Psychometric Validation of the MOS Social Support Survey (MOS-10) in Newly Diagnosed Patients with Lung Cancer in Mexico

Introduction: Patients newly diagnosed with lung cancer experience a high symptom burden associated with the disease and are frequently diagnosed at advanced stages. Social support is an important resource for coping with the demands associated with the disease and its treatment. In this context, the Medical Outcomes Study Social Support Survey (MOS-SSS) is one of the most widely used instruments for assessing perceived social support. Aim: To examine the factorial structure, internal consistency, and measurement invariance of a 10-item brief version of the MOS Social Support Survey (MOS-10) in a Mexican sample of patients newly diagnosed with lung cancer. Methods: A non-experimental instrumental study was conducted using non-probability convenience sampling. The sample comprised 200 patients newly diagnosed with lung cancer. An exploratory factor analysis (EFA) was performed, followed by a confirmatory factor analysis (CFA) in the same sample. A sensitivity analysis using diagonally weighted least squares (DWLS) based on a polychoric correlation matrix was also conducted. Measurement invariance across sex and age groups was examined, and internal consistency was estimated using Cronbach’s alpha and McDonald’s omega. Results: The EFA identified a two-factor structure, Emotional/Informational/Affective Support and Tangible Support, which explained 69.55% of the variance. After CFA re-specification, a 10-item solution with satisfactory fit indices was obtained. The DWLS sensitivity analysis showed an overall factorial pattern consistent with that obtained using maximum likelihood estimation, although its fit indices should be interpreted cautiously given the estimation procedure used. Internal consistency was high for the total score (α = 0.92; ω = 0.93) and adequate for both dimensions. Evidence supported configural, metric, and scalar invariance across sex, whereas configural invariance was supported across age groups but full metric invariance was not established. Conclusion: The MOS-10 showed satisfactory evidence of factorial validity and internal consistency in this sample of Mexican patients newly diagnosed with lung cancer. However, the factorial structure should be cross-validated in an independent sample, and further studies are needed to examine temporal stability, convergent, discriminant, and criterion-related validity, responsiveness, and clinically meaningful score interpretation.