Psychometric properties of the PRISS Scale

The results of the PRISS scale validation study are detailed in the validation article[1] and are summarized below:

The results of the psychometric analysis of the PRISS scale have shown good test–retest reliability and 64.3% of the intraclass correlation coefficient values ranged between 0.40 and 0.79 (p < 0.01).

Regarding the structural validity, the factorial analysis revealed a structure of three factors – (1) productive, (2) negative-affective and (3) arousal – which represented 56.11% of the variance. Factor 2 (negative-affective) presented the best internal consistency (McDonald’s omega coefficient =0.92–0.93). Specifically, for the frequency and level of concern the internal consistency was 0.93 and for the level of interference in daily life it was 0.92.

In relation to convergent validity, the values of the Kappa coefficient between each item of the PRISS with its corresponding item of the PANSS and the PRISS showed a discrete correlation for half of the items (0.21 to 0.40) and weak for the other half (0.01 to 0.20).

The Pearson correlation coefficients analysed between the PRISS and the PANSS, with the symptoms apathy and avolition from the Scale for the Assessment of Negative Symptoms[2] and with the Disability Assessment Scale of the World Health Organization[3] , presented values that oscillated between 0.38 and 0.42 for the PANSS, between 0.32 and 0.42 for the two SANS items, and between 0.40 and 0.42 for the WHO-DAS. In conclusion, the results of the psychometric analysis indicate that the PRISS is a reliable and valid scale to measure subjective experiences in schizophrenia and provides valuable complementary information to clinical evaluation.

Notes

[1] Moreno‐Küstner, B., Fábrega‐Ruz, J., Gonzalez‐Caballero, J. L., Reyes‐Martin, S., Ochoa, S., Romero‐Lopez‐Alberca, C., … & Salvador‐Carulla, L. (2022). Patient‐reported impact of symptoms in schizophrenia scale (PRISS): Development and validation. Acta Psychiatrica Scandinavica, 145(6), 640-655. DOI: 10.1111/acps.13417

[2] Kay SR, Fiszbein A, Vital-Herne M, Fuentes LS. The Positive and Negative Syndrome Scale–Spanish adaptation. J Nerv Ment Dis. 1990 Aug;178(8):510-7. PMID: 2380697.

[3] Vázquez-Barquero, J.L. et al. (2000) Spanish version of the new World Health Organization Disability Assessment Schedule II (WHO-DAS-II): initial phase of development and pilot study. Cantabria disability work group. Actas Esp Psiquiatr. 8(2):77-87

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