Diagnosis of paediatric Lyme arthritis using a clinical score.

Diagnosis of Lyme arthritis (LA) in children and adolescents may be difficult due to non-specific clinical manifestations and unreliable serological tests for antibodies to Borrelia burgdorferi. In a national prospective study, 186 children with arthritis were examined in whom the attending physicians had considered the diagnosis of LA. Ultimately, LA was confirmed in 87 patients and these were compared with the remaining 99 children in whom arthritis was attributable to other causes. In comparison to patients with other causes of arthritis, patients with LA had a higher frequency of episodic arthritis and initial knee joint arthritis, reported tick bites more frequently, were older, had a lower frequency of initial arthralgias, and there were fewer large joints involved. A score was developed in a group of these patients and tested in a second group. It enabled patients with LA to be distinguished from those with other causes of arthritis: within a range from 12 to −7 points, a score of 2.5 or less excluded LA whereas 6 or more points were highly indicative of LA. If only those children with a score result between 2.5 and 6 had been tested for antibodies to B. burgdorferi, the number of tests would have been reduced by 63%.