Obesity and the Risk for Occupational Injuries

OBESITY AND THE RISK FOR OCCUPATIONAL INJURIES

Eric T. Brown
Safety 757 – Principles of Occupational Epidemiology
University of Wisconsin- Whitewater
Semester Project- Research Proposal

Abstract

Background:
Over two-thirds of the United States adult population is classified as either overweight or obese.  Obesity has been associated with the increase of risk factors for acquiring health conditions such as osteoarthritis, obstructive sleep apnea and chronic diseases such as coronary artery disease, Type 2 diabetes, hypertension, hyperlipidemia and has been linked to the prevalence of increased risk of stroke, anxiety and depression.  Often overlooked are the direct influences that obesity related health conditions and co-morbidities have on physical limitations, fatigue and the risk for occupational injuries.

Objective:
The objective of this study is to examine the correlation between obesity and the risk for non-fatal occupational injuries by performing a comparative statistical analysis of normal weight and obese worker populations.  The goal of the investigation is to examine the impact that obesity has as a risk factor for occupational injury to identify the associations between Body Mass Index (BMI) categories and occupational injuries.

Method:
A retrospective case-control study will be conducted to identify and compare data about obese worker populations and normal weight worker populations to examine information regarding the causal association that BMI has on non-fatal occupational injuries to identify the risk factors associated with obesity and impacts they have on occupational injury rates.

Keywords:
obesity, occupational injury, body mass index, safety, workers’ compensation


Introduction

Obesity is an overwhelming public health concern worldwide, with increasing prevalence, which has more than doubled over the past 30-years (WHO, 2011) with worldwide figures reaching over 1.5 billion adults who are either overweight or obese (WHO, 2011).  Obesity has been associated with the increase of risk factors for acquiring health conditions such as osteoarthritis of the knees and hips, obstructive sleep apnea and chronic diseases such as coronary artery disease, Type 2 diabetes, hypertension, hyperlipidemia and has been linked to the prevalence of increased risk of stroke, anxiety and depression.  Often overlooked are the direct influences that obesity related health conditions and co-morbidities have on physical limitations, fatigue and risk for occupational injuries.  “Obese employees may be at increased risk of occupational injury for a number of reasons, including compromised gait and mobility, fatigue due to sleep apnea, poor ergonomic fit and the use of potentially sedating medications to treat diseases associated with obesity.” (Pollack and Cheskin, 2007).  I have chosen to research the topic of obesity and the correlation with the risk for occupational injury.

The basis for the research of this topic, is to gain insight and information regarding the impact obesity plays in the risk for occupational injury, frequency, severity and cost of workers’ compensation claims and the cost drivers based on co-morbidities that lead to increased risk of acquiring other serious health conditions.

There has been limited statistical analysis on the correlation between increased workers’ compensation claim costs and obese employee populations (Qin et al., 2014; Ostbye, Dement and Krause, 2007; Finkelstein, 2005); however by targeting obesity in the workplace, employers can impact the overall health of its workforce to reduce absenteeism and decrease the frequency and cost of workers’ compensation claims associated with obese employees.

According to the Centers for Disease Control and Prevention (CDC) more than one-third (35.9%) of adults age 20 years and older in the United States are classified as obese and two-thirds (69.2%) of United States adults are classified as either overweight or obese.  Obesity is defined as having a body mass index (BMI) value of 30 or greater, 25.0 to 29.9 is classified, as “overweight” and 18.5 to 24.9 is a “normal” weight.  Based on 2012 data from the Behavioral Risk Factor Surveillance System (BRFSS), there was higher prevalence of adult obesity in the Midwest (29.5%) and the South (29.4%) with lower prevalence observed in the Northeast (25.3%) and the West (25.1%).  Non-Hispanic blacks appeared to have the highest age-adjusted rate of obesity at 49.5% compared with Mexican Americans (40.4%), all Hispanics (39.1%) and non-Hispanic whites (34.3%).  Findings show that there is no significant relationship between obesity and education among men; however there is a trend among women that shows that those with college degrees are less likely to be obese compared with less educated women and that higher income women are less likely to be obese than low-income women.

Obesity has been shown to increase the risk factors for acquiring health conditions and diseases such as coronary artery disease, diabetes, hypertension, high cholesterol, osteoarthritis of the knees and hips and obstructive sleep apnea and has also been linked to the prevalence of increased risk of stroke, anxiety and depression.   Studies have shown that obesity related health conditions and co-morbidities have a direct influence on chronic disease (Craig, Congleton, Kerk, Amendola and Gaines, 2006), physical limitations, ergonomics and fatigue (Cavuoto and Nussbaum, 2012) and that such conditions result in delays in recovery, higher risk of complications with medical procedures and overall de-conditioning of health (Qin et al., 2014; Ostbye, Dement and Krause, 2007; Finkelstein, 2005).

