Long-term results after lung volume reduction surgery in patients with α 1 -antitrypsin deficiency

Physical Activity, Exercise Capacity and Sedentary Behavior in People with Alpha-1 Antitrypsin Deficiency: A Scoping Review

Alpha-1 antitrypsin deficiency (AATD) is a hereditary disorder and a genetic risk factor for chronic obstructive pulmonary disease (COPD). Physical activity (PA) is important for the prevention and treatment of chronic disease. Little is known about PA in people with AATD. Therefore, we aimed to map the research undertaken to improve and/or measure PA, sedentary behaviour (SB) or exercise in people with AATD. Searches were conducted in CINAHL, Medline, EMBASE and clinical trial databases for studies published in 2021. Databases were searched for keywords (physical activity, AATD, exercise, sedentary behavior) as well as synonyms of these terms, which were connected using Boolean operators. The search yielded 360 records; 37 records were included for review. All included studies (n = 37) assessed exercise capacity; 22 studies reported the use of the six-minute walk test, the incremental shuttle walk test and cardiopulmonary exercise testing were reported in three studies each. Other objective measures of exercise capacity included a submaximal treadmill test, the Naughton protocol treadmill test, cycle ergometer maximal test, endurance shuttle walk test, constant cycle work rate test, a peak work rate test and the number of flights of stairs a participant was able to walk without stopping. A number of participant self-reported measures of exercise capacity were noted. Only one study aimed to analyze the effects of an intensive fitness intervention on daily PA. One further study reported on an exercise intervention and objectively measured PA at baseline. No studies measured SB. The assessment of PA and use of PA as an intervention in AATD is limited, and research into SB absent. Future research should measure PA and SB levels in people with AATD and explore interventions to enhance PA in this susceptible population.

Comparison of a Wearable Accelerometer/Gyroscopic, Portable Gait Analysis System (LEGSYS+TM) to the Laboratory Standard of Static Motion Capture Camera Analysis

Examination of gait patterns has been used to determine severity, intervention triage and prognostic measures for many health conditions. Methods that generate detailed gait data for clinical use are typically logistically constrained to a formal gait laboratory setting. This has led to an interest in portable analysis systems for near clinical or community-based assessments. The following study assessed with the wearable accelerometer/gyroscopic, gait analysis system (LEGSYS+^TM) and the standard of static motion capture camera (MOCAP) analysis during a treadmill walk at three different walking speeds in healthy participants (n = 15). To compare each speed, 20 strides were selected from the MOCAP data and compared with the LEGSYS+ strides at the same time point. Both scatter and bland-Altman plots with accompanying linear regression analysis for each of the parameters. Each stride parameter showed minimal or a consistent difference between the LEGSYS+ and MOCAP, with the phase parameters showing inconsistencies between the systems. Overall, LEGSYS+ stride parameters can be used in the clinical setting, with the utility of phase parameters needing to be taken with caution.

[Treatment of chronic obstructive pulmonary disease and emphysema]

We summarized the available data on therapeutic, surgical and endoscopic treatment of chronic obstructive pulmonary disease and emphysema that may be used like a bridge to lung transplantation. Treatment of chronic obstructive pulmonary disease and emphysema is expensive. Certain limitations in lung transplantation make to create new methods of treatment of severe emphysema. However, one should be ready for possible complications and carefully select patients for certain treatment to avoid false negative results. Reducing costs or developing cheaper treatments is important for the future and availability of care. The risks and complications associated with surgical treatment of emphysema can make endoscopic surgery preferable for these patients, and this undoubtedly requires further research.

