walk test. This confirms the validity of the physical functioning
scale. In the other scales NYHA functional class and the six
minute walk test also contributed consistently to the
explained variance, although the effect was small (10–28%).
On the one hand, the SF-36 seemed to differentiate clearly
between different grades of severity of disease, as measured by
the NYHA functional classification, the six minute walk test,
and peak oxygen uptake; on the other hand, most of the variability
in quality of life remained unexplained by the
established indicators of the severity of congestive heart failure.
This seems consistent with the findings of Wilson and
colleagues,36 who showed little or no relation between
perceived exercise intolerance—as measured by the Minnesota
living with heart failure questionnaire—and objective
measures of circulatory or ventilatory dysfunction.
These results raise the question as to which predictors
besides the most obvious prognostic somatic variables
influence the quality of life in congestive heart failure.
According to Steptoe and colleagues,18 psychological adjustment
may be a major determinant of quality of life. The influence
of other variables on quality of life—such as neurohumoral
factors and cytokines, which are known to be increased
in congestive heart failure20 37—is presently unclear. It is also
possible that the daily hassles of the disease cause chronic
stress. Depending on the degree of underlying vulnerability,
this could lead to a feeling of hopelessness followed by
depression and reduced quality of life.38 3