There are varying schools of thought regarding the relationship between obesity and traumatic occupational injuries, frequency and severity of workers’ compensation claims and associated health costs.  Several studies have been conducted over the past several years to research obesity and its correlation with an increase of work related injuries (Ostbye, Dement and Krause, 2007; Pollack et al, 2007; Qin et al., 2014, Janssen, Bacon and Pickett, 2011; Soteriades, Hauser and Kawachi, 2008; Bhattacherjee et al, 2003; Craig, Congleton, Kerk, Amendola and Gaines, 2006) and the rise in both direct and indirect costs associated with occupational injuries and workers’ compensation costs.   These studies report that obese persons are 26-107% more likely to have had an occupational injury than their normal weight counterparts.

A 2007 published literature review by Johns Hopkins Bloomberg School of Public Health in an article titled “Obesity and workplace traumatic injury: Does the science support the link?” (Injury Prevention, Vol. 13, 297-302, 2007), concluded that, although obese employees are slightly more likely to be injured than non-obese employees, the published data does not clearly show obesity as a prominent risk factor for injury.  The researchers suggested that additional research was necessary and cited that further study on the potential associations between obesity and occupational injury as they relate to contributing injury factors from fatigue, sleep apnea, gait disturbances, physical limitations, poor ergonomic fit from larger body circumference may be useful in future studies.  Additional research may also be beneficial to investigate the potential link to risk factors between occupational injuries for those individuals who use chronic medications for conditions associated with obesity; especially cardiac and diabetes medications, antibiotics and antihistamines.

A 2007 retrospective cohort study conducted by Duke University Medical Center from the Duke Health and Safety Surveillance System that included 11,728 health care and 34,858 university employees to determine the relationship between body mass index (BMI) and the number and types of workers’ compensation claims, associated costs and lost workdays found there to be a clear relationship between BMI and the rate of workers’ compensation claims.  Results of the study showed that there was a direct correlation between obesity and the number of workers’ compensation claims filed (11.65 claims per 100 full-time equivalents (FTEs) for obese employees) as compared to (5.80 claims per 100 FTEs for recommended weight employees).  The comparison on lost workdays was (183.63 vs. 14.19 lost work days per 100 FTEs), medical expenses ($51,091 vs. $7503 per 100 FTEs) and indemnity claim costs ($59,178 vs. $5396 per 100 FTEs).  The study also presented strong evidence that workers’ compensation claims affected by BMI were related to lower extremity, wrist, hand and back and that falls, slips, lifting and overexertion were the main cause of the injuries and that Certified Nursing Assistants, Housekeepers, Laundry Staff, Nurses and Facility Maintenance employees had the greatest risk for occupational injuries.

Study findings published in the Scandinavian Journal of Work, Environment and Health (2013) and summarized in an article by Liberty Mutual Insurance entitled “Obesity in the Workplace” (Research to Reality, 2013), indicated that obesity was associated with a 25 percent higher risk of work-related injury, independent of all other relevant factors, such as age, work hours and occupational hazards.

In 2013, researchers from National Council on Compensation Insurance, Inc. (NCCI, 2013) published a review of scientific literature for studies regarding the evidence of obesity contributing to the increased cost of workers’ compensation and the relationship between obesity and work-related injuries.  The study showed that based on workers’ compensation indemnity benefit payments, the duration of obese claimant’s was more than 5 times the duration of non-obese claimant’s.

Within a review of the literature, a study conducted in Canada to analyze obesity and its relationship with occupational injuries in the Canadian Workforce (Janssen, Bacon & Pickett, 2011),  researchers developed a “biophysical framework” to address the link between obesity and injury.  “Based on existing evidence, this framework established that obesity is associated with a number of risk factors for unintentional injury (increased co-morbidities, increased use of psychotropic medications, altered gait and balance, increased forces involved in falls, lower neural sensitivity, greater extremity friction and sleep apnea and fatigue).” (Janssen, Bacon & Pickett, 2011).   The framework was developed to provide a theoretical base for analysis to complement existing and future research studies examining the relationship between obesity and injury, because the biophysical framework takes into account both direct and indirect risk factors from the physical effects of obesity.

