Rationale: Early diagnosis and treatment is considered important to prevent lung damage in primary ciliary dyskinesia (PCD).
Objectives: Few studies have addressed long-term evolution of lung function after PCD diagnosis. We investigated whether long-term lung function was dependent on age or level of lung function at PCD diagnosis.
Methods: An observational, single-center, cross-sectional, and three-decade longitudinal study of FEV(1) and FVC related to age at diagnosis until current age was performed. Linear regression was used to describe the relation between first measured lung function values and age at diagnosis across the cohort. Courses of lung function after diagnosis and the according slopes were used to group patients into increasing, stable, or decreasing courses. Additionally, slopes from courses of 10 years of follow-up were related to age at diagnosis and initial level of lung function, respectively, using linear regression.
Measurements and main results: Seventy-four children and adults with PCD were observed for median 9.5 (range, 1.5-30.2) years during which 2,937 lung function measurements were performed. First measured FEV(1) was less than 80% of predicted in one-third of preschool-diagnosed children. During observation, 34% of patients lost more than 10 percentage points, 57% were stable, and 10% improved more than 10 percentage points in FEV(1). Courses of lung function after diagnosis were related to neither age at diagnosis nor initial level.
Conclusions: Our study strongly suggests that PCD is a disease of serious threat to lung function already at preschool age, and with a high degree of variation in courses of lung function after diagnosis that was not linked to either age or level of lung function at diagnosis. Early diagnosis did not protect against decline in lung function.