Improving the Measurement of Functional Somatic Symptoms with Item Response Theory

More than 40 questionnaires have been developed to assess functional somatic symptoms (FSS), but there are several methodological issues regarding the measurement of FSS. We aimed to identify which items of the somatization subscale of the Symptom Checklist–90 (SCL-90) are more informative and discriminative between persons at different levels of severity of FSS. To this end, item response theory was applied to the somatization scale of the SCL-90, collected from a sample of 82,740 adult participants without somatic conditions in the Lifelines Cohort Study. Sensitivity analyses were performed with all the participants who completed the somatization scale. Both analyses showed that Items 11 “feeling weak physically” and 12 “heavy feelings in arms or legs” were the most discriminative and informative to measure severity levels of FSS, regardless of somatic conditions. Clinicians and researchers may pay extra attention to these symptoms to augment the assessment of FSS.

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Use of item response theory to understand differential functioning of DSM-IV major depression symptoms by race, ethnicity and gender

Psychological Medicine ◽

10.1017/s0033291708003875 ◽

2008 ◽

Vol 39 (4) ◽

pp. 591-601 ◽

Cited By ~ 56

Author(s):

L. A. Uebelacker ◽

D. Strong ◽

L. M. Weinstock ◽

I. W. Miller

Keyword(s):

Item Response Theory ◽

Major Depression ◽

Item Response ◽

American Indians ◽

Somatic Symptoms ◽

Depression Symptoms ◽

Depression Symptom ◽

Response Theory ◽

English Speaking ◽

Dsm Iv

BackgroundPsychological literature and clinical lore suggest that there may be systematic differences in how various demographic groups experience depressive symptoms, particularly somatic symptoms. The aim of the current study was to use methods based on item response theory (IRT) to examine whether, when equating for levels of depression symptom severity, there are demographic differences in the likelihood of reporting DSM-IV depression symptoms.MethodWe conducted a secondary analysis of a subset (n=13 753) of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) dataset, which includes a large epidemiological sample of English-speaking Americans. We compared data from women and men, Hispanics and non-Hispanic Whites, African Americans and Whites, Asian Americans and Whites, and American Indians and Whites.ResultsThere were few differences overall, although the differences that we did find were primarily limited to somatic symptoms, and particularly appetite and weight disturbance.ConclusionsFor the most part, individuals responded similarly to the criteria used to diagnose major depression across gender and across English-speaking racial and ethnic groups in the USA.

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