Abstract
Dear Editor,
We have read the interesting article by Koder and Topçakar, which investigates the effects of e-cigarette use on nasal mucociliary clearance (NMC), with great interest. The fact that e-cigarette users showed NMC muscle function significantly worse compared with nonsmokers (14.08 ± 5.99 vs 10.80 ± 5.28 minutes, P = .027) reinforces the current literature on this topic and is an important finding in this novel area of research. Nevertheless, we would like to discuss some methodological points, which might have an impact on the interpretation of these findings.
A major limitation to be noted by the authors is that 95% of e-cigarette users were former traditional cigarette smokers, and their mean period of cessation was only 11.2 ± 6.7 months. Previous studies showed that smoking-induced ciliated cell impairment becomes irreversible for a long time, even after stopping, and there are reports on insufficient recovery of mucus clearance years after quitting. 1 This confound makes it difficult to conclusively attribute the NMC impairment observed in this population solely to e-cigarette exposure and not a lagging effect from previous traditional smoking. Furthermore, the large discrepancy in duration of exposure for traditional cigarette users (average 9.7 pack-years) and e-cigarette users (mean 19.3 months) reduces the ability to compare groups comparably.
Moreover, the saccharin test is commonly applied to assess NMC as it is easy to use and relatively inexpensive, but this subjective taste perception may be biased by a subject’s sense of taste and by changes in chemosensory function because of smoking.2 -4 Altered taste perception can be experienced by both cigarette and e-cigarette users, thus introducing a possible bias in saccharin test outcomes. 5 Objective evaluations, such as rhinoscintigraphy or high-speed video microscopy of the ciliary beat frequency, may provide more representative results in future research. 6
Nevertheless, the work of the authors highlights a critical public health issue and consideration for e-cigarette safety. Their findings are consistent with other recent work indicating that e-cigarette aerosols can provoke oxidative stress and inflammation in the respiratory epithelium.7,8 We do concur with the authors that promoting e-cigarettes as a benign alternative to traditional smoking should not be encouraged by healthcare providers; instead, we recommend focusing on evidence-based smoking cessation methods. It will be important to address this knowledge gap through rigorous prospective (longitudinal) studies with large sample sizes, e-cigarette-naive subjects, and accurate NMC measurements.
