Incidence of inflammatory myopathies in Victoria, Australia, and evidence of spatial clustering.

Abstract

OBJECTIVE: To determine the incidence of idiopathic inflammatory myopathies (IIM) in Victoria, Australia, and look for evidence of space-time or spatial clustering. METHODS: Cases of IIM diagnosed between 1989 and 1991 were identified by muscle biopsy and hospital discharge diagnosis review. Diagnosis was verified by medical record review and included if Bohan and Peter criteria for definite or probable disease were met. The pair-wise Euclidean distances between cases' residences were computed using grid references, and temporal distances were calculated between biopsy dates. The Mantel test for space-time clustering was computed. Each patient was also characterized by statistical local area..