Am J Psychiatry 1994; 151:1453-1462
Copyright © 1994 by American Psychiatric Association
A multisite investigation of the reliability of the Scale for the Assessment of Negative Symptoms
KT Mueser, SL Sayers, NR Schooler, RM Mance and GL Haas
Department of Psychiatry, Medical College of Pennsylvania, Eastern Pennsylvania Psychiatric Institute.
OBJECTIVE: The Scale for the Assessment of Negative Symptoms is a widely
used instrument for measuring negative symptoms in schizophrenia, but few
studies have examined its reliability. This study examined the interrater,
internal, and test-retest reliabilities of the scale and its factor
structure in the context of a multisite study. METHOD: Two hundred seven
patients with schizophrenia who were participating in the Treatment
Strategies in Schizophrenia study were assessed with the Scale for the
Assessment of Negative Symptoms following a symptom exacerbation and again
3-6 months later. All assessments were performed by trained psychiatrists
who were treating the patients. RESULTS: Interrater reliabilities ranged
from low to high for the items on the Scale for the Assessment of Negative
Symptoms but were statistically significant in most cases. Most
correlations between individual items and subscale 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 reliability statistics between sites were
found, although differences in mean scale ratings between sites were
present. A factor analysis indicated three factors corresponding to the
Affective Flattening or Blunting subscale, the Avolition-Apathy and
Anhedonia-Asociality subscales, and the Alogia and Inattention subscales.
CONCLUSIONS: The results suggest that the Scale for the Assessment of
Negative Symptoms has good reliability and is a useful instrument for the
measurement of negative symptoms in multisite clinical studies. The
internal reliability of the Alogia, Avolition- Apathy, and Inattention
subscales could be improved by replacing some items and including
additional items.
