Psychometric properties and validation of the English version Giessen Subjective Complaints List (GBB-8)

(2022) 10:60 Petrowski et al. BMC Psychology https://doi.org/10.1186/s40359-022-00741-8 Open Access RESEARCH Psychometric properties and validation of the English version Giessen Subjective Complaints List (GBB‑8) Katja Petrowski1,2*, Markus Zenger3,4, Bjarne Schmalbach2, Christina Diane Bastianon2 and Bernhard Strauss5 Abstract Background: The present study investigated the psychometric properties of the newly developed English version of the Giessen Subjective Complaint List-8 (GBB-8), a questionnaire assessing psychosomatic symptoms with regard to exhaustion, gastrointestinal, musculoskeletal and cardiovascular. Methods: A U.S. sample of 638 participants (47.6% female) was recruited by MTurk to participate in this cross-sectional online survey. Validation instruments included the Patient Health Questionnaire-4, Perceived Stress Scale, short version of the Trier Inventory for Chronic Stress. Results: Reliability was high with ω’s between .80 and .86 for all subscales. Confirmatory factor analyses yielded comparable good model fit for a four-dimensional model as well as a higher order model. Multi-group confirmatory factor analyses confirmed measurement invariance of the GBB-8 across sex and age. Regarding convergent validity, correlations with other instruments were highly significant and of large magnitude as expected. Conclusion: The English version of the GBB-8 has shown excellent psychometric properties. Therefore, it can be recommended for the assessment of psychosomatic complaints in contexts where short screening instruments are necessary. Keywords: Giessen subjective complaint list, English version, Psychometric properties, Validation, Assessment, Psychosomatic Background Somatic complaints are highly represented in society [1–3] as well as in patients involved in the health care system [4, 5]. Although these are not directly connected to medical conditions, patients with severe medical conditions commonly utter somatic symptoms. However, somatic symptoms are associated to symptoms of anxiety and depression [2]. The assessment of somatic symptom stress is key in epidemiological research, since such are *Correspondence: 1 Department of Internal Medicine III, Dresden University of Technology, Fetscherstrasse 74, 01307 Dresden, Germany Full list of author information is available at the end of the article known to reduce the health-related quality of life and are related to a greater use of the health care services [2, 6, 7]. So far, the assessment comparability of the somatic symptom burden in the general population has been limited by a lack of agreement on the scales used stated by Zijlema et al. [8]. In their recent systematic review, Zijlema et al. [8] identified 40 self-report somatic symptoms questionnaires and assessed them regarding their usability for large scale population studies. The authors suggested the Patient Health Questionnaire-15 [9] and the somatization scale of Symptom Checklist 90 [10]. However, the Symptom Checklist 90 lacks the brevity needed in epidemiological research. Even for gerontic patients or older patients 15 items of the PHQ might © The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativeco mmons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Petrowski et al. BMC Psychology (2022) 10:60 be still too long. Therefore, shorter version of the PHQ (including the PHQ-4) and other scales with the assessment of somatic symptoms should be used. Shorter psychometrically sound questionnaires have several benefits: the drop-out rate as well as the rate of missing values are lower in shorter surveys, and the participants experience less boredom or fatigue. In German speaking societies, a scientifically sound scale for the assessment of subjective health complaints is the Giessen Subjective Complaints List (Gießener Beschwerdebogen—GBB [11]). The GBB-24 consists of 24 health complaints rated on a Likert scale ranging from 0 (not at all) to 4 (very much). The individual complaints can be aggregated on four scales: exhaustion, gastrointestinal complaints, musculoskeletal complaints, cardiovascular complaints. These scales correspond well to commonly reported symptom clusters [8]. After continuous improvement, the 24-item version of the GBB24 came into application for the evaluation of physical complaints after medical assessments, social stressors, psychotherapy, symptom strain in minority and marginalized groups. The GBB is also used for basic documentation in psychosomatic medicine and psychotherapy [11]. In order to use the GBB in epidemiological research, a shorter version would be necessary. Therefore, an 8-item brief version of the Giessen Subjective Complaints List was developed. The following criteria were applied for the shortened scale: (1) maintaining the original factor structure and having an equal number of items per factor (as is the case in the original long form), (2) the selected items should be among those with the highest item totalcorrelation from each subscale, (3) the selected items should have a mean above 0.5 in the general population to avoid floor effects. Psychometric analyses of the German version of theGBB-8 yielded excellent scale properties with regard to item characteristics and factor structure. The eight symptoms included in the questionnaire are among the top 15 symptoms reported by Zijlema et al. [8] as the most frequently assessed. This shows the relevance of the chosen criteria not only due to their psychometric quality but also regarding their content. A factor structure that allows for the computation of subscales, including norms for each subscale, provides an advantage over measures providing only one overall score. Strong measurement invariance can be largely confirmed regarding gender, age, and age × gender. The factors are more easily interpretable and highlight the specific areas of complaint. Given the norms and the confirmed factor structure, the subscales can be used independently. In sum, the psychometric properties of the GBB-8 (...truncated)