Pattern analysis in vasculitides
We read with great interest the recent paper by Grayson et al., which compared patterns of arteriographic lesions in patients with Takayasu's arteritis (TAK) and giant cell arteritis (GCA).
Using a similar methodology as in a previous paper by our group (2), Grayson et al. confirmed that arterial involvement is contiguous in the aorta and usually symmetric in paired branch vessels for TAK, and extended these findings for GCA.
Because biomathematical pattern analysis of vascular lesions in inflammatory diseases is a new concept, we believe a few additional limitations should be underlined. First, both the study by Grayson et al. as well as our previous work only considered vascular patterns present at a given time point. Therefore, we were not able to incorporate the dynamic progression of vascular lesions observed in these diseases, which is truly a critical issue. Second, vascular patterns may be strongly influenced by the delineation of vascular beds used for the analysis. For instance, we distinguished femoral and iliac arteries and did not consider thoracic aorta has a whole, while Grayson et al. used other subdivisions of the vascular tree. Because underlying determinants of vascular targeting are largely unknown, we believe it would be best not to regroup various anatomical segments together. Third, classification models used by Grayson et al. to distinguish between TAK and GCA have incorporated the age at disease onset, which may be difficult to elicit in TAK where a long past of non-specific and sometimes poorly recognized symptoms may precede a more formal diagnosis.
While we believe that these novel methods will have important implications for future classification of vasculitides, the finding that TAK and GCA may exist on a spectrum within the same disease should be interpreted with caution.
1. Grayson PC, Maksimowicz-McKinnon K, Clark TM, et al. Distribution of arterial lesions in Takayasu's arteritis and giant cell arteritis. Ann Rheum Dis 2012 Feb 10 (Epub ahead of print).
2. Arnaud L, Haroche J, Toledano D et al. Cluster analysis of arterial involvement in Takayasu arteritis reveals symmetric extension of the lesions in paired arterial beds. Arthritis Rheum 2011;63:1136-40.
Conflict of Interest: