medwireNews: Initiating ivacaftor (IVA) as early as 6-years-old rather than later can significantly improve outcomes for individuals with cystic fibrosis (CF), show US study results.
The observational study included data for individuals from the Cystic Fibrosis Foundation Patient Registry who were aged between 6 and 25 years at IVA initiation and found that the mean percent predicted forced expiratory volume in 1 second (ppFEV1) was significantly higher in those who began the treatment at a younger versus older age.
The findings “suggest that, although improved lung function is likely to occur with IVA at any age, progressive lung damage cannot be completely reversed with later treatment,” write Christian Merlo, from Johns Hopkins School of Medicine in Baltimore, Maryland, and co-authors in Thorax.
The researchers compared pulmonary outcomes in 602 individuals presenting with CFTR-gating mutations as well as a clinical diagnosis of CF who were grouped into cohorts based on age at IVA initiation: 6–10 years, 11–15 years, 16–20 years, and 21–25 years.
Three analyses were conducted comparing IVA initiation at ages 6–10 years with 11–15 years, ages 11–15 years with 16–20 years, and ages 16–20 years with 21–25 years. For each analysis, outcomes were compared over a 5-year outcome assessment period when both groups were in the same age range and receiving IVA.
As well as measuring ppFEV1, the team assessed pulmonary exacerbation (PEx) outcomes, defined as the receipt of home intravenous antibiotics or clinician-reported hospitalization for PEx.
Baseline clinical and demographic characteristics were balanced across the cohorts, after using a standardized morbidity/mortality ratio to reweight the demographic and clinical characteristics of the older initiators to resemble those of the younger ones based on propensity scores adjusting for factors such as gender, health insurance type, any medications, and all-cause hospitalizations, report Merlo and colleagues.
Mean ppFEV1 was significantly higher across all younger versus older age comparator groups throughout the study period, with the very highest recorded in the very youngest cohort. Specifically, ppFEV1 was 101.82% versus 90.09% for those initiating IVF when aged 6–10 versus 11–15 years, 92.88% versus 80.65% for those initiating it when aged 11–15 versus 16–20 years, and 81.17% versus 74.40% for those who initiated it at ages 16–20 versus 21–25 years.
The greatest difference in lung function as measured by FEV1 was seen in those who initiated IVA during early (11–15 years) versus later (16–20 years) adolescence, note Merlo et al, at a significant 11.2 percentage points.
Initiating IVA at the younger age of 6–10 years versus 11–15 years was also associated with a significant 52% lower PEx rate when measured at age 11–15 years. And while rates of PEx were numerically lower for individuals who were aged 11–15 years versus 16–20 years and 16–20 years versus 21–25 years when they initiated IVA, the findings were not statistically significant.
This result “further supports the potential for sustained benefits and mitigation of disease progression with early IVA treatment,” write Merlo and colleagues.
They conclude: “The present findings provide real-world evidence of the benefit of initiating IVA earlier versus later in life, which can alter the course of CF by preserving lung function and minimising PEx, potentially improving long-term outcomes and survival.”
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