Functional Index Questionnaire: structural validity study in Brazilian patients with anterior knee pain

ABSTRACT OBJECTIVE: To assess the Functional Index Questionnaire (FIQ) structure using confirmatory factor analysis (CFA) in Brazilian patients with anterior knee pain. METHODS: Brazilian patients of both sexes (n = 100), aged ≥ 18 years, with anterior knee pain for at least 3 months were included...

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Main Authors: André Pontes-Silva, Almir Vieira Dibai-Filho, Flávio de Oliveira Pires, Carlos Eduardo Girasol, Gabriel Gardhel Costa Araujo, Plínio da Cunha Leal, José Djalma Arrais Junior, Cid André Fidelis-de-Paula-Gomes, Christian Emmanuel Torres Cabido
Format: Article
Language:English
Published: Associação Paulista de Medicina 2025-06-01
Series:São Paulo Medical Journal
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Online Access:http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-31802025000500200&lng=en&tlng=en
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author André Pontes-Silva
Almir Vieira Dibai-Filho
Flávio de Oliveira Pires
Carlos Eduardo Girasol
Gabriel Gardhel Costa Araujo
Plínio da Cunha Leal
José Djalma Arrais Junior
Cid André Fidelis-de-Paula-Gomes
Christian Emmanuel Torres Cabido
author_facet André Pontes-Silva
Almir Vieira Dibai-Filho
Flávio de Oliveira Pires
Carlos Eduardo Girasol
Gabriel Gardhel Costa Araujo
Plínio da Cunha Leal
José Djalma Arrais Junior
Cid André Fidelis-de-Paula-Gomes
Christian Emmanuel Torres Cabido
author_sort André Pontes-Silva
collection DOAJ
description ABSTRACT OBJECTIVE: To assess the Functional Index Questionnaire (FIQ) structure using confirmatory factor analysis (CFA) in Brazilian patients with anterior knee pain. METHODS: Brazilian patients of both sexes (n = 100), aged ≥ 18 years, with anterior knee pain for at least 3 months were included. Eligible participants completed an online form that collected personal and clinical data as well as responses to the assessment tools. We used CFA and the following fit indices: chi-square/degrees of freedom (DF), comparative fit index (CFI), Tucker–Lewis index (TLI), root mean square error of approximation (RMSEA), and standardized root mean square residuals (SRMR). RESULTS: The majority of the respondents were women, young adults, overweight, with incomplete higher education, were physically active, and had pain in sitting or squatting positions. The mean duration of pain was 38.24 months, and the mean pain intensity was 4.54 points. The model fit indices were as follows: χ2/DF = 2.08, TLI = 0.978, CFI = 0.969, RMSEA = 0.104, and SRMR = 0.077. Therefore, the one-dimensional structure with eight items yielded an RMSEA value above the 0.08 cutoff point, suggesting a poorer fit and more residual error than is acceptable for a well-fitting model. Using the modification indices within the CFA, we observed a correlation between Items 2 (climbing up two flights of stairs [16 steps]) and 6 (climbing up four flights of stairs [32 steps]) and Items 3 (squatting) and 4 (kneeling), indicating the similarity in the response pattern for these items. After adding these correlations to the model, we obtained improved fit indices (χ2/DF = 1.51, TLI = 0.990, CFI = 0.985, RMSEA = 0.072, and SRMR = 0.061). CONCLUSION: This version of the FIQ should be used with caution, as the unidimensional model demonstrates substantial residuals, mainly because of item redundancy.