Management of lung disease in alpha-1 antitrypsin deficiency: what we do and what we do not know

Management of lung disease in patients with alpha-1 antitrypsin deficiency (AATD) includes both non-pharmacological and pharmacological approaches. Lifestyle changes with avoidance of environmental pollutants, including tobacco smoke, improving exercise levels and nutritional status, all encompassed under a disease management program, are crucial pillars of AATD management. Non-pharmacological therapies follow conventional treatment guidelines for chronic obstructive pulmonary disease. Specific pharmacological treatment consists of administering exogenous alpha-1 antitrypsin (AAT) protein intravenously (augmentation therapy). This intervention raises AAT levels in serum and lung epithelial lining fluid, increases anti-elastase capacity, and decreases several inflammatory mediators in the lung. Radiologically, augmentation therapy reduces lung density loss over time, thus delaying disease progression. The effect of augmentation therapy on other lung-related outcomes, such as exacerbation frequency/length, quality of life, lung function decline, and mortality, are less clear and questions regarding dose optimization or route of administration are still debatable. This review discusses the rationale and available evidence for these interventions in AATD.

Alpha1-antitrypsin Disease, Treatment and Role for Lung Volume Reduction Surgery

Chronic obstructive pulmonary usually is subcategorized into 2 groups: chronic bronchitis and emphysema. The main cause of chronic bronchitis and emphysema is smoking; however, alpha1-antitrypsin also has been seen to cause emphysema in patients who are deficient. As symptoms and lung function decline, treatment modalities, such as lung volume reduction surgery, have been used in individuals with chronic obstructive pulmonary disease and upper lobe predominant emphysema. This article analyzes multiple published series where lung volume reduction surgery has been used in individuals with alpha1-antitrypsin deficiency and their overall outcomes.

Lower lobe lung volume reduction surgery: a case report

Lung volume reduction surgery (LVRS) is an option for select patients with advanced chronic obstructive pulmonary disease (COPD). Current guidelines recommend LVRS for patients with appropriate physiology and heterogeneous distribution of emphysema predominately involving upper lobes. We present an unusual case of a 72-year-old male with an advanced COPD who suffered with recurrent exacerbations despite optimal medical management. He underwent a two-stage bilateral lower lobe LVRS for heterogeneous lower lobe emphysema via video-assisted thoracoscopic (VATS) approach. This resulted in a significant subjective as well as objective improvement in his pulmonary functions, 6-min walk distance and subsequent discontinuation of supplemental oxygen.

Diagnosis and treatment of lung disease associated with alpha one-antitrypsin deficiency: A position statement from the Thoracic Society of Australia and New Zealand

AATD is a common inherited disorder associated with an increased risk of developing pulmonary emphysema and liver disease. Many people with AATD-associated pulmonary emphysema remain undiagnosed and therefore without access to care and counselling specific to the disease. AAT augmentation therapy is available and consists of i.v. infusions of exogenous AAT protein harvested from pooled blood products. Its clinical efficacy has been the subject of some debate and the use of AAT augmentation therapy was recently permitted by regulators in Australia and New Zealand, although treatment is not presently subsidized by the government in either country. The purpose of this position statement is to review the evidence for diagnosis and treatment of AATD-related lung disease with reference to the Australian and New Zealand population. The clinical efficacy and adverse events of AAT augmentation therapy were evaluated by a systematic review, and the GRADE process was employed to move from evidence to recommendation. Other sections address the wide range of issues to be considered in the care of the individual with AATD-related lung disease: when and how to test for AATD, changing diagnostic techniques, monitoring of progression, disease in heterozygous AATD and pharmacological and non-pharmacological therapy including surgical options for severe disease. Consideration is also given to broader issues in AATD that respiratory healthcare staff may encounter: genetic counselling, patient support groups, monitoring for liver disease and the need to establish national registries for people with AATD in Australia and New Zealand.

Treatment of lung disease in alpha-1 antitrypsin deficiency: a systematic review

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is a rare genetic condition predisposing individuals to chronic obstructive pulmonary disease (COPD). The treatment is generally extrapolated from COPD unrelated to AATD; however, most COPD trials exclude AATD patients; thus, this study sought to systematically review AATD-specific literature to assist evidence-based patient management.

