Characteristics of agricultural and occupational injuries by
workers’ compensation and other payer sources
Celestin Missikpode, PhD
1
, Corinne Peek-Asa, PhD
2
, Brad Wright, PhD
3
, Marizen Ramirez,
PhD
2
1
Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, Iowa
2
Department of Occupational and Environmental Health, College of Public Health, University of
Iowa, Iowa City, Iowa
3
Department of Health Management and Policy, College of Public Health, University of Iowa, Iowa
City, Iowa
Abstract
Background: Workers’ compensation claims data are routinely used to identify and describe
work-related injury for public health surveillance and research, yet the proportion of work-related
injuries covered by workers’ compensation, especially in the agricultural industry, is unknown.
Methods: Using data from the Iowa Trauma Registry, we determined the sensitivity and
specificity of the use of workers’ compensation as a payer source to ascertain work-related injuries
requiring acute care comparing agriculture with other rural industries.
Results: The sensitivity of workers’ compensation as a payer source to identify work-related
agricultural injuries was 18.5%, suggesting that the large majority of occupational agricultural
injuries would not be accurately identified through workers’ compensation records. For rural
nonagricultural, rural occupational injuries, the sensitivity was higher (64.2%). Work-related
agricultural injuries were most frequently covered by private insurance (39.6%) and public
insurance (21.4%), while rural nonagricultural injuries were most frequently covered by workers’
compensation (65.2%).
Conclusions: Workers’ compensation claims data will not include the majority of work-related
agricultural injuries.
Correspondence Corinne Peek-Asa, PhD, Associate Dean for Research, College of Public Health, Professor, Occupational and
Environmental Health, Director, Injury Prevention Research Center, University of Iowa, 145 North Riverside Dr, 100 CPHB, S143,
Iowa City, IA 52242. [email protected].
AUTHORS CONTRIBUTIONS
CPA conceptualized the work, and CM, BW, and MR contributed to the analytic plan. CPA acquired the data, CM conducted the
analysis, and all authors contributed to the interpretation of the findings. CM and CPA developed an outline for the manuscript and
CM created the first draft. All authors have contributed to and approved the final version, and all authors are accountable for this work.
DISCLOSURE BY AJIM EDITOR OF RECORD
Rodney Ehrlich declares that he has no conflict of interest in the review and publication decision regarding this article.
ETHICS STATEMENT
This project was approved by the University of Iowa Human Subjects Office. Data were obtained through a Data Use Agreement with
the Iowa Department of Public Health.
CONFLICTS OF INTEREST
The authors declare no conflicts of interest.
HHS Public Access
Author manuscript
Am J Ind Med
. Author manuscript; available in PMC 2020 January 06.
Published in final edited form as:
Am J Ind Med
. 2019 November ; 62(11): 969–977. doi:10.1002/ajim.23040.
Author Manuscript Author Manuscript Author Manuscript Author Manuscript
Keywords
agricultural industry; and specificity; sensitivity; workers’ compensation; work-related injuries
1 | INTRODUCTION
Agriculture is a hazardous occupation that exposes farmers and their family members to
high risk for fatal and nonfatal injuries. Agricultural injuries place a heavy burden on
families, farm operations, insurers, and the economy. The total national medical and
productivity cost for agricultural injuries has been estimated at $4.57 billion annually.
1
Farm
operations are complicated workplaces because farm properties often involve hazardous
terrain, animals and crops, machinery, work buildings, as well as one or multiple homes.
Farming can be a primary or secondary source of income as well as a hobby. In addition,
farms range from very small to very large operations and can have a range of business
registrations that vary by ownership status and business organization—each of which has
implications for insurance coverage.
Workers’ compensation insurance covers medical expenses and lost wages resulting from
occupational injuries and illnesses.
2
Workers’ compensation programs were established to
cover costs of workplace injuries and to limit workers’ rights to sue employers. Some studies
have reported shifting of work-related injury costs from workers’ compensation to other
healthcare coverage and/or to workers themselves.
3–8
Coverage for agricultural injuries
might be even more complicated than other workplaces because injuries could be covered by
property, home, or personal health insurance, even when the injury was occupational in
nature. Although studies have reported cost-shifting from workers’ compensation to other
insurance coverage systems, the magnitude of this practice is not clear.
9,10
As a result of
these factors, the performance metric of using workers’ compensation claims to reliably
capture work-related injuries is not known. In addition, it is not clear what types of factors
are associated with the type of insurance used to cover the direct healthcare costs of an
agricultural injury.
