Correlation between the Personal and Social Performance scale (PSP) and the Positive and Negative Syndrome Scale (PANSS) in a Greek sample of patients with schizophrenia

BACKGROUND Psychosocial dysfunction is one of schizophrenia's core features, often leading to a deprecation of independent living and significant failure to maintain a competent quality of life. Cognitive and occupational performance as well as psychosocial functioning is moreover recognized as determinants of treatment response. Therefore, the elaboration of measures regarding social performance besides scales that assess psychopathology is essential. The Personal and Social Performance (PSP) scale has been found to be as much valid as reliable for assessing social functioning in the acute and stable stage of schizophrenia. The aim of this study was to estimate the correlation between the PSP and Positive and Negative Syndrome Scale (PANSS) (convergent validity) in patients with schizophrenia during routine clinical practice. METHODS A longitudinal study with a six-month follow-up is presented. Correlation between the PSP scale and the Positive and Negative Syndrome Scale (PANSS) was conducted in a Greek sample of 2010 patients with schizophrenia in outpatient setting in two successive visits. PANSS and PSP scales were used for the assessment of psychopathological symptoms and social and personal functioning. RESULTS The PSP subscales scores were well correlated with each other with Spearman correlation coefficients (r) ranging from 0.56 to 0.76 on both visits in three out of the four main areas, whereas in the category of "disturbing and aggressive behavior" the correlations were lower but still significant. Furthermore, total PSP score showed high association to PANSS total score in the first (r = -0.59) as well as in the second visit (r = -0.50). Regression analysis showed that one point decrease of PANSS's total score is associated with a 0.42 points increase on the PSP scale. PSP and PANSS scales exhibited high convergent validity. CONCLUSIONS The PSP could provide additional valuable information in the assessment of schizophrenia related social functioning and treatment response.