This biophysical framework may be an important element to consider including in this and future studies that examine obesity, since it takes into account both direct and indirect risk factors, which are often overlooked in statistical analysis research, but that may prove helpful in truly defining the role obesity plays in occupational injuries.

Given the limited research that exists on the impact of obesity on the increased risk of occupational injury and the correlation obesity has on the rising cost of workers’ compensation claims, additional studies may be necessary to better establish the impact on occupational injuries and lost work time.  Research does show a direct correlation with increased costs associated with workers’ compensation claims, occupational injuries and obesity; however additional research is necessary to clearly explore the direct relationships between obesity and traumatic occupational injuries, especially the mechanism of obesity related injuries.  Further research may also be necessary to determine the possible cost impact of obesity related weight reduction programs for employers and delay in recovery from injury due to de-conditioned physical state, which reduces the ability to physically participate in physical therapy and work conditioning programs, which in turn contribute to increased lost time from work and increased duration of treatment.

Future studies may also be needed to measure the potential cost impacts of employer based integrated health programs including health promotion/wellness, weight control and workplace injury prevention programs.

Objectives

The objective of this study is to examine the correlation between obesity and the risk for non-fatal occupational injuries by performing a comparative statistical analysis of normal weight and obese worker populations.  The goal of the investigation is to examine the impact that obesity has as a risk factor for occupational injury to identify the associations between Body Mass Index (BMI) categories and occupational injuries.

Based on the growing prevalence of obesity worldwide, the aging workforce and the increasing costs of medical treatment, obesity is a public health concern that warrants additional research to explore the global health impact and costs associated with occupational injury.  There has been limited statistical analysis on the correlation between increased workers’ compensation costs and obese employee populations; however by targeting obesity in the workplace, employers can impact the overall health of their employees to reduce presenteeism, absenteeism and decrease the frequency, duration and cost of workers’ compensation claims.

Research Hypothesis

There is a correlation between obesity and the risk for occupational injuries.   The null hypothesis is that there is no correlation between obesity and the risk for occupational injuries.

Research Methods

A retrospective case-control study will be conducted to identify and compare data about obese worker populations and normal weight worker populations to examine information regarding the causal association that Body Mass Index (BMI) has on non-fatal occupational injuries.  The study will be conducted in order to identify the risk factors associated with obesity and impacts they have on occupational injury rates.  The workers who have sustained occupational injuries will be the “case” subjects and the workers who have not sustained occupational injuries will be the “control” subjects.

“Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health.  Body mass index (BMI) is a simple index of weight-for-height that is commonly used to classify overweight and obesity in adults.  It is defined as a person’s weight in kilograms divided by the square of his/her height in meters (kg/m2).   Body mass index (BMI) provides the most useful population-level measure of overweight and obesity as it is the same for both sexes and for all ages of adults.” (WHO, 2014).   Obesity is defined as having a BMI value of 30 or greater, 25.0 to 29.9 is classified, as “overweight” and 18.5 to 24.9 is classified “normal” weight.

Information regarding Body Mass Index (BMI) categories and occupational injury rates and statistics will be collected from the Centers for Disease Control (CDC), National Health Interview Survey (NHIS), Bureau of Labor Statistics (BLS), National Institute for Occupational Safety & Health (NIOSH) – Center for Workers’ Compensation Studies (CWAS), National Electronic Injury Surveillance System (NEISS) and the Behavioral Risk Factor Surveillance System (BRFSS).

Table 1-1- The Association between Obesity and Non-Fatal Occupational Injuries

                                               Health Outcome (Occupational Injury)

Exposure Status Has sustained an Occupational Injury Has not sustained Occupational Injury

Total

Obese Workers A) Obese workers who have sustained an occupational injury. B) Obese workers who have not sustained an occupational injury. (A+B) All obese workers.
Normal Weight Workers C) Normal weight workers who have sustained an occupational injury. D) Normal weight workers who have not sustained an occupational injury. (C+D) All normal weight workers.
Total (A+C)  All workers who have sustained an occupational injury. (B+D) All workers who have not sustained an occupational injury. (A+B+C+D) All study subjects.

A comparative analysis of normal weight and obese employees and the number of occupational injuries in the BMI categories will be performed to identify whether there is a statistical association between obesity and risk for occupational injuries.   By comparing normal weight workers and obese workers we will measure the association between frequency of the exposure variable (obesity) and frequency of the outcome variable (occupational injury) to determine an odds ratio (OR).