From the research perspective, understanding the characteristics of payer sources is
important because insurance claims data are often used to identify the incidence of health
conditions such as injuries. In particular, workers’ compensation claims are a common
source of information on work-related injury, including the identification of injury
incidence, emerging injury trends, high-risk populations, and risk factors, and the evaluation
of compensation policies and programs.
11–17
To the extent that other payer sources cover
work-related injuries, reliance on workers’ compensation data would lead to underestimates
of workplace injury incidence and introduce bias in trend and risk factor analyses.
The use of workers’ compensation claims as a research tool is also limited because of the
variability in state laws, which hinders comparison and generalizability. A total of 31 states
require that all agricultural operations regardless of size have workers’ compensation
insurance. Other states provide exemptions for agriculture. In the state of Iowa, all
agricultural operations with a payroll exceeding $2500 must carry workers’ compensation
for their employees.
18
However, the employer’s family members are exempt. Studies that
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utilize workers’ compensation may suffer from potential self-selection since workers’
compensation is not universally required of all agricultural operations. Therefore, studies
that examine the utilization of workers’ compensation, as well as other payer sources, are
essential to understanding the scope of agricultural injury.
Using a state trauma registry that independently identifies farm status and occupational
injuries, this study examines trends in payer sources. The first objective was to determine the
sensitivity and specificity of workers’ compensation as an indicator of work-related
agriculture injuries compared with rural injuries from other industries. The second objective
was to describe the distribution and characteristics of occupational injuries based on the
payer, comparing agricultural and rural nonagricultural work-related rural injuries. Lastly,
we aimed to investigate factors associated with length of hospital stay and hospital charges
for agricultural and rural nonagricultural work-related injuries based on payer source.
2 | MATERIALS A ND METHODS
2.1 | Data source and study populations
Data were from the Iowa State Trauma Registry, which is a statewide trauma patient
database managed by the Iowa Department of Public Health. The trauma registry is the
surveillance component used to measure the statewide performance of the Iowa Trauma
System. The Trauma System encompasses all of the state’s 122 acute care facilities, each
accredited as providing trauma care at Level I, II, III, or IV. Trauma Level I facilities provide
the highest level of care as well as leadership in education, research, and system planning;
Level II trauma care facilities provide definitive trauma care for all levels of severity; Level
III trauma care facilities provide stabilization for all trauma patients and may provide
surgical and/or critical care when appropriate; and, Level IV trauma care facilities provide
initial evaluation and stabilization, and may manage less severe trauma or transfer to a
higher level of care if necessary.
Iowa trauma care facilities accredited as Level I, II, or III are required to report specific data
about trauma patients to the Iowa Trauma Registry. Level IV facilities report on a voluntary
basis, and each year approximately 50% of facilities submit data. To ensure consistency in
the information collected, the Iowa Department of Public Health and the University of Iowa
Injury Prevention Research Center provide a trauma registry data dictionary with training for
all hospitals. Abstracted information from medical records is submitted by trauma nurses/
registrars at each trauma care facility within 90 days of the injury and entered into the
trauma registry. The University of Iowa Injury Prevention Research Center has served as the
trauma system evaluator for many years and has access to the data through a Data Sharing
Agreement (DSA 268).
The sample used in this study included patients treated from 2005 through 2013 who had a
rural residence. Rural residence was identified through Rural-Urban Continuum Codes of 7
(small town core) to 10 (unincorporated). This group was then categorized based on whether
the injury was agricultural or not. Agricultural injuries were defined as “a nonhousehold
injury incurred on the farm (International Classification of Diseases [ICD], Clinical
Modification, 9th edition, 849.1) by any farmer, farmworker, farm family member, or other
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individuals, or any nonfarm injury incurred by a farmer, farmworker, or farm family member
in the course of handling, producing, processing, transporting, or warehousing farm
commodities.” The sample was also categorized based on whether the injury was work-
related or not. An injury was defined as work-related if it occurred at a workplace or during
an activity related to work-function (eg, traveling to a meeting). Of the 113 662 occupational
injuries among rural patients in the trauma registry, there were 3935 (3.4%) agricultural
injuries, 107 728 (94.8%) rural nonagricultural injuries, and 1999 (1.8) missing.
