The test-retest reliability and the minimal detectable change of the Purdue pegboard test in schizophrenia

The Purdue pegboard test is widely used in measuring the hand dexterity of patients with schizophrenia. In patients with schizophrenia, the test-retest reliability and minimal detectable change (MDC) of this test remain largely unknown, limiting the interpretability of this popular measure. The purpose of this study was to estimate the test-retest reliability and the MDC of the Purdue pegboard test for patients with schizophrenia.

A total of 147 patients with schizophrenia participated in this study. The participants were administrated the five subtests of the Purdue pegboard test, three trials in a row at both of the two sessions 1 week apart. The intraclass correlation coefficient (ICC) was used to examine the test-retest reliability and the MDC was calculated on the basis of standard error of measurement.

The test-retest reliabilities of the five subtests were moderate to good (ICC = 0.73-0.88). The MDC (MDC%) was 3.0 (22.9%) for the dominant hand subtest, 3.1 (26.1%) for the nondominant hand subtest, 3.0 (31.7%) for the both hands subtest, 6.1 (17.7%) for the dominant + nondominant + both hands subtest, and 8.5 (35.3%) for the assembly subtest.

Our results reveal that the Purdue pegboard test has moderate-to-good test-retest reliability but substantial random measurement error. These findings should enable clinicians and researchers to monitor and interpret the changes in the hand dexterity of patients with schizophrenia more accurately and confidently.