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spelling doaj-art-7dfa262fc6b14d7b8b7136331d28a3432025-08-20T02:38:45ZengAssociação Paulista de MedicinaSão Paulo Medical Journal1806-94602025-06-01143510.1590/1516-3180.2024.0153.r1.07032025Functional Index Questionnaire: structural validity study in Brazilian patients with anterior knee painAndré Pontes-Silvahttps://orcid.org/0000-0002-3983-5342Almir Vieira Dibai-Filhohttps://orcid.org/0000-0001-5403-8248Flávio de Oliveira Pireshttps://orcid.org/0000-0002-9497-8928Carlos Eduardo Girasolhttps://orcid.org/0000-0002-3901-582XGabriel Gardhel Costa Araujohttps://orcid.org/0000-0003-0972-5342Plínio da Cunha Lealhttps://orcid.org/0000-0003-1336-8528José Djalma Arrais Juniorhttps://orcid.org/0009-0000-1420-6657Cid André Fidelis-de-Paula-Gomeshttps://orcid.org/0000-0001-6627-7537Christian Emmanuel Torres Cabidohttps://orcid.org/0000-0002-4800-0128ABSTRACT OBJECTIVE: To assess the Functional Index Questionnaire (FIQ) structure using confirmatory factor analysis (CFA) in Brazilian patients with anterior knee pain. METHODS: Brazilian patients of both sexes (n = 100), aged ≥ 18 years, with anterior knee pain for at least 3 months were included. Eligible participants completed an online form that collected personal and clinical data as well as responses to the assessment tools. We used CFA and the following fit indices: chi-square/degrees of freedom (DF), comparative fit index (CFI), Tucker–Lewis index (TLI), root mean square error of approximation (RMSEA), and standardized root mean square residuals (SRMR). RESULTS: The majority of the respondents were women, young adults, overweight, with incomplete higher education, were physically active, and had pain in sitting or squatting positions. The mean duration of pain was 38.24 months, and the mean pain intensity was 4.54 points. The model fit indices were as follows: χ2/DF = 2.08, TLI = 0.978, CFI = 0.969, RMSEA = 0.104, and SRMR = 0.077. Therefore, the one-dimensional structure with eight items yielded an RMSEA value above the 0.08 cutoff point, suggesting a poorer fit and more residual error than is acceptable for a well-fitting model. Using the modification indices within the CFA, we observed a correlation between Items 2 (climbing up two flights of stairs [16 steps]) and 6 (climbing up four flights of stairs [32 steps]) and Items 3 (squatting) and 4 (kneeling), indicating the similarity in the response pattern for these items. After adding these correlations to the model, we obtained improved fit indices (χ2/DF = 1.51, TLI = 0.990, CFI = 0.985, RMSEA = 0.072, and SRMR = 0.061). CONCLUSION: This version of the FIQ should be used with caution, as the unidimensional model demonstrates substantial residuals, mainly because of item redundancy.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-31802025000500200&lng=en&tlng=enPatellofemoral pain syndromeKneeOsteoarthritisPainReproducibility of resultsMusculoskeletal disordersConsensus-based Standards for the Selection of HealthMeasurement Instruments (COSMIN)Chronic PainPatient-Reported Outcome Measures (PROMs)
spellingShingle André Pontes-Silva
Almir Vieira Dibai-Filho
Flávio de Oliveira Pires
Carlos Eduardo Girasol
Gabriel Gardhel Costa Araujo
Plínio da Cunha Leal
José Djalma Arrais Junior
Cid André Fidelis-de-Paula-Gomes
Christian Emmanuel Torres Cabido
Functional Index Questionnaire: structural validity study in Brazilian patients with anterior knee pain
São Paulo Medical Journal
Patellofemoral pain syndrome
Knee
Osteoarthritis
Pain
Reproducibility of results
Musculoskeletal disorders
Consensus-based Standards for the Selection of Health
Measurement Instruments (COSMIN)
Chronic Pain
Patient-Reported Outcome Measures (PROMs)
title Functional Index Questionnaire: structural validity study in Brazilian patients with anterior knee pain
title_full Functional Index Questionnaire: structural validity study in Brazilian patients with anterior knee pain
title_fullStr Functional Index Questionnaire: structural validity study in Brazilian patients with anterior knee pain
title_full_unstemmed Functional Index Questionnaire: structural validity study in Brazilian patients with anterior knee pain
title_short Functional Index Questionnaire: structural validity study in Brazilian patients with anterior knee pain
title_sort functional index questionnaire structural validity study in brazilian patients with anterior knee pain
topic Patellofemoral pain syndrome
Knee
Osteoarthritis
Pain
Reproducibility of results
Musculoskeletal disorders
Consensus-based Standards for the Selection of Health
Measurement Instruments (COSMIN)
Chronic Pain
Patient-Reported Outcome Measures (PROMs)
url http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-31802025000500200&lng=en&tlng=en
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