Reliability of the performance-based measure of executive functions in people with schizophrenia

The Performance-based measure of Executive Functions (PEF) with four domains is designed to assess executive functions in people with schizophrenia. The purpose of this study was to examine the test-retest reliability of the PEF administered by the same rater (intra-rater agreement) and by different raters (inter-rater agreement) in people with schizophrenia and to estimate the values of minimal detectable change (MDC) and MDC%.

Two convenience samples (each sample, n = 60) with schizophrenia were conducted two assessments (two weeks apart). The intraclass correlation coefficient (ICC) was analyzed to examine intra-rater and inter-rater agreements of the test-retest reliability of the PEF. The MDC was calculated through standard error of measurement.

For the intra-rater agreement study, the ICC values of the four domains were 0.88-0.92. The MDC (MDC%) of the four domains (volition, planning, purposive action, and perfromance effective) were 13.0 (13.0%), 12.2 (16.4%), 16.2 (16.2%), and 16.3 (18.8%), respectively. For the inter-rater agreement study, the ICC values of the four domains were 0.82-0.89. The MDC (MDC%) were 15.8 (15.8%), 17.4 (20.0%), 20.9 (20.9%), and 18.6 (18.6%) for the volition, planning, purposive action, and performance effective domains, respectively.

The PEF has good test-retest reliability, including intra-rater and inter-rater agreements, for people with schizophrenia. Clinicians and researchers can use the MDC values to verify whether an individual with schizophrenia shows any real change (improvement or deterioration) between repeated PEF assessments by the same or different raters.