Predicting the performance of daily activities of patients with chronic lung disease.

40 men and 60 women between the ages of 40 and 59 yr. of age and having the diagnosis of chronic obstructive lung disease as measured by Fev1 values of less than 70% predicted pulmonary function were administered an outcome measure of functional ability, the Sickness Impact Profile. A prediction equation for functional ability, the variables of sex, socioeconomic status, respiratory impairment, and self-reporting of symptoms for analysis. In the two-variable model socioeconomic status and self-reporting of breathing difficulty contributed to 28% of the total variability in functional ability scores. In the three-variable model, adding the third independent variable of respiratory impairment (Fev1) did not significantly increase the explained variability in the outcome measure.