The assessment of negative symptoms in schizophrenia has advanced since the 2006 NIMH-MATRICS Consensus Statement, leading to the development of second-generation rating scales like the Brief Negative Symptom Scale and the Clinical Assessment Interview for Negative Symptoms. These scales address the limitations of first-generation tools, such as the inclusion of aspects that are not negative symptoms and the lack of assessment of the subject’s internal experience. However, psychometric validation of these scales is still in progress, and they are not yet recommended by regulatory agencies, thus limiting their use in clinical trials and settings. Complementing these traditional methods, remote digital phenotyping offers a novel approach by leveraging smartphones and wearable technology to capture real-time, high-resolution clinical data. Despite the potential to overcome traditional assessment barriers, challenges remain in aligning these digital measures with clinical ratings and ensuring data security. Equally important is patient acceptance, as the success of remote digital phenotyping relies on the willingness of patients to use these technologies. This review provides a critical overview of both second-generation scales and remote digital phenotyping for assessing negative symptoms, highlighting future research needs.

The Positive and Negative Syndrome Scale (PANSS-30) is the standard instrument for assessing symptoms of schizophrenia and related psychotic disorders. However, its long administration time and structural issues have prompted the development of shorter versions. The PANSS-6, derived through Item Response Theory and Rasch analysis of the PANSS-8, emerged as a potential alternative. Comprising three positive and three negative symptom items, the PANSS-6 offers a more feasible assessment tool. However, its measurement properties have never been systematically reviewed. We applied the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) guideline for systematic reviews and meta-analytical procedures to assess the psychometric properties of the PANSS-6. COSMIN comprises several steps: literature search, risk-of-bias assessments, assessing the updated criteria for good measurement properties, grading the quality of the evidence and feasibility aspects. We included 13 publications. The PANSS-6 showed sufficient content validity, structural validity, measurement invariance, reliability, criterion validity, construct validity and responsiveness according to COSMIN. On some of them only a small body of evidence is currently available. For internal consistency, cross-cultural validity and measurement error there was not enough evidence for a definite rating. Its short administration time of only 15-20 mins renders feasibility good. The PANSS-6 does not cover all schizophrenia symptoms but focuses on the core symptoms in favor of a feasible administration time. The evidence available on its measurement properties yields sufficient results for its purpose - the assessment of symptom severity and its change. According to COSMIN it can potentially be recommended for use.