Novel Machine Learning Identifies Five Asthma Phenotypes Using Cluster Analysis of Real-World Data

BACKGROUND

Asthma classification into different sub-phenotypes is important to guide personalized therapy and improve outcomes.

OBJECTIVES

This study sought to further explore asthma heterogeneity through determination of multiple patient groups by using novel machine learning (ML) approaches and large-scale real-world data.

METHODS

We used electronic health records of patients with asthma followed at the Cleveland Clinic between 2010 and 2021. We employed k-prototype unsupervised ML to develop a clustering model where predictors were age, gender, race, body mass index (BMI), pre- and post-bronchodilator (BD) spirometry measurements, and the usage of inhaled/systemic steroids. We applied elbow and silhouette plots to select the optimal number of clusters. These clusters were then evaluated through LightGBM's supervised ML approach on their cross validated F1 score to support their distinctiveness.

RESULTS

Data from 13,498 patients with asthma with available post-BD spirometry measurements were extracted to identify 5 stable clusters. Cluster 1 included a young non-severe asthma population with normal lung function and higher frequency of acute exacerbation (0.8 /patient-year). Cluster 2 had the highest BMI (mean (SD): 44.44 (7.83) kg/m2), and the highest proportion of female (77.5%) and African Americans (28.9%). Cluster 3 comprised patients with normal lung function. Cluster 4 included patients with lower FEV1% of 77.03 (12.79) and poor response to bronchodilators. Cluster 5 had the lowest FEV1% of 68.08 (15.02), the highest post-BD reversibility, and the highest proportion of severe asthma (44.9%) and blood eosinophilia (>300 cells/μL) (34.8%).

CONCLUSION

Using real-world data and unsupervised ML, we classified asthma into 5 clinically important sub-phenotypes where group-specific asthma treatment and management strategies can be designed and deployed.

Mitochondrial DNA Copy Number Variation in Asthma Risk, Severity, and Exacerbations

Rationale

Although airway oxidative stress and inflammation are central to asthma pathogenesis, there is limited knowledge of the relationship of asthma risk, severity, or exacerbations to mitochondrial dysfunction, which is pivotal to oxidant generation and inflammation.

Objectives

We investigated whether mitochondrial DNA copy number (mtDNA-CN) as a measure of mitochondrial function is associated with asthma diagnosis, severity, oxidative stress, and exacerbations.

Methods

We measured mtDNA-CN in blood in two cohorts. In the UK Biobank (UKB), we compared mtDNA-CN in mild and moderate-severe asthmatics to non-asthmatics. In the Severe Asthma Research Program (SARP), we evaluated mtDNA-CN in relation to asthma severity, biomarkers of oxidative stress and inflammation, and exacerbations.

Measures and Main Results

In UK Biobank, asthmatics (n = 29,768) have lower mtDNA-CN compared to non-asthmatics (n = 239,158) (beta, -0.026 [95% CI, -0.038 to -0.014], P = 2.46×10-5). While lower mtDNA-CN is associated with asthma, mtDNA-CN did not differ by asthma severity in either UKB or SARP. Biomarkers of inflammation show that asthmatics have higher white blood cells (WBC), neutrophils, eosinophils, fraction exhaled nitric oxide (FENO), and lower superoxide dismutase (SOD) than non-asthmatics, confirming greater oxidative stress in asthma. In one year follow-up in SARP, higher mtDNA-CN is associated with reduced risk of three or more exacerbations in the subsequent year (OR 0.352 [95% CI, 0.164 to 0.753], P = 0.007).

Conclusions

Asthma is characterized by mitochondrial dysfunction. Higher mtDNA-CN identifies an exacerbation-resistant asthma phenotype, suggesting mitochondrial function is important in exacerbation risk.

Defining and Promoting Pediatric Pulmonary Health: Developing Biomarkers for Pulmonary Health

Children with inherited and/or acquired respiratory disorders often arrive in adolescence and adulthood with diminished lung function that might have been detected and prevented had better mechanisms been available to identify and to assess progression of disease. Fortunately, advances in genetic assessments, low-cost diagnostics, and minimally- invasive novel biomarkers are being developed to detect and to treat respiratory diseases before they give rise to loss of life or lung function. This paper summarizes the Developing Biomarkers for Pulmonary Health sessions of the National Heart, Lung, and Blood Institute- sponsored 2021 Defining and Promoting Pediatric Pulmonary Health workshop. These sessions discussed genetic testing, pulse oximetry, exhaled nitric oxide, and novel biomarkers related to childhood lung diseases.

