Brief Symptom Inventory
The BSI (Brief Symptom Inventory) is a 53-item self-report questionnaire that measures psychological symptom distress over the past seven days across 9 dimensions (Somatization, Obsessive-Compulsive, Interpersonal Sensitivity, Depression, Anxiety, Hostility, Phobic Anxiety, Paranoid Ideation, Psychoticism) plus 3 global indices including GSI. T-score ≥63 = clinical caseness. Derogatis & Melisaratos (1983).
The BSI is a validated 53-item self-report measure of psychological symptom distress across 9 dimensions (Somatization, OC, Interpersonal Sensitivity, Depression, Anxiety, Hostility, Phobic Anxiety, Paranoid Ideation, Psychoticism) plus 3 global indices. Derogatis & Melisaratos (1983).
What the BSI measures
The Brief Symptom Inventory (BSI) is a validated 53-item self-report symptom inventory developed by Leonard Derogatis and Norman Melisaratos (1983) as a shortened version of the SCL-90-R. It is one of the most widely used psychiatric symptom assessment tools in clinical trials, outcome monitoring, and psychological research. The BSI produces scores on 9 symptom dimensions and 3 global indices.
BSI Nine Symptom Dimensions
Each dimension produces a raw score (sum of item ratings ÷ number of items in that dimension) and a T-score relative to the normative sample. Dimension T-score ≥ 63 on two or more subscales, alongside GSI T ≥ 63, supports the clinical caseness determination.
The nine dimensions and their clinical focus are:
| Dimension | Abbrev. | Clinical Focus |
|---|---|---|
| Somatization | SOM | Physical complaints linked to autonomic arousal — cardiovascular, gastrointestinal, respiratory, and musculoskeletal distress |
| Obsessive-Compulsive | O-C | Thoughts, impulses, and behaviours that are experienced as irresistible, persistent, and ego-dystonic |
| Interpersonal Sensitivity | I-S | Feelings of personal inadequacy and inferiority; self-deprecation and discomfort in interpersonal comparisons |
| Depression | DEP | Dysphoric mood, loss of interest, hopelessness, suicidal ideation, and reduced motivational energy |
| Anxiety | ANX | Nervousness, tension, trembling, and free-floating apprehension; somatic correlates of anxiety |
| Hostility | HOS | Thoughts, feelings, and actions characteristic of anger — irritability, aggression, and resentment |
| Phobic Anxiety | PHOB | Persistent, irrational fear and avoidant behaviour triggered by people, places, or situations |
| Paranoid Ideation | PAR | Projective thinking, suspiciousness, grandiosity, centrality, and fears of loss of autonomy |
| Psychoticism | PSY | Withdrawn, isolated, schizoid lifestyle; hallucinations and thought disorder symptoms on a continuum |
Note: The 53 BSI items are distributed across these nine dimensions; four items contribute to global indices but are not assigned to any single dimension subscale. Per-dimension item counts are specified in the proprietary scoring manual (Derogatis, 1993).
How to administer the BSI
Respondents rate each symptom on a 5-point distress scale (0 = not at all to 4 = extremely) for the past seven days. The BSI takes about 8–10 minutes to complete.
The BSI-18 is a brief 18-item version covering only Somatization, Depression, and Anxiety with a GSI, designed for medical settings and population screening. Both BSI and BSI-18 are published by Pearson Assessments and require purchase for clinical and research use.
BSI scoring and interpretation
The Global Severity Index (GSI), the mean of all 53 items, is the single best indicator of current distress level and psychiatric caseness. Scores are interpreted using age- and gender-referenced T-scores (mean=50, SD=10); a T-score ≥63 on the GSI (or ≥2 dimensions at T≥63) indicates clinical caseness.
Interpreting BSI T-Scores
BSI dimension and global index scores are expressed as T-scores normed against a published adult reference sample (mean = 50, SD = 10). Because the BSI is a multidimensional profile measure rather than a unidimensional screener, there are no literature-supported mild/moderate/severe total-score bands. The validated threshold is a single caseness criterion.
