Rate of pulmonary function decline in South African children with cystic fibrosis.

Abstract

Background: Pulmonary function tests (PFT) objectively measure the extent and progression of cystic fibrosis (CF) lung disease. The rate of PFT decline has not been studied in developing countries.

Objectives: This study investigated the average annual rates of pulmonary function decline in South African children with cystic fibrosis (CF) from 1999 to 2006.

Design: The individual medical records and best PFT over three-monthly intervals were retrospectively reviewed and analysed using the mixed model regression method.

Setting: CF clinic at Red Cross War Memorial Children’s Hospital, Cape Town, South Africa – a tertiary level paediatric teaching hospital.

Subjects: 79 children over five years of age with CF.

Primary outcome measures: Estimated mean forced expiratory volume in one second (FEV1) at six years of age and average annual rate of FEV1 decline.

Results: 1139 PFT were recorded, with a median (IQR) of 14 (6 – 21) PFT per patient. With no covariates in the model, the estimated mean (SE) FEV1 at age six years was 73.83 (3.34) percent predicted and the annual FEV1 decline was 0.23 (0.43)%. FEV1 at age six was affected by age at CF diagnosis, genotype, and year of birth. Rate of FEV1 decline was significantly affected by Pseudomonas aeruginosa colonisation and genotype.

Conclusions: Although FEV1 at age six years was low compared to developed countries, the annual rate of FEV1 decline in South African children with CF was minimal setting the scene for improved survival in this population.