Association between spirometry controlled chest CT scores using computer-animated biofeedback and clinical markers of lung disease in children with cystic fibrosis

Improvement in Lung Clearance Index and Chest Computed Tomography Scores with Elexacaftor/Tezacaftor/Ivacaftor Treatment in People with Cystic Fibrosis Aged 12 Years and Older - The RECOVER Trial

Rationale: Clinical trials have shown that use of elexacaftor/tezacaftor/ivacaftor (ETI) is associated with improvements in sweat chloride, pulmonary function, nutrition, and quality of life in people with cystic fibrosis (CF). Little is known about the impact of ETI on ventilation inhomogeneity and lung structure. Objectives: RECOVER is a real-world study designed to measure the impact of ETI in people with CF. The primary endpoints were lung clearance (lung clearance index; LCI2.5) and FEV1. Secondary endpoints included spirometry-controlled chest computed tomography (CT) scores. Methods: The study was conducted in seven sites in Ireland and the United Kingdom. Participants ages 12 years and older who were homozygous for the F508del mutation (F508del/F508del) or heterozygous for F508del and a minimum-function mutation (F508del/MF) were recruited before starting ETI and were followed up over 12 months. LCI2.5 was measured using nitrogen multiple breath washout (MBW) at baseline and at 6 and 12 months. Spirometry was performed as per the criteria of the American Thoracic Society and the European Respiratory Society. Spirometry-controlled chest CT scans were performed at baseline and at 12 months. CT scans were scored using the Perth Rotterdam Annotated Grid Morphometric Analysis (PRAGMA) system. Other outcome measures include weight, height, Cystic Fibrosis Quality of Life Questionnaire-Revised (CFQ-R), and sweat chloride. Measurements and Main Results: One hundred seventeen people with CF ages 12 and older were recruited to the study. Significant improvements were seen in LCI scores (-2.5; 95% confidence interval [CI], -3.0, -2.0) and in the percents predicted for FEV1 (8.9; 95% CI, 7.0, 10.9), FVC (6.6; 95% CI, 4.9, 8.3), and forced expiratory flow between 25% and 75% of expired volume (12.4; 95% CI, 7.8, 17.0). Overall PRAGMA-CF scores reflecting airway disease improved significantly (-3.46; 95% CI, -5.23, -1.69). Scores for trapped air, mucus plugging, and bronchial wall thickening improved significantly, but bronchiectasis scores did not. Sweat chloride levels decreased in both F508del/F508del (-43.1; 95% CI, -47.4, -38.9) and F508del/MF (-42.8; 95% CI, -48.5, -37.2) groups. Scores on the Respiratory Domain of the CFQ-R improved by 14.2 points (95% CI, 11.3, 17.2). At 1 year, sweat chloride levels were significantly lower for the F508del/F508del group compared with scores for the F508del/MF group (33.93 vs. 53.36, P < 0.001). Conclusions: ETI is associated with substantial improvements in LCI2.5, spirometry, and PRAGMA-CF CT scores in people with CF ages 12 years and older. ETI led to improved nutrition and quality of life. People in the F508del/F508del group had significantly lower sweat chloride on ETI treatment compared with the F508del/MF group. Clinical trial registered with www.clinicaltrials.gov (NCT04602468).

The clinical impact of Lumacaftor-Ivacaftor on structural lung disease and lung function in children aged 6-11 with cystic fibrosis in a real-world setting

BACKGROUND

Data from clinical trials of lumacaftor-ivacaftor (LUM-IVA) demonstrate improvements in lung clearance index (LCI) but not in FEV1 in children with Cystic Fibrosis (CF) aged 6-11 years and homozygous for the Phe508del mutation. It is not known whether LUM/IVA use in children can impact the progression of structural lung disease. We sought to determine the real-world impact of LUM/IVA on lung structure and function in children aged 6-11 years.

