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Chron Respir Dis. 2017 November; 14(4): 420–421.
Published online 2017 October 30. doi:  10.1177/1479972317733863
PMCID: PMC5729735

COPD in exclusive narghile smokers: Some points to verify

Dear Editor,

I read with great interest the paper of Bahtouee et al. “The prevalence of chronic obstructive pulmonary disease in hookah smokers.”1 The topic of the paper is very interesting since the social phenomenon of narghile use has developed to a worrying extent.2 However, five serious methodological points were noted in the above paper and should be highlighted.

The first point concerns the lack of precision about which spirometric norms were applied. In fact, only the following sentence was cited “the pulmonary function test results were expressed as percentages of the expected values adjusted for age, sex, height, weight, body mass index, and race.”1 It is central to reminder that numerous respiratory functional laboratories allow the default settings for spirometric norms offered by the manufacturer (especially, European Respiratory Society (ERS)/European Community for Steel and Coal3). The use of the above norms resulted in misinterpretation of spirometry data in a significant proportion of subjects and this could result in inappropriate diagnosis and/or management.4 Moreover, a recent North African study does not recommend the use of the recent multiethnic norms derived by the ERS global lung initiative to interpret spirometry in local adults’ population.5

The second point concerns the use of a fixed threshold of 80% to classify spirometric values as normal or abnormal. The use of a fixed threshold as a lower limit of normal (LLN) has been widely criticized and more importantly, clinicians may have to review and revise previous diagnoses.6 Actually, the use of the Z-score is encouraged by scholarly societies.7

The third point concerns the applied spirometric criteria (only FEV1) to define reversibility. Since 2005, the use of the forced vital capacity (FVC) was recommended by scholarly societies,8 and in case of COPD patients, several papers promoted its inclusion in the bronchodilator response.911 On the one hand, an improvement in FVC provides helpful information about the function of small airways, the most important sites of inflammatory and remodeling processes that are difficult to measure.9 On the other hand, the appraisal of FVC was proposed as a mean to get supplementary information regarding hyperinflation.9

The fourth point concerns the “unusual” applied definition to retain the diagnosis of a restrictive ventilator defect (RVD; FEV1 < 80% and FEV1/FVC > 0.81). Moreover, authors haven’t neither argued their choice by a solid reference nor discussed the above definition as a serious study limitation. In a similar Tunisian comparative study including 36 exclusive narghile smokers (ENSs) of more than 10 narghile years and 106 exclusive cigarette smokers for more than 10 pack-years,12 the recommended international definition for an RVD (total lung capacity < LLN8) was applied. In that study,12 the percentages of ENS having restrictive or obstructive or mixed ventilator defects were different from those reported by Bahtouee et al.1 (respectively, 36% vs. 7.4%, 8% vs. 10.2%, and 3% vs. 0.8%). In addition, in a study named “spirometric profile of narghile smokers,”13 where expiratory flows and static lung volumes were determined in 110 ENS, all forced expiratory flows were reduced (compared to 81.6% of subjects with normal lung function in Bahtouee et al.’s study1). In addition, a different spirometric profile of ENS was advanced13: 36% had lung hyperinflation, 14% had small airway obstruction, 14% had RVD, and 6% had large airway obstruction. Surprisingly, the above two studies12,13 were omitted by Bahtouee et al.,1 which can be considered as a striking form of bibliographical bias.

The present Letter to Editor is a call for researchers and physicians to keep a watchful eye on any manuscript on the effects of narghile use on lung function.

References

1. Bahtouee M, Maleki N,, Nekouee F. The prevalence of chronic obstructive pulmonary disease in hookah smokers. Chron Respir Dis 2017. DOI: 10.1177/1479972317709652. [PubMed]
2. Akl EA, Ward KD, Bteddini D, et al. The allure of the waterpipe: a narrative review of factors affecting the epidemic rise in waterpipe smoking among young persons globally. Tob Control 2015; 24 Suppl 1: i13–i21. [PMC free article] [PubMed]
3. Standardized lung function testing. Report working party. Eur Physiopathol Respir. 1983;19 Suppl 5:1–95. [PubMed]
4. El Attar MN, Hadj Mabrouk K, Ben Abdelaziz A, et al. Applicability of the old European respiratory society/European community for steel and coal reference equations for spirometry interpretation in Tunisian adult population. La Tunisie Medicale 2014; 92: 574–580. [PubMed]
5. Ben Saad H, El Attar MN, Hadj Mabrouk K, et al. The recent multi-ethnic global lung initiative 2012 (GLI2012) reference values don’t reflect contemporary adult’s North African spirometry. Respir Med 2013; 107: 2000–2008. [PubMed]
6. Quanjer PH, Stanojevic S, Cole TJ, et al. Multi-ethnic reference values for spirometry for the 3-95-yr age range: the global lung function 2012 equations. The Eur Respir J 2012; 40: 1324–1343. [PMC free article] [PubMed]
7. Tejero E, Prats E, Casitas R, et al. Classification of airflow limitation based on Z-score underestimates mortality in patients with chronic obstructive pulmonary disease Am J Respir Crit Care Med 2017; 196:298–305. [PubMed]
8. Pellegrino R, Viegi G, Brusasco V, et al. Interpretative strategies for lung function tests. The Eur Respir J 2005; 26: 948–968. [PubMed]
9. Ben Saad H, Prefaut C, Tabka Z, et al. The forgotten message from gold: FVC is a primary clinical outcome measure of bronchodilator reversibility in COPD. Pulm Pharmacol and Ther 2008; 21: 767–773. [PubMed]
10. Toren K, Bake B, Olin AC, et al. Measures of bronchodilator response of FEV1, FVC and SVC in a Swedish general population sample aged 50–64 years, the SCAPIS pilot study. Int J Chron Obstruct Pulmon Dis 2017; 12: 973–980. [PMC free article] [PubMed]
11. Ben Saad H. Promoting the inclusion of vital-capacity data in the bronchodilator response. Int J Chron Obstruct Pulmon Dis 2017; 12: 1243–1245. [PMC free article] [PubMed]
12. Ben Saad H, Khemiss M, Nhari S, et al. Pulmonary functions of narghile smokers compared to cigarette smokers: a case-control study. The Libyan J of Med 2013; 8: 2 2650. [PubMed]
13. Ben Saad H, Khemis M, Bougmiza I, et al. Spirometric profile of narghile smokers. Rev Mal Respir 2011; 28: e39–51. [PubMed]

Articles from Chronic Respiratory Disease are provided here courtesy of SAGE Publications