The odds ratio (OR) will provide statistical evidence of whether an association between obesity and risk for occupational injuries exists.  Provided that the results of the study are statistically significant, an odds ratio of more than 1.0 will suggest a positive association between the exposure (obesity) and the outcome (occupational injury).  If the odds ratio is equivalent to 1.0, there may be no direct association between the exposure and the outcome.  In contrast, if the odds ratio is less than 1.0, the results may suggest that there is a possible protective factor that would prevent occupational injury, perhaps from greater bone density or cushioning due to increased adipose tissue in the obese worker population.

Confounding Variables

Potential confounding variables that may need to be addressed when selecting the study groups would include: age, sex, type of occupation, race/ethnicity, smoking status, income, education level, activity level of occupation and chronic health conditions (co-morbidities).

Age and sex may need to be considered by gathering an evenly split sample of ages and sexes within each group.  The type of occupation may need to be examined and grouped based on activity level of occupations, such as sedentary, moderate activity and heavy (labor intensive).  Smoking status could be broken down by current smokers and non-smokers or could be evaluated further by current smokers, former smokers and non-smokers.  Finally, chronic health conditions and co-morbidities may play a dramatic role in the risk factors associated with other health outcomes and risk factors for occupational injury, that may impact the results of the study; however it may be too difficult to identify and examine chronic health conditions given the retrospective nature of the study and existing data, unless it is well defined within the context of previous research design.

Conclusions

It would be concluded from a review of the literature and from the anticipated results of the proposed study, that there is a direct correlation between obesity and risk for occupational injury.  It is important as researchers to investigate both the direct and indirect risk factors from the physical effects of obesity in order to mitigate the risk of future occupational injuries.  By exploring the potential association between obesity and traumatic occupational injury we can better understand and identify areas for future investigation, which would include studying the impact obesity plays in the frequency and cost of workers’ compensation claims associated with occupational injuries, the cost drivers based on the co-morbidities of obesity, the obesity related mechanism of injuries and the increased risk of acquiring health conditions due to obesity.  Future research to measure the potential cost impacts of employer based integrated health programs including health promotion and wellness, weight control and workplace injury prevention programs, may also help us better understand the global impact that obesity has in relation to occupational injuries.


References

 Bhattacherjee, A., Chau, N., Sierra, C. O., Legras, B., Benamghar, L., Michaely, J.P.,  Mur,   J.M. (2003). Relationships of Job and Some Individual Characteristics to Occupational Injuries in Employed People: A Community-Based Study. Journal of Occupational Health, 45(6), 382–391. doi:10.1539/joh.45.382

Cavuoto, L.A., & Nussbaum, M.A. (2013). Obesity-related differences in muscular capacity during sustained isometric exertions.  Applied Ergonomics, 44 (2), 254-260.  doi: 10.1016/j.apergo.2012.07.011

Craig, B. N., Congleton, J. J., Kerk, C. J., Amendola, A. A., & Gaines, W. G. (2006). Personal and non-occupational risk factors and occupational injury/illness. American Journal of  Industrial Medicine, 49(4), 249–260. doi:10.1002/ajim.20290

Finkelstein, E., Fiebelkorn, I. C., & Wang, G. (2005). The Costs of Obesity Among Full-time Employees. American Journal of Health Promotion, 20(1), 45–51. doi:10.4278/0890-1171-20.1.45

Hertz, R.P., Unger, A.N., McDonald, M, Lustik, M.B., Biddulph, J. (2004).  The impact of obesity on work limitations and cardiovascular factors in the U.S. workforce.  Journal of Occupational and Environmental Medicine, 46, 1196-1230.

Janssen, I., Bacon, E., & Pickett, W. (2011). Obesity and Its Relationship with Occupational Injury in the Canadian Workforce. Journal of Obesity, 2011, 1–6. doi:10.1155/2011/531403

Khatutsky, G., Wiener, J. M., Anderson, W. L., & Porell, F.W. (2012). Work-related injuries among certified nursing assistants working in US nursing homes. RTI Press publicationNo. RR-0017-1204. Research Triangle Park, NC: RTI Press. Retrieved from
www.rti.org/rtipress

Laws, C., Schmid, F. (2012).  Indemnity benefit duration and obesity.  June 2012 Retrieved from http://www.ncci.com/documents/Obesity-2012.pdf

Liberty Mutual Research Institute for Safety (2013, Summer).  Obesity in the workplace: Public health issues challenges employers.  Research to Reality, 16(1), 3-6

Munir, F., Yarker, J., & Haslam, C. (2007). Use of prescribed medication at work in employees with chronic illness. Occupational Medicine, 57(7), 480–487. doi:10.1093/occmed/kqm058

Ogden, C.L., Carroll, M.D., Kit, B.K., Flegal, K.M.  Prevalence of obesity in the United States, 2009-2010.  NCHS data brief, no 82. Hyattsville, MD: National Center for Health Statistics. (2012).

