Work Limitations Questionnaire

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The Work Limitations Questionnaire (WLQ) is a 25-item, self-administered questionnaire measuring the degree to which health problems interfere with ability to perform job roles. It was designed for assessing groups of individuals ("respondents") who are currently employed. The WLQ indicates the degree to which health problems interfere with specific aspects of job performance (on-the-job disability), and the productivity impact of these work limitations.

Abbreviated Name: WLQ

Author(s): Debra Lerner & Benjamin C. Amick

Purpose: To assess the on-the-job impact of chronic health problems and/or treatment ("work limitations")

Population: Adult

Age Range : Working population

Type of Instrument: Disability / Physical functioning

Mode of Administration:

Self-administered 10 minutes Likert scale Global score Scores by dimension Lower scores show better QoL Yes

Rater:

Time required: Response Options: Scoring:

Score Direction:

Weighting:

Number of Items: 25

Original Language: English

Existing Translations : Spanish, French

Copyright: 1998, The Health Institute; Debra Lerner, Ph.D.; Benjamin Amick III, Ph.D.; and GlaxoWellcome, Inc. All Rights Reserved.

Contact for information and permission to use:

Debra Lerner, Ph.D

The Health Institute

New England Medical Center

750 Washington Street

NEMC #345, Boston, MA 02111, USA

Dimensions covered by the questionnaire :

• Physical demands (6 items)

• Mental-Interpersonal demands (9 items)

Key References:

1. Lerner D, Amick BC 3rd, Rogers WH, Malspeis S, Bungay K, Cynn D. The Work Limitations Questionnaire. Med Care 2001;39:72-85.

Objective: The objective of this work was to develop a psychometrically sound questionnaire for measuring the on-the-job impact of chronic health problems and/or treatment ("work limitations"). Research Design: Three pilot studies (focus groups, cognitive interviews, and an alternate forms test) generated candidate items, dimensions, and response scales. Two field trials tested the psychometric performance of the questionnaire (studies 1 and 2). To test recall error, study 1 subjects were randomly assigned to 2 different questionnaire groups, a questionnaire with a 4-week reporting period completed once or a 2-week version completed twice. Responses were compared with data from concurrent work limitation diaries (the gold standard). To test construct validity, we compared questionnaire scores of patients with those of healthy job-matched control subjects. Study 2 was a cross-sectional mail survey testing scale reliability and construct validity. Subjects: The study subjects were employed individuals (18-64 years of age) from several chronic condition groups (study 1, n = 48; study 2, n = 121) and, in study 1, 17 healthy matched control subjects. Measures: Study 1 included the assigned questionnaires and weekly diaries. Study 2 included the new questionnaire, SF-36, and work productivity loss items. Results: In study 1, questionnaire responses were consistent with diary data but were most highly correlated with the most recent week. Patients had significantly higher (worse) limitation scores than control subjects. In study 2, 4 scales from a 25-item questionnaire achieved Cronbach alphas of > or = 0.90 and correlated with health status and self-reported work productivity in the hypothesized manner (P < or = 0.05). Conclusions: With 25 items, 4 dimensions (limitations handling time, physical, mental-interpersonal, and output demands), and a 2-week reporting period, the Work Limitations Questionnaire demonstrated high reliability and validity.

The Work Limitations Questionnaire (WLQ)§

The WLQ is a 25-item, self-administered questionnaire measuring the degree to which health problems interfere with ability to perform job roles. It was designed for assessing groups of individuals ("respondents") who are currently employed. The WLQ indicates the degree to which health problems interfere with specific aspects of job performance (on-the-job disability), and the productivity impact of these work limitations.

