A multicentre validation study of a smartphone application to screen hand arthritis.

BACKGROUND: Arthritis is a common condition, and the prompt and accurate assessment of hand arthritis in primary care is an area of unmet clinical need. We have previously developed and tested a screening tool combining machine-learning algorithms, to help primary care physicians assess patients presenting with arthritis affecting the hands. The aim of this study was to assess the validity of the screening tool among a number of different Rheumatologists. METHODS: Two hundred and forty-eight consecutive new patients presenting to 7 private Rheumatology practices across Australia were enrolled. Using a smartphone application, each patient had photographs taken of their hands, completed a brief 9-part questionnaire, and had a single examination result (wrist irritability) recorded. The Rheumatologist diagnosis was entered following a 45-minute consultation. Multiple machine learning models were applied to both the photographic and survey/examination results, to generate a screening outcome for the primary diagnoses of osteoarthritis, rheumatoid and psoriatic arthritis. RESULTS: The combined algorithms in the application performed well in identifying and discriminating between different forms of hand arthritis. The algorithms were able to predict rheumatoid arthritis with accuracy, precision, recall and specificity of 85.1, 80.0, 88.1 and 82.7% respectively. The corresponding results for psoriatic arthritis were 95.2, 76.9, 90.9 and 95.8%, and for osteoarthritis were 77.4, 78.3, 80.6 and 73.7%. The results were maintained when each contributor was excluded from the analysis. The median time to capture all data across the group was 2 minutes and 59 seconds. CONCLUSIONS: This multicentre study confirms the results of the pilot study, and indicates that the performance of the screening tool is maintained across a group of different Rheumatologists. The smartphone application can provide a screening result from a combination of machine-learning algorithms applied to hand images and patient symptom responses. This could be used to assist primary care physicians in the assessment of patients presenting with hand arthritis, and has the potential to improve the clinical assessment and management of such patients.

A case report of basic calcium phosphate deposition disease mimicking septic arthritis.

We report a case of a 53-year-old man who presented with a diagnostic dilemma mimicking septic arthritis. It is important to consider the diagnosis of calcific peri-arthritis clinically and recognize the hallmarks on radiograph and magnetic resonance imaging as this disease process resolves completely with conservative management like in our patient, and does not require operative intervention.

Skin, muscle and joint disease from the 17th century: scurvy.

We report three cases of scurvy, with differing musculoskeletal presentations, from a tertiary teaching hospital in Sydney, Australia. Case 1 was a man with cerebral palsy who presented with knee swelling following a minor injury. In Case 2, a patient with thalassaemia major presented with purpuric rash, difficulty walking and distal thigh swelling and ecchymosis. Case 3 was a man with Down's syndrome who presented with acute ankle arthritis. Scurvy in Cases 1 and 3 were related to abnormal dietary preferences, whereas in Case 2, scurvy was thought to be related to thalassaemia. All three cases responded rapidly to vitamin C replacement. The subjects did not appear malnourished as they had adequate carbohydrate and protein intake.

Brucellosis mimicking Henoch-Schönlein purpura.

A young male immigrant from Syria with a vasculitic-appearing leg rash, asymmetrical polyarthritis, microscopic haematuria, and raised inflammatory markers was provisionally diagnosed with Henoch-Schönlein purpura. Skin biopsy showed leukocytoclastic vasculitis. Low-grade fevers persisted despite non-steroidal anti-inflammatory therapy, and Brucella sp. was subsequently grown from both blood and synovial fluid aspirates. Further tests gave positive results for B. abortus, and triple antibiotic therapy produced a rapid clinical response. Cutaneous vasculitis has rarely been described in brucellosis, and this is the first report in the English medical literature of brucellosis mimicking Henoch-Schönlein purpura.