Natural history of Ross River virus‐induced epidemic polyarthritis

Objective: To describe the natural history, treatment and cost of Ross River virus‐induced epidemic polyarthritis (RRV disease). Design: Questionnaire‐based longitudinal prospective study. Participants and setting: Patients in the greater Brisbane area, Queensland, diagnosed with RRV disease by their general practitioners based on clinical symptoms and paired serological tests between November 1997 and April 1999. Main outcome measures: Scores on two validated quality‐of‐life questionnaires (Clinical Health Assessment Questionnaire and Medical Outcomes Study Short Form 36) were obtained soon after diagnosis and one, two, three, six and 12 months thereafter. Scores were compared between patients diagnosed with RRV disease alone and those with RRV disease plus other conditions. Results: 67 patients were enrolled. Most patients with RRV disease alone had severe acute symptoms, but followed a consistent path to recovery within three to six months. Other conditions, often chronic rheumatic diseases or depression, were identified in half the cohort; their quality‐of‐life scores suggested stable chronic illness between six and 12 months after diagnosis. Non‐steroidal anti‐inflammatory drugs (NSAIDs) were taken by 58% of patients (average use, 7.6 weeks; range, 2–22 weeks). Time off work averaged 1.9 days, and direct cost to the community was estimated as $A1018 per patient. Conclusions: Symptom duration and frequency of long‐term symptoms may have been overestimated by previous studies of RRV disease. Disease persisting six to 12 months after RRV diagnosis was largely attributable to other conditions, highlighting the need to seek other diagnoses in RRV patients with persistent symptoms.