Department of Rheumatology, University of Leeds, Leeds and 1 Department of Rheumatology, Northwick Park Hospital, Harrow, UK
Correspondence to: S. Mackie, Department of Rheumatology, Leeds General Infirmary, Great George Street, Leeds, West Yorkshire LS1 3EX, UK. E-mail: sarah.mackie{at}doctors.org.uk
We are grateful to Dr Jansen and colleagues for their interesting and constructive letter. Naturally, we agree that retrospective literature review is not an appropriate methodology for defining a clinical syndrome, particularly given the likely publication bias implied by the geographical origins of the case reports we analysed. Our objective was not to formulate a definition of the post-streptococcal reactive arthritis but to investigate whether it appears to exist at all as a discrete entity. We found considerable heterogeneity within the existing literature, certainly more than the criteria proposed by Ayoub and Ahmed [1] might suggest. Furthermore, criteria thus framed in relation to acute rheumatic fever may be quite useful in paediatrics, but might potentially disguise the complexity of the relationship between the gastrointestinal tract, the immune system and the joints; for example, the onset of adult Still's disease often features a sore throat.
A large prospective epidemiological study would be required to demonstrate whether there is a true association between arthritis and sore throats in general or streptococcal infections in particular. It is worth recalling that although Reiter's syndrome was originally linked to genitourinary and gut infections by recognition of sporadic cases, the linkage is more securely based on epidemiological studies, albeit uncontrolled ones, such as those of Paronen and colleagues [2, 3] and Csonka [4]. Moreover, in another instance it was originally proposed that a specific form of arthritis may be linked to HIV infection, based on sporadic observations; however, these observations have not been borne out by epidemiological studies and any linkage may well be spurious. Post-streptococcal reactive arthritis might well be important both for its own sake and as an opportunity for investigation of key mechanisms in arthritis, but the need for a homogeneous group of patients should not distract from the question of the extent to which the condition is itself homogeneous.
The authors have declared no conflicts of interest.
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