diseases (asthma, eczema, and rhinitis). Urbanization of the living area was measured to correct for the association between high urbanization levels and a higher prevalence of asthma. 3,4 We identified a total of 3,987 individuals being treated with ADHD medication and matched them with 15,948 control subjects. Table 1 shows the characteristics of the study population. The multivariable analysis revealed that asthma, rhinitis, and eczema were significantly more common in case subjects than in control subjects, with asthma showing the strongest preponderance (Fig 1). No significant association was seen between asthma severity and the presence of ADHD. Similar studies also found a higher co-occurrence of both diseases than would be expected by chance. 5 However, in our study we determined an association of a history of asthma before the first prescription of ADHD medication. This study supports the hypothesis that in adults asthma is more common among patients with ADHD than in the general population. ADHD and asthma both have an early onset, and it is therefore difficult to determine the effect of asthma on ADHD in adults. Future studies should determine the underlying mechanism and the possible clinical implications of the association between ADHD and asthma. Jurjen van der Schans, MSc Brech Aikman, MSc Groningen, the Netherlands Tjalling W. de Vries, MD, PhD Leeuwarden, the Netherlands Pieter J. Hoekstra, MD, PhD Eelko Hak, PhD Groningen, the Netherlands AFFILIATIONS: From the PharmacoTherapy, -Epidemiology, and -Economics Research Group (Mr van der Schans, Ms Aikman, and Dr Hak), Groningen Research Institute of Pharmacy, University of Groningen; the Medical Center Leeuwarden (Dr de Vries); and the Department of Child and Adolescent Psychiatry (Dr Hoekstra), University Medical Center Groningen, University of Groningen. FINANCIAL/NONFINANCIAL DISCLOSURES: None declared. CORRESPONDENCE TO: Jurjen van der Schans, MSc, PharmacoTherapy, -Epidemiology, and -Economics, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, the Netherlands; e-mail: j.van.der.schans@rug.nl Copyright Ó 2017 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved. DOI: http://dx.doi.org/10.1016/j.chest.2017.03.052 Acknowledgments Additional information: The e-Appendix can be found in the Supplemental Materials section of the online article. References 1. van der Schans J, Cicek R, de Vries TW, Hak E, Hoekstra PJ. Association of atopic diseases and attention-deficit/hyperactivity disorder: a systematic review and meta-analyses. Neurosci Biobehav Rev. 2017;74(Pt A):139-148. 2. Fasmer OB, Riise T, Eagan TM, et al. Comorbidity of asthma with ADHD. J Atten Disord. 2011;15(7):564-571. 3. Elholm G, Linneberg A, Husemoen LL, et al. The Danish urban-rural gradient of allergic sensitization and disease in adults. Clin Exp Allergy. 2016;46(1):103-111. 4. Pitts M, Mangle L, Asherson P. Impairments, diagnosis and treatments associated with attention-deficit/hyperactivity disorder (ADHD) in UK adults: results from the lifetime impairment survey. Arch Psychiatr Nurs. 2015;29(1):56-63. 5. Instanes JT, Klungsøyr K, Halmøy A, Fasmer OB, Haavik J. Adult ADHD and comorbid somatic disease: a systematic literature review [published online ahead of print September 22, 2016]. J Atten Disord. http://dx.doi.org/10.1177/1087054716669589. Pretest Probability in the Assessment of Acute Dyspnea in the ED To the Editor: It is with great interest that we read the article by Zanobetti et al 1 published in this issue of CHEST regarding point-of-care ultrasonography (PoCUS) and its implications in the diagnosis of acute dyspnea in the ED. In this study, the authors found that the average time needed to formulate a diagnosis by using PoCUS was significantly shorter than that of a typical ED diagnosis. Adjusted odds ratio 4.0 3.5 3.0 2.5 2.0 1.5 1.5 1.4 2.9 2.4 2.3 2.8 1.0 0.5 0.0 Rhinitis Eczema Asthma Asthma severity: Intermittent Persistent Mild Persistent Moderate-Severe Figure 1 – Multivariable conditional logistic regression model, with 95% confidence intervals, of the association between attention-deficit/ hyperactivity disorder in adults and atopy defined according to condi- tion and level of severity. The odds ratio is adjusted for age, sex, ur- banization level, and other atopic diseases (asthma, eczema, and rhinitis). Asthma severity was estimated on the basis of various medi- cation proxies (see e-Appendix 1). journal.publications.chestnet.org 1407