58 Pulmonary exacerbations in CF patients with the G551D-CFTR mutation treated with ivacaftor

Flume, Patrick A.; Wainwright, Claire; Tullis, Elizabeth; Rodriguez, Sally; Davies, Jane C.; Wagener, J.

doi:10.1016/s1569-1993(13)60200-3

Cited by 4 publications

(3 citation statements)

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“…Ramsey et al ( 3 ) reported that in patients aged 12 years or older with the specified gating mutation, the mean percent predicted forced expiratory volume in 1 second (ppFEV 1 ) was 10.5 percentage points higher after 48 weeks of ivacaftor treatment versus placebo, and the ivacaftor group was 55% less likely to have a pulmonary exacerbation. Similar results have been reported in younger children ( 4 , 5 ). These patients will take ivacaftor for many years, and it is hoped that it will change their slope of lung function decline (“slope-change effect”), as well as improve lung function during the initial treatment phase (“step-change effect”).…”

Section: Abbreviationssupporting

confidence: 91%

“…Randomized controlled trials have found that ivacaftor improves lung function and reduces the incidence of pulmonary exacerbations ( 3 – 5 ). Ramsey et al ( 3 ) reported that in patients aged 12 years or older with the specified gating mutation, the mean percent predicted forced expiratory volume in 1 second (ppFEV 1 ) was 10.5 percentage points higher after 48 weeks of ivacaftor treatment versus placebo, and the ivacaftor group was 55% less likely to have a pulmonary exacerbation.…”

Section: Abbreviationsmentioning

confidence: 99%

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Using Negative Control Outcomes and Difference-in-Differences Analysis to Estimate Treatment Effects in an Entirely Treated Cohort: The Effect of Ivacaftor in Cystic Fibrosis

Daniel¹,

Carr²,

Bilton³

et al. 2021

American Journal of Epidemiology

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When an entire cohort of patients receives a treatment it is difficult to estimate the treatment effect in the treated because there are no directly comparable untreated patients. Attempts can be made to find a suitable control group, (e.g. historical controls), but underlying differences between the treated and untreated can result in bias. We show how negative control outcomes (NCO) combined with difference-in-differences analysis can be used to assess bias in treatment effect estimates and obtain unbiased estimates under certain assumptions. Causal diagrams and potential outcomes are used to explain the methods and assumptions. We apply the methods to UK Cystic Fibrosis (CF) Registry data to investigate the effect of ivacaftor, introduced in 2012 for a subset of the CF population with a particular genotype, on lung function and days receiving intravenous antibiotics (IV days). We consider two NCOs: outcomes measured in the pre-ivacaftor period and outcomes in individuals ineligible for ivacaftor due to their genotype. Ivacaftor was found to improve lung function in year one (~6.5 increase in FEV1%), was associated with reduced lung function decline (~0.5 decrease in annual FEV1% decline, though confidence intervals include 0), and reduced the rate of IV days (~60% over 3 years).

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Section: Abbreviationssupporting

confidence: 91%

Section: Abbreviationsmentioning

confidence: 99%

Using Negative Control Outcomes and Difference-in-Differences Analysis to Estimate Treatment Effects in an Entirely Treated Cohort: The Effect of Ivacaftor in Cystic Fibrosis

Daniel¹,

Carr²,

Bilton³

et al. 2021

American Journal of Epidemiology

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“…Infants with CF have been shown to have impaired lung function in the first year of life without overt respiratory symptoms [ 3 , 35 ]. Other studies have reported associations between respiratory symptoms and lung function outcomes during periods of pulmonary exacerbation in toddlers [31] , school aged children, and adults with CF [36] . In toddlers and children, elevated LCI measurements, as well as ventilation and perfusion defects in magnetic resonance imaging (MRI), were reported in clinical stable patients and during exacerbations.…”

Section: Comparison With Literaturementioning

confidence: 98%

Respiratory symptoms do not reflect functional impairment in early CF lung disease

Korten

Oestreich

Frey

et al. 2021

Journal of Cystic Fibrosis

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Background: Lung disease can develop within the first year of life in infants with cystic fibrosis (CF). However, the frequency and severity of respiratory symptoms in infancy are not known. Methods:We assessed respiratory symptoms in 50 infants with CF and 50 healthy matched controls from two prospective birth cohort studies. Respiratory symptoms and respiratory rate were documented by standardized weekly interviews throughout the first year. Infants performed multiple breath washout in the first weeks of life. Results:We analyzed 4552 data points (2217 in CF). Respiratory symptoms (either mild or severe) were not more frequent in infants with CF (OR:1.1;95% CI:[0.76, 1.59]; p = 0.6). Higher lung clearance index and higher respiratory rate in infants with CF were not associated with respiratory symptoms. Conclusions:We found no difference in respiratory symptoms between healthy and CF infants. These data indicate that early CF lung disease may not be captured by clinical presentation alone.

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Potentiators (specific therapies for class III and IV mutations) for cystic fibrosis

Patel

Sinha

Dwan

et al. 2015

Cochrane Database of Systematic Reviews

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58 Pulmonary exacerbations in CF patients with the G551D-CFTR mutation treated with ivacaftor

Cited by 4 publications

References 0 publications

Using Negative Control Outcomes and Difference-in-Differences Analysis to Estimate Treatment Effects in an Entirely Treated Cohort: The Effect of Ivacaftor in Cystic Fibrosis

Using Negative Control Outcomes and Difference-in-Differences Analysis to Estimate Treatment Effects in an Entirely Treated Cohort: The Effect of Ivacaftor in Cystic Fibrosis

Respiratory symptoms do not reflect functional impairment in early CF lung disease

Potentiators (specific therapies for class III and IV mutations) for cystic fibrosis

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