METHODS

Standard review methodology was used with meta-analysis and narrative synthesis (PROSPERO-CRD42015019354). Eligible studies were those of any treatment used in severe AATD. Randomized controlled trials (RCTs) were the primary focus; however, case series and uncontrolled studies were eligible. All studies had ≥10 participants receiving treatment or usual care, with baseline and follow-up data (>3 months). Risk of bias was assessed appropriately according to study methodology.

RESULTS

In all, 7,296 studies were retrieved from searches; 52 trials with 5,632 participants met the inclusion criteria, of which 26 studies involved alpha-1 antitrypsin augmentation and 17 concerned surgical treatments (largely transplantation). Studies were grouped into four management themes: COPD medical, COPD surgical, AATD specific, and other treatments. Computed tomography (CT) density, forced expiratory volume in 1 s, diffusing capacity of the lungs for carbon monoxide, health status, and exacerbation rates were frequently used as outcomes. Meta-analyses were only possible for RCTs of intravenous augmentation, which slowed progression of emphysema measured by CT density change, 0.79 g/L/year versus placebo (P=0.002), and associated with a small increase in exacerbations 0.29/year (P=0.02). Mortality following lung transplant was comparable between AATD- and non-AATD-related COPD. Surgical reduction of lung volume demonstrated inferior outcomes compared with non-AATD-related emphysema.

CONCLUSION

Intravenous augmentation remains the only disease-specific therapy in AATD and there is evidence that this slows decline in emphysema determined by CT density. There is paucity of data around other treatments in AATD. Treatments for usual COPD may not be as efficacious in AATD, and further studies may be required for this disease group.

α1-Antitrypsin Deficiency

α1-Antitrypsin deficiency is an autosomal codominant condition that predisposes to emphysema and cirrhosis. The condition is common but grossly under-recognized. Identifying patients' α1-antitrypsin deficiency has important management implications (ie, smoking cessation, genetic and occupational counseling, and specific treatment with the infusion of pooled human plasma α1-antitrypsin). The weight of evidence suggests that augmentation therapy slows the progression of emphysema in individuals with severe α1-antitrypsin deficiency.

Comparing Clinical Outcomes in Upper versus Lower Lobe Endobronchial Valve Treatment in Severe Emphysema

BACKGROUND

Lung volume reduction surgery has been recommended for patients with upper lobe predominant emphysema and was associated with less favorable outcomes in patients with non-upper lobe predominant emphysema. The value of endobronchial valve (EBV) treatment in lower lobe predominant emphysema has not been studied.

OBJECTIVES

To confirm the equivalence of upper and lower lobe valve treatments in patients with heterogeneous emphysema.

METHODS

A retrospective analysis from the Endobronchial Valve for Emphysema Palliation Trial (VENT), where patients with heterogeneous emphysema received Zephyr® EBV (Pulmonx Corp., Redwood City, Calif., USA) or medical treatment, was performed. Patients with low interlobar collateral ventilation and accurate placement of valves in the target lobes were identified. Safety and efficacy were compared between patients who underwent upper versus lower lobe treatment.

RESULTS

Of the 331 patients, 60 had low interlobar collateral ventilation and successful lobar exclusion (45 patients with upper lobe treatment and 15 patients with lower lobe treatment). There was no difference in baseline characteristics between the groups except for a higher destruction score (70.3 vs. 60.7%; p = 0.0010) and a higher heterogeneity index (24 vs. 13%; p = 0.0005) for the upper lobe cohort. At 180 days, both groups had improved clinically. There were no significant differences in mean changes or responder rates of forced expiratory volume in 1 s (+23.8 vs. +22.9%), the St. Georges Respiratory Questionnaire (-6.50 vs. -7.53 points), the 6-min walk test (+24.1 vs. +44.0 m), target lobe volume reduction (-1,199 vs. -1,042 ml), or in the adverse event rate between both cohorts.

