INCIDENCE OF MYOPATHY IN PATIENTS TREATED WITH ANTIMALARIALS - A REPORT OF 3 CASES AND A REVIEW OF THE LITERATURE

A retrospective review of 4405 patients' charts identified 214 patient s who initiated antimalarial therapy between January 1987 and April 19 93 for different rheumatic disorders (mean duration of therapy of 17 m onths). From these, three patients with myopathy were found for a tota l of 303 patient-years of therapy, for an incidence of 1 in 100 patien t-years (95%, confidence interval 0.2-3). All three patients had rheum atoid arthritis and had received chloroquine for between 12 and 18 mon ths with a maximum dose of 250 mg/daily. All had a muscle biopsy, but only one showed the classical rimmed vacuoles. All patients improved w ithin 2 months after the drug was stopped. A review of the literature was carried out with special reference to the significance of clinical myopathy with a negative biopsy. We found that positive biopsies are usual only if the duration of symptoms have been allowed to persist fo r more than 6 months.