Polish version of the Self-evaluation of Negative Symptoms (SNS)

Aim. The aim of the study was to create a Polish version of the Self-evaluation of Negative Symptoms (SNS) scale, to assess its internal consistency, and to make correlations between the SNS scores and the Brief Negative Symptom Scale (BNSS) scores in the group of patients with schizophrenia. Methods. The procedure of Polish adaptation of the French-language version of the SNS scale, comprising 20 items organized in 5 subscales: asociality, blunted affect, alogia, avolition and anhedonia, was carried out. Psychometric tests were performed in 40 patients with paranoid schizophrenia (20 men and 20 women) with severity of symptoms on the Positive and Negative Syndrome Scale (PANSS) 56 +/- 16 points, receiving unchanged pharmacological treatment in the last 3 months. Results. The Polish version of the SNS scale was accepted by the author of the scale, Professor Sonia Dollfus. The reliability analysis showed high values of the Cronbach's alpha coefficient for the whole scale (0.91) and for the subscales (0.61-0.85). The SNS and its subscales showed significant correlations with the total BNSS score and with the scores of the BNSS subscales, which confirms the validity of the scale. Conclusions. A statistically significant level of consistency of the whole scale and its individual domains with the results of the clinical assessment with the BNSS, speaks for the adequacy of the self - assessment of negative symptoms by a patient with schizophrenia. Good psychometric properties of the Polish version of the SNS obtained in the study can indicate its usefulness in the research on negative symptoms conducted in Poland.