Prevalence of Primary, Prominent, and Predominant Negative Symptoms of Schizophrenia in Routine Inpatient Psychiatric Care

Background and Objectives: Prevalence data of different classes of negative symptoms in an inpatient setting are scarce. Most of the data are collected in clinical trials under strict inclusion criteria, using older psychometric scales with known content validity flaws. The objectives of this study were to report the prevalence of different classes of negative symptoms in a naturalistic inpatient setting using both older and newer psychometric scales and to determine whether second-generation psychometric scales were not inferior to older scales in detecting negative symptoms. Materials and Methods: Negative symptoms were evaluated using older-generation (Positive and Negative Symptoms Scale, PANSS) and second-generation (Brief Negative Symptoms Scale, BNSS, and Self-Evaluation of Negative Symptoms Scale, SNS) measures. Primary, prominent, core, and predominant negative symptoms were calculated according to various descriptions used in other studies. Results: A total of 323 participants were included in this study. The mean score of the PANSS negative symptoms subscores was 25.33 (SD = 6.86, 95% CI 24.57–26.09), the mean total BNSS score was 36.48 (SD = 15.93, 95% CI 34.74–38.23), and the mean SNS total score was 18,9 (SD = 8.99, 95% CI 17.91–19.89). The prevalence of primary negative symptoms was similar in all groups. PANSS and BNSS categorized 71% of the sample as having prominent negative symptoms. The average prevalence of predominant negative symptoms, as measured by PANSS and BNSS, was 9.6%, whereas SNS reported 76.2%. Conclusions: Negative symptoms were highly prevalent in our inpatient sample. Most of our participants had primary and prominent negative symptoms; however, only a small fraction met the criteria for predominant negative symptoms. Prevalence data were similar between PANSS, BNSS, and SNS, showing that BNSS and SNS are not inferior to PANSS.