Refining scores based on patient reported outcomes – statistical and medical perspectives

  • Background: Patient Reported Outcomes (PRO) are gaining more and more importance in the context of clinical trials. The assessment of PRO is frequently performed by questionnaires where the multiple items of a questionnaire are usually pooled within summarizing scores. These scores are used as variables to measure subjective aspects of treatments and diseases. In clinical research, the calculation of these scores is mostly kept very simple, e.g. by a simple summation of item values. In the medical literature, there is hardly any guidance for performing a refinements of questionnaires and for deducing adequate scores. In contrast, in psychometric literature, there are plenty of more sophisticated methods, which overcome typical assumptions made in traditional (sum) scores, however to the prize of more complicated algorithms, which might be difficult to communicate. When faced with the practical task to refine an existing questionnaire, there exist a clear gap of guidance for applied medical researchers. By this article we try to fill this important gap between psychometric theory and medical application by illustrating our methodological choices on the example of a clinical PRO questionnaire. Methods: Based on our experiences with the refinement of the BCTOS, a PRO questionnaire to assess aesthetic and function after breast conserving therapy in breast cancer patients, we present the following general steps that we performed by refining the BCTOS questionnaire and its scores: 1. Refinement of the length of the questionnaire and the (item-factor) structure. 2. Selection of the factor score estimation method. 3. Validation of the refined questionnaire and scores with respect to validity, reliability and structure based on a validation cohort. Results: Our step-step-step procedure helped us to shorten the current form of the BCTOS and to redefine the factor structure. By this, the compliance of patients can be increased and the interpretation of the results becomes more coherent. Conclusions: We present a step-by-step procedure to refine an existing medical questionnaire along with its scores illustrated and discussed by the refinement of the BCTOS. Trial registration: Due to the character of the study (no intervention study), no registration was performed.

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Author:Manuel Feißt, André Hennigs, Jörg Heil, Helfried MoosbruggerGND, Augustin Kelava, Ilona Stolpner, Meinhard Kieser, Geraldine Rauch
Pubmed Id:
Parent Title (English):BMC medical research methodology
Publisher:BioMed Central ; Springer
Place of publication:London ; Berlin ; Heidelberg
Document Type:Article
Year of Completion:2019
Date of first Publication:2019/07/31
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2019/08/26
Tag:Factor scores; Latent variables; Patient reported outcomes; Questionnaire refinement
Issue:1, Art. 167
Page Number:9
First Page:1
Last Page:9
Open Access: This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.
Institutes:Psychologie und Sportwissenschaften / Psychologie
Dewey Decimal Classification:1 Philosophie und Psychologie / 15 Psychologie / 150 Psychologie
Licence (German):License LogoCreative Commons - Namensnennung 4.0