The WLQ fills an important gap in measurement. Previously, the work consequences of health problems have been quantified in population-based and clinical studies, using a variety of indicators and measurement approaches. Rates of employment and job loss, and post-illness return to work are among the most frequently used outcome indicators. The social role disability scales contained within several well-known health status questionnaires have been another source of valuable information. Typically, they measure partial and total decrements in ability to perform paid and unpaid (e.g., housework) roles. Within the private sector, rates of employee work absences are widely used to indicate the impact of health in the workplace and, specifically, to estimate productivity loss due to missed work time. The WLQ addresses the impact on health problems on-the-job. Unlike other survey instruments, it asks respondents to report on their limitations handling specific types of job demands. The WLQ is more comprehensive than other comparable scales and indicators, and it provides the user with a greater breadth and depth of information.

The WLQ items ask respondents to rate their level of difficulty (or, on one scale, their level of ability) to perform 25 specific job demands. These demands have four defining features: 1) a wide range of jobs in the US include these demands; 2) a wide variety of physical and emotional health problems can make it difficult to perform these demands effectively; 3) the demands are considered important to the job from the perspective of job incumbents; and 4) losses in individual work productivity are frequently related to the degree to which these demands are performed.

Responses to the 25 items are combined into four work limitation scales. These capture the multi-dimensionality of job roles (most jobs involve numerous tasks). They also reflect an important characteristic of many health problems, which is that they may result in limitations in performing some activities but not others.

The WLQ's Time Management scale (Question 1) contains five items addressing difficulty performing a job's time and scheduling demands. The six-item Physical Demands scale (Question 2) covers a person's ability to perform job tasks that involve bodily strength, movement, endurance, coordination and flexibility. The Mental/Interpersonal Demands Scale (Questions 3 and 4) has nine items. Six items pertain to difficulty performing cognitive job tasks and/or tasks involving the processing of sensory information. Three items address a person's problems interacting with people on-the-job. The fourth scale is the Output Demands scale (Question 5). It contains five items concerning decrements in a person's ability to meet demands for quantity, quality, and timeliness of completed work.

While comprehensive, the WLQ is brief and easy to administer. It is usually self-administered by respondents. A phone version is also available. It has been translated into several languages. The average amount of time it takes to complete the WLQ by self-administration is 5-10 minutes.

§ Work Limitations Questionnaire, 1998, The Health Institute; Debra Lerner, Ph.D.; Benjamin C. Amick III, Ph.D.; and GlaxoWellcome, Inc. All Rights Reserved.

Following a 4-year development process, the WLQ's became available for use in 1999. The results of several studies of the WLQ's psychometric performance have provided evidence of its reliability, validity, and precision.

The following sections describe the initial steps in the WLQ's development, results of psychometric tests and considerations for users. Details of several of these studies are provided in Medical Care (39:1,pp. 72-85, 2001).

To enhance our understanding of the on-the-job impact of health problems our initial studies included patient and population-based samples. Patients involved in these initial studies represented several different chronic condition groups (e.g., respiratory diseases including asthma, gastrointestinal disorders including Crohn's Disease and liver disease, mental illnesses including depression and generalized anxiety, epilepsy, chronic daily headache syndrome, and rheumatoid arthritis. Parallel studies have included patients with heart disease, low back pain, and occupational injuries (see Spine, 25:3152-3160, 2000).

Content Validity

Content validity tests assure that the questions included in a survey instrument represent the attributes of the concept that is purportedly being measured. The first item pool for the WLQ was developed by: 1) reviewing the work classification literature, which identified categories of job and occupational demands relevant to a large number of jobs in the United States; 2) convening a series of four focus groups consisting of employed patients who had one of the aforementioned chronic conditions; 3) conducting cognitive interviews with employed patients; and, 4) conducting a review of the candidate items by a physician expert panel.

Each focus group participant was asked to describe his/her job demands, health status, a "good" health day and a "bad" health day, and how health problems and medical care affected the performance of specific job demands. This process, involving 18 participants, generated 70 job-demand-level limitation items and 7 candidate dimensions (i.e., categories of work limitations).

The next step involved evaluating questionnaire content using cognitive interview methods. Approximately 40 employed, chronically ill patients participated. Items were rated for comprehensibility, ease of recalling information necessary to respond and ease of formulating a response. Individual interviews were conducted with each person. Each participant was given a mock questionnaire and asked to read each question (aloud or silently), paraphrase the question in his or her own words, and answer the question while thinking aloud. At the end of the interview, participants were given the opportunity to comment further on the questions and suggest new items. In addition to assessing content validity, the process can aid in identifying problems related to item reliability and systematic bias.

