Internal consistency of measures for ICD-11 personality disorder severity and traits: A systematic review and meta-analysis.

A number of measures and scales have been developed for the ICD-11 personality disorder (PD) diagnosis, including severity and trait dimensions. The present systematic review and meta-analysis sought to evaluate the internal consistency of these measures across different populations and cultures. A systematic search was conducted across four databases where relevant studies were subjected to explicit eligibility criteria resulting in 49 included studies and 370 effect sizes. Study characteristics were tabulated, their methodological quality was evaluated, and findings were synthesized using random effects meta-analysis. Findings overall indicated that measures of ICD-11 PD severity and trait domains have adequate levels of internal consistency (α/ω = 0.82, 95% CI [0.81; 0.83], I 2  = 97.3%). Aspects such as sample, country, language, format, and measured construct were significant sources of variation. Additional meta-analyses revealed that some measures performed better than others for certain dimensions. Internal consistency was overall supported across ICD-11 measures of severity and trait domains. Future research should further investigate the interrater reliability, test-retest reliability and stability, and alignment with interview-based PD diagnoses.