Impact of Bronchiectasis on COPD Severity and Alpha-1 Antitrypsin Deficiency as a Risk Factor in Individuals with a Heavy Smoking History

Rationale

Bronchiectasis is common among those with heavy smoking histories, but risk factors for bronchiectasis, including alpha-1 antitrypsin deficiency, and its implications for COPD severity are uncharacterized in such individuals.

Objectives

To characterize the impact of bronchiectasis on COPD and explore alpha-1antitrypsin as a risk factor for bronchiectasis.

Methods

SubPopulations and InteRmediate Outcome Measures In COPD Study (SPIROMICS) participants (N=914; ages 40-80 years; ≥20-pack-year smoking) had high-resolution computed tomography (CT) scans interpreted visually for bronchiectasis, based on airway dilation without fibrosis or cicatrization. We performed regression-based models of bronchiectasis with clinical outcomes and quantitative CT measures. We deeply sequenced the gene encoding -alpha-1 antitrypsin, SERPINA1, in 835 participants to test for rare variants, focusing on the PiZ genotype (Glu366Lys, rs28929474).

Measurements and Main Results

We identified bronchiectasis in 365 (40%) participants, more frequently in women (45% versus 36%, p=0.0045), older participants (mean age=66[standard deviation (SD)=8.3] versus 64[SD=9.1] years, p=0.0083), and those with lower lung function (forced expiratory volume in 1 second [FEV1 ] percentage predicted=66%[SD=27] versus 77%[SD=25], p<0.0001; FEV1 to forced vital capacity [FVC] ratio=0.54[0.17] versus 0.63[SD=0.16], p<0.0001). Participants with bronchiectasis had greater emphysema (%voxels ≤-950 Hounsfield units, 11%[SD=12] versus 6.3%[SD=9], p<0.0001) and parametric response mapping functional small airways disease (26[SD=15] versus 19[SD=15], p<0.0001). Bronchiectasis was more frequent in the combined PiZZ and PiMZ genotype groups compared to those without PiZ, PiS, or other rare pathogenic variants (N=21 of 40 [52%] versus N=283 of 707[40%], odds ratio [OR]=1.97; 95% confidence interval [CI]=1.002, 3.90, p=0.049), an association attributed to White individuals (OR=1.98; 95%CI = 0.9956, 3.9; p=0.051).

Conclusions

Bronchiectasis was common in those with heavy smoking histories and was associated with detrimental clinical and radiographic outcomes. Our findings support alpha-1antitrypsin guideline recommendations to screen for alpha-1 antitrypsin deficiency in an appropriate bronchiectasis subgroup with a significant smoking history.

Impact of Bronchiectasis on COPD Severity and Alpha-1 Antitrypsin Deficiency as a Risk Factor in Individuals with a Heavy Smoking History

Rationale

Bronchiectasis is common among those with heavy smoking histories, but risk factors for bronchiectasis, including α1-antitrypsin deficiency and its implications for COPD severity are uncharacterized in such individuals.

Objectives

To characterize the impact of bronchiectasis on COPD and explore α1-antitrypsin as a risk factor for bronchiectasis.

Methods

SPIROMICS participants (N=914; ages 40-80 years; ≥20 pack-years smoking) had HRCT scans interpreted visually for bronchiectasis, based on airway dilation without fibrosis or cicatrization. We performed regression-based models of bronchiectasis with clinical outcomes and quantitative CT measures. We deeply sequenced the gene encoding α1-antritrypsin, SERPINA1, in 835 participants to test for rare variants, focusing on PiZ (Glu³⁶⁶Lys, rs28929474).

Measurements and Main Results

We identified bronchiectasis in 365 (40%), more frequently in women (45% versus 36%, p=0.0045), older participants (mean age=66[SD=8.3] versus 64[SD=9.1] years, p=0.0083), and those with lower lung function (FEV₁%predicted=66%[SD=27] versus 77%[SD=25], p<0.0001; FEV₁/FVC=0.54[0.17] versus 0.63[SD=0.16], p<0.0001]. Participants with bronchiectasis had greater emphysema (%voxels ≤-950HFU, 11%[SD=12] versus 6.3%[SD=9], p<0.0001) and PRM^fSAD (26[SD=15] versus 19[SD=15], p<0.0001). Bronchiectasis was more frequent in the combined PiZZ and PiMZ genotype groups compared to those without PiZ, PiS, or other rare pathogenic variants (N=21 of 40[52%] versus N=283 of 707[40%], OR=1.97; 95%CI=1.002, 3.90, p=0.049), an association attributed to whites (OR=1.98; 95%CI = 0.9956, 3.9; p=0.051).

