Polymyalgia rheumatica (PMR) is an inflammatory disease that affects people aged > 50 years, and is characterised by pain and morning stiffness in the shoulder and pelvic girdle with synovitis of the proximal joints and extra-articular synovial structures. It is currently mainly treated with glucocorticoids (GCs). The aim of the study was to evaluate changes in inflammatory markers and their correlations with cortisol levels after treatment with 6-methylprednisolone (6-MP) or modified-release prednisone (MR-P) in patients with "early" PMR.
The study involved 81 GC-naïve with "early" PMR diagnosed on the basis of the 2012 EULAR/ACR criteria: 38 treated with 6-MP at a starting dose of 12 mg at 8.00 a.m, gradually tapered to 8, 4 and 2 mg/day, and 43 treated with MR-P at a starting dose of 10 mg at 10 p.m, tapered to 7, 5, 3, 2 and 1 mg. The markers of inflammation (ESR mm/h, CRP mg/dL and fibrinogen mg/dL), the circulating serum levels of cytokines (TNFa and IL-6), and morning serum cortisol levels were evaluated at baseline and during GC treatment.
There were significant differences between baseline and the end of treatment in the serum levels of IL-6 (5.3 ± 9.3 vs 2.8 ± 3.3 pg/mL; p < 0.05) and CRP (2.1 ± 3.3 vs 0.9 ± 1.7 mg/dL; p < 0.01) in the patients treated with MR-P, and in serum cortisol levels (15.8±6.4 vs 13.6+5.6 µg/dL; p < 0.01) in the patients treated with 6-MP. After the first month of treatment, 76.7% of the patients treated with MR-P had IL6 levels at or below the upper normal limit, whereas 52.6% of those treated with 6-MP had normal IL6 levels (p < 0.05). There was also a significant difference in the percentage of patients in whom the daily GC dose was tapered within eight months (6.7% in the MR-P group vs 25% in the 6-MP group; p < 0.001) and, by the end of the study, respectively 59.5% vs 35.1% patients were receiving a low GC dose or had discontinued treatment altogether (OR 2.7, 95% CI 1.0-6.77; p < 0.001). After six and 12 months, respectively 10.3% and 14.3% of the patients had discontinued MR-P, as against none of the patients treated with 6-MP (p < 0.05).
In this prospective observational study of PMR patients receiving low-dose GCs, the changes in inflammatory markers were similar in those treated with 6-MP or MR-P, whereas morning cortisol levels remained unchanged only in the MR-P group. During the first month of treatment, MR-P chronotherapy given at bedtime significantly decreased IL-6 levels. The percentage of patients stopping GC treatment was higher in the MR-P group than in the 6-MP group.