Conceptual Foundations for Health Measurements

Disability and Handicap Examples of Conceptual Foundations for Measurement Scales

Three Perspectives: Disease, Sickness & Illness (Underlying pathology; biologically defined: the practitioner’s perspective. The illness seen in terms of a biological theory of disorder) Illness (The person’s subjective experience of their symptoms. What the patient brings to the doctor) Sickness (Social & cultural conceptions of the condition: cultural beliefs and reactions such as fear or stigma. These affect how the patient reacts, and also what is considered a disorder suitable for medical treatment) Disease = biomedical representation of a condition in terms of etiology, symptom complexes & biological explanations. Every culture has beliefs about health and disease; these are learned by individuals, who incorporate these beliefs (fear of cancer; belief that thinness is desirable, etc) into their presentation of symptoms to the doctor. So, the underlying disease is filtered through cultural perceptions to produce the illness as presented to you. This sometimes leads to phenomena such as “the hidden diagnosis” – the idea that a patient sometimes comes to you with a symptom that is not what they actually want to discuss, but they are afraid to raise the real issue (their parents are fighting; they fear they may have an incurable condition, etc). Sickness = more diffuse societal view of the diagnostic label. E.g. what does “cancer” mean to people? The answer varies hugely according to their culture The Illness = the individual’s reaction to the disease, as modified by social & cultural expectations The good MD has to be aware of each level. Insufficient to treat only the disease without treating how it is affecting the patient. Sometimes, cultural views affect our classification of disease: Thomas Szasz spoke of the myth of mental illness 3

WHO Classifications International Classification of Diseases (ICD) Etiological framework Diagnosis of health condition Disease process, signs & symptoms International Classification of Impairments, Disabilities & Handicaps (ICIDH) How people live; body functions Framework to describe activities & participation Covers non fatal outcomes

Conceptions of Disability “a disability is any restriction or lack of ability (resulting from an impairment) to perform an activity in the manner or within the range considered normal for a human being” (WHO International Classification of Impairments, Disabilities, and Handicaps, 1980.)

ICIDH* - 1 Impairment Disability Handicap Internal, body Applied Societal (N.b. dotted arrows indicate that one stage may, but need not, influence the next) * International Classification of Impairment, Disability & Handicap

Issues in the Definition Defining disability in terms of activity limitations is neat, but what activities? What level of limitation should be used? Same expectations for everyone, or relative to age, sex, etc.? Threshold: does not perform an activity, versus cannot perform it? Maybe doesn’t, but could?

ICIDH - 2 Appeared March, 2001 Conceptual changes: From consequences of disease (1980) to components of health (2000) Uses more positive language (‘activity’ & ‘participation’ instead of ‘disability’ & ‘handicap’) Broadens concept of disability More on environmental factors in which the person lives

ICIDH - 2 Health Condition (disorder / disease) Body Functions & structures Activities Participation BODY Structure & Function PERSON Activities SOCIETY Participation impairment limitation restriction

Body Functions Mental functions Sensory Voice & speech CVD, hematological, etc. Digestive, metabolic & endocrine Genitourinary Neuro-musculoskeletal Skin

Activities & Participation Learning Communication Movement Self-care Domestic activities Interpersonal Major life activities Community Exchanging information Communicating Mobility Personal maintenance Home life Social relationships Work & employment Social & civic life

Low negative affect High negative affect A ‘Circumplex’ Model High positive affect active, elated, excited Strong engagement Pleasantness content, happy, satisfied aroused, astonished, concerned Low negative affect High negative affect relaxed, calm, placid distressed, fearful, hostile April 8, 2004. This is intended to go with the discussion on Bradburn’s 2-factor model. Source: Adapted from Tellegen A. Structures of mood and personality and their relevance to assessing anxiety, with an emphasis on self-report. In Tuma AH, Maser JD (eds.) Anxiety and the anxiety disorders. Hillsdale, NJ: Erlbaum, 1985. inactive, still, quiet sad, lonely, withdrawn sluggish, dull, drowsy Disengagement Unpleasantness Low positive affect

Health-Related Quality of Life QoL is deliberately subjective & value-specific Invented in the USA How universally applicable is it? Definition will surely vary across cultures (naïve early enthusiasm for QoL as final outcome) Handicap reflects impairment + environment, so measures may perform differently in different environments

Quality of Life (from a consumer’s perspective) Quality of life is… “Having the important people in your life see your strengths and talents” “A good night’s sleep” “Validation of worth and affirmation of experience” “Having control of your own life” “Taking control of your health condition” “Life free from stigma” “Having a ‘real’ job” “Having a purpose” “Being free to come and go” Carne, B. A consumer perspective. Can J Community Mental Health 1998, Suppl 3: 21.

The Deceptive Simplicity of HRQOL… Health-Related Quality of Life Or Quantity? (How would we we measure quality?) Definition? What model? (Caused by Associated with? or ?) Of life or Living?

Mapping Physical Measures onto Quality of Life Clinical / Physical Markers (the clinician’s concern) cover part of Disease-Specific Dysfunction cover part of Health-Related Quality of Life cover part of Overall Quality of Life (the patient’s concern) Source: SH Kaplan et al. Medical Care, 2000