Conclusions

Bronchiectasis was common in those with heavy smoking histories and was associated with detrimental clinical and radiographic outcomes. Our findings support α1-antitrypsin guideline recommendations to screen for α1-antitrypsin deficiency in an appropriate bronchiectasis subgroup with a significant smoking history.

Epidemiology of Asthma: Prevalence and Burden of Disease

Asthma, a common airway disease, results in a significant burden to both patients and society worldwide. Yet, despite global political commitment backed by the United Nations, progress to reduce the burden of asthma remains inadequate. This is particularly true in low-income countries. To date, progress has been delayed by the lack of uniform data collection, imperfect surveillance methods, inadequate resources, poor access to effective therapies, substandard asthma education, ineffective governmental policies, rapid urbanization, progressive increase in asthma prevalence, increased life expectancy and obesity rates worldwide, asthma heterogeneity and disease complexity, smoking, and environmental exposures to allergens and pollution. A thorough understanding of the challenges facing the international community is essential to define future strategies to improve the burden of asthma.

The Impact of Insulin Resistance on Loss of Lung Function and Response to Treatment in Asthma

Rationale: The role of obesity-associated insulin resistance (IR) in airflow limitation in asthma is uncertain. Objectives: Using data in the Severe Asthma Research Program 3 (SARP-3), we evaluated relationships between homeostatic measure of IR (HOMA-IR), lung function (cross-sectional and longitudinal analyses), and treatment responses to bronchodilators and corticosteroids. Methods: HOMA-IR values were categorized as without (<3.0), moderate (3.0-5.0), or severe (>5.0). Lung function included FEV1 and FVC measured before and after treatment with inhaled albuterol and intramuscular triamcinolone acetonide and yearly for 5 years. Measurements and Main Results: Among 307 participants in SARP-3, 170 (55%) were obese and 140 (46%) had IR. Compared with patients without IR, those with IR had significantly lower values for FEV1 and FVC, and these lower values were not attributable to obesity effects. Compared with patients without IR, those with IR had lower FEV1 responses to β-adrenergic agonists and systemic corticosteroids. The annualized decline in FEV1 was significantly greater in patients with moderate IR (-41 ml/year) and severe IR (-32 ml/year,) than in patients without IR (-13 ml/year, P < 0.001 for both comparisons). Conclusions: IR is common in asthma and is associated with lower lung function, accelerated loss of lung function, and suboptimal lung function responses to bronchodilator and corticosteroid treatments. Clinical trials in patients with asthma and IR are needed to determine if improving IR might also improve lung function.

Urinary total conjugated 3-bromotyrosine, asthma severity, and exacerbation risk

Asthma is an inflammatory disease of the airways characterized by eosinophil recruitment, eosinophil peroxidase release, and protein oxidation through bromination, which following tissue remodeling results in excretion of 3-bromotyrosine. Predicting exacerbations and reducing their frequency is critical for the treatment of severe asthma. In this study, we aimed to investigate whether urinary total conjugated bromotyrosine can discriminate asthma severity and predict asthma exacerbations. We collected urine from participants with severe (n = 253) and nonsevere (n = 178) asthma, and the number of adjudicated exacerbations in 1-yr longitudinal follow-up was determined among subjects enrolled in the Severe Asthma Research Program, a large-scale National Institutes of Health (NIH)-funded consortium. Urine glucuronidated bromotyrosine and total conjugated forms were quantified by hydrolysis with either glucuronidase or methanesulfonic acid, respectively, followed by liquid chromatography-tandem mass spectrometry analyses of free 3-bromotyrosine. Blood and sputum eosinophils were also counted. The majority of 3-bromotyrosine in urine was found to exist in conjugated forms, with glucuronidated bromotyrosine representing approximately a third, and free bromotyrosine less than 1% of total conjugated bromotyrosine. Total conjugated bromotyrosine was poorly correlated with blood (r2 = 0.038) or sputum eosinophils (r2 = 0.0069). Compared with participants with nonsevere asthma, participants with severe asthma had significantly higher urinary total conjugated bromotyrosine levels. Urinary total conjugated bromotyrosine was independently associated with asthma severity, correlated with the number of asthma exacerbations, and served as a predictor of asthma exacerbation risk over 1-yr of follow-up.

