FOCUS ON RESEARCH 15.1: TESTING A THEORY: THE CONSEQUENCES OF DISEASE
To explore the impact of disease on the constructs defined by the WHO
( Johnson and Pollard 2001).Background
In 1980 the World Health Organization (WHO 1980) proposed a model to describe the
consequences of disease. The aim of the model was to clarify terminology and to present
a structure for understanding disease that went beyond a simple medical perspective. The
model proposed a sequence of consequences of disease which suggested that disease
resulted either in impairment, then disability, then handicap or in a direct path from
impairment to handicap. These constructs are defined as follows. Impairment is the loss
or abnormality of structure or function and often operates at the level of the organ
rather than the individual. Lung cancer may cause impairment to the lungs and heart
disease results in impairment of the cardiovascular system. Disability refers to the
restriction or lack of ability to perform activities and operates at the level of the indi-
vidual. For example, lung cancer and heart disease may both result in the inability to
climb stairs. Finally, handicap refers to disadvantage and role limitation and operates
as the level of the individual as they exist within their social context. Lung cancer
and heart disease may prevent an individual from bringing in an income and being
financially independent. The WHO model treats these concepts as separate and suggests
some degree of causal link between then.Aims
In this paper, Johnston and Pollard (2001) aimed to empirically test the WHO model
of the consequences of disease and first to see whether existing measurements allow
separation of the three main concepts and second to assess whether there was any
support for the causal link between them.Methodology
Design The study used cross-sectional and longitudinal designs with three patients
groups. Disabled adults were examined using a cross-sectional design and MI and stroke
patients were explored using a longitudinal design.Participants MI patients: 108 male and female patients were recruited within 72
hours of admission to a coronary care unit following an MI. They were interviewed on
admission and 1 week, 2 months, 6 months and 12 months after discharge.
Stroke patients: 68 men and women were recruited within 20 days of admission
for stroke. They were interviewed in hospital and then one and six months after
discharge.
Disabled patients: 101 male and female disabled adults were selected from a
primary care data base. They were interviewed once.374 HEALTH PSYCHOLOGY