Page 348 - The Vasculitides, Volume 1: General Considerations and Systemic Vasculitis

322 Vanessa Quick and John Kirwan

It is uncertain to what degree aortic involvement so noted on imaging studies resolves with
standard GCA therapy, or whether it predicts a more chronic and relapsing GCA course
requiring continued or more aggressive treatment [64, 68, 133]. Standard chest radiography,
echocardiogram, CT, MRI and PET imaging have all been used to screen for emerging
thoracic aortic dilatation [12, 38, 63, 67, 131, 134]. However there are no prospective studies
comparing the sensitivity of these studies separately or together in discerning thoracic aortic
aneurysm formation. Mackie and Pease [55] advocate tight control of blood pressure without
regular imaging.

Treatment and Outcome

The British Society of Rheumatology (BSR) and European League Against Rheumatism
(EULAR) recommended early initiation of high-dose glucocorticoid therapy before TAB,
although the evidence for this approach is weak with a level of evidence equal to 3 and
strength of recommendation equal to C [11, 12]. The case can be made for early intervention
with empiric treatment in patients with visual loss since untreated, the other eye is at
heightened similar risk in up to one-third of cases for the ensuing three weeks [121],
moreover partial visual improvement in vision is more likely if treatment commences within
the first day of visual loss [135]. A similar approach may be advocated in those with features
of impending visual loss such as amaurosis fugax, diplopia and jaw claudication. However, if
the likelihood of GCA is low to moderate, withholding treatment and awaiting TAB that later
returns negative would avoid unnecessary treatment. Figure 5, which show the proportion of
positive TAB biopsies in relation to the number of weeks taking glucocorticoids among
several reported cohorts [8, 87, 136-138], suggests a 5% to 10% loss of TAB positivity for
each week of treatment. While those with initially high likelihood of GCA pretreatment will
have persistently high rates of TAB positivity weeks later, the latter would not likely
influence therapeutic decisions unless such patients suffer later relapse or manifest treatment
related side effects that questioned need for continued therapy. A bilateral TAB length of >
3cm so noted in one-half of specimens, predicted the subsequent need for glucocorticoid
therapy in 94% of patients [139], whereas a negative TAB measuring >2 cm performed
before six days of starting prednisolone led to cessation of therapy without later visual loss
[140].

Although there are no RCT of the use of glucocorticoids in GCA [11, 12], most experts
agree with daily morning treatment of prednisone at doses of 40 mg to 60 mg until symptoms
and laboratory abnormalities resolve [7, 11, 12, 122]. Alternate daily glucocorticoids were not
as effective as a daily regimen, alone or in association with adjuvant methotrexate for GCA
[122, 141]. In fact, the symptomatic response that follows glucocorticoid treatment is so
striking and rapid in GCA, that it is a diagnostic criterion of the disease [122]. Patients with
PMR experience improvement in symptoms related to systemic inflammation over two to
three days while symptoms related to impaired blood flow such as jaw claudication and visual
disturbance generally take longer to respond and resolve [142]. Although sustained visual loss
may be permanent and unresponsive to therapy [143], the risk of further progression is low
[144]. Although prednisone in the dose range of 10 mg to 40 mg per day was effective in
several cohorts [90, 145, 146], the results were not considered conclusive due to small sample

Complimentary Contributor Copy