The pulmonary and extrapulmonary effects of the disease
have an impact on physical, emotional, and mental
well-being in COPD patients. Although the assessment
of COPD relies mainly on the degree of airflow
limitation (i.e., the decrease in forced expiratory volume
in one second (FEV1)), there is evidence that FEV1 has
a relatively poor correlation with symptoms, HRQoL
and daily functioning. Therefore, other models in
addition to strict medical models are increasingly used
to explain differences in daily functioning and HRQoL
in chronically ill patients. These models presume that
biological factors as well as psychological and social factors play a significant role in the explanation of functioning and HRQoL in chronic illnesses. One of the
psychological factors that is considered important in this
context is illness perceptions. Illness perceptions are the
central concept of the Common Sense Model (CSM). This model suggests that people have personal beliefs about their illness that often do not match medical views but that nevertheless determine, to a large extent, how people respond to their illness. These illness perceptions include beliefs about consequences, the timeline of the disease, ability to control the disease and the extent to which the treatment helps in controlling the disease. They also include perceptions of symptoms attributed to the disease (identity), understanding of the disease, concerns and emotional response to the disease. The CSM presumes that these various dimensions
of illness perceptions are logically related to health
behaviours and HRQoL. Therefore, these perceptions
are considered key elements for understanding the ways
that people attempt to manage threats to their health. The CSM is depicted in Figure 1.