Realities of expectorated sputum collection in the pediatric cystic fibrosis clinic.

Objectives: To determine the proportion of pediatric patients with cystic fibrosis who do not produce expectorated sputum during routine ambulatory clinic visits and to identify clinical predictors of these patients.

Design: Cross-sectional study.

Setting: The cystic fibrosis clinic at The Hospital for Sick Children, Toronto, Ontario.

Participants: One hundred eighty-three patients aged 6 to 18 years who attended the cystic fibrosis clinic between March 1, 2004, and November 30, 2004.

Intervention: Study patients were asked to expectorate sputum for bacterial culture.

Main Outcome Measures: The proportion of patients unable to produce expectorated sputum was determined. Age, sex, forced expiratory volume in 1 second, pancreatic sufficiency, body mass index, and antibiotic use were compared between patients producing sputum and those not producing sputum.

Results: Eighty-three patients (45%) did not expectorate sputum. Patients not producing sputum as compared with those producing sputum were younger (mean age, 10.3 years vs 13.9 years, respectively; difference, 3.6 years; 95% confidence interval, 2.6-4.5) and had higher forced expiratory volume in 1 second (mean forced expiratory volumes in 1 second, 88% of predicted vs 72% of predicted, respectively; difference, 16%; 95% confidence interval, 10.1-22.2). Eighty-eight percent of patients not producing sputum had cough and 45% reported sputum production at home.

Conclusions: Almost half of pediatric patients with cystic fibrosis aged 6 years and older do not expectorate sputum in the clinic, although nearly half of these patients do report producing sputum at home. The utility of home collection on the morning of a clinic visit and/or hypertonic saline induction should be evaluated to increase the number of useful specimens for microbiological culture.