title: Correlation between skin prick test using commercial extract of cow's milk protein and fresh milk and food challenges.
abstract: The skin prick test (SPT) is regarded as an important diagnostic measure in the diagnostic work-up of cow's milk protein allergy. It is not known whether commercial extracts have any advantage over fresh milk. The aims of the study were to (i) compare the diagnostic capacity of SPTs for the three main cow's milk proteins (alpha-lactalbumin, casein and beta-lactoglobulin) with fresh milk and (ii) determine a cut-off that discriminates between allergic and tolerant children in a controlled food challenge. A study was carried out on 104 children consecutively attending two paediatric allergy clinics for suspected cow's milk allergy. A clinical history, SPTs with fresh cow's milk and commercial extracts of its three main proteins and a challenge test were performed on all the children. A study of the validity of the prick test was also performed by taking different cut-off points for fresh milk and its proteins. Twenty-eight of 104 challenge tests (26.9%) were positive. At a cut-off point of 3 mm, fresh milk showed the greatest negative predictive value (98%), whereas casein showed the greatest positive predictive value (PPV, 85%). Calculation of 95% predicted probabilities using logistic regression revealed predictive decision points of 12 mm for lactalbumin, 9 mm for casein, 10 mm for beta-lactoglobulin and 15 mm for fresh cow's milk. We found that the greater the number of positive SPTs for milk proteins, the more likely the positive response to challenge. Having a positive SPT for all three milk proteins had PPV of 92.3% and would seem more clinically useful than any cut-off. Both fresh milk and cow's milk extract of the three main proteins could be useful in the diagnostic work-up of cow's milk allergy. Finding positivity to all three cow's milk proteins seems to be a simpler and more useful way of avoiding oral food challenges.
authors.affiliation: Department of Paediatrics, San Camillo de Lellis Hospital, Rome, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Calvani
authors.forename: Calvani
authors.initials: C
authors.lastname: Mauro
authors.forename: Claudia
authors.initials: C
authors.lastname: Alessandri
authors.forename: Alessandri
authors.initials: A
authors.lastname: Claudia
authors.forename: Tullio
authors.initials: T
authors.lastname: Frediani
authors.forename: Frediani
authors.initials: F
authors.lastname: Tullio
authors.forename: Sandra
authors.initials: S
authors.lastname: Lucarelli
authors.forename: Lucarelli
authors.initials: L
authors.lastname: Sandra
authors.forename: Stefano
authors.initials: S
authors.lastname: Miceli Sopo
authors.forename: Miceli Sopo
authors.initials: MS
authors.lastname: Stefano
authors.forename: Valentina
authors.initials: V
authors.lastname: Panetta
authors.forename: Panetta
authors.initials: P
authors.lastname: Valentina
authors.forename: Daniela
authors.initials: D
authors.lastname: Zappalã
authors.forename: Zappala'
authors.initials: Z
authors.lastname: Daniela
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Zicari
authors.forename: Zicari Anna
authors.initials: ZA
authors.lastname: Maria
mesh_terms: D000818:Animals; D002364:Caseins; D002417:Cattle; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007768:Lactalbumin; D007782:Lactoglobulins; D008297:Male; D016269:Milk Hypersensitivity / Q000175:diagnosis*; D012680:Sensitivity and Specificity; D012882:Skin Tests / Q000379:methods*
chemical_list: D002364:Caseins; D007782:Lactoglobulins; D007768:Lactalbumin