2.2 | Study variables
Patient variables included age, sex, and injury information. Injury variables included
mechanism measured through external cause of injury ICD codes (machinery, transportation,
fall, cut/pierce, struck by/against, and other), type of injury measured through ICD diagnosis
codes (amputation, burn, crushing, dislocation/sprain, fracture, head injury/spinal cord
injury/nerves, internal organ/blood vessels, open wound, other Injury), severity of injury
measured by injury severity score (ISS), length of hospital stay, and hospital charges. ISS is
an anatomically based consensus-driven scoring system that measures injury severity based
on the threat to life in trauma patients. ISS-based ISSs have been validated for predicting
mortality and scores are categorized as mild (ISS = 1–8), moderate (ISS = 9–15), and severe
(ISS = 16+). We further created three age groups: less than 18 years, 18 to 64 years, and 65+
years; and three injury severity groups: minor injuries (ISS = 1–8), moderate injuries (ISS =
9–15), and severe injuries (ISS = 16+).
19
Hospital trauma level based on the American
College of Surgeons levels of I through IV, described above, was collected for each patient.
20
Payer source was the main exposure variable in this analysis. Payer source was collected
through the medical record as part of the trauma registry, and represent payers to which a
claim was submitted. Payer source had 18 categories that were combined into five payer
groups: public (Medicare, Medicare/Medicaid, Medicaid, welfare, other federal government,
other local government, and other state government, CHAMPUS, CHAMPUS/VA); private
(HMO, PPO, self-insured, auto insurance, commercial insurance); uninsured (charity, no
charge, and self pay); other (research fund, teaching fund, victim’s fund, other), and
workers’ compensation as a separate fifth category. Employer-provided health insurance
would be classified as private insurance. An injury hospitalization could be billed to five
separate payer sources. Of the total sample size (113 662), 22.9% and 81.3% had unknown/
missing responses for the first payer and second payer sources, respectively. Because a
missing response on the second payer source could mean there was no other payer, we
limited our analysis to the primary payer source (first payer). However, we used workers’
compensation information from any of the five payer fields to ensure complete information
on workers’ compensation payer. Workers’ compensation was the second payer source for
fewer than 3% of cases.
2.3 | Statistical analysis
The data showed a relatively high percentage of missing data (22.9%) on the main exposure,
primary payer source. Missingness was differential by work-relatedness of injury (main
outcome), patient age, sex, injury severity, type of injury, hospital level, and calendar year,
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suggesting that the primary payer source was missing in a nonrandom manner. Because the
main outcome (ie, work-related injury) was fully observed, we used multiple imputations of
five simulated datasets for this analysis.
21
Variables incorporated into the imputation model
included age, sex, the severity of the injury, length of hospital stay, trauma care level,
primary payer, hospital charges, type of injury, year of hospitalization, and survival status at
discharge (alive or deceased).
We determined the sensitivity and specificity of the use of workers’ compensation to identify
work-relatedness of an injury, calculated separately for agricultural and rural nonagricultural
injuries. Sensitivity and specificity were calculated using the trauma registry designation of
work-relatedness as the gold standard. Sensitivity measured the probability of correctly
identifying a true work-related injury (an accepted case definition of the trauma registry) by
workers’ compensation as a payer source. Specificity measured the proportion of nonwork-
related injuries that were correctly identified as such by workers’ compensation.
To examine the distribution of payer sources for work-related injuries based on whether they
were agricultural or not, we further restricted our analysis to only work-related injuries. Of
the 9079 work-related injuries, there were 2074 (22.8%) agricultural injuries; 6816 (75.1%)
rural nonagricultural injuries; and 189 (2.1%) missing. This subset of patients was also used
to examine factors associated with workers’ compensation use and to investigate factors
related to the length of hospital stay and hospital charges. We calculated the percentages of
work-related injuries billed to each payer source. We reported the uncertainty around these
percentages as well as the uncertainty around the sensitivity and specificity to account for
the use of five imputed datasets described above.
Adjusted logistic regression models were used to examine factors associated with the odds
of work-related injury hospitalization being billed to workers’ compensation. Adjusted
models included age, sex, the severity of the injury, mechanism of injury, and trauma care
level. We found that hospital charges were not normally distributed and corrected this
through a log transformation. All analyses were conducted in SAS (version 9.4; SAS
Institute, Cary, NC).
3 | RESULTS
Table 1 shows the sensitivity and specificity of using workers’ compensation to identify
work-related injuries that required acute care. For rural nonagricultural occupational injuries,
the sensitivity was 64.2%, which indicates that of all occupational injuries 33.8% would not
be identified by using workers’ compensation as a defining criterion. A sensitivity of 18.5%
was much lower for agricultural work-related injuries, indicating that 81.5% of such injuries
would not be identified through workers’ compensation claims databases (high proportion of
false negatives). However, the specificity of workers’ compensation was high for both
agricultural (98.8%) and rural nonagricultural injuries (95.5%), suggesting that few
nonworkplace injuries have workers’ compensation as a payer source (low proportion of
false positives).
