Autoimmune Comorbidities in Patients with Metastatic Melanoma: a Retrospective Analysis of Us Claims Data

Background: Immunotherapies have advanced the treatment of metastatic melanoma; however, they are associated with immune-related toxicities. Patients with pre-existing autoimmune comorbidities are commonly excluded from clinical trials investigating immunotherapies in metastatic melanoma. Since information on pre-existing autoimmune comorbidities in "real-world" patients with newly diagnosed metastatic melanoma is limited, we sought to estimate the prevalence of autoimmune comorbidities and its change over time.

Methods: Data were obtained from a large US claims database, MarketScan®, from 2004 to 2014. Records of patients with newly diagnosed metastatic or non-metastatic melanoma and of general population were analyzed. Autoimmune comorbidities were defined as presence of autoimmune disorders, which were obtained from the list of diseases at the American Autoimmune-Related Diseases Association web portal ( www.aarda.org ). The prevalence of pre-existing autoimmune comorbidities and its change over the 11-year period were calculated. Logistic regression analyses were performed to evaluate the relationship between clinical and demographic factors and pre-existing autoimmune comorbidities in patients with metastatic melanoma.

Results: This study assessed the prevalence and change of prevalence over a period of 11 years of 147 autoimmune comorbidities. Among 12,028 patients with newly diagnosed metastatic melanoma, the prevalence rate of pre-existing autoimmune comorbidities increased from 17.1% in 2004 to 28.3% in 2014 (P < 0.001). The prevalence rates of autoimmune comorbidities increased from 11.7% in 2004 to 19.8% in 2014 in patients with non-metastatic melanoma and 7.9% in 2004 to 9.2% in 2014 in the general population. In addition, patients with bone or gastrointestinal melanoma metastases, those with more comorbid diseases, or female patients, were found to have a higher risk of autoimmune comorbidities.

Conclusions: The prevalence of pre-existing autoimmune comorbidities in patients with newly diagnosed metastatic melanoma was high, and increased over 11 years. In comparison, a lower prevalence of autoimmune comorbidities was seen in patients with newly diagnosed non-metastatic melanoma and in the general population. Increases in prevalence for these population groups were also observed over 11 years. Impact of autoimmune comorbidities on treatment decisions in patients with metastatic melanoma should be explored.