Rapid responses are electronic letters to the editor. They enable our users to debate issues raised in articles published on thebmj.com. Although a selection of rapid responses will be included online and in print as readers' letters, their first appearance online means that they are published articles. If you need the url (web address) of an individual response, perhaps for citation purposes, simply click on the response headline and copy the url from the browser window. Letters are indexed in PubMed.
I strongly agree with the sentiments of the letter posted by Achim
Nestel(1) in response to the article by Hassan et al(2) regarding the
rarity of C-reactive protein (CRP)-negative giant cell arteritis and the
vital importance of simple blood tests to assist in diagnosis.
However, whilst CRP-negative giant cell arteritis is rare it is not
confined to case reports. A study of 119 cases of biopsy-proven giant cell
arteritis published in 2006(3) revealed that the sensitivity of
erythrocyte sedimentation rate (ESR) was up to 86% and the sensitivity of
CRP was 97.5%. Combining ESR and CRP gave a sensitivity of 99% for
detecting giant cell arteritis.
There were 2 cases out of 119 of CRP-negative disease (although ESR
was elevated in both). This study(3) identified 1 case with normal ESR and
CRP - 'a double negative' which is 0.8% of cases (not 4% as stated by
Hassan et al(2)).
1. Achim R Nestel. BMJ 2011;342:doi:10.1136/bmj.d3685 (Published 20
2. Nada Hassan, Bhaskar Dasgupta, Kevin Barraclough. BMJ
2011;342:doi:10.1136/bmj.d3019 (Published 23 May 2011)
3. Parikh et al. Prevalence of a normal C-reactive protein with an
elevated erythrocyte sedimentation rate in biopsy-proven giant cell
arteritis. Ophthalmology 2006;113:1842-5.