Correspondence between symptoms and preference-based health status measures in the STOP study

Pulmonary exacerbations (PEx) in cystic fibrosis (CF) patients decrease lung function, increase symptoms and reduce health-related quality of life (HRQoL). We evaluated associations between 8 symptom-based questions from the Cystic Fibrosis Respiratory Symptom Diary - Chronic Respiratory Infection Symptom Score (CFRSD-CRISS) and the 5-level EuroQOL-5 Dimensions (EQ-5D-5 L) summary score and hypothesized the CFRSD-CRISS would be well-correlated with quality-of-life measures among CF patients with PEx.

CF patients who had CFRSD-CRISS and EQ-5D-5L measurements on the day of the initial PEx, 7 days later, and at the end of intravenous antibiotic treatment were included. We examined age-stratified (<18 versus ≥18 years old) characteristics, including the percent predicted of forced expiratory volume in 1 s (ppFEV1), CFRSD-CRISS measurements, and domains of the EQ-5D. We also calculated age-stratified Pearson correlation coefficients between the EQ-5D-5L and CFRSD-CRISS items at each of the 3 time points.

A total of 169 patients were analyzed. Patients reported having problems performing usual activities and with pain/discomfort on the first day of the PEx and these measures improved by the end of treatment. PpFEV1 improved in both age categories by the end of PEx treatment but was not associated with the change in summary EQ-5D-5 L over the time of PEx treatment (r-squared = 0.029). Correlations were weak (generally <0.4) between the elements of the EQ-5D-5 L versus the CFRSD-CRISS.

Value assessment of treatments for CF PEx will require the collection of preference-weighted measures rather than only the symptom-based questions of the CFRSD-CRISS.