Ostbye, T., Dement, J.M., Krause, K.M. (2007).  Obesity and workers’ compensation: Results from the Duke Safety Surveillance System.  Archives of Internal Medicine, 2007; 167: 766-733. Retrieved from http://cfm.mc.duke.edu /wysiwyg/downloads/Obesityand WorkersComp.pdf.

Peltonen, M., Lindroos, A. K., & Torgerson, J. S. (2003). Musculoskeletal pain in the obese: a comparison with a general population and long-term changes after conventional and surgical obesity treatment. Pain, 104(3), 549–557. doi:10.1016/s0304-3959(03)00091-5

Pollack, K.M., Cheskin, L.J. (2007).  Obesity and workplace traumatic injury: does the science support the link?  Injury Prevention, 2007; 13(5): 297-302. doi: 10.1136/ip.2006.014787.  Retrieved from http://www.ncbi.nlm.nih.gov /pmc/ articles /PMC2610625.

Pollack, K. M., Sorock, G. S., Slade, M. D., Cantley, L., Sircar, K., Taiwo, O., & Cullen, M.R. (2007). Association between Body Mass Index and Acute Traumatic Workplace Injury in Hourly Manufacturing Employees. American Journal of Epidemiology, 166(2), 204–211. doi:10.1093/aje/kwm058

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Soteriades, E. S., Hauser, R., Kawachi, I., Christiani, D. C., & Kales, S. N. (2008). Obesity and risk of job disability in male firefighters. Occupational Medicine, 58(4), 245–250. doi:10.1093/occmed/kqm153

U.S. Department of Health and Human Services Centers for Disease Control and Prevention. Adult Obesity Facts.  Retrieved from http://www.cdc.gov/obesity/data/ adult.html

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Xiang, H., Smith, G. A., Wilkins, J. R., Chen, G., Hostetler, S. G., & Stallones, L. (2005). Obesity and Risk of Nonfatal Unintentional Injuries. American Journal of Preventive Medicine, 29(1), 41–45. doi:10.1016/j.amepre.2005.03.013

 

Obesity and the Risk for Occupational Injuries

OBESITY AND THE RISK FOR OCCUPATIONAL INJURIES

Eric T. Brown
Safety 757 – Principles of Occupational Epidemiology
University of Wisconsin- Whitewater
Semester Project- Research Proposal

Abstract

Background:
Over two-thirds of the United States adult population is classified as either overweight or obese.  Obesity has been associated with the increase of risk factors for acquiring health conditions such as osteoarthritis, obstructive sleep apnea and chronic diseases such as coronary artery disease, Type 2 diabetes, hypertension, hyperlipidemia and has been linked to the prevalence of increased risk of stroke, anxiety and depression.  Often overlooked are the direct influences that obesity related health conditions and co-morbidities have on physical limitations, fatigue and the risk for occupational injuries.

Objective:
The objective of this study is to examine the correlation between obesity and the risk for non-fatal occupational injuries by performing a comparative statistical analysis of normal weight and obese worker populations.  The goal of the investigation is to examine the impact that obesity has as a risk factor for occupational injury to identify the associations between Body Mass Index (BMI) categories and occupational injuries.

Method:
A retrospective case-control study will be conducted to identify and compare data about obese worker populations and normal weight worker populations to examine information regarding the causal association that BMI has on non-fatal occupational injuries to identify the risk factors associated with obesity and impacts they have on occupational injury rates.

Keywords:
obesity, occupational injury, body mass index, safety, workers’ compensation

Obesity is an overwhelming public health concern worldwide, with increasing prevalence, which has more than doubled over the past 30-years (WHO, 2011) with worldwide figures reaching over 1.5 billion adults who are either overweight or obese (WHO, 2011).  Obesity has been associated with the increase of risk factors for acquiring health conditions such as osteoarthritis of the knees and hips, obstructive sleep apnea and chronic diseases such as coronary artery disease, Type 2 diabetes, hypertension, hyperlipidemia and has been linked to the prevalence of increased risk of stroke, anxiety and depression.  Often overlooked are the direct influences that obesity related health conditions and co-morbidities have on physical limitations, fatigue and risk for occupational injuries.  “Obese employees may be at increased risk of occupational injury for a number of reasons, including compromised gait and mobility, fatigue due to sleep apnea, poor ergonomic fit and the use of potentially sedating medications to treat diseases associated with obesity.” (Pollack and Cheskin, 2007).  I have chosen to research the topic of obesity and the correlation with the risk for occupational injury.

