Work Productivity and Activity Impairment questionnaire

Abstract

The Work Productivity and Activity Impairment questionnaire (WPAI) is a brief, self-administered Patient-Reported Outcome (PRO) instrument designed to quantify the functional impact of health problems on an individual’s ability to work and perform regular daily activities. It typically consists of six core questions that assess impairment over the past seven days. The WPAI yields four primary metrics, calculated as percentage scores: percentage of work time missed due to health (Absenteeism), percentage impairment while working (Presenteeism), overall work impairment, and non-work activity impairment.

The scale has been adapted into several specialized versions to accommodate different research needs. Key forms include the WPAI-GH (General Health), which focuses on general health status; the WPAI-SHP (Specific Health Problems), which links impairment to a particular disease or condition; the combined WPAI-GH/SHP; and the WPAI+CIQ:AS (Allergy Specific, including Classroom Impairment Questions), often utilized in studies related to allergic diseases and their impact on academic or workplace concentration.

Keywords

Work productivity, Work Productivity, activity impairment, Presenteeism, Absenteeism, health economics, functional status, patient-reported outcomes, WPAI, clinical trials.

Authors

Reilly MC, Zbrozek AS, Dukes EM (Original development, 1993); Mapi Research Institute in collaboration with Reilly Associates (Dutch version translation and adaptation, 2006).

Purpose

The primary purpose of the WPAI questionnaire is to provide a standardized, quantifiable measure of productivity loss attributable to health issues. It serves as a crucial tool in pharmacoeconomic studies and clinical trials, allowing researchers to calculate the indirect costs associated with specific diseases or the benefits derived from therapeutic interventions. By capturing both time missed from work (absenteeism) and reduced effectiveness while at work (presenteeism), the WPAI offers a more holistic view of the burden of illness than measures focusing solely on absence.

Furthermore, the WPAI aims to assess the impact of health conditions on non-work-related daily functioning, providing insight into the individual’s overall quality of life and functional status outside of their professional environment. This allows for a comprehensive evaluation of treatment efficacy beyond traditional clinical endpoints.

Construct

The WPAI measures the construct of health-related productivity impairment. This construct is operationalized through four distinct domains, each yielding a percentage score:

• Percent Work Time Missed (Absenteeism): The proportion of scheduled work time lost due to health problems.
• Percent Impairment While Working (Presenteeism): The degree of reduced effectiveness or performance while at work due to health problems.
• Percent Overall Work Impairment: A composite score reflecting the total loss of work productivity (combining absenteeism and presenteeism).
• Percent Activity Impairment: The degree to which health problems interfere with regular, non-work activities (e.g., household chores, socializing, exercise).

The WPAI is conceptually rooted in health economics, treating productivity loss as a critical, measurable outcome that affects both the individual and society.

Validity

The WPAI has demonstrated strong psychometric properties across numerous studies and disease states. Concurrent validity is supported by significant correlations between WPAI scores (especially overall work impairment) and other measures of disease severity, functional status, and quality of life. For instance, higher WPAI impairment scores consistently correlate with lower scores on generic health status measures like the SF-36.

Known-groups validity is also well-established, as the instrument effectively differentiates between patients with varying levels of disease activity or severity. Furthermore, its sensitivity to change makes it highly valuable in longitudinal clinical trials, proving its ability to detect improvements or deteriorations in productivity following therapeutic intervention.

Reliability

The reliability of the WPAI is generally considered acceptable for a brief PRO instrument. Studies assessing test-retest reliability over short periods (e.g., one to two weeks in stable patient populations) typically yield moderate-to-high coefficients, indicating stability of the scores when the underlying health condition has not changed.

While the internal consistency (Cronbach’s alpha) is sometimes lower for the individual components due to the brief, non-summative nature of the scale (it measures distinct aspects rather than a single latent factor), the overall composite scores and domain scores exhibit adequate reliability for use in clinical research.

