To the Editor:
We were very interested in the recent paper by Choe and colleagues examining the relationship between bone damage and inflammatory cytokines in gout1. The authors stated that radiographic damage in the feet was scored according to the modified Sharp-van der Heijde (SvdH) method, as described by our group. However, the authors used a foot erosion score of 0–5 and joint space narrowing (JSN) score of 0–4. A combined foot erosion and narrowing score of 0–9 was also used in the analysis. We are also rather puzzled by the reporting of the foot radiographic damage scores in Table 1 of that paper, which show a range of 0–5 for erosion scores and 0–4 for narrowing scores. These data appear to refer to a single joint rather than a combined score.
We wish to clarify the radiographic damage scoring method modified for gout2. The gout-modified method includes the joints of the SvdH rheumatoid arthritis system3, plus the distal interphalangeal joints of the hands. Erosion is scored according to the SvdH method as 0–5 in the hands and as 0–10 in the feet. JSN is scored according to the SvdH method as 0–4 in both the hand and foot joints. The maximum possible score for erosions is 200 for the hands and 120 for the feet; the maximum possible score for JSN is 160 for the hands and 48 for the feet. The maximum possible combined score in the hands is 360 and in the feet 168, and for the hands and feet, 528.
We hope that this information will provide clarity to ensure that scoring is done in a correct and uniform manner by groups involved in future gout research.