To the Editor: In discussing the methodological limitations of their important assessment of the risks and benefits of antipsychotic polypharmacy, Dr. Centorrino et al. did not include the potential shortcomings of one of their primary outcome measures, the Positive and Negative Syndrome Scale scores extracted from medical records. We are aware of no work establishing the validity and reliability of a retrospective Positive and Negative Syndrome Scale instrument and wonder if scoring patients without interviews may have underestimated the differences among subjects and biased results toward the authors’ findings of no baseline or outcome differences between monotherapy and polytherapy groups. In particular, negative items like poor rapport, difficulty in abstract thinking, lack of spontaneity and flow of conversation, and stereotyped thinking may be difficult to rate reliably from routine inpatient clinical charts on the Positive and Negative Syndrome Scale’s seven-point scale. Absent more specific prospective measures, inclusion of prospective Global Assessment of Functioning (GAF) scale scores likely to be available in charts along with raters’ retrospective GAF scale scores might be of value in assessing the clinical characteristics and outcomes of psychotic patients treated with antipsychotic monotherapy or polytherapy.