Pulmonary Exacerbation Score in Cystic Fibrosis Patients: Reliability and Validity Testing

Background: Lung disease in cystic fibrosis (CF) is characterized by recurrent pulmonary exacerbations (PEs), but consensus on diagnostic criteria for PE is lacking. The use of a consistent definition of PE as an outcome measure in CF clinical trials would allow meaningful comparison across centers. The aim of this study was to assess the reliability and validity of a simplified version of the Seattle Pulmonary Exacerbation Score (SPEX). Materials and Methods: A cross-sectional observational study with review of case notes was conducted on pediatric patients with CF in an outpatient setting. Inter-investigator reliability was assessed using the kappa coefficient of agreement, and intra-investigator reliability was examined following re-evaluation 21 months after the initial assessment. The validity of the SPEX was analyzed using independent clinical assessment as the "gold standard." The performance of the original and simplified scores was compared. Results: Inter- and intra-investigator reliability of SPEX scores were excellent (kappa = 0.91 and 0.98, respectively). Validity testing yielded a kappa coefficient of 0.63. The sensitivity and specificity of the SPEX in detecting PE were 89.4% and 84%, respectively. The SPEX performed as well as the original measure. Conclusions: The SPEX is objective and repeatable. This quick and simple-to-use measure performed as well as the original version and is applicable to a real-life pediatric population outside of the context of narrowly defined clinical parameters. The use of the SPEX to diagnose PE consistently in children with CF is thus recommended.