Diabetes associated with higher health care utilization and poor outcomes after COPD-related hospitalizations

OBJECTIVES

Readmissions after hospitalizations for acute exacerbation of chronic obstructive pulmonary disease (COPD) have a high socioeconomic burden. Comorbidities such as diabetes increase the risk for hospital readmissions, but the impact of diabetes on hospital outcomes remains unknown. The aim of this study was to evaluate the effect of complicated or uncomplicated diabetes on outcomes and health care costs related to admissions and readmissions in patients 35 years and older with an index admission for COPD.

STUDY DESIGN

This was a retrospective longitudinal data analysis. We analyzed data from the Healthcare Cost and Utilization Project (HCUP) Nationwide Readmissions Database.

METHODS

We analyzed the 2012-2015 HCUP Nationwide Readmissions Database and used multivariable weighted regression analyses to adjust for confounding factors. Individuals with any chronic pulmonary disease other than COPD were excluded.

RESULTS

Of 1,728,931 patients hospitalized for COPD, 522,020 (30.2%) had a diagnosis of diabetes. Risk of all-cause 30-day readmission was higher among patients with complicated diabetes (adjusted odds ratio [OR], 1.15; 95% CI, 1.11-1.18) and uncomplicated diabetes (adjusted OR, 1.10; 95% CI, 1.08-1.12) compared with patients without diabetes. Diabetes was associated with longer length of stay, higher rates of hospital complications during index hospitalizations and 30-day readmissions, and a higher health care cost. Although diabetes was not associated with higher hospital mortality, routine hospital discharges were less common and the need for home health care upon discharge was higher among those with diabetes.

CONCLUSIONS

Patients hospitalized for COPD and coexisting diabetes have worse clinical outcomes and higher 30-day readmissions compared with patients hospitalized for COPD without diabetes. Optimizing medical therapies and targeted interventions for both diseases is needed to alleviate disease burden to individuals and to society.

Eosinophilia Is Associated with Improved COVID-19 Outcomes in Inhaled Corticosteroid-Treated Patients

BACKGROUND

In addition to their proinflammatory effect, eosinophils have antiviral properties. Similarly, inhaled corticosteroids (ICS) were found to suppress coronavirus replication in vitro and were associated with improved outcomes in coronavirus disease 2019 (COVID-19). However, the interplay between the two and its effect on COVID-19 needs further evaluation.

OBJECTIVE

To determine the associations among preexisting blood absolute eosinophil counts, ICS, and COVID-19-related outcomes.

METHODS

We analyzed data from the Cleveland Clinic COVID-19 Research Registry (April 1, 2020 to March 31, 2021). Of the 82,096 individuals who tested positive, 46,397 had blood differential cell counts obtained before severe acute respiratory syndrome coronavirus 2 testing dates. Our end points included the need for hospitalization, admission to the intensive care unit (ICU), and in-hospital mortality. The effect of eosinophilia on outcomes was estimated after propensity weighting and adjustment.

RESULTS

Of the 46,397 patients included in the final analyses, 19,506 had preexisting eosinophilia (>0.15 × 103 cells/μL), 5,011 received ICS, 9,096 (19.6%) were hospitalized, 2,129 required ICU admission (4.6%) and 1,402 died during index hospitalization (3.0%). Adjusted analysis associated eosinophilia with lower odds for hospitalization (odds ratio [OR] [95% confidence interval (CI)]: 0.86 [0.79-0.93]), ICU admission (OR [95% CI]: 0.79 [0.69-0.90]), and mortality (OR [95% CI]: 0.80 [0.68-0.95]) among ICS-treated patients but not untreated ones. The correlation between absolute eosinophil count and the estimated probability of hospitalization, ICU admission, and death was nonlinear (U-shaped) among patients not treated with ICS, and negative in treated patients.

CONCLUSIONS

The association between eosinophilia and improved COVID-19 outcomes depends on ICS. Future randomized controlled trials are needed to determine the role of ICS and its interaction with eosinophilia in COVID-19 therapy.

Intranasal Corticosteroids Are Associated with Better Outcomes in Coronavirus Disease 2019

BACKGROUND

Sites of entry for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are highly expressed in nasal epithelial cells; however, little is known about the impact of intranasal corticosteroids (INCS) on coronavirus disease 2019 (COVID-19)-related outcomes.

OBJECTIVE

To determine the association between baseline INCS use and COVID-19-related outcomes.