Within the research of this topic I seek to gain additional insights and information regarding the serious implications regarding the impact obesity plays in the frequency, severity and cost of workers’ compensation claims and the cost drivers based on the co-morbidities of obesity and the increased risk of acquiring health conditions and diseases.  There has been limited statistical analysis on the correlation between increased workers’ compensation claim costs and obese employee populations (Qin et al., 2014; Ostbye, Dement and Krause, 2007; Finkelstein, 2005); however by targeting obesity in the workplace, employers can impact the overall health of its workforce to reduce absenteeism and decrease the frequency and cost of workers’ compensation claims associated with obese employees.

According to the Centers for Disease Control and Prevention (CDC) more than one-third (35.9%) of adults age 20 years and older in the United States are classified as obese and two-thirds (69.2%) of United States adults are classified as either overweight or obese.  Obesity is defined as having a body mass index (BMI) value of 30 or greater, 25.0 to 29.9 is classified, as “overweight” and 18.5 to 24.9 is a “normal” weight.  Based on 2012 data from the Behavioral Risk Factor Surveillance System (BRFSS), there was higher prevalence of adult obesity in the Midwest (29.5%) and the South (29.4%) with lower prevalence observed in the Northeast (25.3%) and the West (25.1%).  Non-Hispanic blacks appeared to have the highest age-adjusted rate of obesity at 49.5% compared with Mexican Americans (40.4%), all Hispanics (39.1%) and non-Hispanic whites (34.3%).  Findings show that there is no significant relationship between obesity and education among men; however there is a trend among women that shows that those with college degrees are less likely to be obese compared with less educated women and that higher income women are less likely to be obese than low-income women.

Obesity has been shown to increase the risk factors for acquiring health conditions and diseases such as coronary artery disease, diabetes, hypertension, high cholesterol, osteoarthritis of the knees and hips and obstructive sleep apnea and has also been linked to the prevalence of increased risk of stroke, anxiety and depression.   Studies have shown that obesity related health conditions and co-morbidities have a direct influence on chronic disease (Craig, Congleton, Kerk, Amendola and Gaines, 2006), physical limitations, ergonomics and fatigue (Cavuoto and Nussbaum, 2012) and that such conditions result in delays in recovery, higher risk of complications with medical procedures and overall de-conditioning of health (Qin et al., 2014; Ostbye, Dement and Krause, 2007; Finkelstein, 2005).

There are varying schools of thought regarding the relationship between obesity and traumatic occupational injuries, frequency and severity of workers’ compensation claims and associated health costs.  Several studies have been conducted over the past several years to research obesity and its correlation with an increase of work related injuries (Ostbye, Dement and Krause, 2007; Pollack et al, 2007; Qin et al., 2014, Janssen, Bacon and Pickett, 2011; Soteriades, Hauser and Kawachi, 2008; Bhattacherjee et al, 2003; Craig, Congleton, Kerk, Amendola and Gaines, 2006) and the rise in both the direct and indirect costs associated with occupational injuries and workers’ compensation costs.   These studies report that obese persons are 26-107% more likely to have had an occupational injury than their normal weight counterparts.

A 2007 published literature review by Johns Hopkins Bloomberg School of Public Health in an article titled “Obesity and workplace traumatic injury: Does the science support the link?” (Injury Prevention, Vol. 13, 297-302, 2007), concluded that, although obese employees are slightly more likely to be injured than non-obese employees, the published data does not clearly show obesity as a prominent risk factor for injury.  The researchers suggested that additional research was necessary and cited that further study on the potential associations between obesity and occupational injury as they relate to contributing injury factors from fatigue, sleep apnea, gait disturbances, physical limitations, poor ergonomic fit from larger body circumference may be useful in future studies.  Additional research may also be beneficial to investigate the potential link to risk factors between occupational injuries for those individuals who use chronic medications for conditions associated with obesity; especially cardiac and diabetes medications, antibiotics and antihistamines.

