Background The Fibromyalgia Rapid Screening Tool (FiRST) is a brief questionnaire designed to screen for fibromyalgia (FM). Objective To assess the diagnostic accuracy and psychometric properties of FiRST in Mexican patients with chronic musculoskeletal pain (CMP). Methods This cross-sectional validation study included patients who met the 2016 ACR criteria for FM and controls with other rheumatic diseases. Diagnostic accuracy was assessed using receiver operating characteristic (ROC) analysis, sensitivity, specificity, likelihood ratios, and Youden’s index. The construct, criterion, and known-groups validity were tested using correlations and predefined hypotheses. Rasch analysis was used to evaluate item fit, dimensionality, local dependence, targeting, reliability, and differential item functioning (DIF). Results A total of 1307 patients were analyzed (FM = 319; non-FM = 988). A cutoff of ≥ 5 resulted in the best diagnostic balance (sensitivity, 84.3%; specificity, 76.4%). Construct validity was supported, with 93% of hypotheses being confirmed. Rasch analysis indicated unidimensionality, acceptable item fit, minimal local dependence, and minimal sex-related DIF. Person–item maps showed adequate targeting of moderate-to-severe cases but lower precision for milder symptoms. A ceiling effect was observed, with some patients clustering at the maximum score, limiting discrimination among the most severe cases. Conclusions FiRST showed acceptable validity and diagnostic accuracy for FM screening in Mexican patients with CMP. A cutoff of ≥ 5 is recommended, although additional items may be needed to improve sensitivity at both ends of the FM severity spectrum. <Table Float="No" ID="Taba"> <tgroup cols="2"> <colspec align="left" colname="c1" colnum="1" /> <colspec align="left" colname="c2" colnum="2" /> <tbody> <row> <entry align="left" nameend="c2" namest="c1"> Key Points • FiRST showed good diagnostic and psychometric performance. • The FiRST exhibited limitations, including ceiling effects and a restricted item distribution. The tool could benefit from the addition of more difficult items to assess varying disease severity levels better. • In clinical settings, a negative FIRST result provides high confidence in ruling out fibromyalgia, whereas a positive result requires further evaluation. </entry> </row> </tbody> </tgroup> </Table>

Diagnostic accuracy and psychometric properties of the fibromyalgia rapid screening tool in Mexican patients with chronic musculoskeletal pain

期刊论文
发表日期：

2025年11月28日

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Imelda Vergara-Sánchez,
Gabriel Horta-Baas

摘要

Background

The Fibromyalgia Rapid Screening Tool (FiRST) is a brief questionnaire designed to screen for fibromyalgia (FM).

Objective

To assess the diagnostic accuracy and psychometric properties of FiRST in Mexican patients with chronic musculoskeletal pain (CMP).

Methods

This cross-sectional validation study included patients who met the 2016 ACR criteria for FM and controls with other rheumatic diseases. Diagnostic accuracy was assessed using receiver operating characteristic (ROC) analysis, sensitivity, specificity, likelihood ratios, and Youden’s index. The construct, criterion, and known-groups validity were tested using correlations and predefined hypotheses. Rasch analysis was used to evaluate item fit, dimensionality, local dependence, targeting, reliability, and differential item functioning (DIF).

Results

A total of 1307 patients were analyzed (FM = 319; non-FM = 988). A cutoff of ≥ 5 resulted in the best diagnostic balance (sensitivity, 84.3%; specificity, 76.4%). Construct validity was supported, with 93% of hypotheses being confirmed. Rasch analysis indicated unidimensionality, acceptable item fit, minimal local dependence, and minimal sex-related DIF. Person–item maps showed adequate targeting of moderate-to-severe cases but lower precision for milder symptoms. A ceiling effect was observed, with some patients clustering at the maximum score, limiting discrimination among the most severe cases.

Conclusions

FiRST showed acceptable validity and diagnostic accuracy for FM screening in Mexican patients with CMP. A cutoff of ≥ 5 is recommended, although additional items may be needed to improve sensitivity at both ends of the FM severity spectrum.

Key Points

• FiRST showed good diagnostic and psychometric performance.

• The FiRST exhibited limitations, including ceiling effects and a restricted item distribution. The tool could benefit from the addition of more difficult items to assess varying disease severity levels better.

• In clinical settings, a negative FIRST result provides high confidence in ruling out fibromyalgia, whereas a positive result requires further evaluation.