CONCLUSION

Patients with lower and upper lobe predominant emphysema benefit equally from EBV therapy when interlobar collateral ventilation is low and lobar exclusion is achieved. Patients with lower lobe disease did not have increased adverse events compared to patients with upper lobe emphysema.

A review of α1-antitrypsin deficiency

α(1)-Antitrypsin (AAT) deficiency is an underrecognized genetic condition that affects approximately 1 in 2,000 to 1 in 5,000 individuals and predisposes to liver disease and early-onset emphysema. AAT is mainly produced in the liver and functions to protect the lung against proteolytic damage (e.g., from neutrophil elastase). Among the approximately 120 variant alleles described to date, the Z allele is most commonly responsible for severe deficiency and disease. Z-type AAT molecules polymerize within the hepatocyte, precluding secretion into the blood and causing low serum AAT levels (∼ 3-7 μM with normal serum levels of 20-53 μM). A serum AAT level of 11 μM represents the protective threshold value below which the risk of emphysema is believed to increase. In addition to the usual treatments for emphysema, infusion of purified AAT from pooled human plasma-so-called "augmentation therapy"-represents a specific therapy for AAT deficiency and raises serum levels above the protective threshold. Although definitive evidence from randomized controlled trials of augmentation therapy is lacking and therapy is expensive, the available evidence suggests that this approach is safe and can slow the decline of lung function and emphysema progression. Promising novel therapies are under active investigation.

Successful treatment of ventilator dependent emphysema with Chartis treatment planning and endobronchial valves

INTRODUCTION

Emphysema is a leading cause of disability and death. Patients who require ventilator support as a result of respiratory failure have limited treatment options. We report a successful outcome for a ventilator dependent patient in whom endobronchial valves were inserted into lobes assessed as being without collateral ventilation.

PRESENTATION OF CASE

A 54 year old male patient had been ventilator dependent for two months due to respiratory insufficiency from emphysema. Prior to admission, FEV(1) was 0.89L (25% predicted) and RV was 4.5L (205% predicted). CT scan showed destruction of right lower and middle lobes and left lower lobe. Chartis assessment showed the absence of collateral ventilation. Zephyr endobronchial valves were placed in left and right lower lobes. Lung volume reduction bilaterally was confirmed on chest X-ray and CT scan the following day. On day three, ventilator support was discontinued and there was no requirement for supplementary oxygen. At 30 days post procedure, the RV reduced to 3.2L (142% predicted) and the FEV(1) increased to 1.32L (38% predicted).

DISCUSSION

Hyperinflation in emphysema compromises lung function. For this ventilator dependent patient, there were no other treatment options. Endoscopic lung volume reduction was successfully achieved by bilateral lower lobe placement of Zephyr endobronchial valves with a prior assessment using Chartis to determine the absence of collateral flow in the targeted lobes. The patient achieved an impressive 48% improvement in FEV(1) and a 29% reduction in RV.

CONCLUSION

Endoscopic lung volume reduction assisted by Chartis to plan treatment resulted in a clinical and a health-economic benefit.

Alpha-1 antitrypsin (AAT) deficiency - what are the treatment options?

Alpha-1 antitrypsin (AAT) deficiency is an under-recognized genetic condition that predisposes to liver disease and early-onset emphysema. Although AAT is mainly produced in the liver, its main function is to protect the lung against proteolytic damage from neutrophil elastase. The most common mutation responsible for severe AAT deficiency, the so-called Z variant, reduces serum levels by promoting polymerization of the molecule within the hepatocyte, thereby reducing secretion. Serum levels below the putative protective threshold level of 11 micromolar (mumol/L) increase the risk of emphysema. In addition to the usual treatments for emphysema, infusion of purified AAT from pooled human plasma represents a specific therapy for AAT deficiency and raises serum and epithelial lining fluid levels above the protective threshold. Substantial evidence supports the biochemical efficacy of this approach, particularly for the weekly infusion regimen. Definitive evidence of clinical efficacy is still needed, as the two available randomized controlled trials showed non-significant trends towards slowing rates of loss of lung density on lung computerized axial tomography. However, concordant results of prospective cohort studies suggest that augmentation therapy has efficacy in slowing the rate of decline of lung function in patients with moderate airflow obstruction and severe deficiency of AAT. Overall, augmentation therapy is well-tolerated and, despite its failure to satisfy criteria for cost-effectiveness, is recommended because it is the only currently available specific therapy for AAT deficiency.

