Association between clinical laboratory indicators and WOMAC scores in Qatar Biobank participants: The impact of testosterone and fibrinogen on pain, stiffness, and functional limitation.

Objectives: The association between baseline laboratory parameters and experienced well-being in healthy individuals remains uncertain. This study explored the relationship between clinical laboratory profiles and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores for pain, stiffness, and physical functional limitation in healthy individuals in Qatar.

Methods: Clinical laboratory data were collected from 1,764 Qatar Biobank participants who also completed the WOMAC questionnaire: lipid profiles (high-density lipoprotein, low-density lipoprotein, cholesterol, and triglycerides), endocrine markers (TSH, T3, T4, estradiol, and testosterone), and two inflammatory markers (CRP and fibrinogen). Multiple linear regression was used with 11 clinical indicators as independent variables and the subscale and total WOMAC scores as dependent variables. Multivariate effects of each indicator on the outcomes were assessed, and univariate effects were examined when significant.

Results: Testosterone had a significant impact on all WOMAC subscales (pain, stiffness, and functional limitation) and the total WOMAC score. Higher testosterone levels were associated with a reduction in pain (β = -0.03, t = -3.505, p < 0.001, 95% CI = -0.052, -0.015), stiffness (β = -0.01, t = -2.265, p = 0.024, 95% CI = -0.018, -0.001), physical dysfunction (β = -0.08, t = -3.265, p = 0.001, 95% CI = -0.135, -0.034), and total WOMAC scores (β = -0.127, t = -3.444, p < 0.001, 95% CI = -0.199, -0.055). Elevated fibrinogen levels were associated with an increase in stiffness (β = 0.155, t = 2.241, p = 0.025, 95% CI = 0.019, 0.290), physical dysfunction (β = 1.17, t = 2.808, p = 0.005, 95% CI = 0.354, 1.997), and total WOMAC scores (β = 1.610, t = 2.691, p = 0.007, 95% CI = 0.437, 2.784).

Conclusion: Testosterone may protect against pain, stiffness, and physical dysfunction, while high fibrinogen levels might be a surrogate of systemic inflammation that enhances stiffness and limits physical function. Measuring multiple clinical and laboratory markers in healthy individuals may enhance our understanding of the molecular mechanisms underlying pain.