title: Validation of a 4-item Negative Symptom Assessment (NSA-4): a short, practical clinical tool for the assessment of negative symptoms in schizophrenia.
abstract: The 16-item Negative Symptom Assessment (NSA-16) scale is a validated tool for evaluating negative symptoms of schizophrenia. The psychometric properties and predictive power of a four-item version (NSA-4) were compared with the NSA-16. Baseline data from 561 patients with predominant negative symptoms of schizophrenia who participated in two identically designed clinical trials were evaluated. Ordered logistic regression analysis of ratings using NSA-4 and NSA-16 were compared with ratings using several other standard tools to determine predictive validity and construct validity. Internal consistency and test--retest reliability were also analyzed. NSA-16 and NSA-4 scores were both predictive of scores on the NSA global rating (odds ratio = 0.83-0.86) and the Clinical Global Impressions--Severity scale (odds ratio = 0.91-0.93). NSA-16 and NSA-4 showed high correlation with each other (Pearson r = 0.85), similar high correlation with other measures of negative symptoms (demonstrating convergent validity), and lesser correlations with measures of other forms of psychopathology (demonstrating divergent validity). NSA-16 and NSA-4 both showed acceptable internal consistency (Cronbach α, 0.85 and 0.64, respectively) and test--retest reliability (intraclass correlation coefficient, 0.87 and 0.82). This study demonstrates that NSA-4 offers accuracy comparable to the NSA-16 in rating negative symptoms in patients with schizophrenia.
authors.affiliation: Pfizer Global R&D, Ann Arbor, MI, USA. larryd349@comcast.net
authors.forename: Larry
authors.initials: L
authors.lastname: Alphs
authors.forename: Robert
authors.initials: R
authors.lastname: Morlock
authors.forename: Cheryl
authors.initials: C
authors.lastname: Coon
authors.forename: Pilar
authors.initials: P
authors.lastname: Cazorla
authors.forename: Armin
authors.initials: A
authors.lastname: Szegedi
authors.forename: John
authors.initials: J
authors.lastname: Panagides
mesh_terms: D000328:Adult; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011569:Psychiatric Status Rating Scales; D011788:Quality of Life; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D012559:Schizophrenia / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D011795:Surveys and Questionnaires