Association of spinal degenerative disc disease with thyroid autoimmunity

Objective Autoimmune thyroiditis (ATD) has been linked to various forms of arthritis. The relationship with spinal degenerative disc disease (DDD) is not known. We studied the association between ATD and spinal DDD. Methods We performed a cross-sectional analysis of patients who had data on both anti-thyroid peroxidase antibodies (TPOAb) and anti-thyroglobulin antibodies (TgAb) from January 1997 to January 2014 in Clinical Looking Glass (CLG), a data analysis software platform. Spinal DDD was confirmed by radiological diagnosis. Results Of the 7698 patients for whom the TPOAb and TgAb values were available, 4383 patients with complete data for the following covariates; age, gender, race, ethnicity, smoking, diabetes, body mass index and thyroid stimulating hormone (TSH) levels, were included. Thirty-three percent had ATD, while 67% did not. The unadjusted odds ratio (OR) of having spinal DDD with ATD was 1.5 (95% confidence interval (CI)1.3, 1.7), p < 0.001. After adjustment for covariates, ATD remained associated with a higher frequency of spinal DDD, OR 1.8 (95% CI 1.6, 2.2), p < 0.001. Stratifying by BMI and TSH levels showed similar results. Additional analyses excluding patients with known connective tissue diseases and spondyloarthritis (SpA) also showed consistent results. Conclusion ATD is associated with increased frequency of spinal DDD independent of BMI and TSH levels, and among those without connective tissue diseases or SpA. This finding suggests that there may be an important link between thyroid autoimmunity and spinal DDD.