7. Methods


7.1 Data bases

7.11 SLOSH

A major effort has been made to maintain and extend the SLOSH (Swedish Longitudinal Occupational Survey of Health) cohort which is a nationally representative sample of 39,000 persons who at baseline (2005-2011) were employed. SLOSH follows this sample prospectively with biennial questionnaires in two versions, one for working respondents and one for those not in paid work. The questionnaires cover work environment, experiences of exit from work, social situation outside of work, and health. Prospective and retrospective linkage to administrative registers provide independently sources data on education, workplace, income, marital status, sickness absences, purchases of prescribed drugs, hospital admissions (with diagnoses) and cause-specific mortality. Access to the database has been provided within SSC and the cohort has also provided results to the IPD-work consortium. Efforts are now made to make the cohort available also to researchers outside Stockholm University.

See The SLOSH Website

7.12 LETA data base

Within the center we have also made a six-wave longitudinal dataset based on questionnaire studies available for researchers and student who want to test research questions and hypotheses using longitudinal data. This so-called LETA database (Longitudinell Enkätundersökning om Tjänstemäns Arbetsmiljö [Longitudinal Survey on White-collar Workers’s Situation]) is free for use after a simple application procedure

7.13 IPD Consortium

In order to provide better evidence regarding the role of psychosocial factors, SSC (E+I+S) has participated in a unique international effort to pool individual-participant data (IPD) from many different studies with a total of >100.000 participants, the “IPD-work” consortium. As a first step, measurements have been harmonized across studies.

7.14 AllSweden database

The data base (I) contains 10 million people with annual data covering >20 years from 12 linked nationwide health and sociodemo- graphic registers, including ULF data for 100.000 individuals.

7.2 Questionnaires

7.21 Questionnaire data base

When the Stockholm Stress Center was established we decided to create a database consisting of all questionnaire instruments that have been used in data collections by the various partners and research groups. This questionnaire database has been continually updated and represents an important source for new data collections as well as for facilitating the use of similar and comparable measures across projects. The database is also being used by students planning their own data collections. An additional benefit of this striving is represented by the identification and development of a very small set of items recommended to be used in as many projects as possible to facilitate comparisons between data collections.

7.22 Online questionnaires

Other methodological developments among various methodological approaches that have been developed over the past years are online questionnaires, in various softwares. Within the center there is great expertise in questionnaire development, testing and validation, with several participants teaching this subject at all levels of education. As a result, there are well developed survey test lab procedures for pre-screening, evaluations and the testing of measurement properties.

7.23 Methods to measure modern working life practices

The development and validation of new measures to assess factors characteristic of modern working life practices represents another important line of research. For instance, we have focused on the validation of measures of commitment to organizational change  validated a measure of job insecurity for use in South Africa, and developed and started to validate new measures to assess new facets of the modern working life such as job insecurity climate .

7.24 Short depression scale

A brief six item scale for the assessment of depression, The Symptom Checklist-core depression (SCL-CD6) scale, was developed and psychometrically tested. The psychometric properties of the Swedish Demand-Control Questionnaire have been evaluated in a longitudinal context. Additionally, a shortened version of the Effort-Reward Imbalance Questionnaire was validated as well as an instrument to measure coping outcome expectancy according to the CATS theory.

7.25 Sickness questionnaire

To capture the subjective aspect of a sickness response, the Sickness Questionnaire was developed and psychometrically evaluated and tested in response to inflammatory stimulation. Since few behavioral tests of social communication and problem solving exist, we are currently developing such a test, which is investigated in dyads of sleep deprived and non-sleep deprived subjects. The goal is to develop ecologically valid tests that directly measure functions that are of central importance for successful cooperation in working life and for later application in this area. Another important methodological development (P+S) regards using inflammatory bacterial stimuli to study subjective, objective and brain responses to inflammatory stress. We have now established the model, and collaborate with several other international and national groups to take this model to the next level, and to combine data to increase statistical power.

7.26 Karolinska Sleep Questionnaire

We have carried out several validations of the Karolinska Sleep Questionnaire

7.27 Karolinska Sleepiness Scale

We have made a major review of the usefuleness of the Karolinska Sleepiness Scale in field and laboratory studies

7.3 Other methods

7.31 Sleep wake predictor

We have validated the “Sleep wake predictor”, a mathematical model for the prediction of dangerous sleepiness/fatigue (Ingre et al in press). This particular validation was carried out on air crew and the results have been incorportated in the crew scheduling software (BAM) of Jeppesen AB (a subsidiary of Boeing). The model is available at www.michaelingre.com.

7.32 Webapplication for measuring ratings and cognitive functioning

We have developed a webapplication (app), the Karolinska WakeApp, measuring several cognitive functions. The app can be used on smartphones, tablets and computers, and allows for the possibility to record ratings and measurements of cognitive process in opera- tional settings and people’s own homes. A validation experiment has been carried out and we are now planning to combine large-scale epidemiology with objective measures of cognitive processes.

7.33 Methods for recording of cardiovascular paramters, movement, sleep, immunological changes


Planned research

7.1 Extending SLOSH

SLOSH, the Swedish Longitudinal Occupational Survey of Health, is the only nationally representative work environment cohort study in the world, which in 2014 will be doubled in size to include around 35,000 persons. SLOSH is extensively used within SSC, in particular by E+S+W+I. A comprehensive strategy is now being employed to increase possibilities for (and interest among) researchers also outside of SSC to utilize these data without compromising the privacy of the participants. This will be partly funded by SSC. An interactive website is currently in beta version.

7.2 Stress scale

The established stress scales often include many items that do not in themselves involve stress but may be a consequence of stress. One of our tasks will be to validate a number of stress items from the SLOSH scale against change in work or private life across time.

7.3 Sleep fragmentation

We have just started to develop software that will handle results from polysomnographical studies, display scoring and spectral results together, analyze low frequency dominance in the spectral data (a hypothesized sleep quality indicator) and compute the presence of long uninterrupted sleep in the sleep episode (a hypothesized sleep quality indicator).