α1-Antitrypsin deficiency, chronic obstructive pulmonary disease and the serpinopathies

α1-Antitrypsin is the prototypical member of the serine proteinase inhibitor or serpin superfamily of proteins. The family includes α1-antichymotrypsin, C1 inhibitor, antithrombin and neuroserpin, which are all linked by a common molecular structure and the same suicidal mechanism for inhibiting their target enzymes. Point mutations result in an aberrant conformational transition and the formation of polymers that are retained within the cell of synthesis. The intracellular accumulation of polymers of mutant α1-antitrypsin and neuroserpin results in a toxic gain-of-function phenotype associated with cirrhosis and dementia respectively. The lack of important inhibitors results in overactivity of proteolytic cascades and diseases such as COPD (chronic obstructive pulmonary disease) (α1-antitrypsin and α1-antichymotrypsin), thrombosis (antithrombin) and angio-oedema (C1 inhibitor). We have grouped these conditions that share the same underlying disease mechanism together as the serpinopathies. In the present review, the molecular and pathophysiological basis of α1-antitrypsin deficiency and other serpinopathies are considered, and we show how understanding this unusual mechanism of disease has resulted in the development of novel therapeutic strategies.

National Emphysema Treatment Trial state of the art: genetics of emphysema

Although a hereditary contribution to emphysema has been long suspected, severe alpha1-antitrypsin deficiency remains the only conclusively proven genetic risk factor for chronic obstructive pulmonary disease (COPD). Recently, genome-wide linkage analysis has led to the identification of two promising candidate genes for COPD: TGFB1 and SERPINE2. Like multiple other COPD candidate gene associations, even these positionally identified genes have not been universally replicated across all studies. Differences in phenotype definition may contribute to nonreplication in genetic studies of heterogeneous disorders such as COPD. The use of precisely measured phenotypes, including emphysema quantification on high-resolution chest computed tomography scans, has aided in the discovery of additional genes for clinically relevant COPD-related traits. The use of computed tomography scans to assess emphysema and airway disease as well as newer genetic technologies, including gene expression microarrays and genome-wide association studies, has great potential to detect novel genes affecting COPD susceptibility, severity, and response to treatment.

Bronchoscopic lung volume reduction in severe emphysema

Lung volume reduction surgery (LVRS) produces physiological, symptomatic, and survival benefits in selected patients with advanced emphysema. Because it is associated with significant morbidity, mortality, and cost, nonsurgical alternatives for achieving volume reduction have been developed. Three bronchoscopic lung volume reduction (BLVR) approaches have shown promise and reached later-stage clinical trials. These include the following: (1) placement of endobronchial one-way valves designed to promote atelectasis by blocking inspiratory flow; (2) formation of airway bypass tracts using a radiofrequency catheter designed to facilitate emptying of damaged lung regions with long expiratory times; and (3) instillation of biological adhesives designed to collapse and remodel hyperinflated lung. The limited clinical data currently available suggest that all three techniques are reasonably safe. However, efficacy signals have been substantially smaller and less durable than those observed after LVRS. Studies to optimize patient selection, refine treatment strategies, characterize procedural safety, elucidate mechanisms of action, and characterize short- and longer-term effectiveness of these approaches are ongoing. Results will be available over the next few years and will determine whether BLVR represents a safe and effective alternative to LVRS.

