Relationship of CT densitometry to lung physiological parameters and health status in alpha-1 antitrypsin deficiency: initial report of a centralised database of the NIHR rare diseases translational research collaborative

Densitometric and Functional Progression in Patients with Alpha-1 Antitrypsin Deficiency Genotype SZ

Smoking is a key determinant of chronic obstructive pulmonary disease (COPD) development in patients with the SZ genotype. Few studies have evaluated the impact of other factors associated with emphysema progression. Objectives: To evaluate the progression of lung function and densitometric parameters in PiSZ alpha-1 antitrypsin deficiency (AATD) patients, and to assess the impact of smoking, exacerbation frequency, severity and time since diagnosis. The study also explores correlations between functional and densitometric measures, as well as regional emphysema patterns. Methods: This two-year observational study included 31 PiSZ AATD patients stratified by time since diagnosis (<5 vs. ≥5 years), smoking status (current, former, and never smokers), and exacerbation frequency (<2 vs. ≥2 exacerbations/year). Functional [forced expiratory volume in 1 s (FEV1), carbon monoxide diffusion (DLCO), and carbon monoxide transfer coefficient (KCO)] and densitometric [15th percentile lung density (PD-15) and lung volume with density less than -950 Hounsfield Units (HU-950)] parameters were assessed at baseline and follow-up. Mixed-effects models evaluated disease progression, while correlation and regional analyses highlighted structural-functional relationships and spatial emphysema patterns. Results: Patients diagnosed <5 years previously exhibited faster PD-15 decline (-6.0 ± 1.4 HU/year) than those diagnosed ≥5 years previously (-5.1 ± 1.3 HU/year; p < 0.05). Current smokers showed the most pronounced deterioration in PD-15 (-7.1 ± 1.6 HU/year) and HU-950 (+0.8 ± 0.3% volume/year) versus never smokers (-4.6 ± 1.3 HU/year and +0.4 ± 0.2% volume/year; p < 0.05). Frequent and severe exacerbations, along with pulmonary-related hospitalizations, worsened structural decline, particularly in basal regions. Strong correlations between both PD-15 and HU-950 with FEV1, DLCO, and KCO were observed in advanced stages (≥5 years since diagnosis). Conclusions: This study underscores the pivotal role of densitometry in PiSZ AATD, highlighting its ability to detect early structural changes often missed by functional measures. These findings support integrating densitometry into clinical practice to guide personalized interventions and improve outcomes.

Is It Time Alpha-1 Antitrypsin Deficiency Had a Specific Patient Reported Outcome Measure? A Review

Alpha-1 antitrypsin deficiency (AATD) is a rare cause of chronic lung and liver disease without its own patient reported-outcome measure (PROM). PROMs for Chronic Obstructive Pulmonary Disease (COPD) are commonly used instead, but AATD differs from COPD in several ways. We reviewed whether the PROMs used in the AATD literature adequately assess quality-of-life in these patients. 11 studies used PROMs as their primary outcomes; 21 included them as secondary outcomes. The St George's Respiratory Questionnaire (SGRQ) was the most commonly used PROM, used by 7 of the 11 primary outcome studies. Others included the COPD Assessment Tool, SF-36, LCOPD, EQ-5D, and the Chronic Respiratory Diseases Questionnaire. Several studies assessed SGRQ as being associated with respiratory disease severity as measured by FEV1% predicted, exacerbation rate, oxygen use and exercise tolerance. However, no studies used PROMs which included assessment of liver-related symptoms, other extra-pulmonary manifestations of AATD, or concerns related to genetics or finances. These factors are likely to have an impact on quality of life in AATD. A specific AATD-PROM is therefore required to holistically address the quality of life effects of an AATD diagnosis.

Advancing the understanding and treatment of lung pathologies associated with alpha 1 antitrypsin deficiency

