Typically, untreated disease is markedly disabling due to the combination of pain, extensive stiffness and accompanying constitutional features. Corticosteroid therapy is therefore indicated and can result in a dramatic improvement for many patients. However, there is no evidence to suggest that it alters the likelihood of developing giant cell arteritis.
Prednisolone 15 mg daily is highly effective in most patients, although a few may need up to 25 mg daily.11-13 Moderate-dose corticosteroids have been the first-line treatment for over 50 years, but were introduced before the widespread use of placebo-controlled trials to confirm effectiveness.12
After several weeks of treatment, approximately one-third of patients are able to gradually reduce their prednisolone over many months and can eventually stop.14 Different weaning protocols have been devised, although the ideal approach remains controversial and individual tailoring may be necessary.
The British Society of Rheumatology has proposed a regimen15 which is globally accepted2 and reflected in local guidelines.16 This recommends prednisolone 15 mg daily for three weeks, then tapering to 12.5 mg daily for an additional three weeks, 10 mg daily for 4–6 weeks and then a reduction of 1 mg daily every 4–8 weeks thereafter. Disease relapse, defined by a recurrence of symptoms accompanied by a rise in inflammatory markers, warrants an escalation of prednisolone to the last effective dose before recommencing the weaning schedule from that dose.
The British weaning schedule is more rapid than most others, but involves at least 46 weeks of prednisolone therapy. This is a much longer period of exposure compared to most other inflammatory diseases. In practice the majority of patients will need corticosteroids for at least two years and a large proportion will require ongoing low-dose prednisolone to control their symptoms.17 There are currently few data to help predict which patients will require ongoing therapy. Extended exposure to prednisolone is inevitable for these patients.
Adverse effects
Corticosteroids cause dose-dependent adverse effects. While the doses of prednisolone used in polymyalgia rheumatica might be lower than what was historically considered acceptable in many inflammatory conditions, they still confer a burden of morbidity.
The damage from prolonged use of low–moderate doses of corticosteroids is multimodal and has been better appreciated in recent years with more sophisticated investigative methods (Table 2).18-20 Screening for these complications and treating them is important in mitigating their impact, although prevention is preferable.
In polymyalgia rheumatica the morbidity from similar doses of corticosteroids is both greater and occurs more frequently than in other rheumatic diseases.21 It is not clear why, and this area warrants further research as it may have therapeutic implications. The cumulative effect, however, is that up to 81% of patients develop adverse events in the first year.5 Furthermore polymyalgia rheumatica is a disease of older people who are at risk of complications as a consequence of these adverse events.
Uncontrolled inflammation itself can also cause problems, therefore corticosteroid therapy in polymyalgia rheumatica is a balance. Aim to achieve the minimum total exposure to prednisolone while maintaining control of the disease.4