Systemic corticosteroids reduce blood eosinophil counts
medwireNews: Systemic corticosteroid (SCS) treatment reduces blood eosinophil counts and low levels are maintained for weeks after treatment is discontinued, show real-world data.
“This study provides insights in the effect of SCS therapy on blood eosinophil counts over time in patients with asthma and index blood eosinophil counts ≥150 cells/µL,” say Beth Hahn (GSK, Research Triangle Park, North Carolina, USA) and fellow researchers.
Using electronic medical records and claims data from the Reliant Medical Group between 2011 and 2015, the researchers studied the eosinophil counts of 1198 patients with asthma in the 12 months before they received their first SCS prescription of 35 mg/day and for at least 12 months afterwards.
In the first month of receiving SCS, average blood eosinophil counts decreased significantly (p<0.05 for all) by 30% among the 642 patients with index counts of 150 cells/µL or above, by 34% in the 262 with counts of 300 cells/µL or above, and by 36% among the 135 with counts of 400 cells/µL or above.
The average reductions in blood eosinophil counts for the three groups at this 1-month point were 112 cells/µL, 202 cells/µL, and 290 cells/µL, respectively.
The average time between SCS cessation and the eosinophil count recorded at 1 month was 19 days, the team notes, although 32.7% of patients were still receiving SCS treatment at this time.
Mean blood eosinophil counts started to rise with time since SCS cessation, so that by month 3, when the mean time since SCS cessation was 79.1 days, the absolute and percentage reductions in blood eosinophil counts were smaller compared with at month 1, but still lower than pretreatment counts.
Patients with index counts of 150 cells/µL or above had an average 18% (65 cells/µL) reduction, while patients with counts of 300 cells/µL and above and 400 cells/µL and above had reductions of 26% (150 cells/µL) and 32% (246 cells/µL), respectively.
The researchers note in the Journal of Asthma that by month 3, mean blood eosinophil counts returned to near index levels in the patients with levels of 150 cells/µL or above, whereas “[i]n contrast, although blood eosinophil counts in the ≥400 cells/µL subgroup increased at a similar rate, these remained proportionally lower compared with index levels than the other two groups at Month 3.”
The findings indicate that “the temporal association between SCS and blood eosinophil count is greatest up to 1-month post-SCS initiation,” say Hahn et al. They highlight that “[t]his effect should be considered when making clinical assessments of blood eosinophil counts after recent SCS treatment.”
Nevertheless, they point out that while blood eosinophil counts started to rise after discontinuation, which was a median 10 days across all patients, they remained 70–229 cells/µL below index at month 1 and 32–177 cells/µL below index at month 3.
And post-hoc analyses showed that among patients with an index blood eosinophil count of at least 150 cells/µL, 21% of those who discontinued SCS therapy within 7 days still had counts below this cutoff at 1 month, as did 26% and 25% of those who discontinued SCS at 14 and 21 days, respectively.
“As SCS reduces blood eosinophil counts, the time frame of SCS discontinuation is an important consideration when identifying patients with eosinophilic asthma,” the team concludes.
By Lucy Piper
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