Seropositive Rheumatoid Arthritis Associated With Higher Parkinson's Disease Risk

Rheumatoid arthritis (RA), a chronic inflammatory condition affecting the joints, may be associated with an elevated risk of developing Parkinson's disease (PD), according to a recent retrospective cohort study published in JAMA Neurology by Jihun Kang and team of researchers. While the connection between these two conditions has long been speculated, this study provides valuable insights into the potential association and its implications for patient care.

The study, which utilized data from the Korean National Health Insurance Service database, included a population-based sample of individuals diagnosed with RA between 2010 and 2017. A total of 119,788 patients with RA were identified and followed up until 2019. After applying strict exclusion criteria, 54,680 patients with RA (39,010 with seropositive RA [SPRA] and 15,670 with seronegative RA [SNRA]) were included in the analysis, along with a control group of 273,400 age- and sex-matched individuals without RA.

● Out of the 328,080 individuals analyzed in the study, with a mean age of 58.6 years and a standard deviation of 10.1, 1,093 individuals developed Parkinson's disease (PD), including 803 individuals from the control group and 290 individuals with rheumatoid arthritis (RA).

● The analysis revealed that participants with RA had a 1.74-fold higher risk of developing PD compared to the control group, with a 95% confidence interval (CI) ranging from 1.52 to 1.99.

● Further examination of the data indicated that the increased risk of PD was primarily associated with seropositive RA (SPRA), with an adjusted hazard ratio (aHR) of 1.95 and a 95% CI ranging from 1.68 to 2.26.

● However, patients with seronegative RA (SNRA) did not show a significantly increased risk of PD, with an aHR of 1.20 and a 95% CI ranging from 0.91 to 1.57. When comparing the two RA subgroups, individuals with SPRA had a higher risk of PD compared to those with SNRA, with an aHR of 1.61 and a 95% CI ranging from 1.20 to 2.16.

● The analysis did not identify any significant interactions between covariates that could affect the risk of PD.

● These results underscore the importance of recognizing the potential link between RA and PD and highlight the need for heightened awareness among healthcare professionals.

● The study suggests that physicians should be attentive to the increased risk of PD in patients with RA, particularly those with seropositive RA, and consider referring them to a neurologist if they exhibit early motor symptoms of PD without synovitis.

Although the exact mechanisms underlying the association between RA and PD remain unclear, chronic inflammation has been proposed as a potential contributing factor. Further research is needed to delve deeper into the underlying biological processes and to investigate potential therapeutic strategies that may mitigate the risk or progression of PD in patients with RA.

It is worth noting that this study focused on a Korean population, and additional research is necessary to validate these findings in diverse populations. Nonetheless, the study provides valuable evidence for clinicians, emphasizing the importance of vigilance and timely referral for individuals with RA who show signs of PD.

Reference:

Kang, J., Eun, Y., Jang, W., Cho, M. H., Han, K., Jung, J., Kim, Y., Kim, G.-T., Shin, D. W., & Kim, H. (2023). Rheumatoid arthritis and risk of Parkinson disease in Korea. JAMA Neurology, 80(6), 634–641. https://doi.org/10.1001/jamaneurol.2023.0932.