Development and Validation of the “Physical Functional Impact Index on Chronic Pain” (PFIICP): A Formative Model Approach
DOI:
https://doi.org/10.20344/amp.23516Keywords:
Chronic Pain, Pain Measurement, Quality of Life, Reproducibility of Results, Surveys and QuestionnairesAbstract
Introduction: The development and validation of reliable and valid instruments to assess chronic pain and its impact on daily functioning are crucial in both clinical and research settings. The aim of this study was to develop and validate the scale ‘Physical Function Impact Index on Chronic Pain’ – PFIICP, a novel 12-item questionnaire designed to evaluate the physical functional impact on chronic pain.
Methods: A formative measurement model was used. In comparison with other established scales that have emotional, cognitive and social considerations, PFIICP is designed to be more objective, as it focuses only on the relationship between physical performance and the subject’s pain.
Results: Data were collected from n = 285 patients at baseline and n = 58 patients at follow-up (3 - 6 months later). Spearman’s rho correlations between the 12 items ranged from 0.153 to 0.793, all statistically significant (p < 0.05), indicating that each item contributes uniquely to the construct. The intraclass correlation coefficient (ICC) for test-retest reliability was 0.788 (95% CI: 0.731 - 0.833), demonstrating good stability over time. Convergent validity was supported by strong Pearson correlations with established measures, including the Brief Pain Inventory (BPI; r = 0.739, p < 0.05) and the Pain Disability Index (PDI; r = 0.739, p < 0.05).
Conclusion: These findings suggest that the PFIICP is a robust tool for assessing the functional impact of chronic pain through a formative model approach.
Downloads
References
Azevedo LF, Costa-Pereira A, Mendonca L, Dias CC, Castro-Lopes JM. Epidemiology of chronic pain: a population-based nationwide study on its prevalence, characteristics and associated disability in Portugal. J Pain. 2012;13:773-83. DOI: https://doi.org/10.1016/j.jpain.2012.05.012
Antunes F, Pereira RM, Afonso V, Tinoco R. Prevalence and characteristics of chronic pain among patients in portuguese primary care units. Pain Ther. 2021;10:1427-37. DOI: https://doi.org/10.1007/s40122-021-00308-2
Üstün TB, Chatterji S, Bickenbach J, Kostanjsek N, Schneider M. The international classification of functioning, disability and health: a new tool for understanding disability and health. Disabil Rehabil. 2003;25:565-71. DOI: https://doi.org/10.1080/0963828031000137063
Leitão A. Classificação internacional de funcionalidade, incapacidade e saúde (CIF). Lisboa: Direcção-Geral da Saúde; 2004.
Bollen KA, Lennox R. Conventional wisdom on measurement: a structural equation perspective. Psychol Bull. 1991;110:305-14. DOI: https://doi.org/10.1037//0033-2909.110.2.305
Diamantopoulos A, Winklhofer HM. Index construction with formative indicators: an alternative to scale development. J Market Res. 2001;38:269-77. DOI: https://doi.org/10.1509/jmkr.38.2.269.18845
Associação Portuguesa para o Estudo da Dor. O que é a dor?. [cited 2025 Apr 11]. Available from: https://www.aped-dor.org/index.php/sobre-a-dor/definicoes.
World Health Organization. International classification of diseases, eleventh revision (ICD-11). [cited 2025 Apr 11]. Available from: https://icd.who.int/browse11.
European Pain Fedreation. What is the definition of pain?. [cited 2025 Apr 11]. Available from: https://europeanpainfederation.eu/history/what-is-pain/.
Cleeland C, Ryan M. Pain assessment: global use of the brief pain inventory. Ann Acad Med Singap.1994;23:129-38.
Azevedo LF, Costa Pereira A, Dias C, Agualusa L, Lemos L, Romão J, et al. Tradução, adaptação cultural e estudo multicêntrico de validação de instrumentos para rastreio e avaliação do impacto da dor crónica. Dor. 2007;15:38-9.
Tait RC, Pollard CA. Pain disability index: psychometric and validity data. Arch Phys Med Rehabil. 1987;68:438-41.
Podsakoff PM, MacKenzie SB, Lee JY, Podsakoff NP. Common method biases in behavioral research: a critical review of the literature and recommended remedies. J Appl Psychol. 2003;88:879. DOI: https://doi.org/10.1037/0021-9010.88.5.879
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2025 Acta Médica Portuguesa
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
All the articles published in the AMP are open access and comply with the requirements of funding agencies or academic institutions. The AMP is governed by the terms of the Creative Commons ‘Attribution – Non-Commercial Use - (CC-BY-NC)’ license, regarding the use by third parties.
It is the author’s responsibility to obtain approval for the reproduction of figures, tables, etc. from other publications.
Upon acceptance of an article for publication, the authors will be asked to complete the ICMJE “Copyright Liability and Copyright Sharing Statement “(http://www.actamedicaportuguesa.com/info/AMP-NormasPublicacao.pdf) and the “Declaration of Potential Conflicts of Interest” (http:// www.icmje.org/conflicts-of-interest). An e-mail will be sent to the corresponding author to acknowledge receipt of the manuscript.
After publication, the authors are authorised to make their articles available in repositories of their institutions of origin, as long as they always mention where they were published and according to the Creative Commons license.
