Specificity and sensitivity of the Self-assessment of Negative Symptoms (SNS) in patients with schizophrenia.

OBJECTIVES

Negative symptoms can be present at any stage of schizophrenia but their evaluation remains challenging. Self-evaluations may be particularly useful in screening negative symptoms quickly and effectively. The purpose of this study was to determine the sensitivity, the specificity, and the threshold beyond which the negative symptoms are considered pathological in a comparative study between patients with schizophrenia and healthy subjects using the Self-assessment of Negative Symptoms (SNS).

METHODS

One hundred and nine patients with schizophrenia and schizoaffective disorders (DSM-5) and 99 healthy controls were included and evaluated with the SNS. AUROC analyses were performed to assess the discriminant performance of the SNS scale for screening negative symptoms in the whole sample of patients but also in 2 patient sub-samples without high scores of depression or negative symptoms.

RESULTS

The SNS (AUROC = 0.942 ± 0.046; p < 0.001) appears to be an appropriate screening tool for distinguishing between SZ and HC with a threshold value of 7, and the sensitivity and specificity were 92.7% (95CI = [86.1-96.8]) and 85.9% (95CI = [77.4-92.1]) respectively. A threshold at 7 was also observed in the samples without patients with high level of depressive or negative symptoms.

CONCLUSION

These results indicate that SNS might be a valuable tool for screening negative symptoms in clinical practice regardless the level of depressive and negative symptoms. Further studies using SNS in subjects at high risk for psychosis or with a first psychotic episode would be useful in the detection of negative symptoms.