Impact of lung function interpretation approach on pediatric bronchiolitis obliterans syndrome diagnosis after lung transplantation.

BACKGROUND

The diagnostic criteria for bronchiolitis obliterans syndrome (BOS) are predominantly adult-focused. The relationship between application and impact of reference equation choice on pediatric baseline lung function achieved and subsequent BOS diagnosis remains unclear.

METHODS

Lung function spirometry data (FEV(1), FVC and FEF(25-75)) from pediatric subjects transplanted at the Great Ormond Street Hospital over a 10-year period were collated. Baseline values achieved after lung transplantation and BOS rates were examined. Raw values were compared with 2 different reference equations (the "Brompton" and modern collated "All-age" equations). The impact of FEF(25-75) baseline definition was investigated.

RESULTS

Fifty subjects were included, 17 males and 33 females, transplanted at a median (range) age of 14.0 years (3.2 to 17.3 years, 83% >10 years old), and followed for 1,028 (388 to 2,613) days post-transplantation. Raw values underestimated baseline lung function attainment for all indices. Magnitude of baseline lung function was affected by reference equation choice. Mean FEV(1) values were: Brompton 97.9% (SD 20.3%) and All-age 86.3% (SD 15.4%) of predicted (p < 0.0001). BOS 0p incidence was significantly higher for All-age predicted than for raw values (64% and 40%, respectively, p = 0.027). Modification of FEF(25-75) baseline (to either FEV(1) or FVC baseline) led to a reduction in BOS 0p detection (p < 0.01).

CONCLUSIONS

Modern collated reference equations should be used for lung function monitoring in pediatric subjects after lung transplantation. Standardization of FEF(25-75) baseline definition is urgently required. These data question the utility of the FEF(25-75) criterion as an early marker of BOS 0p in pediatric subjects.