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Figure 1 shows the percentages of injury hospitalizations billed to different categories of
payer source. Among work-related injuries, workers’ compensation was less frequently used
as a payer source for agricultural injuries compared with rural nonagricultural injuries. A
higher proportion (39.6%) of agricultural injuries was paid by private insurance (HMO,
PPO, self-insured, auto insurance, commercial insurance). Public sources were the second
most frequent payer of agricultural injuries (21.4%). Other work-related rural injuries were
most frequently covered by workers’ compensation (65.2%), followed by private insurance
(12.3%).
For both males and females, fewer than 20% of agricultural work-related injuries were billed
to workers’ compensation insurance (Table 2). In agriculture, a higher proportion (not
statistically significant) of men’s occupational injuries was charged to workers’
compensation (19.1%) than women (16.7%). In other industries, 70.1% of women’s and
64.3% of men’s occupational injuries had workers’ compensation as the payer (P < .05).
Minors less than 18 years of age (12.0%) and workers over age 65 years (6.7%) were also
less likely to have workers’ compensation as a payer. Age differences were significant for
both agricultural and rural nonagricultural injuries. Among agricultural injury mechanisms,
falls had the highest proportion billed to workers’ compensation (23.2%) and cutting/
piercing injuries (16.7%) and machinery (16.8%) the lowest (
P
< .05). In contrast, among
rural nonagricultural occupational injuries, machinery had the highest proportion billed to
workers’ compensation (74.6%) with transportation (62.5%) and falls (63.0%) the lowest (
P
< .05). For both agricultural and rural nonagricultural occupational injuries, amputation, and
crushing injuries had the highest proportion of workers’ compensation as a payer source.
Burns were the least likely to use workers’ compensation.
Table 3 shows the percent difference in hospital charges for factors associated with work-
related agricultural and rural nonagricultural injuries that required acute care. For example,
compared with public payers, average charges for agricultural injuries paid by workers’
compensation were 77% less and for rural nonagricultural injuries were 59.8% less. Severity
of injury, payer source, and trauma care level were associated with hospital charges in both
models. Higher levels of care and higher severity of injury were associated with larger
hospital charges. Compared with public coverage, workers’ compensation and private
insurance coverage were associated with lower hospital charges. The data show that age and
sex were not associated with hospital charges.
Table 4 shows factors associated with occupational injuries billed to workers’ compensation
insurance. For both work-related agricultural and rural nonagricultural injuries, older adults
were less likely to have work-related injuries covered by workers’ compensation. Compared
with hospital Level IV (community hospitals), hospitals Levels II and III were more likely to
have work-related injuries billed to workers’ compensation. The rural nonagricultural injury
data showed that the most severe injuries as well as injuries resulting from fall, cut/pierce,
and other mechanisms (fire, burn, environment, etc) were less likely to be billed to workers’
compensation compared with minor injuries and injuries resulting from struck by/against,
respectively. The results from the rural nonagricultural injury data also showed that injuries
treated at a Level I hospital were less likely to bill work-related injuries to workers’
compensation compared with Level IV.
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4 | DI SCUSSI ON
Based on its low sensitivity, workers’ compensation as a payer source would not be a good
measure to identify all work-related injuries that require acute care. In particular, workers’
compensation would fail to identify 71.5% of work-related agricultural injuries and 35.7%
of rural nonagricultural injuries. However, those injuries identified through workers’
compensation would be accurately identified as work-related, as indicated by its high
specificity. Consistent with previous results, workers’ compensation data do not provide an
accurate measure of injury incidence. In a study conducted in the state of Washington,
27.4% of work-related injuries did not have workers’ compensation listed as a payer.
9
An
analysis of the Illinois trauma registry showed that 25% of occupational injuries did not have
workers’ compensation listed as a payer.
22
Other studies based on hospital discharge or
emergency department data have also reported a considerable fraction (20%) of occupational
injuries not covered by workers’ compensation programs.
23,24
In contrast, Canada, with a
national workers’ compensation insurance program, reported that 95% of work-related
injuries were covered by the national system.
25
No previous studies have examined
agricultural injuries specifically. Our findings show that agricultural work-related injuries
are far less likely than other industries to use workers’ compensation as a payer source.
