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Abstract

We thank De Vita et al for pointing out the potential linkages between obesity, psoriasis, and COPD exacerbation. To address this interesting issue, we repeated the self-controlled case series design1Goto T. Tsugawa Y. Faridi M.K. Camargo Jr., C.A. Hasegawa K. Reduced risk of acute exacerbation of COPD after bariatric surgery: a self-controlled case series study.Chest. 2018; 153: 611-617Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar with stratification by coexistence of psoriasis (defined as International Classification of Diseases, Ninth Revision, Clinical Modification codes of 696.xx).2Icen M. Crowson C.S. McEvoy M.T. Dann F.J. Gabriel S.E. Maradit Kremers H. Trends in incidence of adult-onset psoriasis over three decades: a population-based study.J Am Acad Dermatol. 2009; 60: 394-401Abstract Full Text Full Text PDF PubMed Scopus (164) Google Scholar Because the number of patients with psoriasis was small (n = 10) in the dataset, we fit Poisson regression models using outcomes (ED visit or hospitalization for COPD) as a count outcome. In this exploratory analysis, similar to the original findings, the reduced risk of COPD exacerbation after bariatric surgery was found both in patients with and without psoriasis, while the statistical power was limited in the patients with psoriasis (Table 1). Although the study design (within-person comparisons) precluded us from directly comparing the two groups, the risk reduction appears larger in patients with psoriasis (incidence rate ratio, 0.13; 95% CI, 0.02-1.00) than those without (incidence rate ratio, 0.46; 95% CI, 0.36-0.59) in the 13- to 24-month period after bariatric surgery. The observed finding suggests that bariatric surgery may reverse part of the immunologic relationship between obesity, psoriasis, and COPD exacerbation (eg, decreasing the T helper 17/regulatory T-cell ratio).3Rau M. Schilling A.K. Meertens J. et al.Progression from nonalcoholic fatty liver to nonalcoholic steatohepatitis is marked by a higher frequency of Th17 cells in the liver and an increased Th17/resting regulatory T cell ratio in peripheral blood and in the liver.J Immunol. 2016; 196: 97-105Crossref PubMed Scopus (98) Google Scholar However, given the limited statistical power in the psoriasis group, these findings merit further investigations into the association between bariatric surgery and COPD in patients with psoriasis and on the complex interplay between obesity, psoriasis, and COPD.Table 1Number and Risk of Patients With an ED Visit or Hospitalization for COPD Exacerbation Stratified by Coexistence of PsoriasisTime Interval and Presence of PsoriasisNo. of EventsIRR (95% CI)P ValuePatients with psoriasis (n=10) 13-24 mo before bariatric surgery8Reference… 1-12 mo before bariatric surgery50.63 (0.20-1.91).41 0-12 mo after bariatric surgery20.25 (0.05-1.18).08 13-24 mo after bariatric surgery10.13 (0.02-1.00).050Patients without psoriasis (n = 471) 13-24 mo before bariatric surgery197Reference… 1-12 mo before bariatric surgery2081.06 (0.87-1.28).59 0-12 mo after bariatric surgery750.38 (0.29-0.50)< .001 13-24 mo after bariatric surgery900.46 (0.36-0.59)< .001IRR = incidence rate ratio. Open table in a new tab IRR = incidence rate ratio. ResponseCHESTVol. 154Issue 2PreviewWe agree with Dr Kaminska and colleagues that the beneficial effect of bariatric surgery on acute exacerbation of COPD (AECOPD) is mediated, at least partially, by a reduction in severity of OSA, along with other non-OSA mechanisms (eg, reversal of comorbidities, systemic inflammation). To further address this interesting issue, we reanalyzed the data with stratification according to presence of OSA (defined as International Classification of Diseases, Ninth Revision, Clinical Modification, codes 327.23, 780.53, and 780.5)1 and using the same self-controlled case series design. Full-Text PDF Bariatric Surgery in Obese Patients With Psoriasis and COPD: Killing Three Birds With One Stone?CHESTVol. 154Issue 2PreviewWe read with great interest the paper by Goto et al1 in a recent issue of CHEST (March 2018) reporting that bariatric surgery in patients who are obese was associated with a lower risk of ED visits or hospitalizations for acute exacerbation of COPD. Full-Text PDF