Can personality disorder be accurately assessed in older age? A differential item functioning analysis of ICD‐11 inventories

Abstract

AbstractObjectivesThe contested categorical personality disorder (PD) criteria are not well suited to inform PD diagnoses in older adults. Yet, the classification of PDs is undergoing a critical transition phase with a paradigm shift to a dimensional approach for diagnosing PDs. No special attention was given to the expression of PDs in older age when the dimensional ICD‐11 model was developed. Given that PDs are highly prevalent in older adults, there is an urgent need to examine if ICD‐11 related instruments are able to adequately assess for PDs in older adults.MethodsThe age‐neutrality of ICD‐11 measures was examined in a sample of 208 Dutch community‐dwelling adults (N = 208, M age = 54.96, SD = 21.65), matched on sex into 104 younger (age range 18–64) and 104 older (age range 65–93) adults. An instrument is considered not to be age‐neutral if a collective large level of differential item functioning (DIF) exists in a group of items of an instrument (i.e., 25% or more with DIF). We therefore set out to detect possible DIF in the following ICD‐11 self‐report measures: the Standardized Assessment of Severity of Personality Disorder (SASPD), the Personality Inventory for ICD‐11 (PiCD), and the Borderline Pattern Scale (BPS).ResultsDIF analyses using a non‐parametric odds ratio approach demonstrated that SASPD, PiCD, and BPS were age‐neutral with less than 25% of items showing DIF. Yet, impact of DIF at scale level, examined by way of differential test functioning (DTF), indicated a DTF effect on the SASPD total score.ConclusionsThese results of age‐neutrality of the PiCD and BPS are promising for measuring ICD‐11 traits and the borderline pattern. Yet, the age‐neutral measurement of PD severity requires further research. With a rapidly aging population, its accurate assessment across the entire adult life span, including older age, is a prerequisite for an adequate detection of PDs.