Age-neutrality of the SCID-II: Differential Item Functioning in Younger Outpatients (Aged 20-45) and Older Outpatients (Aged 65+).

Objectives: Measurements are often developed for the assessment of personality disorders (PDs) in younger adults and seldom evaluated on the applicability in older adults. Remarkably, research has not yet been conducted into age-group appropriateness of the gold standard for the assessment of PDs, known as Structured Clinical Interview for DSM-IV Personality Disorders (SCID-II). Therefore, the current study empirically investigated the age-neutrality of the PDs assessed by the SCID-II.

Methods: Age-neutrality was examined in 84 younger adults (aged 20-45 years) and 68 older adults (aged 65-85) by Differential Item Functioning (DIF). The impact of DIF on scale level was further examined using Differential Test Functioning analyzes to examine the impact of the amount of DIF variance in the items on scale level.

Results: Overall, the great majority, 95.8% of the categorically measured items and 87.5% of the dimensionally measured items, was endorsed in the same way by younger adults and older adults with equal scores on the PD scale. Subsequent analyzes revealed no large DTF for PD scales.

Conclusions: Overall the SCID-II in an outpatient population is age-neutral for both categorically and dimensionally scored PD scales.

Clinical Implications: The SCID-II can be used for the assessment of PDs in older adults.