A 2007 retrospective cohort study conducted by Duke University Medical Center from the Duke Health and Safety Surveillance System that included 11,728 health care and 34,858 university employees to determine the relationship between body mass index (BMI) and the number and types of workers’ compensation claims, associated costs and lost workdays found there to be a clear relationship between BMI and the rate of workers’ compensation claims.  Results of the study showed that there was a direct correlation between obesity and the number of workers’ compensation claims filed (11.65 claims per 100 full-time equivalents (FTEs) for obese employees) as compared to (5.80 claims per 100 FTEs for recommended weight employees).  The comparison on lost workdays was (183.63 vs. 14.19 lost work days per 100 FTEs), medical expenses ($51,091 vs. $7503 per 100 FTEs) and indemnity claim costs ($59,178 vs. $5396 per 100 FTEs).  The study also presented strong evidence that workers’ compensation claims affected by BMI were related to lower extremity, wrist, hand and back and that falls, slips, lifting and overexertion were the main cause of the injuries and that Certified Nursing Assistants, Housekeepers, Laundry Staff, Nurses and Facility Maintenance employees had the greatest risk for occupational injuries.

The study findings published in the Scandinavian Journal of Work, Environment and Health (2013) and summarized in an article by Liberty Mutual Insurance entitled “Obesity in the Workplace” (Research to Reality, 2013), indicated that obesity was associated with a 25 percent higher risk of work-related injury, independent of all other relevant factors, such as age, work hours and occupational hazards.

In 2013, researchers from National Council on Compensation Insurance, Inc. (NCCI, 2013) published a review of scientific literature for studies regarding the evidence of obesity contributing to the increased cost of workers’ compensation and the relationship between obesity and work-related injuries.  The study showed that based on workers’ compensation indemnity benefit payments, the duration of obese claimant’s was more than 5 times the duration of non-obese claimant’s.

In my literature review, I came across a previous study conducted in Canada to analyze obesity and its relationship with occupational injury in the Canadian Workforce (Janssen, Bacon & Pickett, 2011), the researchers developed a “biophysical framework” to address the link between obesity and injury.  “Based on existing evidence, this framework established that obesity is associated with a number of risk factors for unintentional injury (increased co-morbidities, increased use of psychotropic medications, altered gait and balance, increased forces involved in falls, lower neural sensitivity, greater extremity friction and sleep apnea and fatigue).” (Janssen, Bacon & Pickett, 2011).   The framework was developed to provide a theoretical base for analysis to complement existing and future research studies examining the relationship between obesity and injury, because the biophysical framework takes into account both direct and indirect risk factors from the physical effects of obesity.

This biophysical framework may be an important element to consider including in this and future studies that examine obesity, since it takes into account both direct and indirect risk factors, which are often overlooked in statistical analysis research, but that may prove helpful in truly defining the role obesity plays in occupational injuries.

Given the limited research that exists on the impact of obesity on the increased risk of occupational injury and the correlation obesity has on the rising cost of workers’ compensation claims, additional studies may be necessary in order to better establish the impact on occupational injuries and lost work time.  Research does show a direct correlation with increased costs associated with workers’ compensation claims, occupational injuries and obesity; however additional research is necessary to clearly explore the direct relationships between obesity and traumatic occupational injuries, especially the mechanism of obesity related injuries.  Further research may also be necessary to determine the possible cost impact of obesity related weight reduction programs for employers and delay in recovery from injury due to de-conditioned physical state, which reduces the ability to physically participate in physical therapy and work conditioning programs, which in turn contribute to increased lost time from work and increased duration of treatment.

Future studies may also be needed to measure the potential cost impacts of employer based integrated health programs including health promotion/wellness, weight control and workplace injury prevention programs.

Objectives

The objective of this study is to examine the correlation between obesity and the risk for non-fatal occupational injuries by performing a comparative statistical analysis of normal weight and obese worker populations.  The goal of the investigation is to examine

the impact that obesity has as a risk factor for occupational injury to identify the associations between Body Mass Index (BMI) categories and occupational injuries.

Based on the growing prevalence of obesity worldwide, the aging workforce and the increasing costs of medical treatment, obesity is a public health concern that warrants additional research to explore the global health impact and costs associated with occupational injury.  There has been limited statistical analysis on the correlation between increased workers’ compensation costs and obese employee populations; however by targeting obesity in the workplace, employers can impact the overall health of their employees to reduce presenteeism, absenteeism and decrease the frequency, duration and cost of workers’ compensation claims.

Research Hypothesis

I hypothesize that there is a correlation between obesity and the risk for occupational injuries.   The null hypothesis is that there is no correlation between obesity and the risk for occupational injuries.