METHODS

Using the Cleveland Clinic COVID-19 Research Registry, we performed a propensity score matching for treatment with INCS before SARS-CoV-2 infection (April 1, 2020, to March 31, 2021). Of the 82,096 individuals who tested positive, 72,147 met inclusion criteria. Our endpoints included the need for hospitalization, admission to the intensive care unit (ICU), or in-hospital mortality.

RESULTS

Of the 12,608 (17.5%) who were hospitalized, 2935 (4.1%) required ICU admission and 1880 (2.6%) died during hospitalization. A significant proportion (n = 10,187; 14.1%) were using INCS before SARS-CoV-2 infection. Compared with nonusers, INCS users demonstrated lower risk for hospitalization (adjusted odds ratio [OR] [95% confidence interval (CI)]: 0.78 [0.72; 0.85]), ICU admission (adjusted OR [95% CI]: 0.77 [0.65; 0.92]), and in-hospital mortality (adjusted OR [95% CI]: 0.76 [0.61; 0.94]). These findings were replicated in sensitivity analyses where patients on inhaled corticosteroids and those with allergic rhinitis were excluded. The beneficial effect of INCS was significant after adjustment for baseline blood eosinophil count (measured before SARS-CoV-2 testing) in a subset of 30,289 individuals.

CONCLUSION

INCS therapy is associated with a lower risk for COVID-19-related hospitalization, ICU admission, or death. Future randomized control trials are needed to determine if INCS reduces the risk for severe outcomes related to COVID-19.

Dietary patterns in patients with asthma and their relationship with asthma-related emergency room visits: NHANES 2005-2016

RATIONALE

Extensive interdependencies exist between dietary intake, metabolic dysregulation, and asthma; however, the dietary pattern in adults with asthma remains unknown.

OBJECTIVES

To evaluate the association between dietary patterns and asthma ER visits and explore the effect of the interaction between race and diet on asthma.

METHODS

Using NHANES data, we compared dietary patterns between adults with asthma with and without asthma-related emergency room (ER) visits in the previous year, and between subjects of different races. The 2015 Healthy Eating Index (HEI-2015) was used to assess alignment between dietary patterns and the 2015-2020 Dietary Guideline for Americans.

RESULTS

Among 1681 individuals included in the study, 193 reported asthma-related ER visit. Patients with asthma had low fruit and vegetable intake, and a low mean (SE) HEI-2015 score [52.6 (0.53)]. Individuals with asthma-related ER visits had lower vegetable consumption compared to those without (median 0.61 vs. 0.85 cup equivalents). Furthermore, non-Hispanic Blacks (NHB) reported lower amount of vegetable (median cup equivalent 0.58 vs. 0.89) and fruit intake (0.17 vs. 0.39) and had a lower HEI-2015 score (49.9 vs. 52.9) comparing to non-Hispanic Whites. No association was discovered between dietary patterns and ER visits in multivariable analysis, or significant interactions between diet and race in predicting the need for ER visits.

CONCLUSIONS

Dietary patterns in adult with current asthma are frequently misaligned with current dietary guidelines. Patients with asthma-related ER visits and of NHB race had lower vegetable consumption; however, the associations disappeared in multivariable analysis. The impact of diet on asthma is not straightforward and deserves further investigation.

Supplemental data for this article is available online at at www.tandfonline.com/ijas.

Benefits of Airway Androgen Receptor Expression in Human Asthma

Rationale: Androgens are potentially beneficial in asthma, but AR (androgen receptor) has not been studied in human airways.Objectives: To measure whether AR and its ligands are associated with human asthma outcomes.Methods: We compared the effects of AR expression on lung function, symptom scores, and fractional exhaled nitric oxide (Fe_NO) in adults enrolled in SARP (Severe Asthma Research Program). The impact of sex and of androgens on asthma outcomes was also evaluated in the SARP with validation studies in the Cleveland Clinic Health System and the NHANES (U.S. National Health and Nutrition Examination Survey).Measurements and Main Results: In SARP (n = 128), AR gene expression from bronchoscopic epithelial brushings was positively associated with both FEV₁/FVC ratio (R² = 0.135, P = 0.0002) and the total Asthma Quality of Life Questionnaire score (R² = 0.056, P = 0.016) and was negatively associated with Fe_NO (R² = 0.178, P = 9.8 × 10^-6) and NOS2 (nitric oxide synthase gene) expression (R² = 0.281, P = 1.2 × 10^-10). In SARP (n = 1,659), the Cleveland Clinic Health System (n = 32,527), and the NHANES (n = 2,629), women had more asthma exacerbations and emergency department visits than men. The levels of the AR ligand precursor dehydroepiandrosterone sulfate correlated positively with the FEV₁ in both women and men.Conclusions: Higher bronchial AR expression and higher androgen levels are associated with better lung function, fewer symptoms, and a lower Fe_NO in human asthma. The role of androgens should be considered in asthma management.