Clinical caseness is met when either of the following conditions is satisfied (Derogatis & Melisaratos, 1983; Michel et al., 2024):
- GSI T-score ≥ 63, or
- T-score ≥ 63 on two or more of the nine symptom dimensions.
A T-score of 63 corresponds approximately to the 90th percentile of the normative outpatient sample and signals that the level of psychological distress warrants further clinical evaluation. Scores below this threshold should still be interpreted within clinical context — the caseness rule identifies a clinically meaningful threshold, not a clean diagnostic boundary.
Separate normative tables are available for adult outpatient, adult non-patient (community), and adolescent non-patient samples. Choosing the appropriate norm group matters: the same raw score can yield different T-scores when referenced against outpatient versus community norms.
Three Global Indices
The BSI produces three global indices that summarize different aspects of the overall symptom burden. All three are reported alongside the nine dimension T-scores (Michel et al., 2024).
| Index | Abbreviation | How It Is Computed | What It Captures |
|---|---|---|---|
| Global Severity Index | GSI | Sum of all 53 item ratings ÷ 53 | Overall severity and breadth of distress; the single best indicator of current psychological status and the primary caseness indicator |
| Positive Symptom Total | PST | Count of items rated > 0 | Number of symptoms endorsed, regardless of intensity; reflects breadth of symptom burden |
| Positive Symptom Distress Index | PSDI | Sum of all item ratings ÷ PST | Average intensity of symptoms that were endorsed; reflects how intensely the respondent experiences each reported symptom |
Interpreting the three indices together provides a richer clinical picture than any one index alone. For example, a high GSI combined with a high PST suggests broad, diffuse distress across many symptom domains. A high GSI with a lower PST but high PSDI points toward fewer symptoms that are each experienced with considerable intensity — a pattern that may reflect a more focal but severe clinical picture. Conversely, a high PST with a relatively low PSDI indicates that many symptoms are acknowledged but none is particularly distressing, which can occur in individuals with broad subclinical worry who lack frank psychological distress.
BSI vs BSI-18 vs SCL-90-R
Three scales from the same family — choose based on clinical setting, administration time, and dimensional coverage needed.
| Feature | SCL-90-R | BSI | BSI-18 |
|---|---|---|---|
| Items | 90 | 53 | 18 |
| Admin time | ~12–15 min | ~8–10 min | ~4–5 min |
| Symptom dimensions | 9 | 9 | 3 (SOM, DEP, ANX) |
| Global indices | 3 (GSI, PST, PSDI) | 3 (GSI, PST, PSDI) | 1 (GSI only) |
| Primary use case | Detailed outpatient / research profiling | Outpatient outcome monitoring, clinical trials | Medical settings, population screening |
| Additional items (not in any dimension) | 7 | 4 | — |
| Publisher | Pearson Assessments | Pearson Assessments | Pearson Assessments |
The SCL-90-R is preferred when comprehensive dimensional profiling is required and administration time is not a constraint. The BSI achieves comparable reliability and validity across all nine dimensions in roughly half the time, making it the most common choice in outpatient clinical research. The BSI-18 sacrifices dimensional breadth to maximize brevity, and is best suited to rapid distress screening in primary care or oncology settings where the full nine-dimension profile is unnecessary (Derogatis, 1993; Michel et al., 2024).
Psychometric properties
In the introductory report (Derogatis & Melisaratos, 1983), test-retest and internal consistency reliabilities were very good for the primary symptom dimensions, and correlations with the comparable SCL-90-R dimensions were high. High convergence with like dimensions of the MMPI supported convergent validity, and factor analytic studies supported construct validity. In 688 outpatients (Thomas, 2012), a bifactor model fit the BSI's internal structure better than unidimensional or oblique models and improved diagnostic accuracy (73% versus 61% and 65%). In a representative Swiss general-population sample of 1,238 adults (Michel et al., 2024), the BSI had good psychometric properties; 18.1% of the general population and 75.2% of psychotherapy outpatients met the caseness criterion.