Compared with other studies, the sensitivity of workers’ compensation for the rural
nonagricultural injuries was also low, at 64.2%. Studies of other workplace injuries have
reported workers’ compensation sensitivity to be higher, including a study of a sample of
patients from New Jersey’s hospital discharge database that found workers’ compensation
sensitivity of 83%.
23
A study of the Washington state trauma registry found that 73% of
work-related injuries listed workers’ compensation as the payer.
9
This suggests that perhaps
rural workplaces are less likely to have workers’ compensation coverage, which is possible
given the higher proportion of very small businesses. These studies, as well as this one, all
included only injuries that required medical care.
The agricultural industry is complex. Most US farms are family-owned and operated, with a
high proportion of sole-proprietor family farms and relatively fewer operated via trusts and
corporations.
26
Businesses operating through trusts and corporations have requirements to
cover employees by workers’ compensation and a variety of insurance options to purchase
coverage. All employees of the business are covered. However, farmers who operate as sole
proprietors or partnerships are self-employed and have no workers’ compensation
requirements; and therefore, have the option of obtaining personal insurance to have some
coverage in the event of injury. In the State of Iowa, sole proprietors and limited liability
company members are not required to purchase workers’ compensation insurance but may
choose to cover themselves.
18
Adding to the complexity, certain types of workers are
exempted by the State of Iowa from mandatory coverage by workers’ compensation
insurance, including domestic/casual workers who make under $1500 from their employer
during the last year before injury; agricultural workers whose employer has a cash payroll of
less than $2500 in the year before the injury; agricultural exchange labor; and, officers of a
family farm corporation as well as their family members.
18
Optional coverage such as a
commercial provider and self-insurance are available for some approved businesses.
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Furthermore, the medical costs of work-related injuries might not be covered by workers’
compensation programs if adjudication determines the injury is not work-related.
27
If
claimants need to delay medical treatment after a claim has been filed, the medical costs are
likely to be paid by other payers or the injured workers themselves. Several studies have
reported a significant portion of work-related injuries that were assigned zero-cost workers’
compensation medical claims due to delayed care. For example, 15.9% of workers’
compensation claimants had zero-cost medical claims in an analysis of administrative data
of 16 employers across the United States.
27
Other studies have also reported the issue of
zero-cost workers’ compensation medical claims.
28–33
The zero-cost workers’ compensation
medical claims are commonly seen in less-acute injuries.
31
We also found that workers’
compensation had the lowest charges for all payer sources, with workers’ compensation
compared with public sources 77% and 60% lower. These lower charges may serve as a
disincentive for healthcare facilities to send claims to workers’ compensation insurers.
We found that both agricultural work-related injuries and rural nonagricultural work-related
injuries not paid by workers’ compensation were associated with older age. This finding is
consistent with Struck by/against a nonworkers’ compensation payer.
10
In general, older
workers have Medicare coverage as typical health insurance beginning at age 65. This may
make it easier for employers to shift their occupational injury costs from workers’
compensation to Medicare. From the perspective of Medicare, if an older worker with
Medicare gets injured on the job, workers’ compensation pays first on healthcare services.
34
Therefore, workers’ compensation should be the primary payer for occupational injuries in
workers with Medicare. The high likelihood of occupational injuries billed to a nonworkers’
compensation payer among older workers deserves further attention to determine whether
financial drivers are influencing billing decisions or if other factors are contributing. It is
possible that the presence of comorbidities, often common in the elderly, may interfere with
the attribution of work-relatedness to an injury in an older worker. It is also possible that
older workers have more resources to draw on for health and income benefits than workers’
compensation benefits. This latter explanation is supported by a study of occupational
injuries showing that higher income and older age were associated with not filing for a
compensation claim.
35
This type of cost-shifting will have a much greater impact in
industries with a high proportion of workers over the age of Medicare eligibility, such as
agriculture, which has a very high proportion of workers over the age of 65.
From the perspective of occupational injury surveillance, workers’ compensation claims data
sources can lead to an underestimate the incidence of work-related injuries and introduce
bias into research studies. Understanding the limitations of the use of workers’
compensation to ascertain work-related injuries can help researchers identify potential
biases, as well as justifying the use of multiple data sources to better capture work-related
injuries.
From the policy perspective, the role of workers’ compensation in farm operations requires
consideration because of the complexities of determining premiums and charge schedules.
Workers’ compensation introduces incentives to reduce injuries through the premiums paid
on coverage, which are often determined based on the number and severity of injuries (eg, if
injuries are low, premiums will be low).
