Objective

The purposes of this study were to examine the practice effects and test–retest reliability of the Continuous Performance Test, Identical Pairs version (CPT-IP) over four serial assessments in patients with schizophrenia.

Method

Fifty-six patients with schizophrenia were assessed with the CPT-IP four times, once per week. The CPT-IP contains four indices: “2-digit score,” “3-digit score,” “4-digit score,” and “total score.”

Results

The four indices showed trivial-to-small practice effects (Cohen’s d = −0.13–0.24), good-to-excellent test–retest reliability (ICC = 0.62–0.88), and unacceptable random measurement error (MDC% = 33.8%–110.8%).

Conclusions

The total score had the best reliability among the four indices. Although practice effects of the four indices all appeared cumulative, all four CPT-IP indices reached a plateau after the second assessment. These results indicate that clinicians should interpret the change scores of the CPT-IP conservatively and use the total-score index in their routine repeated assessments.

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2020
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