Background/Purpose: Whipple’s disease should be considered in patients with recurrent episodes of seronegative arthritis in the large limb, various symptoms (fever, uveitis,…) or biological abnormalities (eosinophilia, C-reactive protein elevation, anaemia, thrombocytosis…) but none of these findings is specific. To determine when Tropheryma whipplei polymerase chain reaction (PCR) is appropriate in patients evaluated for rheumatological symptoms.

Methods: In a retrospective observational study done in five hospitals, we assessed the clinical and radiological signs that prompted T. whipplei PCR testing between 2010 and 2014, the proportion of patients diagnosed with Whipple’s disease, the number of tests performed and the number of diagnoses according to the number of tests, the patterns of Whipple’s disease, and the treatments used. Diagnosis of Whipple’s disease was based on 1- at least one suggestive clinical finding; 2- at least one positive PCR test; and 3- a dramatic response to antibiotic therapy. There were divided in: CWD: Classic Whipple’s disease (duodenal biopsy PAS staining + or T. whipplei immunohistochemistry, or as blood positive by PCR); FWD: Focal Whipple’s disease (joint fluid positive by PCR but duodenal biopsy negative by PAS staining and immunohistochemistry); CTWAA: Chronic T. whipplei-associated arthritis (duodenal biopsy, stool, or saliva positive by PCR but duodenal biopsy and joint fluid negative).

Results: At least one PCR test was performed in each of 267 patients. Rheumatic signs were peripheral arthralgia (n=239, 89%), peripheral arthritis (n=173, 65%), and inflammatory back pain (n=85, 32%). The main extra-articular signs were constitutional symptoms (n=111, 41.8%), diarrhoea (n=70, 26.5%), fever (n=53, 20%), lymphadenopathy (n=14, 5.3%), and neurological signs (n=11, 4.2%). Whipple’s disease was diagnosed in 13 patients (4.9%). The main samples tested and the more frequently positive tests in the centres with diagnoses of Whipple’s disease were saliva and stool. In the centres with no diagnoses of Whipple’s disease, arthritis was less common, whereas constitutional symptoms, fever, and lymphadenopathy were more common. 11 patients with Whipple’s disease had CRP elevation. The annual incidence ranged across centres from 0 to 3.6/100000 inhabitants. The group with Whipple’s disease had a higher proportion of males, older age, and greater frequency of arthritis. When both stool and saliva PCR are positive the predictive value is 91%. When both stool and saliva PCR are negative the negative predictive value is 99%.

Conclusion: Males aged 40-75 years with unexplained intermittent seronegative peripheral polyarthritis, including those without constitutional symptoms, should have T. whipplei PCR tests on saliva, stool and, if possible, joint fluid. When both stool and saliva PCR are positive the positive predictive value is 91%.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/usefulness-of-polymerase-chain-reaction-for-diagnosing-whipples-disease-in-rheumatology/