medwireNews: Canadian researchers have identified risk factors for poor outcomes in patients with systemic lupus erythematosus (SLE) who taper or discontinue hydroxychloroquine (HCQ) treatment, including baseline prednisone use and age at diagnosis.
Identification of these factors “may be useful in personalizing decisions for SLE patients (and their physicians) around medication de-escalation or maintenance, as well as monitoring for flares when HCQ tapering or stopping is needed, such as in the current setting of potential HCQ shortages due to interest in this drug as a therapy for COVID19,” emphasize the study investigators.
They obtained data for 1188 patients with SLE from five Canadian cohorts who were receiving care in lupus clinics between 1999 and 2019. Of these, 398 tapered HCQ, 395 discontinued the drug, and 395 maintained HCQ treatment. The groups were matched for duration of disease and time taking HCQ.
The researchers investigated the primary composite endpoint of poor outcomes, comprising the earliest occurrence of any of the three events – treatment augmentation, increased disease activity as indicated by a minimum SLEDAI-2K increase of 4 points, or hospitalization for SLE – indicative of a flare.
The most common poor outcome across the three cohorts was treatment augmentation, required by 52.8%, 48.9%, and 17.2% of patients in the taper, discontinue, and maintenance arms, respectively. This was followed by increased disease activity, at a respective 19.4, 20.2, and 10.3%, and hospitalization for SLE, at a corresponding 0.8, 0.6, and 0.3%.
In total, 261 patients who tapered HCQ had a poor outcome, translating to the highest event rate of 35.7 events per 100 person–years. In comparison, 226 patients who discontinued and 97 who continued taking HCQ had a poor outcome, translating to event rates of 29.0 and 16.1 events per 100 person–years, respectively.
In multivariable analysis, patients who tapered HCQ at baseline were significantly more likely to have a poor outcome if they were taking prednisone than if they were not, at a hazard ratio (HR) of 1.74 after accounting for confounding factors.
Patients who discontinued HCQ were significantly more likely to have a poor outcome if they were diagnosed with SLE at a younger age (≤25 years old) and if they were Black versus White, with corresponding HRs of 1.75 and 1.61. On the other hand, being a smoker was associated with a significantly decreased risk for poor outcomes, with an adjusted HR of 0.66.
In the maintenance arm, First Nations people were significantly more likely to have a poor outcome than White people, as were patients who were taking versus not taking immunosuppressants, with adjusted HRs of 2.87 and 1.72, respectively.
The researchers also investigated predictors for the three outcomes separately. They found that the risk for treatment augmentation was significantly higher among patients tapering HCQ if they were Asian (HR=1.52 versus White patients) and had active disease at baseline (HR=1.62), and significantly higher among those discontinuing the drug if they were Black (HR=1.69 versus White patients) and diagnosed with SLE at a younger age (HR=1.48). By contrast, the risk for treatment augmentation was reduced among patients discontinuing the drug if they were non-smokers (HR=0.59).
The risk for increased disease activity was significantly reduced in patients who tapered or discontinued HCQ if they had a baseline SLEDAI-2K score of at least 4 points, while there were no specific predictors for SLE-related hospitalizations in any of the three cohorts.
This is likely due to the “relatively low” number of hospitalizations for SLE, say Sasha Bernatsky (McGill University Health Centre, Quebec, Canada) and colleagues.
They conclude in Arthritis Care & Research: “Our results suggest caution in tapering or discontinuation of HCQ in some groups of SLE patients.”
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