Transcript Healthy Worker Effect Related to Tractor Overturn Injuries

Healthy Worker Effect
Related to Tractor
Overturn Injuries
Melvin L. Myers, Henry P. Cole,
Susan C. Westneat
National Institute for Farm Safety
Penticton, British Columbia
June 27, 2007
Acknowledgements

NIOSH grants
– Kentucky Farm Tractor Overturn Telephone
Survey, 2001
– National Tractor Initiative

Invisible population perspective
– Deborah B. Reed
Overview
The Healthy Worker Effect
 Kentucky Farm Tractor Overturn
Telephone Survey
 Missing Decedents
 Invisible Population
 Abbreviated Injury Severity
(AIS) Score

Healthy Worker Effect
Determine the frequency of farmers who
no longer farm as a result of a tractor
overturn-related injury
 Healthy worker effect

– the working population is healthier than the
general population
– the “unhealthy worker” opts out of the
occupation
– the “healthy worker” remains as a farmer
Sample Error
Population studies typically depend on the
extant farming population
 They miss farm households

– That no longer farm because a fatality
– Farmers who leave the farm because of an
injury, e.g., paralysis

Circumstances force people to leave an
occupation because their health is too
impaired to continue in their current job
Kentucky Farm Tractor Overturn
Telephone Survey, 2002
Random sample of 6,063 farm households
 7.98% of Kentucky farm households

– Based on 2001 Census of Agriculture
– Segmented by 6 geographical districts

551 tractor overturns (most recent)
– ROPS-equipped + non-ROPS

537 injury outcomes known
Overturn Injury Outcomes, n=537
permanent
disability, 14,
3%
hospitalized,
71, 13%
outpatient
care, 106,
20%
fatality, 25,
5%
non-injury,
321, 59%
Overturn Injury Outcomes, n=537
321 (59.8%) non-injury
 216 (40.2%) injuries

– 106 (19.7%) outpatient care
– 71 (13.2%) hospitalized
– 14 (2.6%) permanent disabilities
 unable to work
– 25 (4.6%) fatalities
Missing Decedents

Kentucky Farm Tractor Overturn
Telephone Survey, 1924-2002 (8%
sample)
– 25 of 537 overturns resulted in a fatality

Kentucky FACE Program, 1994-2001
(statewide)
– 70 tractor overturn-related deaths

For that period, the telephone survey
undercounted fatalities by 10.7%
Invisible Population
10.7% of the farms where a fatality
occurred were missed by the survey
 How many other farm households stopped
farming because of an overturn-related
injury?

– Not in the sample frame
– But neighbors are aware of these
consequences
Neighbors
Kentucky Farm Tractor Overturn Telephone
Survey (8% of the farming population)
 How about their neighbors?

– did they know of neighbors who had quit farming
because of an overturn-related injury?
– describe the injury
– duplicate reports?




name the county in which the neighbor’s injury occurred
identify the initials of the victim
recall the year in which the injury occurred
injury description
Approach

14 permanent disabilities reported in
the survey (8%)
– Extant population

Determine the proportion of
permanent disabilities to fatalities
(state-wide)
– Index: 70 overturn deaths, 1994-2001

2 of the 14 permanent disabilities
occurred during 1994-2001
– 8% sample
– 23 Statewide
year
1948
1961
1965
1970
1970
1970
1980
1982
1984
1986
1991
2000
2001
2002
Neighbor Reports
Limit to 1994-2001
 Adjusted for duplicates

– 213 reported cases that quit farming
– 13 duplicates
200 farmers quit farming because of
injury statewide
 70 deaths from overturns
 Ratio of former farmers/deaths

– 2.8
number
1994
14
1995
17
1996
22
1997
21
1998
37
1999
37
2000
22
2001
30
Total
200
Adjusted Overturn Injury Outcomes


321 (59.8%) non-injury
216 (40.2%) injuries
– 106 (19.7%) outpatient
care
– 71 (13.2%) hospitalized
– 14 (2.6%) permanent
disabilities
– 25 (4.6%) fatalities
Total: 537


321 (51.9%) non-injury
297 (48.0%) injuries
– 106 (17.2%) outpatient
care
– 71 (11.5%) hospitalized?
– 92 (14.9%) permanent
disabilities
 14 reported extant +
 2.8 disabilities/fatality
– 28 (4.5%) fatalities
 10.7% adjustment
Total: 618
Why So Many Disabled?

Includes moderately
severe injuries
– Some quit farming with
an injury that is
sustainable
– Last straw effect

Crushing injuries are
severe
– Inverts the safety
pyramid
Type of Disabilities
160
140
120
Number
100
80
60
40
20
0
amputations
paralysis
crushing
Injury
fractures
Next Steps

Use the Abbreviated Injury Scale (AIS)
coding system
– Used for traffic-related injuries
– Cost factors developed


Code the injuries reported of neighbors
Determine the frequency of injuries
– By injury severity
Re-estimate the Healthy Worker Effect
Merge into the State-wide estimate for all
overturn-related injuries
 Calculate the social cost of these injuries


Abbreviated Injury Scale (AIS)

Severity
–
–
–
–
–
–
–
(0) No injury
(1) Minor injury
(2) Moderate injury
(3) Serious injury
(4) Severe injury
(5) Critical injury
(6) Maximum (fatal)
injury

Body Part
–
–
–
–
–
–

Head
Eye
Neck
Thorax
Upper extremity
Lower extremity
Maximum Abbreviated
Injury Scale (MAIS)
– Highest score when a
multiple injury
Maximum Abbreviated Injury Scale
(MAIS) Cost Factors


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






Medical
Emergency Service
Market Productivity
HH Productivity
Insurance Admin
Workplace Cost
Legal Costs
Travel Delay
Property Damage
QALY's (intangible)







(0)
(1)
(2)
(3)
(4)
(5)
(6)
No injury
Minor injury
Moderate injury
Serious injury
Severe injury
Critical injury
Maximum (fatal) injury
MAIS-Based Costs, 2002 $
Injury Severity Cost of Injury Human Capital
$2,312
0
(1) Minor
$12,445
$17,694
(2) Moderate
$78,731
$186,116
(3) Serious
$219,276
$370,221
(4) Severe
$410,199
$862,006
(5) Critical
$1,291,583
$2,831,402
(6) Fatal
$1,151,425
$3,966,546
(0) No injury