Psychometric properties of the Short-Form McGill Pain Questionnaire (SF-MPQ) in adult Mexican cancer patients with chronic pain.

Background: Pain is a frequent symptom in cancer patients (CP), and its multidimensional assessment is essential for a comprehensive approach and to establish clinical prognoses. The Short-Form McGill Pain Questionnaire (SF-MPQ) is an internationally recognized tool for the multidimensional assessment of pain, both in clinical and research settings. However, no studies have been reported in Latin America that determine its psychometric properties in CP and chronic pain.

Objectives: To determine the psychometric properties of the SF-MPQ in adult Mexican cancer patients with chronic pain.

Methods: An instrumental design was used with a non-probabilistic convenience sample of 222 cancer patients treated at the pain clinic of a tertiary care hospital. Analyses were conducted to evaluate factorial structure (exploratory and confirmatory factor analysis [CFA]), reliability (internal consistency), measurement invariance, and criterion validity (concurrent and divergent).

Results: CFA verified a 9-item structure divided into 2 factors: (1) Affective-Nociceptive and (2) Neuropathic. A global Cronbach's alpha coefficient of .82 and a global McDonald's Omega index of .82 were identified. Configural, metric, and scalar invariance (ΔCFI ≤ .01; ΔRMSEA ≤ .015) were confirmed regarding the sex variable. Finally, the SF-MPQ showed a positive correlation with the Numerical Rating Scale (rho = .436, p< .01) and a negative correlation with the EORTC-QLQ C30 (rho = -.396, p< .01).

Significance of results: The Mexican version of the SF-MPQ presented adequate psychometric properties and fit indices, making it a valid and reliable instrument for use in clinical and research settings in Mexico. Its use is recommended for the comprehensive assessment of pain in oncology in Mexico, as it allows for the understanding of pain characteristics beyond intensity, guiding the establishment of clinical prognoses.