Alcohol use disorder and healthcare utilization in patients with chronic asthma and obstructive lung disease

Alcohol use disorder (AUD) is associated with significant direct morbidity and mortality. The impact of alcohol on chronic asthma and obstructive lung disease is unknown. AUD treatment may represent a potential target to improve healthcare utilization and healthcare costs in this patient population. Utilizing data from the 2012-2015 Nationwide Readmissions Database (NRD) and Nationwide Emergency Department Sample (NEDS), patients with a primary admission diagnosis of asthma or COPD were identified. Documented substance misuse, rates of hospitalization, frequency of hospital readmission, markers of admission severity, and cost were assessed. Within the NEDS cohort, 2,048,380 patients with a diagnosis of COPD or asthma were identified. Patients with documented AUD were more likely to present with respiratory failure [OR 1.32 (1.26, 1.39); p < 0.001] and more likely to require mechanical ventilation in the emergency room [OR 1.30 (1.19, 1.42); p < 0.001]. Within the NRD cohort, 1,096,663 hospital admissions were identified, of which 4.1% had documented AUD. AUD was associated with an increased length of stay [percentage increase estimate: 5% (4,6); p < 0.001], increased hospitalization cost, and an increased likelihood of 30-day readmission in patients with a primary admission diagnosis of COPD or asthma [OR 1.24 (1.2, 1.28); p < 0.001]. AUD is associated with increased disease morbidity and healthcare utilization in patients admitted with asthma or COPD. This impact persists after adjusting for substance misuse and associated comorbidities. Identifying and treating AUD in this patient population may improve disease, patient, and health-system outcomes.

Diabetes Mellitus Is Associated with Worse Outcome in Patients Hospitalized for Asthma

BACKGROUND

Asthma is a prevalent disease with a high economic cost. More than 50% of its direct cost relates to asthma hospitalizations. Diabetes mellitus (DM) is a significant comorbidity in asthmatic patients, yet its impact on asthma-related hospitalizations is unknown.

OBJECTIVE

To compare the outcome of asthma-related hospitalizations in patients with and without DM.

METHODS

Using Healthcare Cost and Utilization Project Nationwide Readmissions Database, we analyzed data of all adults with index admission for asthma and with no other chronic pulmonary conditions, and compared outcomes between patients with and without DM. Weighted regression analysis was used to determine the impact of DM on hospitalization outcomes. All multivariate regression models were adjusted for patient demographics, socioeconomic status, and chronic medical comorbidities.

RESULTS

A total of 717,200 asthmatic patients were included, with 202,489 (28.3%) having DM. Diabetic patients were older and had more comorbidities. When hospitalized for asthma, diabetic patients had increased hospital length of stay, cost, and risk for 30-day all-cause and asthma-related readmission. They also had a higher risk for developing nonrespiratory complications during their hospital stay compared with nondiabetic patients. The risk of mortality was similar between the 2 groups.

CONCLUSIONS

Patients hospitalized for asthma with coexisting DM had increased hospital length of stay, cost, and risk for readmission. Interventions are urgently needed to reduce the risk for hospital admission and readmission in patients with coexisting DM and asthma. These interventions would have profound economic and societal impact.

Muscle loss contributes to higher morbidity and mortality in COPD: An analysis of national trends

BACKGROUND AND OBJECTIVE

COPD is the third most common cause of death worldwide and fourth most common in the United States. In hospitalized patients with COPD, mortality, morbidity and healthcare resource utilization are high. Skeletal muscle loss is frequent in patients with COPD. However, the impact of muscle loss on adverse outcomes has not been systematically evaluated. We tested the hypothesis that patients hospitalized for COPD exacerbation with, compared to those without, a secondary diagnosis of muscle loss phenotype (all ICD-9 codes associated with muscle loss including cachexia) will have higher mortality and cost of care.

METHODS

The NIS database of hospitalized patients in 2011 (1 January-31 December) in the United States was used. The impact of a muscle loss phenotype on in-hospital mortality, LOS and cost of care for each of the 174 808 hospitalizations for COPD exacerbations was analysed.

