- Chronic Elevated Creatine Kinase (CK) with Major Clinical Events: Elevated mean CK levels over the last 6 months -1 year (defined as ≥ 2X upper limit of age/gender-matched normal, or ≥ 500 units/L if age-matched reference not established) not associated with an acute rhabdomyolysis event, AND at least two major clinical events (as defined in the protocol) in the last year, or at least four major clinical events over the last two years,