METHODS

This real-world observational cohort study was conducted across four paediatric sites in Ireland over 24-months using spirometry-controlled CT scores and LCI as primary outcome measures. Children commencing LUM-/IVA as part of routine care were included. CT scans were manually scored with the PRAGMA CF scoring system and analysed using the automated bronchus-artery (BA) method. Secondary outcome measures included rate of change of ppFEV1, nutritional indices and exacerbations requiring hospitalisation.

RESULTS

Seventy-one participants were recruited to the study, 31 of whom had spirometry-controlled CT performed at baseline, and after one year and two years of LUM/IVA treatment. At two years there was a reduction from baseline in trapped air scores (0.13 to 0.07, p = 0.016), but an increase from baseline in the % bronchiectasis score (0.84 to 1.23, p = 0.007). There was no change in overall % disease score (2.78 to 2.25, p = 0.138). Airway lumen to pulmonary artery ratios (AlumenA ratio) were abnormal at baseline and worsened over the course of the study. In 28 participants, the mean annual change from baseline LCI2.5 (-0.055 (-0.61 to 0.50), p = 0.85) measurements over two years were not significant. Improvements from baseline in weight (0.10 (0.06 to 0.15, p < 0.0001), height (0.05 (0.02 to 0.09), p = 0.002) and BMI (0.09 (0.03 to 0.15) p = 0.005) z-scores were seen with LUM/IVA treatment. The mean annual change from baseline ppFEV1 (-2.45 (-4.44 to 2.54), p = 0.66) measurements over two years were not significant.

CONCLUSION

In a real-world setting, the use of LUM/IVA over two years in children with CF aged 6-11 resulted in improvements in air trapping on CT but worsening in bronchiectasis scores. Our results suggest that LUM/IVA use in this age group improves air trapping but does not prevent progression of bronchiectasis over two years of treatment.

A Short extension to multiple breath washout provides additional signal of distal airway disease in people with CF: A pilot study

BACKGROUND

Adding a slow vital capacity (SVC) to multiple breath washout (MBW) allows quantification of otherwise overlooked signal from under/un-ventilated lung units (UVLU) and may provide a more comprehensive assessment of airway disease than conventional lung clearance index (LCI_2.5).

METHODS

We conducted a pilot study on people undergoing MBW tests: 10 healthy controls (HC) and 43 cystic fibrosis (CF) subjects performed an SVC after the standard end of test. We term the new outcome LCI with Short extension (LCI_ShX). We assessed (i) CF/ HC differences, (ii) variability (iii) effect of pulmonary exacerbation (PEx)/treatment and (iv) relationship with CF computed tomography (CFCT) scores.

RESULTS

HC/ CF group differences were larger with LCI_ShX than LCI_2.5 (P<0.001). Within the CF group UVLU was highly variable and when abnormal it did not correlate with corresponding LCI_2.5. Signal showed little variability during clinical stability (n = 11 CF; 2 visits; median inter-test variability 2.6% LCI_ShX, 2.5% LCI_2.5). PEx signal was significantly greater for LCI_ShX both for onset and resolution. Both MBW parameters correlated significantly with total lung CT scores and hyperinflation but only LCI_ShX correlated with mucus plugging.

CONCLUSIONS

UVLU captured within the LCI_ShX varies between individuals; the lack of relationship with LCI_2.5 demonstrates that new, additional information is being captured. LCI_ShX repeatability during clinical stability combined with its larger signal around episodes of PEx may lend it superior sensitivity as an outcome measure. Further studies will build on this pilot data to fully establish its utility in monitoring disease status.

Lung compartment analysis assessed from N2 multiple-breath washout in children with cystic fibrosis

BACKGROUND

Compartment analysis (CA) based on nitrogen multiple-breath washout (N₂ MBW) has been shown to allow the assessment of specific volume and ventilation of faster- and slower-ventilating lung compartments of the lung in adults with cystic fibrosis (CF). The aim of this study was to extend previous findings into the pediatric age range.

METHODS

Cross-sectional multicenter observational study in children with CF and healthy controls (HC) was done with the assessment of N₂ MBW and spirometry. A two-lung compartment model-based analysis (CA) was used to estimate size and function of faster- and slower-ventilating lung compartments from N₂ MBW.