36
Although workplaces also have incentives to
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reduce charges to employer-provided health insurance, these costs are not tied to workplace
safety through premium negotiations.
To our knowledge, this was the first study to assess whether there is a difference in the
ability of workers’ compensation insurance to capture work-related injuries occurring in the
agricultural industry compared with other occupational industries. Our use of the state
trauma registry offered a more complete method for capturing occupational injuries because
the trauma registry has a specific feature for identification of agricultural and nonagricultural
injuries and work-related and nonwork-related injuries. The trauma registry has five payer
fields, and we were careful to include workers’ compensation from any fields. Most of the
factors associated with the occupational injury not billed to workers’ compensation were
similar to those observed in other studies, lending robustness to our findings.
Perhaps the most important limitation of this study is generalizability because injuries
treated in hospitals generally represent the most severe injuries. It remains possible that this
study was unable to capture the full burden of occupational injuries. These data are from a
single state, and each state has its own policies and organization for workers’ compensation
coverage. Thus, generalizability to other states is limited. We were not able to measure
information bias regarding inaccurate reporting of an injury event as truly meeting the
criteria of a work-related injury. Our analysis focused exclusively on occupational injuries.
The analytic sample in this study included occupational injuries that required acute medical
care, most often through an Emergency Department. Many workers’ compensation injuries
are seen in occupational clinics, when available, or other types of settings. Thus, these
findings reflect only the most severe occupational injuries. The potential for workers’
compensation to under-represent occupational illness may be similar or even larger (since
illnesses are less likely to be tied to occupation than injuries).
37,38
We conducted multiple
imputations as the best way to account for data missing at random, but any time imputation
is used bias may be introduced.
The results of this study indicate that workers’ compensation is not an accurate source to
identify the incidence of work-related injuries, especially in the agricultural industry.
Workers’ compensation samples could be biased in their representation of injured workers
by age, injury severity, and mechanism of injury.
ACKNOWLEDGMENT
This work was supported by the University of Iowa Great Plains Center for Agricultural Health, Centers for Disease
Control and Prevention, National Institute of Occupational Safety and Health (U50 OH007548–11) and the
University of Iowa Injury Prevention Research Center, Centers for Disease Control and Prevention, National Center
for Injury Prevention and Control (R49CE002108).
Funding information
CDC/National Institute for Occupational Health, Grant/Award Number: Great Plains Center for Agricultural Health
U50 OH; CDC/ National Center for Injury Prevention and Control, Grant/Award Number: University of Iowa Injury
Prevention Research Cent
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FIGURE 1.
Frequency distributions of agricultural versus rural nonagricultural occupational injuries by
payer source and 95% confidence interval
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TABLE 1
Sensitivity and specificity of using workers’ compensation to predict work-related injury
Agricultural occupational injuries Rural nonagricultural occupational injuries
Sensitivity (%) and 95%
confidence intervals
Specificity (%) and 95%
confidence intervals
Sensitivity (%) and 95%
confidence intervals
Specificity (%) and 95%
confidence intervals
All
18.5 (16.8, 20.2)
a
98.8 (98.3, 99.3)
b
64.2 (63.1, 65.4)
a
99.5 (99.4, 99.5)
b
By subgroups
Male 18.8 (17.0, 20.5) 98.8 (98.1, 99.4) 63.4 (62.2, 64.7) 99.3 (99.3, 99.4)
Female 15.8 (10.0, 21.5) 99.1 (98.2, 100.0) 69.0 (66.0, 72.0) 99.6 (99.6, 99.7)
Age (y) <18 10.8 (1.5, 20.0) 99.7 (99.2, 100.0) 39.6 (23.4, 55.7) 99.8 (99.7, 99.9)
18‐64 21.6 (19.3, 24.0) 98.8 (98.2, 99.5) 65.1 (63.9, 66.3) 99.2 (99.1, 99.3)
65+ 7.1 (4.4, 9.8) 99.6 (98.9, 100.0) 54.5 (49.5, 59.5) 99.8 (99.7, 99.8)
Injury severity: minor
c
18.6 (16.4, 20.7) 99.0 (98.4, 99.6) 66.7 (65.3, 68.1) 99.4 (99.3, 99.5)
Injury severity: moderate 17.3 (13.5, 21.1) 98.3 (96.9, 99.7) 61.6 (58.8, 64.3) 99.5 (99.4, 99.6)
Injury severity: severe 20.5 (15.3, 25.7) 98.8 (97.1, 100.0) 54.9 (51.2, 58.5) 99.6 (99.4, 99.7)
Abbreviation: ISS, injury severity score.
a
Indicates that 82.5% of agricultural work‐related injuries and 35.8% of rural nonagricultural work‐related injuries would not be identified as work‐related if using workers’ compensation as a defining
criterion (high proportion of false negatives).
b
Indicates that 1.2% of agricultural nonwork‐related injuries and 0.5% of rural nonagricultural nonwork‐related injuries would be identified as work‐ related if using workers’ compensation as a defining
criterion (low proportion false positives).
c
Injury severity was determined by the ISS, with scores of 1‐8 as minor, 9‐15 as moderate, and 16 and above as severe.
