Browsing by Author "Retsch-Bogart, George"

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    Determinants of lung disease progression measured by lung clearance index in children with cystic fibrosis
    (ERS, 2021-07) Stanojevic, Sanja; Davis, Stephanie D.; Perrem, Lucy; Shaw, Michelle; Retsch-Bogart, George; Davis, Miriam; Jensen, Renee; Clem, Charles C.; Isaac, Sarah M.; Guido, Julia; Jara, Sylvia; France, Lisa; McDonald, Nancy; Solomon, Melinda; Sweezey, Neil; Grasemann, Hartmut; Waters, Valerie; Sanders, D. B.; Ratjen, Felix A.; Pediatrics, School of Medicine
    The lung clearance index (LCI) measured by the multiple breath washout (MBW) test is sensitive to early lung disease in children with cystic fibrosis. While LCI worsens during the preschool years in cystic fibrosis, there is limited evidence to clarify whether this continues during the early school age years, and whether the trajectory of disease progression as measured by LCI is modifiable. A cohort of children (healthy and cystic fibrosis) previously studied for 12 months as preschoolers were followed during school age (5–10 years). LCI was measured every 3 months for a period of 24 months using the Exhalyzer D MBW nitrogen washout device. Linear mixed effects regression was used to model changes in LCI over time. A total of 582 MBW measurements in 48 healthy subjects and 845 measurements in 64 cystic fibrosis subjects were available. The majority of children with cystic fibrosis had elevated LCI at the first preschool and first school age visits (57.8% (37 out of 64)), whereas all but six had normal forced expiratory volume in 1 s (FEV1) values at the first school age visit. During school age years, the course of disease was stable (−0.02 units·year−1 (95% CI −0.14–0.10). LCI measured during preschool years, as well as the rate of LCI change during this time period, were important determinants of LCI and FEV1, at school age. Preschool LCI was a major determinant of school age LCI; these findings further support that the preschool years are critical for early intervention strategies.
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    Inter-test reproducibility of the lung clearance index measured by multiple breath washout
    (ERS, 2017-10-01) Engberink, Esther Oude; Ratjen, Felix; Davis, Stephanie D.; Retsch-Bogart, George; Amin, Reshma; Stanojevic, Sanja; Pediatrics, School of Medicine
    The lung clearance index (LCI) has strong intra-test repeatability; however, the inter-test reproducibility of the LCI is poorly defined. The aim of the present study was to define a physiologically meaningful change in LCI in preschool children, which discriminates changes associated with disease progression from biological variability. Repeated LCI measurements from a longitudinal cohort study of children with cystic fibrosis and age-matched controls were collected to define the inter-visit reproducibility of the LCI. Absolute change, the coefficient of variation, Bland–Altman limits of agreement, the coefficient of repeatability, intra-class correlation coefficient, and percentage changes were calculated. LCI measurements (n=505) from 71 healthy and 77 cystic fibrosis participants (aged 2.6–6 years) were analysed. LCI variability was proportional to its magnitude, such that reproducibility defined by absolute changes is biased. A physiologically relevant change for quarterly LCI measurements in health was defined as exceeding ±15%. In clinically stable cystic fibrosis participants, the threshold was higher (±25%); however, for measurements made 24 h apart, the threshold was similar to that observed in health (±17%). A percentage change in LCI greater than ±15% in preschool children can be considered physiologically relevant and greater than the biological variability of the test. Biological variability of lung clearance index is dependent on magnitude; % change is better for tracking patients http://ow.ly/tgbX30dBbCX
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    Testing the effects of combining azithromycin with inhaled tobramycin for P. aeruginosa in cystic fibrosis: a randomised, controlled clinical trial
    (BMJ, 2022) Nichols, David P.; Singh, Pradeep K.; Baines, Arthur; Caverly, Lindsay J.; Chmiel, James F.; Glbson, Ronald L.; Lascano, Jorge; Morgan, Sarah J.; Retsch-Bogart, George; Saiman, Lisa; Sadeghi, Hossein; Billings, Joanne L.; Heltshe, Sonya L.; Kirby, Shannon; Kong, Ada; Nick, Jerry A.; Mayer-Hamblett, Nicole; TEACH Study Group; Pediatrics, School of Medicine
    Rationale: Inhaled tobramycin and oral azithromycin are common chronic therapies in people with cystic fibrosis and Pseudomonas aeruginosa airway infection. Some studies have shown that azithromycin can reduce the ability of tobramycin to kill P. aeruginosa. This trial was done to test the effects of combining azithromycin with inhaled tobramycin on clinical and microbiological outcomes in people already using inhaled tobramycin. We theorised that those randomised to placebo (no azithromycin) would have greater improvement in forced expiratory volume in one second (FEV1) and greater reduction in P. aeruginosa sputum in response to tobramycin. Methods: A 6-week prospective, randomised, placebo-controlled, double-blind trial testing oral azithromycin versus placebo combined with clinically prescribed inhaled tobramycin in individuals with cystic fibrosis and P. aeruginosa airway infection. Results: Over a 6-week period, including 4 weeks of inhaled tobramycin, the relative change in FEV1 did not statistically significantly differ between groups (azithromycin (n=56) minus placebo (n=52) difference: 3.44%; 95% CI: -0.48 to 7.35; p=0.085). Differences in secondary clinical outcomes, including patient-reported symptom scores, weight and need for additional antibiotics, did not significantly differ. Among the 29 azithromycin and 35 placebo participants providing paired sputum samples, the 6-week change in P. aeruginosa density differed in favour of the placebo group (difference: 0.75 log10 CFU/mL; 95% CI: 0.03 to 1.47; p=0.043). Conclusions: Despite having greater reduction in P. aeruginosa density in participants able to provide sputum samples, participants randomised to placebo with inhaled tobramycin did not experience significantly greater improvements in lung function or other clinical outcomes compared with those randomised to azithromycin with tobramycin.