Autologous fibrin sealant reduces the incidence of prolonged air leak and duration of chest tube drainage after lung volume reduction surgery: a prospective randomized blinded study

OBJECTIVE

Prolonged air leak is reported in up to 50% of patients after lung volume reduction surgery. The effect of an autologous fibrin sealant on the intensity and duration of air leak and on the time to chest drain removal after lung volume reduction surgery was investigated in a randomized prospective clinical trial.

METHODS

Twenty-five patients underwent bilateral thoracoscopic lung volume reduction surgery. In each patient, an autologous fibrin sealant was applied along the staple lines on one side, whereas no additional measure was taken on the other side. Randomization of treatment was performed at the end of the resection on the first side. Air leak was assessed semiquantitatively by use of a severity score (0 = no leak; 4 = continuous severe leak) by two investigators blinded to the treatment.

RESULT

Mean value of the total severity scores for the first 48 hours postoperative was significantly lower in the treated group (4.7 +/- 7.7) than in the control group (16.0 +/- 10.1) (P < .001), independently of the length of the resection. Prolonged air leak and mean duration of drainage were also significantly reduced after application of the sealant (4.5% and 2.8 +/- 1.9 days versus 31.8% and 5.9 +/- 2.9 days) (P = .03 and P < .001).

CONCLUSIONS

Autologous fibrin sealant for reinforcement of the staple lines after lung volume reduction surgery significantly reduces prolonged air leak and duration of chest tube drainage.

Functional results of unilateral lung volume reduction surgery in alpha1-antitrypsin deficient patients

Lung volume reduction surgery (LVRS) has been shown to improve lung function and exercise tolerance in patients with severe emphysema. Some predictors of poor outcome have been described but the role of alpha₁-antitrypsin (α₁-AT) deficiency is still not well known. The aim of this study was to analyze the results of unilateral LVRS in our center according to the α₁-AT status. The results of LVRS in 17 deficient patients and 35 nondeficient patients were analyzed at 3–6 months and 1 year after surgery. Compared with baseline, a significant improvement of FEV₁, partial pressure in arterial blood (PaO₂), dyspnea score and walking distance was observed in the two groups at 3–6 months after surgery and the studied parameters remained significantly improved at 1 year in the nondeficient group. By contrast, PaO₂ and walking distance returned towards baseline in the deficient group at 1 year whereas improvement of FEV₁ and dyspnea score was persistent. Mean values of FEV₁ at baseline, 3–6 months, and 1 year were 22 ± 6%, 29 ± 11%, and 26 ± 9% and 28 ± 12%, 38 ± 17%, and 40 ± 17% predicted in the deficient group and in the non-deficient group, respectively. In conclusion, the functional benefit is short-lasting in α₁-AT deficient patients after unilateral LVRS.

Alpha-1-Antitrypsin Deficiency: Current Concepts

Since the condition was first described four decades ago, alpha-1-antitrypsin (A1AT) deficiency has served as a model for other disease processes. A1AT is the archetypal serpin designed to ensnare proteases, a process that involves significant conformational change within the molecule. Mutations in the A1AT gene lead to misfolding of the protein and accumulation within the endoplasmic reticulum of hepatocytes resulting in two different pathologic processes. First, the accumulation of mutant A1AT protein has a directly toxic effect on the liver, resulting in hepatitis and cirrhosis. Second, the resultant decrease in circulating A1AT results in protease-antiprotease imbalance at the lung surface and emphysema ensues. A1AT deficiency therefore can be seen as two distinct disease processes: a conformational disease of the liver and a protease-antiprotease imbalance of the lung. This two-stage model of disease in A1AT deficiency is elegant in its simplicity and goes a long way to explaining the clinical manifestations that occur in patients with the condition. However, some aspects of the disease are not readily explained. Recent findings suggest that there is more to the lung damage in A1AT deficiency than simple proteolytic insult and that the presence of the mutant protein itself is proinflammatory and may indeed cause chronic injury to the cells that produce it. This review discusses some of the emerging concepts in alpha-1-antitrypsin research and outlines the implications these new ideas may have for treatment of this condition.