RESULTS

Of the subjects admitted for a COPD exacerbation, 12 977 (7.4%) had a secondary diagnosis of muscle loss phenotype. A diagnosis of muscle loss phenotype was associated with significantly higher in-hospital mortality (14.6% vs 5.7%, P < 0.001), LOS (13.3 + 17.1 vs 5.7 + 7.6, P < 0.001) and median hospital charge per patient ($13 947 vs $6610, P < 0.001). Multivariate regression analysis showed that muscle loss phenotype increased mortality by 111% (95% CI: 2.0-2.2, P < 0.001), LOS by 68.4% (P < 0.001) and the direct cost of care by 83.7% (P < 0.001) compared to those without muscle loss.

CONCLUSION

In-hospital mortality, LOS and healthcare costs are higher in patients with COPD exacerbations and a muscle loss phenotype.

Asthma over the Adult Life Course: Gender and Hormonal Influences

Asthma is a common disorder that affects genders differently across the life span. Earlier in life, it is more common in boys. At puberty, asthma becomes more common and often more severe in girls and women. The effect of sex hormones on asthma incidence and its severity is difficult to differentiate from other asthma severity risk factors, such as racial background, socioeconomic factors, obesity, atopy, environmental exposure, and, in particular, lung aging. Recognizing gender-associated and age-associated differences is important to understanding the pathobiology of asthma and to providing effective education and personalized care for patients with asthma across the life course.

Impact of Age and Sex on Outcomes and Hospital Cost of Acute Asthma in the United States, 2011-2012

Background

Worldwide, asthma is a leading cause of morbidity, mortality and economic burden, with significant gender and racial disparities. However, little attention has been given to the independent role of age on lifetime asthma severity and hospitalization. We aimed to assess the effect of age, gender, race and ethnicity on indicators of asthma severity including asthma related hospitalization, mortality, hospital cost, and the rate of respiratory failure.

Methods

We analyzed the 2011 and 2012 Healthcare Cost and Utilization Project- National Inpatient Sample (NIS). We validated and extended those results using the National Heart, Lung, and Blood Institute-Severe Asthma Research Program (SARP; 2002–2011) database. Severe asthma was prospectively defined using the stringent American Thoracic Society (ATS) definition.

Results

Hospitalization for asthma was reported in 372,685 encounters in 2012 and 368,528 in 2011. The yearly aggregate cost exceeded $2 billion. There were distinct bimodal distributions for hospitalization age, with an initial peak at 5 years and a second at 50 years. Likewise, this bimodal age distribution of patients with severe asthma was identified using SARP. Males comprised the majority of individuals in the first peak, but women in the second. Aggregate hospital cost mirrored the bimodal peak distribution. The probability of respiratory failure increased with age until the age of 60, after which it continued to increase in men, but not in women.

Conclusions

Severe asthma is primarily a disease of young boys and middle age women. Greater understanding of the biology of lung aging and influence of sex hormones will allow us to plan for targeted interventions during these times in order to reduce the personal and societal burdens of asthma.

Cost effectiveness of bronchial thermoplasty in patients with severe uncontrolled asthma

RATIONALE

Based on its clinical effectiveness, bronchial thermoplasty (BT) was approved by the Food and Drug Administration in 2010 for the treatment of severe persistent asthma in patients 18 years and older whose asthma is not well-controlled with inhaled corticosteroids and long-acting beta-agonist medicines.

OBJECTIVE

Assess the 10 year cost-effectiveness of BT for individuals with severe uncontrolled asthma.

METHODS

Using a Markov decision analytic model, the cost-effectiveness of BT was estimated. The patient population involved a hypothetical cohort of 41-year-old patients comparing BT to usual care over a 10-year time frame. The main outcome measure was cost in 2013 dollars per additional quality adjusted life year (QALY).

RESULTS

Treatment with BT resulted in 6.40 QALYs and $7512 in cost compared to 6.21 QALYs and $2054 for usual care. The incremental cost-effectiveness ratio for BT at 10 years was $29,821/QALY. At a willingness to pay per QALY of $50,000, BT continues to be cost effective unless the probability of severe asthma exacerbation drops below 0.63 exacerbation per year or the cost of BT rises above $10,384 total for all three bronchoscopic procedures needed to perform thermoplasty and to cover the entire bronchial tree (baseline = $6690).

CONCLUSIONS

BT is a cost-effective treatment for asthmatics at high risk of exacerbations. Continuing to follow asthmatics treated with BT beyond 5 years will help inform longer efficacy and support its cost-effectiveness.

