Background/Purpose: Polymyalgia rheumatica (PMR) is a systemic inflammatory syndrome that is characterized by widespread pain and stiffness around the shoulders, pelvic girdle and neck. PMR is usually treated with oral glucocorticoids, most commonly prednisone. However, long-term use of prednisone has been associated with various serious side-effects. Some literature suggested minimum effective dose of prednisone is within the range of 12.5-25 mg of prednisone daily. However, there is limited data suggesting the ideal starting dose of prednisone. Our study is to evaluate the effect of starting prednisone dose on the treatment duration of PMR and to determine the ideal initial prednisone dose that will lead to the shortest time needed to achieve 12 months of prednisone-free period.

Methods: We performed a retrospective chart review on a cohort of 919 adult patients newly diagnosed with PMR who were started on prednisone between January 1, 2010 to December 31, 2018 from the Kaiser San Bernardino and Riverside, Southern California, USA. Patients were excluded if hey had prior conditions that require long-term glucocorticoid use before PMR diagnosed, existing diagnoses of giant cell arteritis, and patients who did not achieve 12 month of prednisone-free period. Potential risk factors (age, Duration and inflammatory markers) were also evaluated. The primary outcome was to compare the duration of prednisone treatment in groups with 4 different starting doses of prednisone. The secondary outcome was to evaluate the treatment duration in patients with added steroid-sparing agents and the incidence of re-treatment with prednisone after achieving 12-month prednisone-free period.

Results: Among 701 patients with PMR diagnosed and was treated with prednisone. Their mean age was 68.7 and 443 (63.2 %) were women. The mean ESR was 45.5. Prednisone at 15mg (n = 191) had the shortest duration (mean of 23.4 months) of treatment before achieving 12-month prednisone free period with p value of 0.019. Out of 191 patients giving prednisone 15mg daily, 171 (89.5%) were started by rheumatologists. Patients who were started at 10mg or less prednisone daily and required steroid-sparing agents (n = 7 out of 202) had the longest duration of treatment (with a mean of 94.3 months) with p value of 0.008. Our study also showed that the percentage of patients requiring re-treatment with prednisone decreased with higher starting doses of prednisone. However, this p-value was not significant.

Conclusion: Based on a systemic literature review about PMR, our study has the largest study population with 701 patients. Out study showed the patients who were treated with medium dose of daily prednisone dose of 15mg achieved 12 months of prednisone-free period in the shortest time. Since the patients treated with both prednisone 10mg daily or less and steroid-sparing agents had a longer duration, we recommend against any starting daily doses of 10mg or less. Patients treated with high prednisone dose had the lowest rate of restarting prednisone after 12 months compared with the other dose groups. With the treatment duration appeared to be longer when taking prednisone 20mg or higher, this suggested that PMR may be a heterogenous diseases with various severity and co-morbid diseases.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-effect-of-starting-prednisone-dose-on-the-treatment-of-polymyalgia-rheumatica/