A MULTISITE INVESTIGATION OF THE RELIABILITY OF THE SCALE FOR THE ASSESSMENT OF NEGATIVE SYMPTOMS

Objective: The Scale for the Assessment of Negative Symptoms is a wide ly used instrument for measuring negative symptoms in schizophrenia, b ut few studies have examined its reliability. This study examined the interrater, internal, and test-retest reliabilities of the scale and i ts factor structure in the context of a multisite study. Method: Two h undred seven patients with schizophrenia who were participating in the Treatment Strategies in Schizophrenia study were assessed with the Sc ale for the Assessment of Negative Symptoms following a symptom exacer bation and again 3-6 months later. All assessments were performed by t rained psychiatrists who were treating the patients. Results: Interrat er reliabilities ranged from low to high for the items on the Scale fo r the Assessment of Negative Symptoms but were statistically significa nt in most cases. Most correlations between individual items and subsc ale total scores were moderate to high, as were coefficient alphas for each subscale, indicating adequate internal consistency. Test-retest correlations were of moderate magnitude. Few differences in reliabilit y statistics between sites were found, although differences in mean sc ale ratings between sites were present. A factor analysis indicated th ree factors corresponding to the Affective Flattening or Blunting subs cale, the Avolition-Apathy and Anhedonia-Asociality subscales, and the Alogia and Inattention subscales. Conclusions: The results suggest th at the Scale for the Assessment of Negative Symptoms has good reliabil ity and is a useful instrument for the measurement of negative symptom s in multisite clinical studies. The internal reliability of the Alogi a, Avolition-Apathy, and Inattention subscales could be improved by re placing some items and including additional items.