Dear Editor,
I read with great interest the study by Gupta et al.[1] published in April-June 2022 issue of the Indian Journal of Occupational and Environmental Medicine. By using spirometry, Gupta et al.[1] found that all the parameters of pulmonary function tests (PFTs) were significantly decreased among hairdressers in Gangtok, India, and almost all the differences were statistically significant. They concluded that occupational exposure of hairdressers imposes the risk of derangement of pulmonary function and the development of respiratory symptoms.[1] Gupta et al.[1] mentioned three study limitations, namely a small sample size, lack of pre-employment pulmonary function status, and not measuring the concentration of chemicals in the salon environment. We believe that the following methodological limitation is relevant. The interpretation of PFTs parameters is usually based on comparisons of data with reference (predicted) values based on healthy subjects with similar anthropometric and racial characteristics.[2] Hence, spirometric prediction equations (SPEs) have been constructed for certain populations.[34] India has already formulated SPEs in adults.[5] In the study methodology, Gupta et al.[1] did not mention which SPEs were utilized to assess the readings of various PFTs parameters. This limitation, therefore, could additionally bring into question the rightness of the study findings.
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REFERENCES
1. Gupta K, Thapa B, Gupta S, Sharma S. Lung function tests in hairdressers of Gangtok: A cross-sectional study Indian J Occup Environ Med. 2022;26:91–4
2. Haynes JM, Kaminsky DA, Stanojevic S, Ruppel GL. Pulmonary function reference equations: A brief history to explain all the confusion Respir Care. 2020;65:1030–8
3. Sooriyakanthan M, Wimalasekera S, Kanagasabai S. Establishment of reference norms for lung function parameters of healthy Sri Lankan Tamils Pulm Med 2019. 2019:2169627
4. Dong L, Chen C, Yang Q, Zheng Y, Feng X, Chen F, et al Predictive equations for adult pulmonary function in Zhejiang Province, China? J Trop Med 2022. 2022:5500899 doi: 10.1155/2022/5500899
5. Chhabra SK, Kumar R, Gupta U, Rahman M, Dash DJ. Prediction equations for spirometry in adults from northern India Indian J Chest Dis Allied Sci. 2014;56:221–9
