Sickness Impact Profile

Abstract

The Sickness Impact Profile (SIP) is a widely recognized, generic psychological instrument designed to objectively quantify an individual’s health status and the resulting behavioral dysfunction caused by illness or health complaints. Developed in the United States, the SIP measures the influence of disease and resulting limitations on daily life activities and general functioning. The full scale comprises 136 descriptive statements distributed across 12 distinct categories, covering physical and psychosocial dimensions of function. The SIP is instrumental in assessing the severity of illness impact and evaluating the effectiveness of health interventions. Due to its comprehensive nature, several shorter, validated versions of the SIP are also frequently utilized in both clinical and research settings.

Keywords

Sickness Impact Profile, SIP, health status, functional status, quality of life, QoL, behavioral changes, generic health measure, questionnaire, activities of daily living, psychometrics.

Authors

Bergner M (1981), Luttik A, Jacobs HM, de Witte LP (1985)

Purpose

The primary purpose of the Sickness Impact Profile (SIP) is to provide a standardized, observable measure of sickness-related dysfunction. It allows clinicians and researchers to assess the severity and extent of limitations imposed by acute or chronic health conditions across diverse populations. The instrument is crucial for evaluating the effectiveness of medical interventions, rehabilitation programs, and long-term care by documenting precise changes in functional status over time.

The scale focuses specifically on measuring observable behavioral changes rather than subjective feelings or symptoms. This objective approach ensures that the measurement reflects actual limitations in daily activities and social roles, making it a powerful tool for health outcomes research, comparative studies, and resource allocation planning in healthcare systems. The SIP is designed to capture the respondent’s perception of their current health-related dysfunction.

Construct

The SIP measures the construct of sickness impact, defined as the extent to which illness causes observable changes in an individual’s daily behavior and functional capacity. This construct is inherently multidimensional, encompassing both physical and psychosocial domains of function, which together represent the holistic experience of living with illness.

The scale captures functions related to: Quality of Life (QoL), Activities of Daily Living (ADLs), Mentale functions, General participation in life roles, and Interpersonal interactions and relationships. By assessing these domains, the SIP provides a comprehensive profile of how sickness affects overall personal and social functioning, moving beyond purely medical diagnoses to assess functional consequences.

Validity

The SIP exhibits strong evidence for various forms of validity, supporting its widespread use as a measure of functional status. Initial development ensured high content validity, as the 136 items were derived from extensive patient interviews to accurately reflect behaviors commonly affected by illness, ensuring relevance across various conditions.

Criterion validity has been established through consistent and expected correlations with other established measures of functional status and disability, such as the Karnofsky Performance Status Scale and various performance-based assessments. Construct validity is robustly supported by its ability to reliably differentiate between patient groups with varying levels of disease severity and by demonstrating appropriate correlations with related constructs like pain, depression, and overall health perception, confirming that it accurately measures the intended construct of sickness-related dysfunction.

Reliability

The Sickness Impact Profile is known for its robust psychometric properties, particularly in terms of reliability. Test-retest reliability studies, typically conducted over short intervals in populations with stable health conditions, consistently yield high correlation coefficients (often exceeding r = 0.85) for both the overall score and the two major dimension scores (Physical and Psychosocial). This demonstrates excellent temporal stability.

Internal consistency, measured using Cronbach’s alpha, is generally high across the full scale and its major subscales, frequently exceeding 0.90. This high consistency confirms that the items within the scale are measuring a unified underlying construct (the impact of sickness) and contribute meaningfully to the total score. Furthermore, inter-rater reliability is high, largely because the SIP relies on patient self-report of observable behavior rather than subjective interpretation by the assessor, minimizing observer bias.

Factor Analysis

Factor analysis performed on the 136 items of the SIP generally supports the intended hierarchical structure. Initial exploratory and subsequent confirmatory factor analyses consistently confirmed the existence of two primary, higher-order factors: the Physical Dimension and the Psychosocial Dimension. These two dimensions capture the overarching, broad impact of illness on the patient’s life.

Below the two primary dimensions, the analysis supports the existence of 12 distinct, lower-level categories (e.g., Ambulation, Body Care and Movement, Social Interaction, Alertness Behavior). While some studies have suggested minor variations in factor structure across different clinical populations or cultures, the core two-factor, 12-category structure remains the most widely accepted model for scoring and clinical interpretation of the standard SIP.

Instrument

Test Type: Psychometric Questionnaire (Self-report)

Format: The full version contains 136 descriptive statements requiring a binary response (Yes/No or Applies to Me/Does Not Apply to Me). Responses are weighted and summed, then converted into a percentage score ranging from 0 (no impact) to 100 (maximum functional impairment).

Language Available: English (Original), Dutch (Luttik A, Jacobs HM, de Witte LP, 1985), and numerous other translated and validated versions globally.

Population Group: Clinical Populations, General Population undergoing treatment or experiencing chronic illness.

Age Group: Adults, Elderly (Volwassenen, Ouderen)

Population Details: Applicable to a broad range of medical conditions, including chronic diseases, acute injuries, and rehabilitation patients, as it is a generic measure of function, not condition-specific.

Test Methodology: The respondent is instructed to indicate which statements describe their usual behavior on that day, specifically related to their health condition. The resulting scores reflect the degree of sickness-related dysfunction across physical and psychosocial domains.

Keywords

Functional limitations, ADL, psychosocial dimension, physical dimension, health measurement, chronic illness, rehabilitation, outcomes research, generic scale.

Authors

Author ORCID Identifier: Information not available in source content.

Affiliation Email addresses: Information not available in source content.

Correspondence Address: Information regarding the original 1981 authors is typically directed through major university departments or associated research institutes, but specific correspondence address is not available in source content.

Permissions & Fee and Test Year

The original SIP was published in 1981 by Bergner M and colleagues. The Dutch adaptation was published in 1985 by Luttik et al. Permissions for use of the SIP may vary depending on the specific version (full 136-item vs. short versions like SIP-68) and the intended setting (academic, non-profit, or commercial). Users are generally advised to contact the original publishing body or copyright holders for specific licensing fees and permissions, especially prior to large-scale clinical or commercial implementation.

Reference’s

• Bergner M. (1981). Development, use, and evaluation of the Sickness Impact Profile. In: Assessment of quality of life in clinical trials of cardiovascular therapies. American Journal of Cardiology, 47(Suppl 1), 71-78.
• Bergner M, Bobbitt RA, Carter WB, Gilson BS. (1981). The Sickness Impact Profile: development and final revision of a health status measure. Medical Care, 19(8), 787-805.
• Luttik A, Jacobs HM, de Witte LP. (1985). De Sickness Impact Profile: ontwikkeling en eerste ervaringen met de Nederlandse vertaling. [The Sickness Impact Profile: development and first experiences with the Dutch translation]. Tijdschrift voor Sociale Geneeskunde, 63(19), 670-675.

The original PDF documentation (Toelichtingsformulier) can be downloaded here: Toelichtingsformulier PDF.

The SIP-68 measurement instrument PDF can be downloaded here: Meetinstrument PDF.

Items of the Sickness Impact Profile

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

The Sickness Impact Profile (SIP) contains 136 items across 12 categories, which are grouped into two main dimensions:

• Physical Dimension:
  • Ambulation
  • Mobility
  • Body Care and Movement
• Psychosocial Dimension:
  • Social Interaction
  • Alertness Behavior
  • Emotional Behavior
  • Communication
• Independent Categories (often included in combined scores):
  • Sleep and Rest
  • Eating
  • Work
  • Home Management
  • Recreation and Pastimes