Axial spondyloarthritis (including ankylosing spondylitis) – this involves the spine, although an RA-like symmetrical small-joint polyarthritis may occur in the context of this condition. Hepatitis C – RA-like symmetrical small-joint polyarthritis may occur in the context of this condition. Hepatitis C may also induce rheumatoid factor auto-antibodies.Rarer causes which usually behave differently but may cause joint pains:
Sarcoidosis, amyloidosis, and Whipples disease can also resemble RA. Hemochromatosis may cause hand joint arthritis. Acute rheumatic fever can be differentiated by a migratory pattern of joint involvement and evidence of antecedent streptococcal infection. Bacterial arthritis (such as by Streptococcus) is usually asymmetric, while RA usually involves both sides of the body symmetrically. Gonococcal arthritis (a bacterial arthritis) is also initially migratory and can involve tendons around the wrists and ankles.Sometimes arthritis is in an undifferentiated stage (i.e. none of the above criteria is positive), even if synovitis is witnessed and assessed with ultrasound imaging. Difficult-to-treat
Rheumatoid arthritis (D2T RA) is a specific classification RA by the European League against Rheumatism (EULAR).Signs of illness:

Persistence of signs and symptoms
Drug resistance
Does not respond on two or more biological treatments
Does not respond on anti-rheumatic drugs with different mechanism of actionFactors contributing to difficult-to-treat disease:

Genetic risk factors
Environmental factors (diet, smoking, physical activity)
Overweight and obese

Genetic factors
Genetic factors such as HLA-DR1B1, TRAF1, PSORS1C1 and microRNA 146a are associated with difficult to treat rheumatoid arthritis, other gene polymorphisms seem to be correlated with response to biologic modifying anti-rheumatic drugs (bDMARDs). Next one is FOXO3A gene region been reported as associated with worst disorder.
Vitamin B6 and B9 play a role in RA management as well. Studies have shown that low plasma levels of pyridoxal-5-phosphate, the metabolically active form of vitamin B6, have been reported in RA patients, which may be associated with the elevated TNF-a production. Folate supplies are also decreased in RA patients who are taking Methotrexate, an anti-rheumatic drug. We see that folate supplementation can reduce the mucosal and gastrointestinal side effects of low dose Methotrexate in patients with RA. This works in a similar pattern to aspirin and vitamin E supplementation. Therefore, RA patients should be advised to consume dietary sources of vitamin B6 and B9 up to the dietary reference value, until further research is undertaken into the toxicity and effectiveness of large dose supplementation. Food containing high source of vitamin E to help treat Rheumatoid Arthritis include almonds, avocados, spinach, sunflower seeds and peanut butter. Vitamin C foods include oranges, orange juice, strawberry, broccoli, brussel sprouts and potatoes. Brown rice, barley, and fish contain sources of vitamin B6 and B9. Lastly, Vitamin D can be included in the diet by incorporating tuna, salmon, orange juice and almond Milk into diet.Minerals
Minerals including fluoride, iron, calcium, and zinc have been studied in the role of RA management. The effects of fluoride supplementation in preventing RA-induced bone loss were examined in a randomized control trial. Results suggest that fluoride therapy may increase vertebral bone mass in RA patients.Approximately, one-third of cases of anaemia in RA patients may be caused by depletion of iron stores.