Brief Symptom Inventory (BSI) - Subject Baseline
This measure appears in the following time-points: Baseline.
Description of Measure
The Brief Symptom Inventory (BSI; Derogatis & Melisaratos, 1983) is a 53-item self-report inventory in which participants rate the extent to which they have been bothered (0 ="not at all" to 4="extremely") in the past week by various symptoms. The BSI has nine subscales designed to assess individual symptom groups: somatization (SOM, e.g., "Faintness or dizziness"), obsessive-compulsive (OC, e.g., "Having to check and double-check what you do"), interpersonal sensitivity (IS, e.g., "Feeling inferior to others"), depression (DEP, e.g., "Feeling no interest in things"), anxiety (ANX, e.g., "Feeling tense or keyed up"), hostility (HOS, e.g., "Having urges to break or smash things"), phobic anxiety (PHB, e.g., "Feeling uneasy in crowds, such as shopping or at a movie"), paranoid ideation (PAR, e.g., "Others not giving you proper credit for your achievements"), and psychoticism (PSY, e.g., "The idea that something is wrong with your mind"). The BSI also includes three scales that capture global psychological distress.
Confirmatory factor analysis was conducted with the Pathways sample, examining each subscale as a single factor solution. The values generated from this analysis are as follows:
- Somatization: chi-square = 71.4; df=14, RMSEA .05; Cronbach's alpha (baseline): .813
- Obsessive-compulsive: chi-square = 67.7; df=9, RMSEA .07; Cronbach's alpha (baseline): .798
- Interpersonal Sensitivity: = chi-square = 11.9; df=2, RMSEA .06; Cronbach's alpha (baseline): .661
- Depression: chi-square = 342.5; df=9, RMSEA .16; Cronbach's alpha (baseline): .805
- Anxiety: chi-square = 161.4; df=9, RMSEA .11; Cronbach's alpha (baseline): .779
- Hostility: chi-square = 187.0; df=5, RMSEA .16; Cronbach's alpha (baseline): .746
- Phobia: chi-square = 22.7; df=5, RMSEA .05; Cronbach's alpha (baseline): .685
- Paranoia: chi-square = 18.7; df=5, RMSEA .04; Cronbach's alpha (baseline): .685
- Psychoticism: chi-square = 20.2; df=5, RMSEA .05; Cronbach's alpha (baseline): .638
Multiple subscale scores are thus provided:
- A score that corresponds to each of the nine subscales listed above. This score is the mean of the individual items which comprise the subscale - [s0bsisom], [s0bsioc], [s0bsiis], [s0bsidep], [s0bsianx], [s0bsihos], [s0bsiphb], [s0bsipar], [s0bsipsy], [s0som_t], [s0oc_t], [s0is_t], [s0dep_t], [s0anx_t], [s0hos_t], [s0phb_t], [s0par_t], [s0psy_t], [s0gsi_t]
- Global Severity Index - GSI [s0bsiGSI]; this score is essentially the mean of all of the subscale scores
- Positive Symptoms Total - PST [s0bsiPST]; a count of the number of items endorsed at a level higher than zero
- Positive Symptoms Distress Index [s0bsiPSD]; the sum of all item values divided by the PST
We also have available two variables which are associated with the clinical status of the case.
- [S0Bsidx1]: count of the number of subscales on which the participant reaches clinical significance
- [S0Bsidx]: marker for cases which reach clinical significance on 2 or more subscales.
Caution should be exercised when using the subscales scores for the BSI. Most researchers agree that the BSI is an appropriate measure of general psychopathology and psychological distress (for a summary of the literature on this issue, see Skeem, Schubert, Odgers, Mulvey, Gardner & Lidz (2006). Reliability for the Global Severity Index (GSI) is reported as .95 (Derogatis & Melisaratos, 1983). However, its utility at the discrete symptom or item level (subscales) is questionable (cf. Benishek, et.al., 1998). Specifically, multiple factor analytic and other studies suggest that the discriminant validity of several BSI subscales is poor. Four factors repeatedly emerge across most factor analytic studies, and the general consensus of the research in this area at the time of this entry (06/05) is that four of the subscales can therefore be used with confidence in their validity: depression, anxiety, somatization and hostility.
In summary, subscales with an acceptable fit include: Somatization, phobia, paranoia and psychoticism. The fit for obsessive-compulsive is questionable while the fit for depression, anxiety and hostility is not acceptable. Testing was also completed for nesting models. In this analysis, the nine factor model represents a statistically significant improvement over the one factor BSI model. However, given the degree of misfit in the nine individual models and the fact that only 4 of the subscales obtain an acceptable fit, it is likely that the nine factor model specified here is not the best solution for this set of items. Also, it should be noted that the fit statistics for these models are very sensitive to sample size. Thus, while the fit is adequate (RMSEA=.07), it is not ideal. These findings support the general research about the potential problems of using these subscale scores alone and the lack of congruence between the results of earlier investigations and the results seen in this sample lend extra caution.
We provide a variable to indicate the clinical significance of each of the subscale scores. The BSI manual (p. 32) describes a set of operational rules for determining whether a subject's scores are elevated to the point of clinical concern. According to the manual, a clinically significant score can be reached in two ways:
- The GSI score is greater than or equal to a T score of 63
- Any two subscales are greater than or equal to a T score of 63 when compared with the norms for the particular population in question.
The Pathways study identified cases with clinically significant BSI scores using the following steps:
- The norms for adolescent non-patients (separate norms for males and females) were used. These norms are contained in Appendix A of the BSI manual. Using the table in Appendix A, we see that on the somatization subscale, a T score of 63 falls at the raw score of 1.59 for males and at 1.39 for females. Male cases which received below a 1.59 were marked as "not clinically significant (0)", those above were marked as "clinical range (1)". This exercise was repeated for males and females on all 9 subscales and the GSI.
- Next, to ascertain cases meeting clinical significance because they had 2 subscales with a score greater than or higher than the score associated with a T score of 63, a count function was used. S0bsiDX1 is a created variable that indicates the number of subscales that are clinically significant (based on the marker from step 1). If the count equals 2 or more, another created variable s0bsiDX is set to 1(clinical range)
- To ascertain cases where the GSI score is greater than or equal to a T score of 63, we rely on the marker assigned in step 1. S0bsiDX = 1 is assigned to all cases which fall into the clinically significant range based on the method documented in either step 2 or step 3.
- Derogatis, L. & Melisaratos, N. (1983). The Brief Symptom Inventory: An introductory report. Psychological Medicine, 13, 595-605.
- Skeem, J.L., Schubert, C.A., Odgers, C., Mulvey, E.P., Gardner, W. Lidz, C. (2006) Psychiatric Symptoms and Community Violence Among High-risk patients: A test of the relationship at the weekly level. Journal of Consulting and Clinical Psychology, 74(5), 967-979.