Harmonization

Time of assessment

For each participant, the CTDA incorporates (whenever possible) time variables that indicate when that participant’s research assessments occurred, relative to (a) an index event and/or (b) baseline assessment in an intervention study.

  • days_t[x] variables are applicable when study includes identification of an index trauma event for participants; ie, for all studies in the PACT/R Data Archive and some studies in the CTPT Data Archive
  • days_AT[x] variables are applicable when study includes intervention (prevention or treatment); ie, for ALL studies in CTPT Data Archive
Variable Variable name /naming convention SPSS variable label (note: case sensitive) Values

# Days Post-Trauma (this individual) at each assessment point

Time point relative to index event.

 days_t1, days_t2, etc.

Time (days) to t1 assessment Time (days) to t2 assessment

                etc

 days_tx = days from index event to tx assessment

# Days Post-Baseline (this individual) at each assessment point

Time point relative to intervention, where baseline =0

 days_AT1, days_AT2, etc

Time (days) to AT1 assessment

Time (days) to AT2 assessment

 days_ATx = days from baseline to ATx assessment

 

Harmonizing item-level data across measures

Child trauma studies use a variety of different measures to assess traumatic stress and other symptoms, as well as risk and protective factors and other covariates. To facilitate cross-study analyses, the Child Trauma Data Archives team develops harmonization algorithms based on expert consensus. We then apply these algorithms to data from each study, to derive harmonized common variables at the item and scale level.

Examples of harmonized variables available from CTDA:

  • child acute traumatic stress symptom items assessed within the first 24 hours post-event
  • child acute traumatic stress symptom items assessed within the first month post-event
  • child posttraumatic stress outcomes assessed at least 3 months post-event
  • parent/caregiver posttraumatic stress outcomes
  • (coming soon) child and parent/caregiver anxiety and depression symptom items

 

The tables below demonstrate the mapping of item content corresponding to DSM IV and DSM 5 criteria for child and adult ASD and PTSD, and adult depression. Each row shows a symptom criterion, with corresponding items from a variety of measures included in CTDA datasets. 

 

 

Exemplar syntax / algorithms

Please contact the CTDA team with any questions.

Exemplar syntax (SPSS) used to apply standard names, labels, values, and value labels:

Exemplar syntax (SPSS) used to derive harmonized common variables at the item level

In general, we follow the following three steps to create harmonized variables for the presence / absence of each symptom for each participant, linked to that participant's actual time of assessment (in days post-trauma). 

  • Compute the "true time" of assessment for each participant using that participant's days since an index trauma (days_t[x]) for each study assessment.
  • Dichotomize each individual item for symptom presence / absence
  • Create common-cross measure harmonized variables