths in 100 PCI-treated patients. This treatment delay-related increase in mortality was significantly higher as compared to the two groups of OHCA patients with shock (2.09) and without shock (1.34), as well as to haemodynamically stable patients (0.34, P < 0.0001). In patients with CS, the time elapsing from the first medical contact to primary PCI is a strong predictor of an adverse outcome. This patient group benefitted most from immediate PCI treatment, hence special efforts to shorten contact-to-balloon time should be applied in particular to these high-risk STEMI patients. NCT00794001.

Whether transcatheter mitral-valve repair improves outcomes in patients with heart failure and functional mitral regurgitation is uncertain. We conducted a randomized, controlled trial involving patients with heart failure and moderate to severe functional mitral regurgitation from 30 sites in nine countries. The patients were assigned in a 1:1 ratio to either transcatheter mitral-valve repair and guideline-recommended medical therapy (device group) or medical therapy alone (control group). The three primary end points were the rate of the composite of first or recurrent hospitalization for heart failure or cardiovascular death during 24 months; the rate of first or recurrent hospitalization for heart failure during 24 months; and the change from baseline to 12 months in the score on the Kansas City Cardiomyopathy Questionnaire-Overall Summary (KCCQ-OS; scores range from 0 to 100, with higher scores indicating better health status). A total of 505 patients underwent randomization: 250 were assigned to the device group and 255 to the control group. At 24 months, the rate of first or recurrent hospitalization for heart failure or cardiovascular death was 37.0 events per 100 patient-years in the device group and 58.9 events per 100 patient-years in the control group (rate ratio, 0.64; 95% confidence interval [CI], 0.48 to 0.85; P = 0.002). The rate of first or recurrent hospitalization for heart failure was 26.9 events per 100 patient-years in the device group and 46.6 events per 100 patient-years in the control group (rate ratio, 0.59; 95% CI, 0.42 to 0.82; P = 0.002). The KCCQ-OS score increased by a mean (±SD) of 21.6±26.9 points in the device group and 8.0±24.5 points in the control group (mean difference, 10.9 points; 95% CI, 6.8 to 15.0; P<0.001). Device-specific safety events occurred in 4 patients (1.6%). Among patients with heart failure with moderate to severe functional mitral regurgitation who received medical therapy, the addition of transcatheter mitral-valve repair led to a lower rate of first or recurrent hospitalization for heart failure or cardiovascular death and a lower rate of first or recurrent hospitalization for heart failure at 24 months and better health status at 12 months than medical therapy alone. (Funded by Abbott Laboratories; RESHAPE-HF2 ClinicalTrials.gov number, NCT02444338.).