The work limitations questionnaire

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The large and growing burden of chronic
disease worldwide is presenting new
challenges in health assessment. For
example, demand has grown recently for
information concerning the impact that
chronic health problems have on a
population’s ability to work, and its work
productivity. Several survey instruments
are now available, which focus specifically
on employment1. In this article, we present
information on a new self-administered,
self-report survey instrument, the Work
Limitations Questionnaire (WLQ©).
The WLQ
The WLQ is an easy to use questionnaire,
measuring the degree to which employed
individuals are experiencing limitations on-
the-job due to their health problems and
health-related productivity loss. The WLQ
has 25 items that ask respondents to rate
their level of difficulty or ability to perform
specific job demands (Figure 1). The job
demands, which are contained in the
WLQ’s items, have four defining features:
1) they occur among a variety of jobs; 2)
many different physical and emotional
health problems may interfere with their
performance; 3) they are considered
important to the job from the worker’s
perspective; and 4) problems performing
them are frequently related to productivity.
The WLQ’s 25 items are aggregated into
four scales. The Time Management scale
contains five items addressing difficulty
handling time and scheduling demands.
The six-item Physical Demands scale
covers a person’s ability to perform job
tasks that involve bodily strength,
movement, endurance, coordination and
flexibility. The Mental-Interpersonal
Demands Scale has nine items addressing
cognitive job tasks and on-the-job social
interactions. The fourth scale is the Output
Demands scale and it contains five items
concerning diminished work quantity and
quality.
Scale score range from 0 (limited none of
the time) to 100 (limited all of the time)
and represent the reported amount of time
in the prior two weeks respondents were
limited on-the-job. Additionally, using an
algorithm, WLQ scale scores can be
converted into an estimate of productivity
loss.
Development Process
The WLQ development process began in
1994 with a grant from Glaxo-Wellcome,
Inc. WLQ research has also been
supported by Pharmacia, Inc., and the
National Institute of Mental Health. Prior to
the WLQ’s development, there had been a
very limited amount of detailed information
available on the work experience of the
employed, chronically ill population. Much
of the information was gleaned from
global indicators, such as the activity
limitation and disability day items
appearing within the US National Health
Interview Survey, and the role disability
scales of health assessment
questionnaires2.
The WLQ itself evolved from a qualitative
and quantitative research process. Early in
that process, we convened multiple focus
groups consisting of employed patients
with chronic disease. Our interactions with
working patients helped us to better
understand how the work activities,
associated with various jobs, were
influenced by different conditions and their
treatments. For example, we found that
several physical and mental conditions
made it difficult for individuals to perform
their job tasks effectively throughout the
workday according to an established or
expected work schedule. Another
important finding was that work
productivity was a sensitive topic for many
of the chronically ill workers we
interviewed, and we learned how, in a non-
threatening manner, to ask about work
productivity. We also found that the act of
recalling information about work
productivity, and the effects of health
problems on productivity, constituted a
relatively difficult response task. These
general findings helped to shape our
measurement approach.
A period of cognitive testing followed, in
which items and item groupings were
evaluated for content validity (relevance to
work and to illness), clarity, and
respondent burden. Finally, a series of
psychometric tests, conducted on the
NSTRUMENTS
USA
The Work Limitations Questionnaire
Debra Lerner, MS, PhD1,2, William H. Rogers, PhD1, Hong Chang, PhD1
1The Health Institute, Division of Clinical Care Research, New England Medical Center, Boston, MA, USA
2Tufts University School of Medicine and the Sackler School of Biomedical Science, Boston, MA, USA
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NEWS LETTER
QOL
9
QoL Newsletter, 2002; 28
(continued on p 10)
Figure 1:
Sample items
All of Most of Some of A Slight None of Does
the the the Bit of the Not
Time Time Time the Time Apply
(100%) (About Time (0%) to My
50%) Job
a. do your work without stopping
to take breaks or rests. 123450
b. stick to a routine or schedule. 123450
c. keep your mind on your work. 123450
d. speak with people in person,
in meetings or on the phone. 123450
e. handle the workload. 123450
All of Most of Some of A Slight None of Does
the the the Bit of the Not
Time Time Time the Time Apply
(100%) (About Time (0%) to My
50%) Job
a. walk or move around different
work locations (for example,
go to meetings). 123450
b. use hand-held tools or equipment
(for example, a phone, pen,
keyboard, computer mouse,
drill, hairdryer, or sander). 123450
Note: Items a. and b. are from the Time Management scale. Items c. and d. are from the Mental-Interpersonal
Demands scale. Item e. is from the Output Demands scale.
In the past 2 weeks, how much of the time were you ABLE TO DO the following without difficulty caused by
physical health or emotional problems?
Note: Items a. and b. are from the Physical Demands scale.
Work Limitations Questionnaire, © 1998, The Health Institute; Debra Lerner, Ph.D.; Benjamin Amick III, Ph.D.; and
GlaxoWellcome, Inc. All Rights Reserved.
In the past 2 weeks, how much of the time did your physical health or emotional problems make it difficult for you
to do the following?

related in the
hypothesized manner9.
Using results generated
within this study, we
developed an approach
to scoring the WLQ,
which enables the user
to translate scale scores
into a single estimate of
productivity loss. Table
1 demonstrates how the
data can be used to
quantify the difference in
productivity from a
relatively «healthy»
employee (WLQ scale
scores = 0), and to
calibrate the productivity
impact of various chronic
conditions. For example, the average WLQ
Index score for an employee sample with
depressive symptoms was approximately
15.