RESULTS

A total of 125 children with CF and 177 HC, median age 10.8 (range, 2.8-18.9) years, were included in the analysis. CA could be calculated in 66 (53%) children with CF compared with 48 (27%) HC (P < .0001). The proportion of the slower-ventilating lung compartment was significantly smaller in children with CF (53.5%; 95% confidence interval [CI]: 51.9%-55.7%) compared with HC (62.2%; 95% CI: 59.0%-65.0%) The regional specific ventilation of the slower compartment (rV_T ,slow/rFRC,slow, %) was significantly lower in children with CF (4.9%; 95% CI: 4.5-5.9) compared with HC (9.7%, 95% CI: 9.2-10.9), and showed inverse correlation to lung clearance index (r²  = -.65; P < .0001), S_acin  × VT (r²  = -.36; P = .003) and S_cond  × VT (r²  = -.51; P < .0001). There was no significant difference in pulmonary parameters between children with CF with and without feasible CA.

CONCLUSION

CA is less feasible in children than in adults and correlated to other MBW parameters. The clinical value of CA is still unclear and is yet to be established.

Structural determinants of long-term functional outcomes in young children with cystic fibrosis

Background

Accelerated lung function decline in individuals with cystic fibrosis (CF) starts in adolescence with respiratory complications being the most common cause of death in later life. Factors contributing to lung function decline are not well understood, in particular its relationship with structural lung disease in early childhood. Detection and management of structural lung disease could be an important step in improving outcomes in CF patients.

Methods

Annual chest computed tomography (CT) scans were available from 2005 to 2016 as a part of the AREST CF cohort for children aged 3 months to 6 years. Annual spirometry measurements were available for 89.77% of the cohort (167 children aged 5–6 years) from age 5 to 15 years through outpatient clinics at Perth Children's Hospital (Perth, Australia) and The Royal Children's Hospital in Melbourne (Melbourne, Australia) (697 measurements, mean±sd age 9.3±2.1 years).

Results

Children with a total CT score above the median at age 5–6 years were more likely to have abnormal forced expiratory volume in 1 s (FEV1) (adjusted hazard ratio 2.67 (1.06–6.72), p=0.037) during the next 10 years compared to those below the median chest CT score. The extent of all structural abnormalities except bronchial wall thickening were associated with lower FEV1 Z-scores. Mucus plugging and trapped air were the most predictive sub-score (adjusted mean change −0.17 (−0.26 – −0.07) p<0.001 and −0.09 (−0.14 – −0.04) p<0.001, respectively).

Discussion

Chest CT identifies children at an early age who have adverse long-term outcomes. The prevention of structural lung damage should be a goal of early intervention and can be usefully assessed with chest CT. In an era of therapeutics that might alter disease trajectories, chest CT could provide an early readout of likely long-term success.

Lung clearance index for early detection of pulmonary complications after allo-HSCT in children

BACKGROUND

Pulmonary chronic graft-vs-host disease (cGvHD) after hematopoietic stem cell transplantation (HSCT) is characterized by impairment of the small airways. Assessment of lung clearance index (LCI) gained from multiple breath washout (MBW) is more sensitive than spirometry in detection of small airways disease. The aim of this study was to describe the development of LCI during the first year after pediatric HSCT and how LCI relates to other pulmonary function parameters and cGvHD.

METHODS

This prospective, longitudinal study included 28 pediatric HSCT-recipients. Spirometry, Sulfur hexafluoride MBW and diffusion capacity of the lungs were performed before and at 3, 6, 9, and 12 months after HSCT. Respiratory symptoms and signs of cGvHD were recorded at each visit.

RESULTS

Before HSCT, 47.8% had abnormal LCI and 12.5% had abnormal forced expiratory volume in 1 second (FEV₁ )_. Patients with persisting respiratory symptoms 12 months post-HSCT had higher median LCI (factor 5.7, P = 0.0018) and lower FEV₁ z-scores (-1.5, P = 0.033) post-HSCT compared to patients free of respiratory symptoms. Overall, post-HSCT LCI values were 3.49 times higher and FEV₁ was 2.31 z-scores lower in eight patients with cGvHD in any organ system compared with patients without cGvHD (P = 0.0089 and P < 0.0001). LCI values during the first 3 months were not predictive of pulmonary cGvHD.

