Antimalarial adherence lowers risk for death by 83% in lupus
Patients with systemic lupus erythematosus who adhere to antimalarial therapy have a 71% lower risk for death than those in nonadherence, and an 83% lower risk than those who discontinue, according to data published in Arthritis Care & Research.
“Antimalarial medication is considered the first-line drug in managing systemic lupus erythematosus for most patients,” Hui Xie, PhD, of Arthritis Research Canada and Simon Fraser University, in British Columbia, told Healio Rheumatology. “These medications have been shown to improve SLE symptoms and reduce inflammation of the lining of the heart and lungs, as well as the development of kidney inflammation, central nervous system impairment, and flares in disease activity. Adherence to prescribed medications is considered key to achieve the full benefits of the medicine.”
To analyze the link between antimalarial adherence and premature death among patients with incident SLE, Xie and colleagues studied data from Population Data BC, which includes information on all provincially funded health care services and professional visits in British Columbia. Using this data, the researchers identified 3,062 patients with incident SLE who used an antimalarial between January 1997 and March 2015. For the purposes of their study, the researchers defined the follow-up period as starting on the first day of having both SLE and antimalarial treatment.
The primary outcome was all-cause mortality. The adherence measure — the proportion of days covered (PDC) during 30-day windows — included three categories, defined as “adherent,” with a PDC of 0.9 or greater, “nonadherent,” with a PDC between 0 and 0.9, and “discontinuer,” with a PDC of 0.
Xie and colleagues initially used Cox’s models for time to death, adjusting for baseline and time‐varying confounders on medication usages, health care use and comorbidities. They then used marginal structural Cox models, including inverse probability weighting designed for causal inference with time‐varying confounders, to examine the impact of antimalarial adherence on premature death.
According to the researchers, 7.9% of the included patients died. Adjusted hazard ratios from the Cox’s model for adherent and non‐adherent patients were 0.2 (95% CI, 0.13-0.29) and 0.62 (95% CI, 0.42-0.91), respectively, compared to those who discontinued. The corresponding adjusted hazard ratios from the marginal structural Cox model were 0.17 (95% CI, 0.12‐0.25) and 0.58 (95% CI, 0.40‐0.85) for adherent and nonadherent patients, respectively. There was a significant trend of mortality risk over the adherence levels (P < .001), the researchers wrote.
“This study is one of the first to examine antimalarial adherence in SLE patients,” Xie said. “We found SLE patients who take their antimalarial medications regularly have a 71% lower risk for death than those who do not take them regularly, and an 83% lower risk than those who discontinue use altogether.”
“The finding is important because a significant number of patients — more than 50% — in the data do not fully comply with antimalarial medications,” he added. “The findings of this study call attention to the need for improved strategies to boost antimalarial adherence among SLE patients to increase survival and prevent premature death.”