Factor Analysis

Traditional exploratory or confirmatory factor analysis is typically not applied to the WPAI in the same manner as multi-item scales designed to measure a single latent psychological construct. This is because the WPAI is fundamentally a set of metrics designed to quantify four distinct economic and functional outcomes (absenteeism, presenteeism, total work impairment, and non-work activity impairment). Each component addresses a separate dimension of impairment, and the resulting scores are calculated percentages rather than derived factor scores. Therefore, the structure is accepted as four separate, albeit related, components of productivity loss.

Instrument

Test Type: Questionnaire (Vragenlijst)

Format: Self-administered Patient-Reported Outcome (PRO) measure, typically completed by the respondent in under five minutes.

Language Available: English (Original), Dutch (Nederlandse versie), and numerous other translations maintained by Mapi Research Institute.

Population Group: Adults (Volwassenen)

Age Group: Typically 18 years and older.

Population Details: Employed individuals capable of working, or individuals whose daily activities are relevant to the non-work activity impairment component. It is widely used across various patient populations in clinical settings and epidemiological studies.

Test Methodology: The questionnaire uses a 7-day recall period. Respondents answer six questions regarding their employment status, hours worked, time missed due to health, time missed due to other reasons, the degree of impairment while working (on a 0-10 scale, converted to a percentage), and the degree of impairment of non-work activities (on a 0-10 scale, converted to a percentage).

Keywords

Pharmacoeconomics, health status, functional impairment, outcome measure, clinical research, quality of life, General Health, economic burden of illness.

Authors

Author ORCID Identifier: N/A (Information not available in source data.)

Affiliation Email addresses: N/A (Information not available in source data.)

Correspondence Address: Correspondence is typically managed through Reilly Associates or the Mapi Research Institute, which handles licensing and international translations.

Permissions & Fee and Test Year

The WPAI was originally developed in 1993 by Reilly MC, Zbrozek AS, and Dukes EM. The Dutch version was adapted in 2006 by the Mapi Research Institute. The scale is proprietary, and permissions for use are generally required. While academic, non-commercial research often receives permission free of charge, commercial use, particularly in pharmaceutical clinical trials, typically requires a licensing agreement and associated fees managed by Reilly Associates or their authorized distributors (such as Mapi Research Trust).

Reference’s

The foundational reference for the WPAI is the original publication detailing its development and initial validation. Subsequent references cover adaptations and psychometric validation across various languages and disease groups.

• Reilly MC, Zbrozek AS, Dukes EM. The validity and reproducibility of a work productivity and activity impairment instrument. Pharmacoeconomics. 1993; 4(5): 353-365.
• Mapi Research Institute (2006). Adaptation and validation of the Dutch version of the WPAI-GH (General Health).
• The original PDF explaining the instrument’s details can be downloaded here: WPAI Toelichtingsformulier (Explanation Form).
• The PDF of the WPAI-GH measurement instrument can be accessed here: WPAI-GH Measurement Instrument.
• The PDF of the WPAI+CIQ:AS measurement instrument can be accessed here: WPAI+CIQ:AS Measurement Instrument.

Items of the Work Productivity and Activity Impairment questionnaire

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

The specific, proprietary wording of the six core questions of the Work Productivity and Activity Impairment questionnaire (WPAI) is not available in the source content provided. However, the instrument assesses the following conceptual domains over the last seven days:

1. Are you currently employed (including self-employed)?
2. During the past seven days, how many hours did you miss from work because of health problems?
3. During the past seven days, how many hours did you miss from work because of reasons other than health problems (e.g., vacation, holiday)?
4. During the past seven days, how many hours did you actually work?
5. During the past seven days, how much did your health problems affect your productivity while you were working? (Rating scale 0 to 10, where 0 = “Health problems had no effect on my work” and 10 = “Health problems completely prevented me from working”).
6. During the past seven days, how much did your health problems affect your normal daily activities, other than work? (Rating scale 0 to 10, where 0 = “Health problems had no effect on my non-work activities” and 10 = “Health problems completely prevented me from doing my non-work activities”).