Precision and accuracy of clinical and radiological signs in premature infants at risk of patent ductus arteriosus
P. Davis, S. Turner-Gomes, K. Cunningham, C. Way, R. Roberts and B. Schmidt
Department of Pediatrics, McMaster University, Hamilton, Ontario.
OBJECTIVE: To determine the precision (interobserver agreement) and
accuracy (agreement with criterion standard) of clinical and radiological
signs in premature infants at risk of patent ductus arteriosus (PDA) with
left-to-right shunting. DESIGN: Masked comparison of clinical and
radiological examination with Doppler flow echocardiography (criterion
standard). SETTING: Neonatal intensive care unit. PATIENTS: One hundred
infants with birth weights less than 1750 g were studied once between days
3 and 7 of life. A third of the cohort was intubated at the time of study.
INTERVENTION: Five independent observers noted the presence or absence of
an increased pulse volume, an active precordium, a heart murmur, a
cardiothoracic ratio greater than 60%, increased pulmonary vascular
markings on a concurrent chest x-ray film, and a relative increase of the
cardiothoracic ratio compared with that from the previous chest x-ray film.
Pulsed and color flow Doppler echocardiography was performed within 4
hours. All 100 tapes were reviewed by a second pediatric cardiologist.
RESULTS: Twenty-three infants had a PDA with left-to-right shunting. The
precision of clinical signs was modest, with average kappa values of 0.15
for pulse volume, 0.32 for precordium, and 0.41 for murmur. Pulse quality
(43%) and murmur (42%) had the highest mean sensitivities. Corresponding
specificities were 74% for pulse volume and 87% for murmur. The combination
of a cardiac murmur with an abnormal pulse volume had the highest positive
predictive value (77%). The radiological examination did not improve the
observers' ability to distinguish between patients with and without PDA.
CONCLUSIONS: The precision and accuracy of clinical and radiological signs
of a PDA with left-to-right shunting are unsatisfactory. Therefore, Doppler
flow echocardiography is required to diagnose PDA confidently in preterm
infants between days 3 and 7 of life.
