Introduction to Health Measurement Scales

Section 1: Introduction

1. What are health measurement scales?

The World Health Organisation defines health as:

a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity. (WHO)

Health measurement scales are therefore instruments (often questionnaires) designed to assess the state of well being of an individual.

2. How are health measurement scales used and why are they important?

Clinical practice

• Health measurement scales can be used by clinicians to assess the quality of life of patients to assist in decision making in the management of diseases (e.g. the use of EuroSCORE to predict the operative risk of cardiac surgery Link).
• In primary care, health measurement scales can be used by General Practitioners to identify individuals at high risk of developing a disease and implement appropriate lifestyle behaviour changes to reduce the risk (e.g. the use of Framingham General Cardiovascular Risk Profile to prevent cardiovascular disease in Primary Care Link).

3. The benefits of health measurement scales

• Formulation of national guidelines for recommendation of treatment where risk factors reached above a specific threshold level (e.g. Joint British Recommendations)
• Reduce healthcare costs: by identifying at risk population and preventing diseases at their early stages
• Effective medical intervention: by identifying the target audience most suitable for a particular type of intervention
• Encourage high risk patients to adopt behaviour changes (e.g. weight loss, smoking cessation) that reduce the risk of diseases (e.g. cardiovascular disease)

4. The limitations of health measurement scales

One may wonder why there are so many competing health measurement scales invented to measure the same outcome. The answer lies in the fact that every scale is open to limitations.

These limitations can be due to:

• Lack of close agreement between scores generated from two different scales measuring the same outcome (e.g. Framingham versus. ASSIGN on measuring a UK cohort Link)
• The choice of variables used in the prediction score (e.g. Total cholesterol-HDL or LDL-HDL ratio is superior for prediction of cardiovascular events Link)

Section 2: Examples of Health Measurement Scales

Health measurement scales may be classified by:

(1) their topic and scope

• Generic (e.g. Physical Activity Index)
• Broad ranging, such as disability (e.g. Functional Independence Measure scale)
• Focus on particular organ system (e.g. Scales from the Framingham Heart Study)
• Specific for particular disease (e.g. GRACE scale for acute coronary syndrome)

(2) their purpose

• Diagnosis (e.g. Geriatric Depression Scale)
• Prediction (e.g. euroSCORE for prediction of mortality from coronary heart disease)
• Evaluation (e.g. Rheumatoid Arthritis Severity Scale)

(3) their design

• Rating scales (e.g. Kurtzke’s expanded disability scale for multiple sclerosis)
• Questionnaires (e.g. Child Health Questionnaire)