Page 347 - The Vasculitides, Volume 1: General Considerations and Systemic Vasculitis

Giant Cell Arteritis 321

accuracy of PET in detecting large-vessel involvement was significantly higher in patients not
receiving immunosuppressive therapy (93.3% vs 64.5%) [117].

Rapid Diagnostic Pathway
The authors advocate a clinical review of patients within 24 hours of suspected GCA,

including access to specialty assessment for the performance of necessary blood tests,
followed by TAUS, and TAB within seven days [13, 14, 55]. The threshold is kept low for
the performance of TAUS or TAB in all patients suspected of GCA awaiting the findings
before commencement of glucocorticoids in the absence of visual disturbances and jaw
claudication [8]. The risk of blindness in other patients with typical GCA while awaiting
results of laboratory studies is carefully weighed against the risk of potentially serious
medication side effects associated with empiric glucocorticoid treatment. The cost
effectiveness of such pathways in secondary care has yet to be calculated, but visual loss
particularly in the elderly, has major consequences for quality of life [14]. While those with
monocular vision loss would trade one in three of their remaining years for unimpaired
vision, this rose to two in three in those with binocular vision [120]. An audit of one of the
authors? participating family practices showed that 100% of patients with a diagnosis of GCA
over a ten year period were eventually referred to secondary care in any case (Personal
Communication). The cost both financially and in glucocorticoid complications of treating
patients with long term glucocorticoids who do not actually have the disease is more difficult
to estimate, but may be substantial.

Prognosis

Clinical studies have not validated the relation of existent classification criteria for GCA
[76] to clinical and laboratory measures to prognosticate relapse likelihood and outcome.
Common features of clinical relapse include recurrent headache, scalp pain and PMR-like
symptoms associated with a raised acute phase response reactants [121-124]. Clinical
symptoms and changes in the acute phase response can occur independently [125]. Acute
phase responses can take several weeks to return to normal after initiating treatment while
symptoms improve over several days [126, 127]. It can be argued that maintaining the lowest
level of acute phase response achieved for each individual patient is an important goal of
therapy [128] but pursuing a normal acute phase response might lead to overtreatment and
unacceptably high rates of glucocorticoid related adverse events. Up to 20% of patients with a
significant asymptomatic rise in ESR failed to relapse clinically [122] although clinicians may
be overly concerned that improved control of the acute phase response may be protective
against late atherosclerosis [129]. It seems reasonable to consider a return to higher dose
treatment to improve prognosis in patients experiencing a returning headache, PMR-like
symptoms, jaw claudication and visual symptoms. Since the advent of glucocorticoids for
GCA, the long term outcome and survival rates have been similar to age matched population
[27, 130] including those with large vessel complications [131], although prior to
glucocorticoids estimated mortality was 12.5% [132]. The presence of clinical or subclinical
aortitis could infer a poorer prognosis [6, 68] but this requires further corroboration.

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