What is polymyalgia rheumatica (PMR) in individuals over 50 with a history of hypertension, diabetes, or osteoarthritis?

What is Polymyalgia Rheumatica?

Polymyalgia rheumatica (PMR) is an inflammatory musculoskeletal disorder affecting adults over age 50, characterized by bilateral proximal pain and morning stiffness in the shoulder and pelvic girdles, accompanied by elevated inflammatory markers and a dramatic response to low-dose glucocorticoid therapy. 1, 2

Core Clinical Features

PMR presents with a distinctive constellation of symptoms that typically develop acutely or over several days to weeks 3:

• Bilateral proximal pain and stiffness affecting the shoulder girdle (most common), pelvic girdle, and neck region 1, 2
• Severe morning stiffness lasting more than 45 minutes, often the most disabling symptom 4
• Systemic inflammatory symptoms including fatigue, low-grade fever, and unintentional weight loss driven by IL-6 signaling 3
• Marked elevation of inflammatory markers with ESR typically >40 mm/hr and elevated CRP 5, 6

Age and Demographics

• Age >50 years is mandatory for the diagnosis, with peak incidence around age 75 5, 2
• Women are affected 2-3 times more frequently than men 5, 3
• Age <60 years is considered highly atypical and requires immediate specialist referral to exclude mimicking conditions 5

Underlying Pathophysiology

The disease involves 4, 3:

• Synovial and periarticular inflammation (not primarily a muscle disease despite the name)
• Mild, remitting, non-erosive synovitis with predominant extraarticular synovial structure involvement
• Muscular vasculopathy
• Subdeltoid and subacromial bursitis visible on ultrasound or MRI

Critical Associations and Mimics

Giant cell arteritis (GCA) coexists in 10-20% of PMR patients and must be actively excluded, as it requires higher glucocorticoid doses and carries risk of vision loss 3, 7. Symptoms suggesting GCA include new headache, jaw claudication, visual changes, or scalp tenderness.

PMR can be mimicked by numerous serious conditions requiring exclusion 5, 7:

• Rheumatoid arthritis (particularly elderly-onset RA)
• Malignancies (lymphoma, multiple myeloma, solid tumors)
• Infections (endocarditis, osteomyelitis, tuberculosis)
• Other inflammatory conditions (RS3PE syndrome, spondyloarthropathy, vasculitis)
• Endocrine disorders (hypothyroidism, hyperparathyroidism)
• Myopathies (polymyositis, statin-induced myopathy)

Relevance of Comorbidities

In patients with hypertension, diabetes, or osteoarthritis, several considerations apply 8:

• These comorbidities increase the risk of glucocorticoid-related adverse effects during treatment 1, 9
• Hypertension and diabetes may worsen with glucocorticoid therapy and require intensified monitoring 8
• Osteoporosis risk is substantially elevated, necessitating bone protection strategies from treatment initiation 8, 4
• Pre-existing osteoarthritis can complicate the clinical picture but does not preclude PMR diagnosis 8

Diagnostic Approach

Diagnosis relies on clinical recognition combined with laboratory confirmation and exclusion of mimics 1, 8:

• Comprehensive laboratory workup including CBC, ESR/CRP, rheumatoid factor, anti-CCP antibodies, glucose, creatinine, liver function, TSH, creatine kinase, and protein electrophoresis 5, 8
• Dramatic response to 12.5-25 mg prednisone daily within days is characteristic but not diagnostic, as other conditions may also respond 5, 7
• Imaging (ultrasound or MRI) showing bilateral subdeltoid bursitis supports the diagnosis 4, 7

Treatment Principles

Glucocorticoids remain the cornerstone of therapy 1, 9:

• Initial dose of 12.5-25 mg prednisone equivalent daily 1, 8
• Treatment typically required for 1-2 years, though 50% of patients experience relapses during tapering 2, 9
• Methotrexate has moderate evidence as a glucocorticoid-sparing agent 1, 9
• IL-6 inhibitors (tocilizumab, sarilumab) show promise for reducing glucocorticoid burden and preventing relapses 9
• TNF-alpha blockers are ineffective in isolated PMR 1, 7

Common Pitfalls

• Initiating glucocorticoids without adequate exclusion of mimics, particularly malignancy and infection in atypical presentations 5
• Failing to monitor for GCA development during the disease course 3, 7
• Inadequate monitoring and prevention of glucocorticoid-related complications in patients with pre-existing diabetes, hypertension, or osteoporosis 8, 4
• Diagnosing PMR in patients under age 60 without exhaustive specialist evaluation 5