New Research
In 2002, we will begin a new two-year
project, which is designed to make WLQ
data and other health and work
productivity indicators highly accessible
and easy to interpret. We have been
awarded a grant from Pharmacia, Inc.,
under the auspices of the Aetna Academic
Medicine and Managed Care Initiative, to
collect and disseminate normative data on
health and work productivity from a
representative household sample within
the United States. Data will be collected
by the National Opinion Research Center.
We will publish normative data for
subgroups defined by major
demographics, health status, occupation,
and industry.
WLQ Users
Clinical researchers, the pharmaceutical
industry, employers, managed care
organizations, and public health
professionals are all seeking accurate
information concerning the work impact of
chronic disease. The pharmaceutical
industry requires sensitive and specific
work disability and productivity indicators
for use in its clinical trials. Employers are
requesting data to assess the impact of
changing employee demographics on
resulting questionnaire forms, led to the
current 25-item version3. Within both
patient and employee populations, this
version of the WLQ has demonstrated
excellent scaling properties, as well as
construct and criterion validity.
Scale alpha’s exceed the recommended
level of .70 in both patient and employee
populations. Construct validity tests have
shown that WLQ scale scores vary with
SF-36 measures of physical and mental
health, type of chronic condition, and
severity within condition groups, such as
depression and osteoarthritis3,5. In a study
of depression patients, Swindle and
colleagues4found that the energy level, a
hallmark depression symptom, predicted
WLQ scores. Low energy corresponded to
decreased work productivity both cross-
sectionally and longitudinally.
Criterion validity tests have been
performed in several settings. For
example, within a sample of private short-
term disability claimants with back pain,
baseline WLQ scores obtained within four
weeks of the claim predicted the duration
of the disability until return to work6. In a
study of patients with rheumatoid arthritis
and in a second with a fibromyalgia sample,
Wolfe and colleagues found that WLQ
scores predicted patient income level7,8.
We conducted a work-site study involving
repeat measures of approximately 900
employees, to determine whether WLQ
scores were significantly related to
objectively-measured employee-level work
productivity. We found that scores were
health and productivity. Some firms are
evaluating the need for, and effectiveness
of, employee health improvement
strategies, such as disease management
programs. Managed care organizations
are being asked to demonstrate «value» to
customers, including purchasers, who are
interested in improving employee function
and limiting the indirect costs of illness.
Finally, public health officials have widened
their surveillance and prevention efforts to
include disability due to chronic disease.
The WLQ can contribute information to all
of these initiatives.
Availability
The WLQ is available royalty-free for non-
commercial applications; commercial
users are charged a fee. Information
about the WLQ, and copies of the
instrument, are available free by request
from WLQ@Lifespan.org.
•
For further Information, please contact
Debra Lerner, M.S., PhD, The Health
Institute Division of Clinical Care Research,
New England Medical Center, Box 345,
750 Washington Street, Boston, MA
02111, USA. Tel: +1 617-636-8636
Fax: +1 617-636-8351
Email: WLQ@Lifespan.org
1. Lynch W and Reidel JE.
Measuring Employee
Productivity: A Guide to Self-Assessment Tools
. 2001
edition. Denver, CO: Institute for Health and Productivity
Management.
2. Lerner DJ. and Bungay K.
Measuring Work Outcomes
. In
:
Pharmacoeconomics and Outcome
s
: Applications for
Patient Care. Module 3: Assessment of Humanistic
Outcomes. Kansas City, MO: American College of Clinical
Pharmacy, 1997.
3. Lerner DJ., Amick BC. III, Rogers WH., et al. The Work
Limitations Questionnaire: a self-administered instrument
for assessing on-the-job work disability.
Medical Care
2001;39(1):72-85.
4. Swindle R, Kroenke K, and Braun LA.
Energy and
Improved Workplace Productivity in Depression
. Investing
in Health: The Social and Economic Benefits of Health
Care Innovation. Sorkin A, Summers K, and Farquar I
(eds.). New York: JAI Press, 2001;14:323-341.
5. Lerner D, Reed J, Massarotti E, et al. The Work Limitation
Questionnaire’s Validity and Reliability among Patients
with Osteoarthritis (OA)».
Journal of Clinical Epidemiology
Jan, 2002;55(2):197-208.
6. Lerner D, Amick III, B C, and Chang H. Duration of
Disability for Low Back Pain among Employees with
Short-Term Disability Insurance. (
In preparation
).
7. Wolfe F and Sesti AM. The Effect of Health-Related Work
Limitations on the Income of Employed Adults with
Rheumatoid Arthritis (RA). Annual Meeting of the
American College of Rheumatology
,
November, 2001.
8. Wolfe,F and Sesti, AM The Effect of Health-Related Work
Limitations on the Income of Employed Adults with
Fibromyalgia. Annual Meeting of the American College of
Rheumatology, November, 2001.
9. Lerner D and Lee J.
Measuring Health-Related Work
Productivity with Self-Reports.
In
:
Stang P and Kessler
RC. (eds.). Health and Work Productivity: Emerging
Issues in Research and Policy. Chicago: University of
Chicago Press
(In press).
NSTRUMENTS
USA
The Work Limitations Questionnaire
(continued from p 9)
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QOL
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QoL Newsletter, 2002; 28
Table 1. The Work Limitations Questionnaire: Estimated
Productivity Impact of Health-Related Work Limitations Based on
WLQ Index Score
WLQ Index Score % decrease in % increase in work
productivity hours to compensate
(compared to healthy) for productivity loss
0----
5 4.9 5.1
10 9.5 10.5
15 14.1 16.2
20 18.1 22.1
25 22.1 28.4
30 25.9 34.9
35 29.5 41.9
40 32.9 49.2
45 36.2 56.8
50 39.4 64.9
Source: ©Lerner, Debra, Rogers, William H., and Chang, Hong, 2001.