Introduction and objectives Progressive respiratory disease accounts for most of the mortality and morbidity in CF. Identification of early lung disease is imperative to recognise young patients who are at high risk of developing future lung damage. The London CF collaboration has shown that infant pulmonary function at one and at two years is essentially normal, and one year HRCT has mild abnormalities only, so new markers need to be identified. We have used ventilation scans (VS) at the CF annual assessment in infants too young to perform standard pulmonary function tests; VS are more sensitive than chest radiography, and have been used to guide immediate management. We hypothesised that an abnormal pre-school lung VS predicted worse spirometry by age six years in CF children.
Methods Data from children born after 2000 under the care of the RBH were retrieved from hospital databases and Port CF. We recorded demographics (gender, age, CFTR genotype, weight, height, ethnicity) and spirometry nearest to 6 years of age because repeatable measurements in a clinical context are feasible at this age. The primary outcome was FEV1% predicted (%p) (GLI reference equation (http://www.lungfunction.org/); and VS at annual assessment. Between 1–5 scans were performed prior to the age 6 year spirometry, and were independently reported as normal or abnormal (at least one abnormal VS). Statistical analysis was performed using Student t test. P < 0.05 was considered significant.
Results 143/217 children (72 females, 71 males) had data on VS and spirometry available; mean age at first spirometry was 6.36 (range 5.0–7.6). The remaining 73 were excluded due to late diagnosis, moving away before the first reliable spirometry, or first being seen later than the window for ventilation scans (1–5 years). Children with ≥1 abnormal VS had a statistically significant reduction in lung function (mean FEV1% p 83.4%) when compared with children with normal ventilation scans (mean FEV1% p%89.6), P = 0.03 (Figure 1).
Conclusion Although abnormal VS predict abnormal first spirometry, the overlap between the two groups means that VS are not a useful clinical tool to delineate a high risk group.