Items were rated for their comprehensibility, redundancy, relevance to job requirements, relevancy to the illness' symptoms, and ease of responding. As a result, 32 items failed, and 38 passed. Of the passing items, 25 were revised slightly and 2 items were added. Thus, 40 items were retained.

Next, a multidisciplinary physician panel reviewed this 40-item pool. Items were evaluated for "clinical sensibility". "Clinical sensibility" means the degree to which performance of the demands could be regarded as an outcome of certain chronic, disabling illnesses. This process resulted in minor modifications.

Item and Scale Reliability

An assessment, conducted at two different work sites, included 15 pairs of coworkers. The coworkers in each pair were matched on job and employer. However, one of the coworkers in each pair (the case) had at least one chronic condition. The control coworker had no chronic conditions. Each pair was blinded to the fact that health status was an eligibility criterion. This test assessed whether employed individuals could report reliably on their job demands, and whether health status biased results. Participants completed a questionnaire that asked if the job demands, which were mentioned in the WLQ items, were present or absent. During the period addressed in the survey, an expert observer (an ergonomist and trained assistants) went to each work site, at different times, and observed people assigned to the same types of jobs as the participants. The observers assessed the presence or absence of the job demands. This triangulation method permits assessment of inter-rater reliability. Results indicated adequate agreement among raters. Agreement was higher for the items addressing mental work demands vs. those measuring physical work demands. These results led to modifications of some physical demand items.

Intra-rater reliability and recall error was assessed in a subsequent study. This study involved the evaluation of 3 candidate response scales. Approximately 40 employed, chronically ill patients participated. Nine separate work limitation items were embedded in three different question stem/response scale formats. Thus, each participant answered the 9 questions 3 times, though each question was posed slightly differently each time. When responses to each set of three questions were compared, they agreed with each other in 79% of the comparisons. However, one form performed worse than the other two. Specifically, responses to questions on one of the forms were mismatched more frequently with those on the other two forms. After debriefing participants, we determined that one of the question stem/response option formats had slightly better accuracy (less recall error). The current WLQ reflects the results of this test.

A 48-item WLQ was assessed in a mail-out/mail-back survey. It included the 40-item pool and 8 new items suggested by the interactions with study participants. The sample included 121 employed patients within three illness groups: rheumatoid arthritis, chronic daily headache syndrome, and epilepsy. Cronbach's □ statistics were between the recommended levels of .70 and .90 for all items or slightly higher. Item-to-total scale score correlation coefficients, corrected for overlap, were greater than the minimum acceptable .20 level and exceeded the more stringent.40 level. Items within each scale were more highly correlated with their assigned scale's score than with the other scales' scores (scaling success rate = 100% for each scale).

A shorter 25 item WLQ was produced by retaining the best performing items. Psychometric test results were excellent. The WLQ's scale structure has been replicated in several other samples (e.g., patients with depression, patients with osteoarthritis, short-term disability claimants with low back pain, and work site samples).

Construct Validity

Construct validity refers to the degree to which scores obtained from an item or scale correspond to scores obtained from tools measuring a parallel or related concept. Several tests established the relationship of WLQ scores to measures of functional health status. The WLQ was compared to the SF-36 role limitation scales (role/physical and role/emotional). In 7 out of 8 multiple linear regressions (adjusted for age and gender), the WLQ scales were related significantly to the scales (n=121).

Work Limitations Questionnaire Scaling Test Results

Scale

Items n

Mean"

(SD)

% Floor

% Ceiling

Scale Alpha

Range of Item-to-Total Corr

Scaling Success5

48-ltem Work Limitations Questionnaire

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Responses

  • ralph bohm
    What is work limitations?
    1 year ago
  • janet
    Is work limitations questionnaire good?
    6 months ago

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