Specific Activity Scale

Abstract

The Specific Activity Scale (SAS) is a concise, self-administered questionnaire designed to evaluate the functional capacity and status of patients diagnosed with cardiovascular disease. Developed by Goldman and colleagues in 1981, the SAS utilizes four key questions to categorize patients into one of four functional classes. These classifications are highly correlated with Metabolic Equivalents (METs) and reflect the patient’s ability to perform routine activities of daily living (ADLs) without experiencing limiting symptoms such as dyspnea or angina. The SAS provides a quick, practical assessment tool for clinical risk stratification and rehabilitative planning.

Keywords

Specific Activity Scale, SAS, functional capacity, METs, cardiovascular disease, cardiac rehabilitation, functional status, questionnaire, Goldman Scale.

Authors

Goldman L, Hashimoto B, Cook EF, Loscalzo A (1981), KNGF-richtlijn Hartrevalidatie (2005) (Dutch adaptation).

Purpose

The primary purpose of the Specific Activity Scale is to provide a standardized, non-exercise method for estimating the functional capacity of individuals with cardiac conditions. By correlating specific self-reported activities with established Metabolic Equivalents (METs), the scale assists clinicians in assigning patients to appropriate risk strata and determining suitable levels of physical activity or rehabilitation intensity. This assessment is crucial for guiding initial treatment plans and predicting long-term patient prognosis.

The instrument is particularly valuable in settings where formal exercise testing may be contraindicated, unavailable, or too costly. It offers a rapid screening method to categorize the patient’s functional status concerning daily life demands, focusing on conditions impacting the circulatory and respiratory systems, especially cardiovascular disease.

Construct

The SAS measures the psychological and physiological construct of functional status, focusing specifically on the maximum level of physical activity a patient can sustain symptom-free. The scale operationalizes functional status by linking self-reported activity levels to estimated MET expenditure. The four resulting classes correspond to specific ranges of activity tolerance, ranging from light activities (Class IV, lowest functional capacity) to strenuous activities (Class I, highest functional capacity).

This construct is fundamentally tied to the patient’s perception of their own limitations in the context of their daily environment. The SAS provides a subjective yet standardized measure of physical performance relative to daily life demands, making it highly relevant for evaluating quality of life and treatment efficacy in patients with chronic heart conditions.

Validity

The Specific Activity Scale demonstrates strong concurrent validity, particularly when compared against objective measures of exercise capacity, such as formal treadmill testing or maximal oxygen consumption (VO2 max). Early validation studies established a significant correlation between the SAS functional classes and the measured MET levels achieved during peak exercise testing. Patients classified into higher functional classes (I and II) consistently demonstrated significantly greater actual MET capacities than those categorized into lower classes (III and IV).

Furthermore, the scale exhibits predictive validity, as the functional class derived from the SAS is often used as a prognostic indicator for adverse cardiac events, morbidity, and mortality in patients undergoing cardiac procedures or managing chronic heart failure. Its ability to accurately estimate physical tolerance makes it a reliable proxy for more invasive or time-consuming diagnostic procedures.

Reliability

While the SAS, being a short categorical scale, does not typically rely on internal consistency measures like Cronbach’s alpha, the instrument demonstrates high inter-rater and test-retest reliability. The straightforward nature of the four questions and the clear, defined classification criteria minimize ambiguity in patient responses and subsequent scoring. Clinicians typically find high agreement when independently scoring the same patient based on their reported activities.

The reliability of the SAS is supported by its consistent clinical adoption across various settings and geographical regions, including the standardized Dutch version adopted by the KNGF guidelines for cardiac rehabilitation in 2005. The stability of the patient’s self-reported activities over short periods, provided their medical status remains stable, contributes significantly to its overall utility as a screening and monitoring tool.

Factor Analysis

Due to the constrained and prescriptive nature of the Specific Activity Scale, which consists of only four defining questions designed primarily for classification based on a hierarchy of metabolic demand, traditional exploratory or confirmatory factor analysis (EFA/CFA) is generally not performed or necessary. The scale operates on the assumption of a single underlying factor: overall functional capacity (estimated in METs).

The structure is inherently unidimensional and prescriptive, grouping responses based on the highest level of activity the patient can sustain without symptoms. Therefore, the scale’s psychometric properties are assessed primarily through its correlation with objective physiological measures rather than internal factor structure analysis.

Instrument

Test Type: Psychometric screening tool / Functional assessment

Format: Brief, self-administered questionnaire (4 items)

Language Available: English, Dutch (Nederlandse versie: KNGF-richtlijn Hartrevalidatie), and various other translations.

Population Group: Clinical population diagnosed with disorders of the circulatory and respiratory systems, specifically cardiovascular disease.

Age Group: Adults and Elderly.

Population Details: Patients undergoing cardiac rehabilitation, individuals requiring risk stratification prior to non-cardiac surgery, or those managing chronic heart conditions (e.g., heart failure, angina pectoris).

Test Methodology: Patients respond to four questions detailing their ability to perform common daily activities. The highest level of activity reported without symptoms determines the functional class (I, II, III, or IV). The original PDF of the Explanation Form can be downloaded here: SAS-form.pdf. The original PDF of the Measurement Instrument can be downloaded here: SAS-meetinstr.pdf.

Keywords

Functional status, cardiac rehabilitation, ADLs, Metabolic Equivalents, circulatory disorders, physical performance, exercise capacity, Goldman L.

Authors

Author ORCID Identifier: Not publicly provided for all authors.

Affiliation Email addresses: Not publicly provided.

Correspondence Address: Goldman L, Brigham and Women’s Hospital, Boston, MA (Affiliation at time of original publication).

Permissions & Fee and Test Year

The original scale was published in 1981 by Goldman, Hashimoto, Cook, and Loscalzo. The scale is widely adopted in clinical practice and research and is generally considered to be in the public domain for non-commercial clinical use, though formal permissions should be sought for large-scale research or commercial adaptations. The official Dutch adaptation was formalized in 2005 by the KNGF-richtlijn Hartrevalidatie.

Reference’s

• Goldman L, Hashimoto B, Cook EF, Loscalzo A. Comparative reproducibility and validity of the Specific Activity Scale and the New York Heart Association Class in measuring functional status in stable angina pectoris. The American Journal of Cardiology. 1981;47(4):806-812.
• KNGF-richtlijn Hartrevalidatie (2005). Koninklijk Nederlands Genootschap voor Fysiotherapie. Amersfoort, The Netherlands. (Reference for the Dutch version).
• Hlatky MA, Boineau RE, Higginbotham MB, et al. A comparison of the Specific Activity Scale and the New York Heart Association Functional Class. Journal of the American College of Cardiology. 1989;14(5):1351-1356.

Items of the Specific Activity Scale

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

The SAS categorizes patients based on the highest level of activity they can perform without symptoms. The four categories and their estimated METs are:

• Class I (Greater than 7 METs): Can perform heavy housework, gardening, or strenuous sports (e.g., swimming, jogging).
• Class II (5 to 7 METs): Can perform moderate activities such as walking 4 mph, climbing a flight of stairs quickly, or moderate yard work.
• Class III (3 to 5 METs): Can perform light activities such as walking 2 mph, light housework, or showering.
• Class IV (Less than 3 METs): Can only perform self-care activities (e.g., dressing, eating) and is symptomatic during minimal exertion.