Polish FIQ Deemed Reliable, Valid Tool for Assessing Fibromyalgia


A cross-sectional analysis showed the reliability and repeatability of the Polish version of the Fibromyalgia Impact Questionnaire were "very good."

The Polish version of the Fibromyalgia Impact Questionnaire (FIQ-Pol) was shown to be a reliable and valid tool to assess the functional disability and health status of patients with fibromyalgia, according to a study published in BMC Public Health.1

Polish FIQ Deemed Reliable, Valid Tool for Assessing Fibromyalgia

Agnieszka Ćwirlej-Sozańska, PhD

Credit: ResearchGate.net

The original FIQ, which is widely used in clinical practice and research, was developed to determine the range of functional problems in this patient population. The tool was developed based on symptoms, function, and overall impact and measures elements of health and functioning that have been determined to be most affected by fibromyalgia. The FIQ has been shown to have excellent psychometric prosperities and distinguishes patients with fibromyalgia from those with other conditions, including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and depressive disorders.2

“The FIQ is one of the most commonly used instruments capable to measure the current health status of patients with fibromyalgia,” explained Agnieszka Ćwirlej-Sozańska, PhD, Institute of Health Sciences, College of Medical Sciences of the University of Rzeszow, University of Rzeszow, Poland, and colleagues. “To the best of our knowledge, the questionnaire used for assessing problems and difficulties in the functioning of people with fibromyalgia has not been translated and adapted in Poland so far.”

In the cross-sectional study, 150 patients with fibromyalgia living in Poland who were associated with FIBRO-MY (the National Association of Patients with Fibromyalgia) and the College of Medical Sciences of the University of Rzeszow completed the FIQ-Pol questionnaire. The reliability, repeatability, validity, and internal structure was then assessed.

The aim of the study was to determine the psychometric properties of the questionnaire. Eligibility criteria included a clinical fibromyalgia diagnosis according to the American College of Rheumatology (ACR) criteria, an informed consent to participate, and were aged ≥18 years.

The FIQ consists of 20 items evaluating wellbeing, pain, fatigue, anxiety, depression, stiffness, rested, work-related factors, and physical functioning. Scores are assessed on a scale of 0 to 10, with 0 indicating no impairment and 10 meaning maximum impairment.

Of the participants included in the study, the mean age was 44.78 years, 121 were female, 80.67% lived in rural areas, and 70% were either married or in a partnership. The scale score reliability of the tool was determined to be very good and the alpha Cronbach’s test result for the whole scale was .84. Repeatability, measured by the test-retest method using the interclass correlation coefficients (ICC), was very good and rated as .96. The internal structure was confirmed via confirmatory factor analysis.

Satisfactory parameter values were obtained after introducing modification indices for the entire scale. Root Mean Square Error of Approximation (RMSEA) was rated as .06, Comparative Fit Index (CFI) was .97, and the Tucker-Lewis Index (TLI) was .96. The theoretical validity was evaluated using correlating the results of the FIQ-Pol version of the FIQ with the results of the 4-point scale Beck’s Depression Inventory (BDI). Both the total score and its domains showed strong positive correlations with the BDI.

Investigators noted the size of the sample group may have limited the study. In future research, the accuracy of the Polish version of the questionnaire could be better established with a greater number of participants. Additionally, future studies should focus on determining the sensitivity of the FIQ-Pol to changes in the clinical status of this patient population.

Based on these results, investigators concluded, “the FIQ-Pol can be used in clinical settings and for research purposes.”


  1. Ćwirlej-Sozańska A, Sozański B, Łyko A, et al. Psychometric properties and validation of the polish version of the Fibromyalgia Impact Questionnaire (FIQ-Pol). BMC Public Health. 2023;23(1):1477. Published 2023 Aug 3. doi:10.1186/s12889-023-16411-2
  2. Burckhardt CS, Clark SR, Bennett RM. The fibromyalgia impact questionnaire: development and validation. J Rheumatol. 1991;18(5):728–33
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