CONCLUSION

LCI is a sensitive marker for cGvHD and high LCI values were associated with persisting respiratory symptoms after 1 year. Further evaluation of MBW in early detection of HSCT-related pulmonary complications require larger patient cohorts and closer follow-up during the first months after HSCT.

Exercise capacity in patients with cystic fibrosis vs. non-cystic fibrosis bronchiectasis

Background

Bronchiectasis is associated with morbidity, low exercise capacity and poor quality of life. There is a paucity of data on exercise capacity using cardiopulmonary exercise test (CPET) in non-cystic fibrosis (CF) bronchiectasis. Our aim was to compare exercise capacity using CPET in CF and non-CF bronchiectasis patients.

Methods

Cross-sectional retrospective/prospective controlled study assessing CPET using cycle ergometer. Exercise parameters and computed tomography (CT) findings were compared. Results: Hundred two patients with bronchiectasis and 88 controls were evaluated; 49 CF (age 19.7 ± 9.7 y/o, FEV₁%predicted 70.9 ± 20.5%) and 53 non-CF (18.6 ± 10.6 y/o, FEV₁%predicted 68.7 ± 21.5%). Peak oxygen uptake (peak V˙O2) was similar and relatively preserved in both groups (CF 1915.5±702.0; non-CF 1740±568; control 2111.0±748.3 mL/min). Breathing limitation was found in the two groups vs. control; low breathing reserve (49% in CF; 43% non-CF; 5% control) and increased V˙E/V˙CO2 (CF 31.4±4.1, non-CF 31.7±4.1 and control 27.2 ± 2.8). Oxygen pulse was lower in the non-CF; whereas a linear relationship between peak V˙O2 vs. FEV₁ and vs. FVC was found only for CF. CT score correlated with V˙E/V˙CO2 and negatively correlated with V˙O2/kg and post exercise oxygen saturation (SpO₂).

Conclusions

CPET parameters may differ between CF and non-CF bronchiectasis. However, normal exercise capacity may be found unrelated to the etiology of the bronchiectasis. Anatomical changes in CT are associated with functional finding of increased V˙E/V˙CO2 and decreased SpO₂. Larger longitudinal studies including cardiac assessment are needed to better study exercise capacity in different etiologies of non-CF bronchiectasis.

Trial registration

ClinicalTrials.gov, registration number: NCT03147651.

Change in lung clearance index with microbiological status in children with cystic fibrosis

The impact of infections caused by bacteria, especially Gram-negative, on the progression of lung disease in cystic fibrosis is well established. Decline in pulmonary function commence already at early age. In this group of patients, the lung clearance index seems to be a better marker than FEV₁ allowing non-invasive monitoring of changes in small airways. The aim of this study was to investigate the association between the microbiological status and LCI derived from multiple breath washout (MBW) technique as well as FEV₁ and FVC in children suffering from cystic fibrosis. Over the 1-year recruitment period, 136 CF patients aged 5-18 with: Staphylococcus aureus (n-27), Pseudomonas aeruginosa (first time (n-27), intermittent (n-9), and chronic (34) infection), Aspergillus fumigatus (n-6) and without pathogenic flora (n-33) were included in the study. Patients had performed a spirometry and MBW test during the visit at outpatient clinic. The study showed that the lung clearance index in patients infected with Aspergillus fumigatus was significantly higher (P < 0.05) than in those with normal throat flora. There was also statistically significant differences in the lung clearance index obtained in subjects with chronic Pseudomonas aeruginosa infection and those with first Pseudomonas aeruginosa infection (P < 0.05). Furthermore, significant statistical differences (P < 0.05) were observed between the groups of patients with chronic Pseudomonas aeruginosa infection FEV₁ > 70% and FEV₁ < 70%. In conclusion, LCI was associated with microbiological status of CF patients. Chronic lung infections, especially Aspergillus fumigatus and Pseudomonas aeruginosa, were associated with increased LCI. Early eradication of pathological flora positively affects the maintenance of lower LCI.

