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Figure 1: The figure depicts the evolution and further development of the Swiss SOS database between 2008 – 2016. The x-axis depicts the time, while the left y-axis depicts the number of patients registered in the database. The right y-axis depicts the number of scientific contributions (oral- or poster presentations, journal publications, or book chapters) as well as the number of Swiss SOS collaborators. Note that the initial months were unrewarding in terms of scientific output. Only after solid patient data had been collected and IRB-approval had been obtained from each centre, publications began to emerge.


2020 | The article on incidence, therapy and outcome of SAH in Switzerland is in the final stage of production.

2016 | The Swiss SOS group meets in Lugano on February 12th 2016, where the future direction and ongoing as well as new projects are discussed.
The data collection for the years 2009 - 2014 is completed for all eight centers in April 2016, and data on n=1952 patients is available with an excellent data completeness of 99.8% for the important variables. These data are presented for the first time at the occasion of the 4th Neurocritical Care Research Meeting on SAH in Houston, Texas (USA). The article on incidence, therapy and outcome of SAH in Switzerland is in the final stage of production.

2015 | The joint annual meeting of Swiss neurosurgeons and neuroradiologists, held the 10.-11.9.2015 is enriched by three oral- and one poster presentation based on data of the Swiss SOS registry. The annual Swiss SOS meeting takes place during this event.
At the occasion of the International Stroke Conference 2015 in Nashville, Tennessee the Swiss SOS group definitively joins the Subarachnoid Hemorrhage International Trialists data repository (SAHIT). Several members of the Swiss SOS study group play an active role for the working group "Common Data Elements" in aneurysmal subarachnoid hemorrhage.
A Swiss standard for neuropsychological outcome assessment after subarachnoid hemorrhage has been developed by the group. This standard has been accepted for publication in the official organ of the European Association of Neurosurgical Societies, the Acta Neurochirurgica. Further articles on this standard are published in German and French language in the Swiss Medical Forum. The standard is presented on the occasion of the 13th International Conference on Neurovascular Events after SAH in Japan. More information concerning this standard as well as download forms can be found here. During the course of the year a publication correlating the count of aSAH with measures of solar activity has been accepted in WORLD NEUROSURGERY, and has recently been highlighted.
The hWFNS trial, as first prospective observational study that is performed in the framework of the Swiss SOS collaborative network, is successfully launched. More info on

2014 | At the occasion of the annual meeting of the SSNS in Zürich, 21 Swiss SOS collaborators were present for a further meeting. At this time, a third scientific paper had been published that based on clinical data collected in the framework of the Swiss SOS with some additional data of the neuropsychological pilot project.(Stienen et al., 2014) A fourth paper had been submitted and was at that time under revision in a peer-reviewed scientific journal. Since the initiation of the group, more than ten congress abstracts had been presented orally or as posters, as well as a book chapter basing on some of the Swiss SOS data.(Stienen et al., 2014) During the meeting, five on-going projects were briefly demonstrated to update all members on the current developments. Some centres were able to present their 2012 and 2013 data - thus the database now comprised about n=1300 registered patient cases. On the occasion of the meeting, preliminary results of the pilot study concerning the neuropsychological outcome assessment were presented, and the implication of the recently introduced “Humanforschungsgesetz” on the Swiss SOS project were evaluated (necessitating re-newel of the IRB-approval at some centres).
On the occasion of the 4th anniversary of the Swiss SOS collaboration, the dataset has been completed with most missing valuables having been re-assessed. The image above depicts the development of the Swiss SOS (figure 1).

