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To the Editors:

We thank Colina et al for their comments concerning our recently published article on the impact of diagnostic delay in SCCH, in which we unfortunately did not have the opportunity to cite their article (Colina M, Govoni M, Orincolo C, Trotta F. Clinical and radiologic evolution of synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome: a single center study of a cohort of 71 subjects. Arthritis Rheum 2009;61:813–21) since the final version of our article was completed by the time their study was published.

Findings from our study and the study by Colina et al have a number of similarities as well as differences. Both articles highlight the fact that the manifestations of SAPHO syndrome are ill recognized, that they occur predominantly in women (67.6% for Colina et al and 88.5% for our study), and that the median age of onset is comparable at 38.5 years (interquartile range [IQR] 33.7–50.2) for Colina et al and 41.5 years (IQR 27–50.75) for our study. Both studies also show that a delay in diagnosis is considerable at 4.6 years (IQR 0.3–5.1) for Colina et al and 3.5 years (IQR 1.0–8.75) for our study, and that the disease has a chronic course in ∼50% of patients (52% for Colina et al versus 47.6% of our patients, who were not able to undertake full- or part-time work because of their illness). Both studies arrive at the following conclusion: greater awareness is required for the manifestations of the disorder.

We do agree with Colina et al that “SAPHO syndrome can be considered a ‘useful concept’ that unifies several disorders that share some clinical, radiologic, and pathologic characteristics,” and that SCCH forms an intrinsic part of this syndrome. It may indeed be that the patients with SCCH described in our study represent a subset of the broader population with more varied manifestations of SAPHO syndrome studied by Colina et al. However, although we concur with Colina and colleagues that SCCH may often be the “first osteoarticular manifestation” of SAPHO syndrome, we do believe that SCCH may also represent an autonomous clinical entity with pathognomonic clinical, scintigraphic, and radiologic features involving the sternum and medial ends of the clavicles and first ribs (associated with pustulosa palmoplantaris in approximately one-third of the cases) but without joint manifestations (peripheral synovitis or arthritis, especially spondylarthropathy including PsA), manifestations of systemic inflammation, or those of severe acne. Similar to the study of SAPHO syndrome patients by Colina et al, our senior author (NATH) examined the evolution of the disorder in a majority of the SCCH patients included in our study (up to 20 years of followup in some cases) and observed no development of joint manifestations or severe acne in any of the patients, although ∼50% developed a chronic course with debilitating effects on their quality of life. This is in keeping with the data from Colina et al, who calculated an odds ratio of 5.7 for a chronic and more severe course of the disease in patients with SAPHO syndrome who demonstrated involvement of the ACW.

In their letter, Colina et al suggested that diagnostic delay “could be due to the fact that the first referral of these patients is usually not to a rheumatologist.” In our study, the 16 patients (30.8%) with a first specialist referral to a rheumatologist had a mean ± SD diagnostic delay of 53.4 ± 62.7 months (median 30.0 months; IQR 6–93), compared with a mean ± SD diagnostic delay of 74.0 ± 74.9 months (median 42 months; IQR 24–108) in the remaining patients (including those who were not initially referred to a specialist). Using various statistical tests, there was no statistically significant difference between the 2 delay periods (P = 0.17 by 1-tailed t-test, P = 0.12 by 1-tailed Mann-Whitney test, and P = 1.000 by median test), suggesting that rheumatologists may just as easily overlook the manifestations of SCCH as any other member of the medical profession.

Finally, we are very pleased that Colina et al support and reinforce our call for increased awareness among specialists from all disciplines, including rheumatologists and general practitioners, of the ill-recognized manifestations of SCCH and SAPHO syndrome in order to avoid the serious impact of lack of diagnosis, misdiagnosis, or diagnostic delay on the various aspects of quality of life.

Willem A. van der Kloot PhD*, Sadhna A. Chotkan MD†, Ad A. Kaptein PhD†, Neveen A. T. Hamdy MD, PhD†, * Leiden University, Leiden, The Netherlands, † Leiden University Medical Center, Leiden, The Netherlands.