Researchers from the University Medical Center Groningen validated and created sum scores for questionnaire data on past-year stress exposure. More specifically the Long-term Difficulties Inventory (LDI) and List of Threatening Experiences (LTE) for adult participants at 1A, 1B, 1C, 2A, and 3A. (sections: mental health (LDI, LTE) and secondary & linked variables).

The stress sum scores can be requested in the Lifelines catalogue or by mail (data@lifelines.nl).

In the Lifelines questionnaires two stress exposure questionnaires are administered: (1) the Long-term Difficulties Inventory (LDI), which measures long-term difficulties and focusses more on potential sources of chronic stress and how much the participant was affected by this type of stress; and (2) the List of Threatening Experiences (LTE) which meaures more acute stressful life events and asks whether participants experienced such an event in the past year.

Before the researchers proceeded with the actual calculations, first the variables were recoded (0=not, 1=somewhat, 2=very much for LDI and 0=no, 1=yes for LTE).

After recoding, the sum scores are calculated by adding all LDI/LTE variables together. Please note that in case one or more items are missing, no sum score is calculated. The missing item is not imputed because stressful life events are generally thought of as being random. Imputing the occurrence of a random event based on the occurrence of another random event is not theoretically sound.

Finally, participants with suspiciosly high scores have been flagged. In other words, participants with 'very much' for each LDI item or 'yes' on each LTI item received such indication. Note that these subjects should not necessarily be excluded: these are very few cases suggesting they might actually represent the unfortunate few who went through all of these events in the past year