Analysis of time-to-event for observational studies: Guidance to the use of intensity models

This paper provides guidance for researchers with some mathematical background on the conduct of time-to-event analysis in observational studies based on intensity (hazard) models. Discussions of basic concepts like time axis, event definition and censoring are given. Hazard models are introduced, with special emphasis on the Cox proportional hazards regression model. We provide check lists that may be useful both when fitting the model and assessing its goodness of fit and when interpreting the results. Special attention is paid to how to avoid problems with immortal time bias by introducing time-dependent covariates. We discuss prediction based on hazard models and difficulties when attempting to draw proper causal conclusions from such models. Finally, we present a series of examples where the methods and check lists are exemplified. Computational details and implementation using the freely available R software are documented in Supplementary Material. The paper was prepared as part of the STRATOS initiative.Comment: 28 pages, 12 figures. For associated Supplementary material, see http://publicifsv.sund.ku.dk/~pka/STRATOSTG8

Integration of gene ontology pathways with North American Rheumatoid Arthritis Consortium genome-wide association data via linear modeling

We describe an empirical Bayesian linear model for integration of functional gene annotation data with genome-wide association data. Using case-control study data from the North American Rheumatoid Arthritis Consortium and gene annotation data from the Gene Ontology, we illustrate how the method can be used to prioritize candidate genes for further investigation

Behaviour patterns preceding a railway suicide: Explorative study of German Federal Police officers' experiences

<p>Abstract</p> <p>Background</p> <p>Constant high-level numbers of railway suicides indicate that prevention strategies against railway suicides are urgently needed. The main question of the present study was whether pre-crash railway suicide behaviour can be identified, using German Federal Police officers experience with suicidal events in railway related environments.</p> <p>Methods</p> <p>To collect information on pre-crash railway suicide behaviour, a questionnaire was used and made available on the German Federal Police intranet. A total of 202 subjects (mean age: 41 years, sex: 84.9% male) were included in the analysis. Multivariate logistic regression analyses were performed to predict the prevention of suicide (first model) or demand for counselling (second model) as outcomes. Sex, age, years of service, number of experienced suicides, suicides personally observed, information on suicides obtained from witnesses and finally either counselling/debriefing (first model) or whether officers had prevented a suicide (second model) were used as predictors.</p> <p>Results</p> <p>A considerable proportion of police officers reported behavioural patterns preceding a suicide. Half of them observed the dropping or leaving behind of personal belongings or the avoidance of eye contact, more than a third erratic gesture, mimic or movement. Erratic communication patterns and general confusion were each reported by about one quarter. One fifth indicated the influence of alcohol. Less frequently observed behaviour was aimlessly wandering (14.3%) and out of the ordinary clothing (4%). About one third of all railway suicide victims committed suicide in stations. Of those, 70% had chosen an eminent spot. The multivariate logistic regression model using prevented suicides as the outcome identified the number of suicides experienced, counselling/debriefing and having personally observed a suicide as variables with significant impact. The model using counselling/debriefing as the outcome identified age and having prevented a suicide as variables with a significant association.</p> <p>Conclusions</p> <p>Our results provide evidence that railway suicides are preceded by identifiable behavioural patterns. This emphasizes the importance of educational efforts, taking into account the knowledge and skills of experienced police officers.</p

Controlled Quantum Secret Sharing

We present a new protocol in which a secret multiqubit quantum state $\ket{\Psi}$ is shared by $n$ players and $m$ controllers, where $\ket{\Psi}$ is the encoding state of a quantum secret sharing scheme. The players may be considered as field agents responsible for carrying out a task, using the secret information encrypted in $\ket{\Psi}$, while the controllers are superiors who decide if and when the task should be carried out and who to do it. Our protocol only requires ancillary Bell states and Bell-basis measurements.Comment: 6 pages, 0 figure, RevTeX4; published version with minor change

Koper, magnesium en selenium bij jongvee op veenweidebedrijven

Het management op het bedrijf (voeding, beweidingsysteem) heeft in het algemeen een grotere invloed op de groei en ontwikkeling van het jongvee dan de mineralenvoorziening

Long-term outcome and chest pain in patients with true versus non-true bifurcation lesions treated with second-generation drug-eluting stents in the TWENTE trial

The objective of this study is to assess 3-year clinical outcome of patients with true bifurcation lesions (TBLs) versus non-true bifurcation lesions (non-TBLs) following treatment with second-generation drug-eluting stents (DES). TBLs are characterized by the obstruction of both main vessel and side-branch. Limited data are available on long-term clinical outcome following TBL treatment with newer-generation DES. We performed an explorative sub-study of the randomized TWENTE trial among 287 patients who had bifurcated target lesions with side-branches ≥2.0 mm. Patients were categorized into TBL (Medina classes: 1.1.1; 1.0.1; 0.1.1) versus non-TBL to compare long-term clinical outcome. A total of 116 (40.4 %) patients had TBL, while 171 (59.6 %) had non-TBL only. Target-lesion revascularization rates were similar (3.5 vs. 3.5 %; p = 1.0), and definite-or-probable stent thrombosis rates were low (both <1.0 %). The target-vessel myocardial infarction (MI) rate was 11.3 versus 5.3 % (p = 0.06), mostly driven by (periprocedural) MI ≤48 h from PCI. All-cause mortality and cardiac death rates were 8.7 versus 3.5 % (p = 0.06) and 3.5 versus 1.2 % (p = 0.22), respectively. The 3-year major adverse cardiac event rate for patients with TBL versus non-TBL was 20.0 versus 11.7 % (p = 0.05). At 1-, 2-, and 3-year follow-up, 6.5, 13.0, and 11.0 % of patients reported chest pain at less than or equal moderate physical effort, respectively, without any between-group difference. Patients treated with second-generation DES for TBL had somewhat higher adverse event rates than patients with non-TBL, but dissimilarities did not reach statistical significance. Up to 3-year follow-up, the vast majority of patients of both groups remained free from chest pain