Long-Term Lung Function and Exercise Capacity in Postinfectious chILD

Background: Severe postinfectious diffuse pulmonary disease may clinically mimic other entities of children's interstitial lung disease and is clinically challenging comprising various disease severities despite treatment. Long-term lung function trend and physical capacity in children with postinfectious diffuse pulmonary disease are rarely reported. We investigated trends in pulmonary function by long-term follow-up and assessed physical capacity in such patients.

Methods: We performed a descriptive, single-center follow-up study in children with biopsy-verified postinfectious diffuse pulmonary disease. Patients with completed primary treatment course were eligible for follow-up, including pulmonary function and exercise (VO_2peak) testing.

Results: Thirty patients with postinfectious diffuse pulmonary disease were identified and included. Median (range) age at diagnose was 27.5 (2–172) months after a mean lag time of 23 months. H. influenzae and rhinovirus were the most frequent pathogens. Fifteen patients were available for follow-up after mean (range) 7.6 (2–15) years of treatment completion. Lung clearance index (LCI_2.5), forced expiratory volume in 1 second (FEV₁), and bronchodilator responsiveness were abnormal in 80%, 53%, and 44%, respectively. Diffusion capacity for monoxide was abnormal in 7% and total lung capacity in 33%. Only 8% demonstrated low VO_2peak, while 40% reported difficulties during physical exertion. Longitudinal data on spirometry (n = 14) remained unchanged from end of treatment throughout follow-up. A significant association was found between zLCI_2.5 and zFEV₁ (multiple linear regression; r² = 0.61; P = 0.0003).

Conclusion: Postinfectious diffuse pulmonary disease in children carries a varying degree of chronic pulmonary impairment with onset of symptoms in the first months of life and a typical considerable lag time before diagnosis. Follow-up several years after the initial injury demonstrated moderate-to-severe peripheral airway impairment although no further lung function decline was found years after completion of treatment. Despite acceptable VO_2peak, a considerable proportion struggled during heavy exercise.

CT evaluation of hyperattenuating mucus to diagnose allergic bronchopulmonary aspergillosis in the special condition of cystic fibrosis

BACKGROUND

Mucus plugging (MP), central bronchiectasis (CB), and consolidation/atelectasia (CA) are conventional CT signs to diagnose allergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis (CF). Hyperattenuating mucus (HAM) has recently been described and may improve diagnostic accuracy. The goal of our study was to compare HAM versus conventional CT signs to diagnose ABPA in CF. Secondary objectives were to determine the optimal threshold of HAM quantitatively and to assess the diagnostic value of HAM using chest radiograph (CXR).

METHODS

The study was retrospective and included 137 patients with CF, aged >6-year-old. The presence of HAM, CB, MP and CA were determined by two radiologists in consensus. HAM was quantified using an absolute mean density value (AMD) and a ratio between mucus and paraspinal muscle (DRM). Sensitivity (Se), Specificity (Sp) and Youden's J-index were calculated. The Cystic Fibrosis Conference Consensus criteria were chosen as Gold Standard.

RESULTS

23 out of 137 CF patients had ABPA. Using CT, the most sensitive structural alteration was MP (Se = 91%), followed by CB (Se = 87%) and CA (Se = 70%) whereas specificities were 28%, 19% and 58%, respectively. Conversely, HAM had the highest specificity (Sp = 100%) whereas Se was 69%. HAM had the highest Youden's J-index (p < 0.001) Quantitative optimal thresholds were AMD > 78 HU (Se/Sp = 71%/98%) and DRM > 1.3 (Se/Sp = 82%/97%). HAM was unseen using CXR (Se = 0%).

CONCLUSION

HAM is the most specific CT biomarker of ABPA in CF, with good sensitivity. Our study suggests that characterization of mucus density may improve the accuracy of imaging criteria to diagnose ABPA early.