Long-term use of antimalarial drugs in rheumatic diseases.

OBJECTIVES

To evaluate long-term use of antimalarial drugs and to analyse all causes of discontinuation.

METHODS

This is a retrospective study of a cohort of rheumatic diseases patients on antimalarials, during a maximum period of 17.5 years. Case was defined as antimalarial treatment discontinuation due to: a) lack of efficacy, b) adverse events, and c) other causes. Survival techniques were used to estimate the incidence rate (IR) per 1,000 patient-years with the 95% Confidence Interval (95% CI) of antimalarial treatment discontinuation. Cox regression models were conducted to evaluate possible associated factors to antimalarial discontinuation.

RESULTS

One thousand, two hundred and ninety-one medical records were reviewed, and 778 patients were included. Patients started 869 different courses of treatment, with a total follow-up of 2,263 person-years. The IR of global discontinuation was 204 (95% CI 186-224). Fifty-two per cent of the treatments stopped were related to adverse events, 14% to lack of efficacy; and 34% to other reasons (refusal to take medication, ocular comorbidity, remission, or pregnancy). Adverse events discontinuations were related to non-ophthalmologic reasons in 54.5% (gastrointestinal, neuro-psychiatric, skin problems), and to ophthalmologic adverse events in 45.5%. Nine patients suffered definite presence of antimalarial retinopathy (IR: 3.97 [IC 95%: 2.06-7.62]) and one of them irreversible loss of vision (IR: 0.44 [IC 95%: 0.06-3.12]). Women, increasing age, and chloroquine vs. hydroxychloroquine use, increased the risk of discontinuation due to ophthalmologic adverse events.

CONCLUSIONS

Results suggest that antimalarials have a good balance between benefit and risk. However, we noted a number of discontinuations due to both inefficacy and adverse events. The potential for an unusual but serious ophthalmologic toxicity emphasises the importance of close ophthalmologic monitoring.