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TABLE 2
Characteristics of agricultural and nonagricultural occupational injuries by mechanism, severity, and type
Agricultural occupational injuries Rural nonagricultural occupational injuries
Variables
Workers’ compensation
N (row %)
Nonworkers’
compensation N (row %) All N
Workers’ compensation
N (row %)
Nonworkers’
compensation N (row %) All N
Sex
a
Male 373 (19.1) 1583 (80.9) 1956 3826 (64.3) 2124 (35.7) 5950
Female 27 (16.7) 135 (83.3) 162 709 (70.1) 302 (29.9) 1011
All 400 (18.9) 1718 (81.1) 2118 4535 (65.1) 2426 (34.9) 6961
Age
a
,
b
(y)
<18 6 (12.0) 44 (88.0) 50 23 (53.5) 20 (46.5) 43
18‐64 369 (21.8) 1324 (78.2) 1693 4286 (65.8) 2230 (34.2) 6516
65+ 25 (6.7) 350 (93.3) 375 226 (56.2) 176 (43.8) 402
All 400 (18.9) 1718 (81.1) 2118 4535 (65.1) 2426 (34.9) 6961
Injury severity
a
Minor 270 (19.0) 1150 (81.0) 1420 3134 (67.6) 1500 (32.4) 4634
Moderate 82 (18.2) 368 (81.8) 450 958 (62.3) 580 (37.7) 1538
Severe 48 (19.4) 200 (80.6) 248 443 (56.1) 346 (43.9) 789
All 400 (18.9) 1718 (81.1) 2118 4535 (65.1) 2426 (34.9) 6961
Mechanism
a
,
b
Machinery 69 (16.8) 342 (83.2) 411 758 (74.6) 258 (25.4) 1016
Transportation 49 (17.0) 239 (83.0) 288 616 (62.5) 369 (37.5) 985
Fall 96 (23.2) 317 (76.8) 413 1576 (63.0) 927 (37.0) 2503
Cut/pierce 18 (16.7) 90 (83.3) 108 317 (63.8) 180 (36.2) 497
Struck by/against 56 (19.7) 228 (80.3) 284 497 (68.8) 225 (31.2) 722
Other
c
112 (18.2) 502 (81.8) 614 771 (62.3) 467 (37.7) 1238
All 400 (18.9) 1718 (81.1) 2118 4535 (65.1) 2426 (34.9) 6961
Type
a
,
b
Amputation 23 (28.8) 57 (71.2) 80 311 (76.4) 96 (23.6) 407
Burn 15 (15.8) 80 (84.2) 95 218 (50.8) 211 (49.2) 429
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Agricultural occupational injuries Rural nonagricultural occupational injuries
Variables
Workers’ compensation
N (row %)
Nonworkers’
compensation N (row %) All N
Workers’ compensation
N (row %)
Nonworkers’
compensation N (row %) All N
Crushing 19 (27.9) 49 (72.1) 68 239 (74.9) 80 (25.1) 319
Dislocation/sprain 29 (17.8) 134 (82.2) 163 203 (59.4) 139 (40.6) 342
Fracture 136 (18.6) 596 (81.4) 732 1986 (67.7) 946 (32.3) 2932
Head/spinal cord 59 (22.4) 204 (77.6) 263 630 (61.0) 403 (39.0) 1033
Internal organ 26 (19.4) 108 (80.6) 134 209 (60.6) 136 (39.4) 345
Open wound 51 (14.6) 298 (85.4) 349 503 (66.4) 254 (33.6) 757
Other injury 42 (17.9) 192 (82.1) 234 236 (59.4) 161 (40.6) 397
All 400 (18.9) 1718 (81.1) 2118 4535 (65.1) 2426 (34.9) 6961
a
Comparison of rural nonagricultural injuries is significant (
P
< .05).
b
Comparison of agricultural injuries is significant (
P
< .05).
c
Other = fire/burn, natural environment, and unspecified.
