Brief Symptom Inventory 18 (BSI-18): A Full Guide for Researchers and Clinicians
Published
The Brief Symptom Inventory 18 (BSI-18) is an 18-item screen for psychological distress. Learn its three subscales, GSI scoring, T-scores and cut-offs.
Introduction
The Brief Symptom Inventory 18 (BSI-18) is an 18-item self-report screen for psychological distress and psychiatric disorders in medical and community populations. Leonard R. Derogatis developed it, and Pearson published its manual in 2001. Patients rate their distress over the past week, and the manual has received more than 1,280 citations.
The BSI-18 covers three symptom areas, somatization, depression and anxiety, and adds a Global Severity Index (GSI) based on all 18 items. This guide explains its structure, scoring rules, T-score interpretation and psychometric evidence.
Key Features of the Brief Symptom Inventory 18 (BSI-18)
Purpose and Use
The BSI-18 serves as a screen for psychological distress and psychiatric disorders. It is recommended for use by health and behavioral health professionals as a psychological screen, and it can also help to:
Monitor treatment progress and assess treatment outcomesPlan treatment by supporting clinical decisionsTarget Population
The BSI-18 is intended for adults aged 18 and older in medical and community populations.
Structure
The 18 items split evenly into three symptom dimensions:
Dimension
What it covers
Items
Somatization (SOM)
Physical complaints such as faintness, pains in the chest, nausea or numbness
6
Depression (DEP)
Sadness, lack of interest, hopelessness, worthlessness and thoughts of ending life
6
Anxiety (ANX)
Nervousness, panic spells, terror and restlessness
6
The Global Severity Index (GSI) combines all 18 items into one index of distress.
Scoring Method
Each item is rated on a 5-point scale from 0 (not at all) to 4 (extremely).
Subscale raw scores: when no responses are missing, sum the items in each dimension, for a range of 0 to 24.GSI raw score: the sum across the three subscales, for a range of 0 to 72.Missing items: estimated values are included for omitted items. Up to 2 omitted items per subscale are allowed; 3 or more in any subscale invalidate the scores.T-scores: raw scores are converted to uniform T-scores (mean 50, SD 10) using community or oncology normative tables, and percentile ranks are also available.Higher scores indicate higher levels of psychological distress.
Interpreting scores: interpretation works at three levels, global, dimensional and item. At the dimensional level, subscales are considered in the order DEP, ANX, then SOM, and a T-score above 63 indicates the clinical range and warrants further evaluation. At the item level, item 17 (suicidal ideation) and items 9, 12 and 18 (panic attacks) deserve particular attention.
Rule
Meaning
GSI T-score of 63 or more, or T-score of 63 or more on any two of the three scales
Commonly cited clinical rule suggesting a need for clinical follow-up
GSI T-score of 57 or more
Alternative cut-off used for cancer patients
GSI T-score of 50 or more
Alternative cut-off used for young adult cancer survivors
Administration Format
The BSI-18 is a self-report questionnaire that takes less than 5 minutes. Pearson sells the forms and manual, and purchasers must meet Pearson's qualifications policy.
Applications of the Brief Symptom Inventory 18 (BSI-18)
The BSI-18 supports several uses:
Screening: a brief psychological screen in medical and community settings.Monitoring: tracking treatment progress and assessing outcomes.Treatment planning: supporting clinical decisions.Research: measuring psychological distress in clinical and research settings.Languages and availability
The BSI-18 is available in several languages:
English: PearsonFrench: Pearson FranceGerman: first psychometric findings for the German versionSpanish: study in Spanish outpatients with psychiatric disordersMandarin Chinese: factorial structure among Chinese drug usersArabic and Russian: translated and back-translated versions have been used in studies, but without independent validationThe BSI-18 is proprietary and must be purchased from Pearson under a commercial license.
Reliability and Validity
The BSI-18 is a short, widely used screen, and its psychometric properties have been examined in several samples, including German community and older adult samples, young adult cancer survivors, college students and young people who report substance use.
