====== Stress sum scores (LDI, LTE) ======

Researchers from the [[https://www.rug.nl/staff/l.schweren/research|University Medical Center Groningen]] validated and created sum scores for questionnaire data on past-year stress exposure. More specifically the [[stress_ldi|Long-term Difficulties Inventory (LDI)]] and [[stress_lte|List of Threatening Experiences (LTE)]] for adult participants at [[1a_questionnaire_2|1A]], [[1B]], [[1C]], [[2a_questionnaire_1|2A]], and [[3a_questionnaire_2|3A]]. ([[sections]]: [[mental health]] ([[stress_ldi|LDI]], [[stress_lte|LTE]]) and [[secondary & linked variables]])\\

The stress sum scores can be requested in the Lifelines catalogue or by mail (data@lifelines.nl).\\
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===== Background =====
In the Lifelines questionnaires two stress exposure questionnaires are administered: (1) the [[stress_ldi|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 [[stress_lte|List of Threatening Experiences (LTE)]] which  measures more acute stressful life events and asks whether participants experienced such an event in the past year.\\
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===== Calculations=====
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). 

=== Sum score ===
After recoding, the sum scores are calculated by adding all LDI or LTE items 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.

=== Suspicious scores ===
Finally, participants with suspiciously 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 represent the unfortunate few who went through all of these events in the past year.\\
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===== Article =====
  * [[https://doi.org/10.1016/j.clnu.2020.06.016| Schweren, L. J., Larsson, H., Vinke, P. C., Li, L., Kvalvik, L. G., Arias-Vasquez, A., ... & Hartman, C. A. (2021). Diet quality, stress and common mental health problems: A cohort study of 121,008 adults. Clinical Nutrition, 40(3), 901-906. https://doi.org/10.1016/j.clnu.2020.06.016]] 
  * [[https://doi.org/10.1016/j.bbi.2021.05.022|Mac Giollabhui, N., Alloy, L. B., Schweren, L. J., & Hartman, C. A. (2021). Investigating whether a combination of higher CRP and depression is differentially associated with worse executive functioning in a cohort of 43,896 adults. Brain, Behavior, and Immunity. https://doi.org/10.1016/j.bbi.2021.05.022]]\\
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===== Variables =====
| **Label English**                                                                        | **Label Dutch**                                                                                                | **Code**              | **Variable**  | **Assessment**                                                                                   | **Age**  |
| Total amount of stress from long-term/chronic stressors experienced by the participant.  | Totale hoeveelheid stress van lange-termijn/chronische stressoren                                              | ldi_sumscore_adu_c_1  | LDI_sum       | [[1a_questionnaire_2|1A]], [[1B]], [[1C]], [[2a_questionnaire_1|2A]], [[3a_questionnaire_2|3A]]  | 18+      |
| Subject answered “very much” to every item on the LDI list                               | Deelnemer heeft "zeer" geantwoord op elk item van de LDI vragenlijst                                           | ldi_flag_adu_c_1      | LDI_flag      | [[1a_questionnaire_2|1A]], [[1B]], [[1C]], [[2a_questionnaire_1|2A]], [[3a_questionnaire_2|3A]]  | 18+      |
| Total number of stressful life events that happened to participant in the past year.     | Totaal aantal stressvolle gebeurtenissen die in het afgelopen jaar plaatsvonden in het leven van de deelnemer  | lte_sumscore_adu_c_1  | LTE_sum       | [[1a_questionnaire_2|1A]], [[1B]], [[1C]], [[2a_questionnaire_1|2A]], [[3a_questionnaire_2|3A]]  | 18+      |
| Subject answered “yes” to every item on the LTE list                                     | Deelnemer heeft "ja" geantwoord op elk item van de LTE vragenlijst                                             | lte_flag_adu_c_1      | LTE_flag      | [[1a_questionnaire_2|1A]], [[1B]], [[1C]], [[2a_questionnaire_1|2A]], [[3a_questionnaire_2|3A]]  | 18+      |