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TABLE 3
Percentage differences in hospital charges for characteristics of work‐related agricultural and nonagricultural injuries
Agricultural occupational injuries Rural nonagricultural occupational injuries
Variables
Percent difference in hospital
charges (95% CI)
a
P value
Percent difference in hospital
charges (95% CI)
a
P value
Payer
Workers’ compensation −77.26 (−110.83, −43.70) <.0001 −59.79 (−79.28, −40.31) <.0001
Private −75.84 (−111.29, −40.40) <.0001 −53.22 (−77.41, −29.05) .0006
Uninsured −14.44 (−58.58, 29.71) .49 −41.57 (−61.29, −21.85) .0001
Other 13.69 (−28.72, 56.09) .50 13.41 (−10.15, 36.97) .24
Public (ref) 0.00 0.00
Age (y)
<18 13.50 (−35.72, 62.72) .59 −2.99 (−53.38, 47.40) .90
18‐64 (ref) 0.00 0.00
65+ −20.64 (−55.13, 13.85) .22 −20.45 (−34.35, −6.55) .0041
Sex (male) 11.01 (−15.30, 37.31) .42 −3.90 (−12.39, 4.59) .37
Injury severity
Minor (ref) 0.00 0.00
Moderate 64.77 (36.73, 92.82) .0002 47.92 (39.28, 56.58) <.0001
Severe 118.28 (93.59, 142.97) <.0001 93.67 (83.53, 103.82) <.0001
Mechanism
Machinery 31.41 (5.41, 57.42) .02 −8.12 (−20.78, 4.53) .21
Transportation 19.80 (−9.28, 48.48) .18 6.09 (−6.36, 18.54) .34
Fall 21.05 (−3.62, 45.72) .09 6.53 (−4.71, 17.77) .25
Cut/pierce −9.57 (−50.61, 31.47) .64 −29.03 (−46.14, −11.92) .001
Other 2.86 (−22.99, 28.72) .83 −20.20 (−31.97, −8.43) <.0001
Struck by/against (ref.) 0.00 0.00
Trauma care level
b
I 118.67 (97.03, 140.32) <.0001 70.67 (58.73, 82.61) <.0001
II 106.24 (84.05, 128.43) <.0001 32.88 (21.35, 44.41) <.0001
III 38.58 (18.40, 58.62) .0002 16.63 (4.70, 28.57) .0066
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Agricultural occupational injuries Rural nonagricultural occupational injuries
Variables
Percent difference in hospital
charges (95% CI)
a
P value
Percent difference in hospital
charges (95% CI)
a
P value
IV (ref) 0.00 0.00
Abbreviation: CI, confidence interval.
a
Percent difference indicates the percentage change compared with the reference.
b
See text for definition.
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TABLE 4
Characteristics associated with worker’s compensation used as a payer source, compared with all other
sources, for work‐related agricultural and nonagricultural injuries
Agricultural
occupational
injuries
Rural
nonagricultural
occupational injuries
Variables aORs and 95% CI aORs and 95% CI
Age
<18 0.46 (0.17, 1.22) 0.62 (0.32, 1.21)
18‐64 (ref) 1.00 1.00
65+ 0.24 (0.15, 0.38) 0.68 (0.54, 0.85)
Sex
Male 1.19 (0.74, 1.91) 0.77 (0.65, 0.90)
Female 1.00 1.00
Injury severity
Minor (ref) 1.00 1.00
Moderate 0.92 (0.67, 1.28) 0.91 (0.79, 1.05)
Severe 0.95 (0.63, 1.43) 0.76 (0.63, 0.93)
Mechanism
Machinery 0.68 (0.42, 1.09) 1.21 (0.96, 1.52)
Transportation 0.80 (0.50, 1.27) 0.81 (0.65, 1.01)
Fall 1.20 (0.77, 1.86) 0.70 (0.58, 0.84)
Cut/pierce 0.71 (0.38, 1.32) 0.69 (0.53, 0.90)
Other 0.93 (0.61, 1.41) 0.76 (0.61, 0.95)
Struck by/against (ref) 1.00 1.00
Trauma care level
a
I 0.96 (0.67, 1.37) 0.81 (0.68, 0.97)
II 4.23 (3.08, 5.81) 3.79 (3.16, 4.55)
III 1.28 (0.90, 1.81) 2.25 (1.88, 2.69)
IV (ref) 1.00 1.00
Abbreviations: aORs, adjusted odds ratios; CI, confidence interval.
a
See text for definition.
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