Alpha 1 antitrypsin deficiency (AATD) is a genetic disorder that alters the functionality and/or serum levels of alpha 1 antitrypsin (AAT). Dysfunctional forms of AAT, or low levels of serum AAT, predispose affected individuals to pulmonary complications. When AATD-associated lung disease develops, the most common pulmonary pathology is emphysema. The development of emphysema and decline in lung function varies by AATD genotype and is accelerated by risk factors, such as smoking. To improve the understanding and treatment of AATD, emerging knowledge and unresolved questions need to be discussed. Here we focus on developments in the areas of disease pathogenesis, biomarkers, and clinical endpoints for trials in AATD, as well as barriers to treatment. The clinical impact of AATD on lung function is highly variable and highlights the complexity of AATD pathogenesis, in which multiple underlying processes are involved. Reduced levels of functional AAT disrupt the protease-antiprotease homeostasis, leading to a loss of neutrophil elastase inhibition and the breakdown of elastin within the lung interstitium. Inflammatory processes also play a critical role in the development of AATD-associated lung disease, which is not yet fully understood. Biomarkers associated with the disease and its complications may have an important role in helping to address AATD underdiagnosis and evaluating response to treatment. To improve access to treatment, the problem of underdiagnosis needs to be addressed and the provision of therapeutic options needs to become uniform. Patients should also be empowered to play a key role in the self-management of the disease. Advancing our understanding of the disease will ultimately improve the life expectancy and quality of life for patients affected by AATD.

Antitrypsin deficiency: still more to learn about the lung after 60 years

The past 60 years have seen multiple publications related to lung disease in α1-antitrypsin deficiency largely reflecting the pathophysiology, biochemical effect and outcomes of augmentation therapy. However, the complexity of disease phenotype and the impact of the natural history presents problems of patient management, study design and hence interpretation of outcome. Although many national and some international registries exist, the lack of consistent in-depth assessment and importantly, the impact of augmentation therapy likely influences our perception of the true natural history. Development of new therapeutic strategies, and even assessment of the role and efficacy of augmentation, remain a challenge as powering such studies for conventional COPD outcomes is impractical due to relative rarity of the genetic condition and the presence of clinical phenotypic variation. The current review approaches these issues, discusses the nature and complexity of assessing patient variability, and provides guidance on further studies required to address them.

Disease burden associated with alpha-1 antitrypsin deficiency: systematic and structured literature reviews

Alpha-1 antitrypsin deficiency (AATD) is a rare genetic disorder characterised by reduced levels of circulating alpha-1 antitrypsin and an increased risk of lung and liver disease. Recent reviews of AATD have focused on diagnosis, epidemiology and clinical management; comprehensive reviews examining disease burden are lacking. Therefore, we conducted literature reviews to investigate the AATD disease burden for patients, caregivers and healthcare systems. Embase, PubMed and Cochrane libraries were searched for AATD publications from database inception to June 2021, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Most published AATD studies were small and short in duration, with variations in populations, designs, measures and outcomes, complicating cross-study comparisons. AATD was associated with significant pulmonary and hepatic morbidity. COPD, emphysema and bronchiectasis were common lung morbidities, where smoking was a key risk factor. Fibrosis and steatosis were the most common liver complications reported in patients with a PiZ allele. Health status analyses suggested a poorer quality of life for AATD patients diagnosed with COPD versus those with non-AATD-associated COPD. The burden for caregivers included loss of personal time due to caring responsibilities, stress and anxiety. AATD was also associated with high direct medical costs and healthcare resource utilisation.

Imaging in alpha-1 antitrypsin deficiency: a window into the disease

Imaging modalities such as plain chest radiograph and computed tomography (CT) are important tools in the assessment of patients with chronic obstructive pulmonary disease (COPD) of any etiology. These methods facilitate differential diagnoses and the assessment of individual lung pathologies, such as the presence of emphysema, bullae, or fibrosis. However, as emphysema is the core pathological consequence in the lungs of patients with alpha-1 antitrypsin deficiency (AATD), and because AATD is associated with the development of other lung pathologies such as bronchiectasis, there is a greater need for patients with AATD than those with non-AATD-related COPD to undergo more detailed assessment using CT. In the field of AATD, CT provides essential information regarding the presence, distribution, and morphology of emphysema. In addition, it offers the option to quantify the extent of emphysema. These data have implications for treatment decisions such as initiation of alpha-1 antitrypsin (AAT) therapy, or suitability for surgical or endoscopic interventions for reducing lung volume. Furthermore, CT has provided vital insight regarding the natural history of emphysema progression in AATD, and CT densitometry has underpinned research into the efficacy of AAT therapy. Moving forward, hyperpolarized xenon gas (129Xe) lung magnetic resonance imaging (MRI) is emerging as a promising complement to CT by adding comprehensive measures of regional lung function. It also avoids the main disadvantage of CT: the associated radiation. This chapter provides an overview of technological aspects of imaging in AATD, as well as its role in the management of patients and clinical research. In addition, perspectives on the future potential role of lung MRI in AATD are outlined.