Mark Zimmerman, MD Professor of Psychiatry and Human Behavior Warren Alpert Medical School of Brown University Rhode Island Hospital Providence, Rhode Island Member of the Current Psychiatry Editorial Board
Disclosure The author reports no financial relationships with any company whose products are mentioned in this article or with manufacturers of competing products.
Screening tests for most psychiatric disorders are based on multi-item scales in which a total score is computed from a sum of item scores, and a cutoff point is established to determine who does and does not screen positive on the test. However, sensitivity, specificity, and positive and negative predictive values are not invariant properties of a screening test with a continuous score distribution. Rather, the performance statistics of a scale can be altered by changing the threshold score to distinguish cases from non-cases. When the screening threshold is lowered, sensitivity increases and specificity decreases.
For screening, a broad net needs to be cast so that all (or almost all) cases are included. Therefore, the cutoff score should be set low to prioritize the sensitivity of the instrument. A screening scale also should have high negative predictive value so that the clinician can be confident that patients who screen negative on the test do not have the disorder.
Screening questionnaires for BPD
Several questionnaires have been developed to screen for PDs (Table 228-35). Some screen for each of the DSM PDs,28,36-42 and some screen more broadly for the presence or absence of any PD.29,43,44 The most commonly studied self-report scale for BPD is the McLean Screening Instrument for Borderline Personality Disorder (MSI-BPD),30 a 10-item self-report scale derived from a subset of questions from the BPD module of a semi-structured diagnostic interview.
The initial validation study30 found that the optimal cutoff score was 7, which resulted in a sensitivity of 81% and specificity of 89%. Three studies have evaluated the scale in adolescents and young adults,45-47 and 3 studies examined the scale in adult outpatients.48-50 Across all 6 studies, at the optimal cutoff scores determined in each study, the sensitivity of the MSI-BPD ranged from 68% to 94% (mean, 80%) and the specificity ranged from 66% to 80% (mean, 72%).
Problems with screening questionnaires. Although screening scales have been developed for many psychiatric disorders, they have not been widely used in mental health settings. In a previous commentary, I argued that the conceptual justification for using self-report screening scales for single disorders in psychiatric settings is questionable.51 Another problem with screening scales is their potential misuse as case-finding instruments. In the literature on bipolar disorder screening, several researchers misconstrued a positive screen to indicate caseness.51 Although this is not a problem with the screening measures or the selection of a cutoff score, caution must be taken to not confuse screening with diagnosis.52
