Study objectives: The development and psychometric properties of an additional disease-specific module of the Questions on Life Satisfaction for adolescents and adults with cystic fibrosis (FLZ(M)-CF) are described. The Questions on Life Satisfaction (FLZ(M)) instrument allows the respondent to rate the subjective importance and her/his satisfaction with different domains of life.
Methods: A preliminary 16-item version of the scale was employed in a study with 243 German patients with cystic fibrosis (CF) [16 to 58 years of age; FEV(1), 15 to 121% of predicted], together with the "general life satisfaction" module and the "satisfaction with health" module of the FLZ(M). Item elimination according to the principle of least common variance resulted in the final nine-item version.
Results: Cronbach alpha for the FLZ(M)-CF was 0.80; the split-half reliability was 0.72. Convergent validity of the scale was indicated by Pearson correlations of r = 0.75 with the generic satisfaction with health scale of the FLZ(M), r = 0.30 with FEV(1)%, and r = - 0.26 with daily time for home therapy. The scale discriminated significantly between patients with and without need for assistance in daily life and between patients with and without a partner.
Conclusions: The FLZ(M)-CF is a reliable and valid instrument, and it is short enough to be used as screening instrument. The combination of generic and disease-specific scales within the FLZ(M) allows comprehensive measurement of life satisfaction for patients with CF who are > 15 years old.