Some of these models for RA focus on single drugs used on multiple patient cohorts (e.g., infliximab [96]), while other models investigate the effectiveness of single drugs versus combinations of drugs (e.g., methotrexate vs. methotrexate+anti-TNF [94], or etanercept vs. methotrexate vs. methotrexate+etanercept [49]). This evidence concerns the gene TNF and rheumatoid arthritis.