Lessons from the National Emphysema Treatment Trial

Medicare coverage for lung volume reduction surgery has been approved recently by the Centers for Medicare and Medicaid Services for the treatment of severe emphysema. The scientific basis for this approval stems largely from findings of the National Emphysema Treatment Trial (NETT). The purpose of this article is to review the contributions of the NETT to the management of chronic obstructive pulmonary disease.

Advances in the management of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), the fourth leading cause of death, seems to be increasing in worldwide prevalence, and carries with it a significant health and economic burden. Smoking cessation is the only available intervention proven to halt disease progression. The authors discuss the role of the newly approved agent, varenicline, in promotion of smoking cessation. The remainder of presently available therapies treat the symptoms of COPD, but do not impact progression of disease. As the understanding of the pathogenesis of COPD improves, new targets for therapies are emerging. Given the large number of potential targets and the results of recent studies, it seems unlikely that a single new agent will result in a cure. Rather, management of COPD should involve a multi-pronged approach including smoking cessation, bronchodilators, treatment of infection, and eventual targeting of inflammatory pathways and genetic predispositions. In this article, the authors discuss presently available therapies as well as agents under development.

Lung volume reduction surgery in patients with emphysema and alpha-1 antitrypsin deficiency

BACKGROUND

The role of lung volume reduction surgery (LVRS) for individuals with alpha-1 antitrypsin (AAT) deficiency is unclear.

METHODS

To assess the role of LVRS in individuals with severe deficiency of AAT, outcomes within the National Emphysema Treatment Trial were analyzed.

RESULTS

Of 1218 randomized subjects, 16 (1.3%) had severe AAT deficiency (serum level < 80 mg/dL) and a consistent phenotype (when available). Characteristics of these 16 patients include 87.5% male; median serum AAT level, 55.5 mg/dL; age, 66 years; forced expiratory volume in 1 second (FEV1), 27% predicted; and 50% had upper-lobe-predominant emphysema. All 10 subjects randomized to LVRS underwent the procedure. Although the small number of subjects hampered statistical analysis, 2-year mortality was higher with surgery (20% versus 0%) than with medical treatment. Comparison of outcomes between the 10 AAT-deficient and the 554 AAT-replete subjects undergoing LVRS showed a greater increase in exercise capacity at 6 months in replete subjects and a trend toward lower and shorter duration FEV1 rise in deficient individuals.

CONCLUSIONS

This study extends to 49 cases the published experience of LVRS in severe AAT deficiency. Although the small number of subjects precludes firm conclusions, trends of lower magnitude and duration of FEV1 rise after surgery in AAT-deficient versus AAT-replete subjects and higher mortality in deficient individuals randomized to surgery versus medical treatment suggest caution in recommending LVRS in AAT deficiency.

Alpha1-antitrypsin deficiency

Alpha1-antitrypsin deficiency is a genetic disorder that affects about one in 2000-5000 individuals. It is clinically characterised by liver disease and early-onset emphysema. Although alpha1 antitrypsin is mainly produced in the liver, its main function is to protect the lung against proteolytic damage from neutrophil elastase. The most frequent mutation that causes severe alpha1-antitrypsin deficiency arises in the SERPINA 1 gene and gives rise to the Z allele. This mutation reduces concentrations in serum of alpha1 antitrypsin by retaining polymerised molecules within hepatocytes: an amount below the serum protective threshold of 11 micromol/L increases risk for emphysema. In addition to the usual treatments for emphysema, infusion of purified alpha1 antitrypsin from pooled human plasma represents a specific treatment and raises the concentrations in serum and epithelial-lining fluid above the protective threshold. Evidence suggests that this approach is safe, slows the decline of lung function, could reduce infection rates, and might enhance survival. However, uncertainty about the cost-effectiveness of this expensive treatment remains.