Limitations
- Not diagnostic. Caseness signals distress that warrants further evaluation; it is not a diagnosis, and a high dimension score (for example Psychoticism) does not confirm a disorder.
- Profile, not severity bands. There are no literature-supported mild/moderate/severe total-score bands; only the T ≥ 63 caseness rule is validated.
- Norm-group dependence. The same raw score yields different T-scores against outpatient, community or adolescent norms, and national norms differ.
- Self-report. Ratings reflect the past seven days and depend on the respondent's willingness and ability to report symptoms.
- Licensed. The BSI is proprietary (Pearson); per-dimension item counts and normative tables are in the scoring manual.
Measuring Psychiatric Symptoms in HiBoop
HiBoop does not offer the BSI; this page is reference material. For broad symptom screening, HiBoop offers the DASS-21, PHQ-9, GAD-7, and PCL-5, scored on submission and tracked over time.
HiBoop does not offer this scale. This page is reference material.This library is an academic and clinical reference. A scale described here is not necessarily offered in HiBoop; each page says whether it is.
Bill this assessment
In the US, the Brief Symptom Inventory is usually billed under these CPT codes. Payer rules vary.
Measurement-based care in practice
For clinicians
HiBoop does not offer this scale. For the scales it does offer, responses are scored on submission and tracked over time, and HiBoop automates delivery across your patient panel.
For individuals
This page is a clinical reference, not a diagnostic tool. If you have concerns about your own symptoms, bring this information to a qualified mental health professional.
Frequently Asked Questions
What GSI T-score indicates clinical caseness on the BSI?
A Global Severity Index (GSI) T-score of 63 or above indicates clinical caseness on the BSI. This threshold represents approximately the 90th percentile relative to the normative sample and signals that the level of psychological distress is elevated enough to warrant clinical attention. Alternatively, meeting T≥63 on two or more of the nine symptom dimensions also meets the caseness criterion.
What is the difference between the BSI, BSI-18, and SCL-90-R?
All three scales measure psychological symptom distress but differ in length and scope. The SCL-90-R (90 items, 12–15 minutes) provides the most detailed profiling across 9 dimensions. The BSI (53 items, 8–10 minutes) covers the same 9 dimensions plus 3 global indices and is preferred for outpatient clinical research. The BSI-18 (18 items, 4–5 minutes) assesses only Somatization, Depression, and Anxiety with a GSI, making it suitable for medical settings and population screening.
Who publishes the BSI and is it freely available?
The BSI is published by Pearson Assessments (formerly National Computer Systems) and requires purchase for clinical and research use. Both the BSI and BSI-18 are proprietary scales; licensing fees apply. The BSI-18 is also available through Pearson and was developed to meet demand for shorter tools in medical and primary care settings.
What does a high BSI Psychoticism subscale score mean?
The BSI Psychoticism subscale (5 items) spans a range from mild interpersonal alienation to more pronounced evidence of psychosis, including auditory hallucinations and thought broadcasting. A high T-score on this dimension warrants careful clinical assessment, though it does not automatically confirm a psychotic disorder — it reflects the degree of psychotic-like distress as self-reported. Clinical context, interview data, and functional assessment are essential for interpretation.
References
- 1.Derogatis LR, Melisaratos N. The Brief Symptom Inventory: an introductory report. Psychol Med. 1983;13(3):595-605.View source
- 2.Thomas ML. Rewards of bridging the divide between measurement and clinical theory: demonstration of a bifactor model for the Brief Symptom Inventory. Psychol Assess. 2012;24(1):101-113.View source
- 3.Michel G, Baenziger J, Brodbeck J, et al. The Brief Symptom Inventory in the Swiss general population: Presentation of norm scores and predictors of psychological distress. PLoS One. 2024;19(7):e0305192.View source
Last reviewed: Jun 3, 2026
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