New Zealand guidelines for the diagnosis of acute rheumatic fever: small increase in the incidence of definite cases compared to the American Heart Association Jones criteria.

AIM: The aim of the study was to compare utilisation of the New Zealand guidelines for the diagnosis of acute rheumatic fever (ARF) compared to the American Heart Association Jones criteria in a cohort of children
METHOD: Retrospective review of 79 consecutive hospital diagnosed cases of ARF referred for secondary penicillin prophylaxis. The 2006 New Zealand guidelines for ARF were applied to the cohort and the diagnostic classification compared to classification using the American Heart Association 1992 Jones criteria. Cases were defined as definite, probable, possible or not ARF. The New Zealand guidelines use subclinical (echocardiographic) carditis as a major criterion of ARF. Monoarthritis, if associated with anti-inflammatory medicine usage likely preventing polyarthritis, is also accepted as a major criterion.
RESULTS: Sixty-six cases were considered to be possible, probable or definite first episode of occurrence ARF. Utilisation of the New Zealand guidelines resulted in 16% (CL 7-29%) more cases defined as definite ARF than using American Heart Association 1992 Jones criteria (59/66 cases vs 51/66 cases). Polyathritis was the most frequent presenting symptom. Of those classified as definite ARF, 11% had monoarthritis with anti-inflammatory usage. Clinical carditis was present in 55% and subclinical carditis in 30%. The utilisation of subclinical carditis as a major criterion influenced the diagnosis to become definite ARF in 8% of the cohort only, as the remainder had polyarthritis or Sydenham's chorea as a major criterion.
CONCLUSION: Utilisation of New Zealand guidelines for the diagnosis of ARF result in a modest increase (16%) in cases classified as definite ARF compared to the 1992 Jones criteria.