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  • Application of linear mixed-effects model with LASSO to identify metal components associated with cardiac autonomic responses among welders: a repeated measures study

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Original Article
Application of linear mixed-effects model with LASSO to identify metal components associated with cardiac autonomic responses among welders: a repeated measures study
  1. Jinming Zhang1,
  2. Jennifer M Cavallari2,
  3. Shona C Fang3,
  4. Marc G Weisskopf4,
  5. Xihong Lin5,
  6. Murray A Mittleman4,6,
  7. David C Christiani1,7
  1. 1 Department of Environmental Health, Harvard T H Chan School of Public Health, Boston, USA
  2. 2 Department of Community Medicine and Health Care, University of Connecticut Health Center, Farmington, USA
  3. 3 Department of Epidemiology, New England Research Institute, Watertown, USA
  4. 4 Department of Epidemiology, Harvard T H Chan School of Public Health, Boston, USA
  5. 5 Department of Biostatistics, Harvard T H Chan School of Public Health, Boston, USA
  6. 6 Cardiovascular Epidemiology Research Unit, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, USA
  7. 7 Pulmonary and Critical Care Division, Massachusetts General Hospital/Harvard Medical School, Boston, USA
  1. Correspondence to Dr David C Christiani, 665 Huntington Avenue, Building I Room 1401, Boston, Massachusetts 02115, USA; dchris{at}hsph.harvard.edu

Abstract

Background Environmental and occupational exposure to metals is ubiquitous worldwide, and understanding the hazardous metal components in this complex mixture is essential for environmental and occupational regulations.

Objective To identify hazardous components from metal mixtures that are associated with alterations in cardiac autonomic responses.

Methods Urinary concentrations of 16 types of metals were examined and ‘acceleration capacity’ (AC) and ‘deceleration capacity’ (DC), indicators of cardiac autonomic effects, were quantified from ECG recordings among 54 welders. We fitted linear mixed-effects models with least absolute shrinkage and selection operator (LASSO) to identify metal components that are associated with AC and DC. The Bayesian Information Criterion was used as the criterion for model selection procedures.

Results Mercury and chromium were selected for DC analysis, whereas mercury, chromium and manganese were selected for AC analysis through the LASSO approach. When we fitted the linear mixed-effects models with ‘selected’ metal components only, the effect of mercury remained significant. Every 1 µg/L increase in urinary mercury was associated with −0.58 ms (−1.03, –0.13) changes in DC and 0.67 ms (0.25, 1.10) changes in AC.

Conclusion Our study suggests that exposure to several metals is associated with impaired cardiac autonomic functions. Our findings should be replicated in future studies with larger sample sizes.

  • metals
  • cardiovascular
  • epidemiology

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/oemed-2016-104067

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    Footnotes

    • Contributors JZ contributed to all aspects of data acquisition, data analysis and interpretation, and preparation of the manuscript. DCC contributed to the study conception and design, data collection, analysis and interpretation. JMC and SCF contributed to the data collection and interpretation of the results. MAM, MGW and XL contributed to the data analysis and interpretation of the results. All authors reviewed and approved the manuscript.

    • Competing interests None declared.

    • Patient consent Obtained.

    • Ethics approval The Harvard T H Chan School of Public Health Institutional Review Board.

    • Provenance and peer review Not commissioned; externally peer reviewed.