Patellofemoral pain syndrome in runners: associations between
symptom severity and social determinants of health
patellofemoral pain; symptom severity; social determinants of
health; social support; pain catastrophizing.
Introduction: Patellofemoral pain syndrome (PFPS) is a
multifactorial musculoskeletal condition common among
recreational runners. Its clinical expression is influenced by
socioeconomic context and psychosocial processes in addition
to biomechanical factors. Cross-sectional studies must therefore
focus on associations between these domains and symptom
severity (functional impact and pain intensity) without implying
causality. Objective: To analyze associations between symptom
severity of PFPS and social determinants of health in
symptomatic runners. Methods: This is an observational cross-
sectional study involving adult runners (18–50 years) with
patellofemoral pain syndrome (PFPS) and a minimum level of
running practice. Symptom severity will be operationalized using
continuous measures: functional status assessed by the Kujala
Anterior Knee Pain Scale and pain intensity measured by the
Numeric Rating Scale. Explanatory variables will include
socioeconomic indicators (income and educational level),
training characteristics (weekly running mileage and technical
supervision), and psychosocial factors (pain catastrophizing
assessed by the Pain Catastrophizing Scale; depressive
symptomatology assessed by the Beck Depression Inventory;
social support assessed by the Medical Outcomes Study Social
Support Survey; and quality of life assessed by the WHOQOL-
BREF). The proposed sample size is approximately 200
participants, based on the criterion of 10–15 subjects per
predictor in multivariable models. Data collection procedures will
combine online screening with in-person administration of
validated instruments. Statistical analysis will include descriptive
statistics, bivariate tests (correlation analyses and group
comparisons), and multivariable modeling using hierarchical
multiple linear regression with blocks (demographic variables,
training characteristics, and psychosocial factors). Regression
assumptions, multicollinearity, and the influence of individual
observations will be assessed. Sensitivity analyses and
alternative models will be reported. Expected results: The study
is expected to identify patterns of association between social
determinants of health and variability in PFPS symptom severity,
highlighting clinically relevant profiles for screening and
intervention. Limitations inherent to the cross-sectional design
and recommendations for future longitudinal studies will be
discussed.