Application of the Asthma Phenotype Algorithm from the Severe Asthma Research Program to an Urban Population

<div><h3>Rationale</h3><p>Identification and characterization of asthma phenotypes are challenging due to disease complexity and heterogeneity. The Severe Asthma Research Program (SARP) used unsupervised cluster analysis to define 5 phenotypically distinct asthma clusters that they replicated using 3 variables in a simplified algorithm. We evaluated whether this simplified SARP algorithm could be used in a separate and diverse urban asthma population to recreate these 5 phenotypic clusters.</p> <h3>Methods</h3><p>The SARP simplified algorithm was applied to adults with asthma recruited to the New York University/Bellevue Asthma Registry (NYUBAR) to classify patients into five groups. The clinical phenotypes were summarized and compared.</p> <h3>Results</h3><p>Asthma subjects in NYUBAR (n = 471) were predominantly women (70%) and Hispanic (57%), which were demographically different from the SARP population. The clinical phenotypes of the five groups generated by the simplified SARP algorithm were distinct across groups and distributed similarly to those described for the SARP population. Groups 1 and 2 (6 and 63%, respectively) had predominantly childhood onset atopic asthma. Groups 4 and 5 (20%) were older, with the longest duration of asthma, increased symptoms and exacerbations. Group 4 subjects were the most atopic and had the highest peripheral eosinophils. Group 3 (10%) had the least atopy, but included older obese women with adult-onset asthma, and increased exacerbations.</p> <h3>Conclusions</h3><p>Application of the simplified SARP algorithm to the NYUBAR yielded groups that were phenotypically distinct and useful to characterize disease heterogeneity. Differences across NYUBAR groups support phenotypic variation and support the use of the simplified SARP algorithm for classification of asthma phenotypes in future prospective studies to investigate treatment and outcome differences between these distinct groups.</p> <h3>Trial Registration</h3><p>Clinicaltrials.gov <a href="http://www.clinicaltrials.gov/ct2/show/NCT00212537">NCT00212537</a></p> </div

Subject characteristics in NYUBAR groups (N = 471).

*<p>Data missing for GERD in 8 subjects, hypertension in 9 subjects, diabetes in 5 subjects, eczema in 8 subjects; data missing for ever intubated in 8 subjects.</p>†<p>Of 267 subjects self-reporting ethnicity as Hispanic, 3% (n = 7) of subjects reported Black race: 5 subjects were in Group 2 and 2 subjects were in Group 5.</p

Lung function in NYUBAR groups (N = 471).

<p>Lung function in NYUBAR groups (N = 471).</p

Subject characteristics of NYUBAR asthma cases (N = 471).

*<p>Data on income missing on 73 subjects, we report percentage for only those reported; data on former smoking status missing on 1 subject.</p>†<p>Of 267 subjects self-reporting ethnicity as Hispanic, 97% (n = 260) of subjects reported White race and 3% (n = 7) reported Black race.</p

Asthma exacerbations and healthcare utilization (HCU) for NYUBAR groups in the year prior to study enrollment.

<p>No exacerbation is shown in black; any OCS or ED visit is shown in dark gray; and any HA is shown in light gray. Data missing in 11 subjects; (p value = .02, χ² test).</p