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Combined Impact of Health Risk Factors on Mortality of a Petroleum Industry Population

Tsai, Shan P. PhD; Bhojani, Faiyaz A. MD, DrPH; Wendt, Judy K. MPH

Journal of Occupational & Environmental Medicine:
doi: 10.1097/JOM.0b013e3181ab59b0
Original Articles

Objective: To assess the combined impact of health risk factors on mortality.

Methods: A 21-year mortality follow-up of 12,896 Shell Oil Company employees was conducted. Relative risks of mortality, expressed as hazard ratios, in relation to the six risk factors, including cigarette smoking, obesity, high blood pressure, total cholesterol, serum glucose, and triglycerides, were calculated using a Cox proportional hazards model.

Results: Employees with health risk factors had higher mortality rates for all-causes combined and for cardiovascular diseases compared to employees without such risk factors. Smoking, obesity, hypercholesterolemia, and hyperglycemia independently and significantly predicted cardiovascular disease mortality. Mortality risks from all causes and from cardiovascular disease increased with the number of risk factors present.

Conclusions: This study found a positive association between several health risk factors and mortality. A greater number of risk factors corresponded to a higher rate of death. Reductions of employee health risk factors may be an effective means of improving employees’ long-term health.

Author Information

From Shell Health, Shell Oil Company, Houston, Tex.

Address correspondence to: Dr Tsai, Shell Oil Company, Shell Health, One Shell Plaza, P.O. Box 2463, Houston, TX 77252-2463; E-mail:

©2009The American College of Occupational and Environmental Medicine