Validation studies:
Psychometric analysis of the BSI-18 in a representative German sample (2017): study linkNorm values and psychometric properties of the BSI-18 in people aged 60 to 95 (2018): study linkValidity of the BSI-18 for identifying depression and anxiety in young adult cancer survivors (2017): study linkValidational study of the BSI-18 in college students (2012): study linkPsychometric properties of the BSI-18 in a Spanish sample of outpatients with psychiatric disorders: study linkNew validity evidence and normative data for the BSI-18 among young people who report substance use (2025): study linkLimitations and Considerations
Keep these points in mind:
Limited validation: the number of validation studies is considered limited.Proprietary: the BSI-18 must be purchased, and buyers must meet Pearson's qualification requirements.Untested translations: the Arabic and Russian versions have not been independently validated.Different cut-offs: cut-offs vary by population, so choose the one that fits your sample.Other Versions And Related Questionnaires
Related versions include:
SCL-90-R: the parent instrument from which the BSI-18 was derived; see the ResRef SCL-90-R guideBSI (53 items): the longer version of the Brief Symptom InventoryBSI-9: a shorter version; see its development paperThese questionnaires are related:
Patient Health Questionnaire-9 (PHQ-9), which assesses depression severity; see the ResRef PHQ-9 guideGeneralized Anxiety Disorder-7 (GAD-7), which measures anxiety symptoms; see the ResRef GAD-7 guideDepression Anxiety Stress Scales-21 (DASS-21), which evaluates depression, anxiety and stressHopkins Symptom Checklist-25 (HSCL-25), which assesses psychiatric symptomsAdditional Resources
The BSI-18 PsycTESTS record: linkThe BSI-18 page in the Rehabilitation Measures Database: linkFor inquiries, contact Leonard R. Derogatis, PhD, at ldero001@umaryland.edu.Browse more psychiatry questionnaires in the ResRef database.Frequently Asked Questions (FAQ)
What does the Brief Symptom Inventory 18 measure?The BSI-18 screens for psychological distress across three symptom areas: somatization, depression and anxiety. It also gives a Global Severity Index (GSI) based on all 18 items.
How is the BSI-18 scored?Items are rated from 0 (not at all) to 4 (extremely) for the past week. Each six-item subscale is summed for a 0–24 score, and the GSI is the sum of all three, from 0 to 72. Raw scores are converted to T-scores.
What is the BSI-18 cut-off score?A commonly cited rule is a GSI T-score of 63 or more, or 63 or more on any two of the three scales, which suggests a need for clinical follow-up. Lower cut-offs have been used in cancer populations.
Is the BSI-18 free to use?No. The BSI-18 is a proprietary instrument under a commercial license, and it must be purchased from Pearson by users who meet its qualification requirements.
A Word from ResRef About the Brief Symptom Inventory 18 (BSI-18)
The BSI-18 is a gold-standard, ultra-brief screening tool for psychological distress. Its robust psychometric properties, short administration time (under 5 minutes), and focus on the three key domains of somatization, depression and anxiety make it highly valuable for both clinical and research settings. While it is a proprietary instrument requiring purchase, its widespread validation and utility justify its status as a leading measure in mental health assessment.
References
Derogatis, L. R. (2000). Brief Symptom Inventory-18. American Psychological Association. https://doi.org/10.1037/t07502-000Franke, G. H., Jaeger, S., Glaesmer, H., Barkmann, C., Petrowski, K., & Braehler, E. (2017). Psychometric analysis of the brief symptom inventory 18 (BSI-18) in a representative German sample. BMC Medical Research Methodology, 17(1). https://doi.org/10.1186/s12874-016-0283-3Petrowski, K., Schmalbach, B., Jagla, M., Franke, G. H., & Brähler, E. (2018). Norm values and psychometric properties of the brief symptom inventory-18 regarding individuals between the ages of 60 and 95. BMC Medical Research Methodology, 18(1). https://doi.org/10.1186/s12874-018-0631-6Recklitis, C. J., Blackmon, J. E., & Chang, G. (2017). Validity of the Brief Symptom Inventory-18 (BSI-18) for identifying depression and anxiety in young adult cancer survivors: Comparison with a Structured Clinical Diagnostic Interview. Psychological Assessment, 29(10), 1189–1200. https://doi.org/10.1037/pas0000427Wang, J., Kelly, B. C., Liu, T., Zhang, G., & Hao, W. (2013). Factorial structure of the Brief Symptom Inventory (BSI)-18 among Chinese drug users. Drug and Alcohol Dependence, 133(2), 368–375. https://doi.org/10.1016/j.drugalcdep.2013.06.017Spitzer, C., Hammer, S., Löwe, B., Grabe, H., Barnow, S., Rose, M., Wingenfeld, K., Freyberger, H., & Franke, G. (2011). Die Kurzform des Brief Symptom Inventory (BSI -18): erste Befunde zu den psychometrischen Kennwerten der deutschen Version. Fortschritte der Neurologie · Psychiatrie, 79(09), 517–523. https://doi.org/10.1055/s-0031-1281602Park, K., Chang, M., & Woo, S. (2012). Validational Study of Brief Symptoms Inventory-18(BSI-18) in College Students. Korean Journal of Clinical Psychology, 31(2), 507–521. https://doi.org/10.15842/kjcp.2012.31.2.006Iza-Fernández, C., González-Roz, A., García-Fernández, J., Cuesta-López, I., & Postigo, Á. (2025). New Validity Evidence, Psychometric Properties and Normative Data for the Brief Symptom Inventory-18 (BSI-18) among Young Populations who Report Substance Use. International Journal of Mental Health and Addiction, 24(4), 2785–2804. https://doi.org/10.1007/s11469-025-01531-0