Patient Activation Measure-13 (PAM-13) is a valid and widely used questionnaire that assess an individual's knowledge, confidence, and skills for self-management of their chronic illness. Although there is some evidence regarding its reliability, the test-retest reliability has not been investigated among patients with substance use disorders (SUDs) or schizophrenia spectrum disorders. We investigated the internal consistency and test-retest reliability of PAM-13 in these populations. Test-retest reliability was analysed using data from 29 patients with SUDs and 28 with schizophrenia spectrum disorders. Cronbach's α and Intraclass Correlation Coefficient (ICC) scores were used to examine internal consistency and test-retest reliability, respectively. Of the 60 collected test-retest questionnaires, 57 were included in the analyses. No mean differences between time one (T1) and time two (T2) were observed in either patient group, except for item 12 in schizophrenia spectrum disorders patients (p < 0.05). Internal consistency for T1 and T2 was 0.75 and 0.84 in SUDs patients and 0.87 and 0.81 in schizophrenia spectrum disorders patients, respectively. The ICC was r = 0.86 in patients with SUDs and r = 0.93 in patients with schizophrenia spectrum disorders. To conclude, PAM-13 showed good internal consistency and test-retest reliability in SUDs and schizophrenia spectrum disorders patients.
Keywords: internal consistency; patient activation measure-13; schizophrenia spectrum disorders; self-management; substance use disorder; test–retest reliability.