Research Methods

I will conduct a retrospective case-control study to identify and compare data about obese worker populations and normal weight worker populations to examine information regarding the causal association that Body Mass Index (BMI) has on non-fatal occupational injuries to identify the risk factors associated with obesity and impacts they have on occupational injury rates.  The workers who have sustained occupational injuries will be the “case” subjects and the workers who have not sustained occupational injuries will be the “control” subjects.

“Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health.  Body mass index (BMI) is a simple index of weight-for-height that is commonly used to classify overweight and obesity in adults.  It is defined as a person’s weight in kilograms divided by the square of his/her height in meters (kg/m2).   Body mass index (BMI) provides the most useful population-level measure of overweight and obesity as it is the same for both sexes and for all ages of adults.” (WHO, 2014).   Obesity is defined as having a BMI value of 30 or greater, 25.0 to 29.9 is classified, as “overweight” and 18.5 to 24.9 is classified “normal” weight.

Information regarding Body Mass Index (BMI) categories and occupational injury rates and statistics will be collected from the Centers for Disease Control (CDC), National Health Interview Survey (NHIS), Bureau of Labor Statistics (BLS), National Institute for Occupational Safety & Health (NIOSH) – Center for Workers’ Compensation Studies (CWAS), National Electronic Injury Surveillance System (NEISS) and the Behavioral Risk Factor Surveillance System (BRFSS).

Table 1-1- The Association between Obesity and Non-Fatal Occupational Injuries

Health Outcome (Occupational Injury)

Exposure Status Has sustained an Occupational Injury Has not sustained Occupational Injury

Total

Obese Workers A) Obese workers who have sustained an occupational injury. B) Obese workers who have not sustained an occupational injury. (A+B) All obese workers.
Normal Weight Workers C) Normal weight workers who have sustained an occupational injury. D) Normal weight workers who have not sustained an occupational injury. (C+D) All normal weight workers.
Total (A+C)  All workers who have sustained an occupational injury. (B+D) All workers who have not sustained an occupational injury. (A+B+C+D) All study subjects.

A comparative analysis of normal weight and obese employees and the number of occupational injuries in the BMI categories will be performed to identify whether there is a statistical association between obesity and risk for occupational injuries.   By comparing normal weight workers and obese workers I will measure the association between frequency of the exposure variable (obesity) and frequency of the outcome variable (occupational injury) to determine an odds ratio (OR).

The odds ratio (OR) will provide statistical evidence of whether an association between obesity and risk for occupational injuries exists.  Provided that the results of the study are statistically significant, an odds ratio of more than 1.0 will suggest a positive association between the exposure (obesity) and the outcome (occupational injury).  If the odds ratio is equivalent to 1.0, there may be no direct association between the exposure and the outcome.  In contrast, if the odds ratio is less than 1.0, the results may suggest that there is a possible protective factor that would prevent occupational injury, perhaps from greater bone density or cushioning due to increased adipose tissue in the obese worker population.

Potential confounding variables that may need to be addressed when selecting the study groups would include: age, sex, type of occupation, race/ethnicity, smoking status, income, education level and chronic health conditions (co-morbidities).  Age and sex may need to be considered by gathering an evenly split sample of ages and sexes within each group.  The type of occupation may need to be examined and grouped based on activity level of occupations, such as sedentary, moderate activity and heavy (labor intensive).  Smoking status could be broken down by current smokers and non-smokers or could be evaluated further by current smokers, former smokers and non-smokers.  Finally, chronic health conditions and co-morbidities may play a dramatic role in the risk factors associated with other health outcomes and risk factors for occupational injury, that may impact the results of the study; however it may be too difficult to identify and examine chronic health conditions given the retrospective nature of the study and existing data, unless it is well defined within the context of previous research design.

Conclusions

I would conclude from my literature review and from the anticipated results of the proposed study, that there is a direct correlation between obesity and risk for occupational injury and that it is important as researchers to investigate both the direct and indirect risk factors from the physical effects of obesity in order to mitigate the risk of future occupational injuries.  By exploring the potential association between obesity and traumatic occupational injury we can better understand and identify areas for future investigation, which would include studying the impact obesity plays in the frequency and cost of workers’ compensation claims associated with occupational injuries, the cost drivers based on the co-morbidities of obesity, the obesity related mechanism of injuries and the increased risk of acquiring health conditions and diseases due to obesity.  Future research to measure the potential cost impacts of employer based integrated health programs including health promotion and wellness, weight control and workplace injury prevention programs, may also help us better understand the global impact that obesity has in relation to occupational injuries.

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