Prevalence of prominent and predominant negative symptoms across different criteria for negative symptom severity and minimal positive symptoms: A comparison of different criteria.

ABSTRACT

Negative symptoms are a source of disability in schizophrenia, but criteria for identifying patients for clinical trials are in flux. Minimum severity for negative symptoms is paired with a definition of minimal psychosis to identify predominant negative symptoms. Two previous successful negative symptoms treatment studies used very different severity and selection criteria. We compared the prevalence of participants meeting those two criteria in a large outpatient sample of participants with schizophrenia. Data from 867 outpatients with schizophrenia who participated in one of four NIMH-funded studies were analyzed. Common data elements included diagnoses, the PANSS, and an assessment of everyday functioning. We compared previous criterion for premoninant negative symptoms based on low levels of agitation and psychosis and different cut-offs for negative symptoms severity. 57 % of the participants met the agitation-based criteria for low scores and 33 % met the psychosis-based criteria. 18 % met total PANSS score ≥ 20 and 8 % met ≥24 prominent negative symptoms criteria. 14 % met low agitation and PANSS≥20 and 2 % met the low psychosis and negative symptoms ≥24 criteria. Participants who met all predominant criteria had more impairments in social functioning (all p < .001, all d > 0.37). Criteria for predominant negative symptoms from previous clinical trials identify widely different numbers of cases, with criteria for negative symptom severity and low symptoms both impacting. All criteria yield the expected profile of relatively specific social deficits. Even in unselected populations who participated in complex research protocols, 14 % meet low- agitation based criteria for predominant negative symptoms and many more participants would be expected to meet criteria with enrichment for the presence of negative symptoms.