Asthma Is More Severe in Older Adults

Background

Severe asthma occurs more often in older adult patients. We hypothesized that the greater risk for severe asthma in older individuals is due to aging, and is independent of asthma duration.

Methods

This is a cross-sectional study of prospectively collected data from adult participants (N=1130; 454 with severe asthma) enrolled from 2002 – 2011 in the Severe Asthma Research Program.

Results

The association between age and the probability of severe asthma, which was performed by applying a Locally Weighted Scatterplot Smoother, revealed an inflection point at age 45 for risk of severe asthma. The probability of severe asthma increased with each year of life until 45 years and thereafter increased at a much slower rate. Asthma duration also increased the probability of severe asthma but had less effect than aging. After adjustment for most comorbidities of aging and for asthma duration using logistic regression, asthmatics older than 45 maintained the greater probability of severe asthma [OR: 2.73 (95 CI: 1.96; 3.81)]. After 45, the age-related risk of severe asthma continued to increase in men, but not in women.

Conclusions

Overall, the impact of age and asthma duration on risk for asthma severity in men and women is greatest over times of 18-45 years of age; age has a greater effect than asthma duration on risk of severe asthma.

Early anion gap metabolic acidosis in acetaminophen overdose

PURPOSE

The study aimed to determine the incidence and clinical significance of early high (>15 mEq/L) anion gap metabolic acidosis in acetaminophen (APAP) overdose.

METHODS

A retrospective review of a cohort of 74 patients presenting within 24 hours of APAP overdose was conducted.

RESULTS

Early high anion gap metabolic acidosis was present in 41% of patients on admission and persisted for 1.5 ± 0.1 days. The anion gap was associated with an elevated lactate level (4.5 ± 1 mmol/L) (r(2) = 0.66, P < .05), which persisted for 1 day. The lactate level increased in proportion to the APAP concentration (r(2) = 0.75, P < .05). Patients with increased anion gap had a higher incidence of confusion (48% vs 3%; P < .001) and lethargy (39% vs 6%; P = .003). Early high anion gap metabolic acidosis was found in the absence of shock or liver failure. All patients were treated with N-acetylcysteine and, despite the early high anion gap metabolic acidosis, none developed hepatic failure or hypoglycemia.

CONCLUSION

Early high anion gap metabolic acidosis in patients with APAP overdose is self-limited and does not predict clinical or laboratory outcomes. Persistent or late metabolic acidosis in the absence of liver failure is not likely due to APAP and should prompt a search for other causes of metabolic acidosis. Finally, APAP overdose should be considered in patients presenting to the emergency department with altered mental status, as this is a treatable condition when detected early.

Prognostic value of a simple evolving disseminated intravascular coagulation score in patients with severe sepsis

OBJECTIVE

We postulated that the coagulopathy initiated by the inflammatory response to severe sepsis would be reflected by changes in the platelet count and prothrombin time that convey prognostic information. To examine this hypothesis, we looked at the utility of a simple evolving disseminated intravascular coagulation (DIC) score that awarded 1 point for each of the following: a) an absolute platelet count <100 x 10/L; b) a prothrombin time >15.0 secs; c) a 20% decrease in platelets; and d) a >0.3-sec increase in prothrombin time in predicting outcome in patients with severe sepsis.

DESIGN

Prospective observational study.

SETTING

Intensive care units of university medical center.

PATIENTS

Patients were 163 critically ill severe sepsis patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were clinically classified as having capillary leak syndrome (n = 24), multiple organ failure with death from sepsis (n = 37), or multiple organ failure with recovery (n = 57) or as well (n = 45) if they showed rapid improvement in their modified Multiple Organ Dysfunction Syndrome (MODS) score (which did not score for thrombocytopenia). Patients with capillary leak syndrome had the highest Acute Physiology and Chronic Health Evaluation II score, modified MODS, and prothrombin time and the lowest platelet counts, whereas well patients had the most normal values. The simple evolving DIC score increased with worsening clinical class and was associated with worsening organ failure (increased modified MODS). Mortality rate increased from 10% for a simple evolving score of 0 to 73% for a score of 4 (p < .01). Overall, 86% of those with a score < or =1 survived, whereas 85% of those with a score of > or =2 developed multiple organ failure and half of them died from sepsis.

CONCLUSIONS

The simple evolving DIC score calculated in the first 48 hrs from two readily available global coagulation markers appears to reflect the severity of the underlying disorder. It can be easily calculated at the bedside and provides useful prognostic information for the patient with severe sepsis.