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To the Editors:

We thank Dr. Zayat and colleagues for their interest in our work. In response, we would like to make the following comments.

The criteria used in this study to characterize UA have been previously employed by others using evidence-based recommendations (1, 2). None of our patients had osteoarthritis according to the definition outlined by the ACR (3, 4).

Ours was clearly a preliminary study to outline the potential benefits of targeted US of a single joint. Our patient selection reflected the reality that patients tend to present to rheumatology clinics at variable time points in their disease course, although we recognize that prespecified limits on disease duration would have been ideal. We indicated in our discussion that larger studies in this area would be of interest.

The purpose of our study was to determine the existence of erosions of the 5th MTP joint only, using US in clinical situations where no other major prognostic measure is available and where time constraints are present, such as in a busy clinic setting. It was not intended to be a comprehensive evaluation of US nor a detailed analysis of all synovial joints. Equally, the study was not designed to measure subsequent clinical outcomes. It is known that erosive disease is associated with a poorer prognosis, as it proves the propensity for joint damage (5). Early determination of joint erosion is therefore useful in planning treatment, and the ability to do this in a timely manner is of value in clinical decision making.

With regard to the specific questions relating to our UA group, 23% of the patients fulfilled criteria for a diagnosis of RA within 12 months of study inclusion, and only 1 of these patients had erosions on US at baseline. Although followup was limited to 12 months, it is likely that with additional time more of these UA patients may have evolved into RA (6). Of the 3 patients in the UA cohort who subsequently fulfilled criteria for a diagnosis of RA, 1 was positive for both anti-CCP antibody and rheumatoid factor in the absence of US erosions, 1 was positive for anti-CCP antibody alone, and the final patient, although negative for both serologic markers, had US erosion at baseline.

This study supports the use of US in the diagnosis of early erosive disease and lays the foundation for a longitudinal study to define the prognostic capability of targeted US in patients who present with inflammatory arthritis.

  • 1
    Verpoort KN, van Dongen H, Allaart CF, Toes RE, Breedveld FC, Huizinga TW. Undifferentiated arthritis: disease course assessed in several inception cohorts. Clin Exp Rheumatol 2004; 22 Suppl 35: S127.
  • 2
    Sokka T. Early rheumatoid arthritis in Finland. Clin Exp Rheumatol 2003; 21( Suppl 31): S1337.
  • 3
    Arnett FC, Edworthy SM, Bloch DA, McShane DJ, Fries JF, Cooper NS, et al. The American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis. Arthritis Rheum 1988; 31: 31524.
  • 4
    Jordan JM. Epidemiology and classification of osteoarthritis. In: HochbergMC, SilmanA, SmolenJ, WeinblattM, WeismanM, editors. Rheumatology. Philadelphia: Elsevier; 2007. p. 1691703.
  • 5
    Odegard S, Landewe R, van der Heijde D, Kvien TK, Mowinckel P, Uhligi T. Association of early radiographic damage with impaired physical function in rheumatoid arthritis: a ten-year, longitudinal observational study in 238 patients. Arthritis Rheum 2006; 54: 6875.
  • 6
    Van Gaalen FA, Linn-Rasker SP, van Venrooij WJ, de Jong BA, Breedveld FC, Verweij CL, et al. Autoantibodies to cyclic citrullinated peptides predict progression to rheumatoid arthritis in patients with undifferentiated arthritis: a prospective cohort study. Arthritis Rheum 2004; 50: 70915.

Barry J. Sheane MB, MRCPI*, Gaye Cunnane MB, PhD, FRCPI*, * St. James's Hospital, Dublin, Ireland.