The effect of cryotherapy on total antioxidative capacity in patients with active seropositive rheumatoid arthritis

Patients with rheumatoid arthritis (RA) have increased oxidative stress, decreased antioxidant levels, and impaired antioxidant capacity. Cold treatments are used to relieve joint inflammation and pain. Therefore, we measured the effect of cold treatments on the antioxidative capacity of RA patients with active disease. Sixty patients were randomized to (1) whole body cryotherapy at −110 °C, (2) whole body cryotherapy at −60 °C, or (3) local cryotherapy. Each treatment was given three times daily for 7 consecutive days in addition to the conventional rehabilitation. Blinded rheumatologist evaluated disease activity before the first and after the last cryotherapy. We collected plasma samples daily immediately before the first and after the second cryotherapy and measured total peroxyl radical trapping antioxidant capacity of plasma (TRAP), which reflects global combined antioxidant capacity of all individual antioxidants in plasma. Baseline morning TRAP levels (mean, 95% CI), adjusted for age, body mass index, disease activity, and dose of prednisolone, were 1244 (1098–1391) µM/l in the local cryotherapy, 1133 (1022–1245) µM/l in the cryotherapy at −60 °C, and 989 (895–1082) µM/l in the cryotherapy at −110 °C groups (p = 0.006). After the first treatment, there was a rise in 1-h TRAP of 14.2 (−4.2 to 32.6) µM/l, 16.1 (−7.4 to 39.6) µM/l, and 23.6 (4.1–43.2) µM/l, respectively. The increase was significant in the whole-body cryotherapy −110 °C group (p < 0.001) but not significant between the groups (p = 0.78). When analyzed for the whole week, the daily morning TRAP values differed significantly between the treatment groups (p = 0.021), but there was no significant change within each treatment group. Whole-body cryotherapy at −110 °C induced a short-term increase in TRAP during the first treatment session with but not during other treatment modalities. The effect was short and the cold treatments did not cause a significant oxidative stress or adaptation during 1 week.