PURPOSE: Pediatric lung disease is often diagnosed and monitored by a simple, easy test that can be done in the primary pediatrician's office or at home in addition to, at times, history and physical alone. In order to validate the use of peak expiratory flow (PEF), our study compares PEF with pulmonary function testing (PFT) in children with airway disease.
METHODS: This is a retrospective validation study. All PFT performed between June 2004 and February 2006 on patients between 4 and 18 years of age were collected from our hospital's pulmonary laboratory database and our pulmonology clinic. PEF values were measured as an integral part of the PFT report. All studies were interpreted by three pediatric pulmonologist. The PFT were categorized as normal, obstructive, restrictive and mixed pattern based not only on numbers, but also on the shape of the flow-volume curve. The PFT with an obstructive component were subsequently subdivided in two groups, according to the forced expiratory volume in 1-second (FEV1) predicted percentage value (>=80% and <80%). Validity statistics assessing the ability of PEF to identify obstructive lung process were calculated. Normal PFT were used as controls.
RESULTS: 329 tests were obtained, 140 were from the hospital's database and 189 from the pulmonology clinic. Subjects' mean age was 9.6 (range 4-18). Among the 329 tests, 155 were reported as normal, 85 obstructive, 47 restrictive and 42 mixed. PEF sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios were calculated. These statistics for PEF validated with PFT (FEV1>=80%) are: 29,19,12,41,0.37 and 3.64 respectively. For PEF validated with PFT (FEV1<80%) are: 70,80,36,94,3.66 and 0.36 respectively.
CONCLUSION: PEF correlated poorly with PFT. PEF appears to be an unreliable tool when used to evaluate and manage patients with pulmonary disease.
CLINICAL IMPLICATIONS: While the majority of children are seen by their primary physician and managed exclusively using history, physical and simple tools such as PEF, the validity and reliability of this test must be considered prior to its use.
DISCLOSURE: Edith Allen, None.