2013 | In preparation of the joint meeting with the neuropsychologists of the Swiss SOS centres, a review on neuropsychological outcome assessment in current studies on aSAH was performed. This second paper of the Swiss SOS group underlined the paradox of a high incidence of neuropsychological deficits (NPD) in aSAH patients, with only little patients being systematically tested for NPD in clinical research.(Stienen et al., 2013) Neurosurgeons and neuropsychologists from KSA, USB, ISB, HUG, KSSG and USZ met in Aarau and agreed on establishing a Swiss standard for neuropsychological testing after aSAH (later on, EOC and CHUV would agree to participate). Results of this standardized neuropsychological patient follow-up would then be implementet into the Swiss SOS project. The definitive test-battery (examining all relevant cognitive domains, preferably using tests available in German, French, Italian, English with normative data available for the Swiss cultural area) still had to be elaborated by an elected task force of neuropsychologists and neurosurgeons. It was decided, that the neuropsychological follow-up visit would likewise measure the quality of life and ability to work, as well as the incidence and severity of depression, fatigue and anxiety. To assess the sensitivity and usability of certain tests in the aSAH patient cohort, it was decided to perform a “pilot study” at both KSA and KSSG using a preliminary test-battery.
On occasion of the international VASOSPASM meeting in July 2013, a further meeting was held. The database at that time contained n=918 patients and the data quality and completeness was critically analysed during the meeting. While most clinical data regarding the in-hospital course and status at discharge was complete, the data on the important 12-months outcome was available in 67% of patients only. Leading researchers of the world attending the VASOSPASM meeting were invited to join the Swiss SOS meeting. Here, bilaterally desired future collaborations with large international databases such as the Subarachnoid Hemorrhage International Trialists data repository (SAHIT) were initiated.(Macdonald et al., 2013)

2012 | Almost two years after the initial meeting, the data collection had risen to a number of n=780 patients (complete 2009 – 2011 data of all seven participating centres). It was decided that an “initiation paper” should be prepared and presented to the group at the annual meeting of the Swiss Society of Neurosurgery (SSNS) in June 2012. Further issues discussed were the improvement of the data safety. The composition of a Secu-Trial® database was decided on with the initial costs and yearly expenses evenly distributed between all centres until research funds would have been received to cover the expenses. Some of the major topics in aSAH research were allocated to the centres that evinced special interest, such as treatment outcomes (ISB), socioeconomic aspects (USZ), radiological aspects (USB), cerebral vasospasm, delayed ischemic neurological deficit and delayed cerebral ischemia (KSA). Since IRB approval was still pending from one centre at that time, none of the data could yet be published.
On the occasion of the SSNS meeting, a Swiss SOS meeting was convened. The local IRBs of every participating centre had approved to the study protocol. The coordinating IRB was the University of Geneva ethics committee, where the study was registered under the number “11-233R (NAC 11-085R)”. Thus, the initiation paper was presented to the group and was published shortly after the meeting in the official organ of the European Association of Neurosurgical Societies (EANS).(Schatlo et al., 2012) As a further important step of the meeting, the refinement of the clinical outcomes was claimed by some of the collaborators. Thus, it was decided as future aim to establish standardized outcomes including established neurological grading scales, but also the neuropsychological and psychosocial aspects of outcome. For this, a subgroup of Swiss SOS members was commissioned to seek the collaboration with the neuropsychological departments of all participating Swiss SOS centres.

2011 | About one year later, an investigator meeting was held in Interlaken. At this time, positive appraisal from the IRB of 4/7 of the participating centres had been retrieved. Data on patients treated in 2009 including the one-year follow-up as well as some preliminary 2010 data was presented. Proposals on research projects were discussed and the definitions of cerebral vasospasm, delayed ischemic neurological deficit and delayed cerebral ischemia – clinically relevant frequent complications and scientifically highly interesting parameters in aSAH-research – were determined. As the collection of the initially proposed basic parameters has been successful, it was decided to add further relevant parameters in the future (e.g. time to treatment, treatment complications, days on the intensive care unit, etc.).

2010 | The Swiss SOS was officially founded on November 23rd 2010, when a group of physicians met in Bern to agree on a basic, merge and critically analyse the Swiss 2008 data, as well as identify and extinguish difficulties encountered during the process of retrospective data collection. From six centres, a pilot dataset of n=278 patients had been compiled in a simple Excel-file, and the prevalence of aSAH per center, the treatment modalities as well as outcomes (morbidity, mortality) were presented. In addition, important points such as 1) the standardized definition of each database parameter (field definitions), 2) type and safety of data management, 3) approval of the IRB from each centre, 4) handling of data analyses, project propositions, and positional assignments were decided on.

2008 | The idea of a joint database to collect data on patients with aneurysmal subarachnoid haemorrhage (aSAH) in whole Switzerland has been developed in 2008. The heads of the departments of KSA, USB, ISB, HUG, CHUV, KSSG and USZ were contacted and asked for collaboration (at that time, no neurovascular service was available at EOC). One or two representative neurovascular neurosurgeons per centre agreed to retrospectively collect some basic parameters (age, gender, haemorrhage severity scores, type of therapy, outcome at discharge) of aSAH patients that had been treated at their centre in the year 2008 for a “pilot study”.