ColloquiumSCINSCAN PAAMOST

dr. N.W. de Jong

Erasmus MC

Rotterdam

Topics

Factors influencing skin test Literature Erasmus MC Demonstration Cut-off value Distribution

Factors influencing skin prick test result

Allergen:

quantitypotencyquality

Design of lancet:

Needle hight needle thicknessShape of shoulder

Drawing of the wheal:

PerformancePen thicknessInk diffusion in skin and adhesive tape

Performance:

PressureAngleTime

Histological features:

Density of mast cellsIgE on mast cellsThickness of skinDensity of receptors

Area determination:

Plus signs (1+ - 5+)Mean diameter L + W /2Area calculation:

π x (D mean/2) 2

L.K. Poulsen, C. Bindslev- Jensen, H.J. Malling Clun. Exp. Allergy 1993,23;61-8

Scanning skin test results

Advantages

Reproducibility ? Accuracy ? Efficiency? Digital ? Cut-off values? Statistical analysis?

Elips Polygonal

Wohrl S, Vigl K, Binder M, Stingl G, Prinz M. Exp Dermatol. 2006 Feb;15(2):119-24

1.Poulsen LK, Lijsberg C, Binslev-Jensen C, Mailing HJ. Precise area determination of skin prick tests: validation of a scanning device and software for a personal computer. Clin Exp Allergy 1993;23:61-8.

2.Poulsen LK, Binslev- Jensen C, Rihoux JP. Quantitative determination of skin reactivity by two semiautomatic devices for skin prick test area measurements. Agents Actions. 1994 Jun;41 Spec No:C134-5.

3.Pijnenborg H, Nilsson L, Dreborg S. Estimation of skin prick tests reactions with a scanning program. Allergy 1996:51:782-8.

4.Eigenmann PA, Sampson HA. Interpreting skin prick tests in the evaluation of food allergy in children. Pediatr Allergy Immunol. 1998 Nov;9(4):186-91.

5.Wohrl S, Vigl K, Binder M, Stingl G, Prinz M. Automated measurement of skin prick tests: an advance towards exact calculation of wheal size. Exp Dermatol. 2006 Feb;15(2):119-24

Literaturescanning method

1.Poulsen LK, Lijsberg C, Binslev-Jensen C, Mailing HJ. Precise area determination of skin prick tests: validation of a scanning device and software for a personal computer. Clin Exp Allergy 1993;23:61-8.

-Cutting and weighting paper-Area by diameters-Hand held scanner

Conclusion: hand held scanner highly precise, easy to use, time consuming (5 min/ skin test)

Literature

2.Poulsen LK, Binslev- Jensen C, Rihoux JP. Quantitative determination of skin reactivity by two semiautomatic devices for skin prick test area measurements. Agents Actions. 1994 Jun;41 Spec No:C134-5.

comparing 2080 spt’s

-digitizer pen

-hand held scanner

Conclusion: digitizer gives larger areas than the scanner, scanner more precise

Literature

3.Pijnenborg H, Nilsson L, Dreborg S. Estimation of skin prick tests reactions with a scanning program. Allergy1996:51:782-8.

Comparing 160 SPT’s:

-Area = π x (D mean/2) 2

-Scanning method:

encircled, transferred to a record sheet by means of translucent tape

Conclusion: Area scanner significant more precise, better CV

Literature

4. Eigenmann PA, Sampson HA. Interpreting skin prick tests in the evaluation of food allergy in children. Pediatr Allergy Immunol. 1998 Nov;9(4):186-91.

Comparing two SPT’s recording methods with oral food challenge (n=160)

-mean wheal diameter

-hand held scanner

sensitivity/ specificity

Conclusion: no significant differences in predictive values between methods

Literature

5.Wohrl S, Vigl K, Binder M, Stingl G, Prinz M. Automated measurement of skin prick tests: an advance towards exact calculation of wheal size. Exp Dermatol. 2006 Feb;15(2):119-24Software automatically analysis scanned images and calculates the size of wheals inner border.

Pilot study:

Comparing 110 SPT’s Histamine. CV area versus Diameter

CV horizontal diameter: 37.9%

CV maximal/ minimal diameter: 25.9%

CV scanning method: 11.9%

Literature

Scanning method

Wohrl S, Vigl K, Binder M, Stingl G, Prinz M. Exp Dermatol. 2006 Feb;15(2):119-24

a. Original imageb. Blue color to greyc. Increase contrastd. Wheal’s contour

middle e. Close gapsf- i superimposition of reconstruction

NW de Jong*, E Hoorn**, PGH Mulder***,H de Groot*, R Gerth van Wijk**Department of Allergology, **Department of Information and Technology, ***Department of Epidemiology & Biostatistics, Erasmus MC, Rotterdam, the Netherlands

SKINSCAN development 1998- …

-Poster 2002: Determination of ICT and SPT reactions with a scanning program

-Analyse 2005: Calculating Heic and Hep index with a scanning program.

 

-Thesis N.W. de Jong 2004: Reproducibility and stability of "in house manufactured" extracts used in the diagnosis of IgE mediated allergy.

NW de Jong*, E Hoorn**, PGH Mulder***,H de Groot*, R Gerth van Wijk*

*Department of Allergology, **Department of Information and Technology, ***Department of Epidemiology & Biostatistics, Erasmus MC, Rotterdam, the Netherlands

Results:Reproducibility SPT; histamine response 8 replicate observations per subject.

Intraoperator c.v 0.82%, Interoperator c.v.: 0.95%, day-to-day c.v. : 1.53%

Comparing with Pijnenborg et al.:Intraoperator c.v.: 1.4%, Interoperator: 2.3%, day -to- day c.v.: 1.9%

Skinscan

Demonstration

Suppression of histamine and grass pollen induced early and late phase skin reaction by levocetirizine (LCTZ). (In press)Dr. N.W de Jong*, E. Hoorn**, Dr. PGH Mulder***, Prof. Dr. R. Gerth van Wijk*

N = 240

Histamine CV SPT 19% (Niemeyer 27.2%) (Lower SPT areas may lead to

big measurement errors when calculated by hand.)

CV ICT 15% (Niemeyer 15.9 %)

Grass pollen CV SPT 20% CV ICT 13%

CV late phase skin 26%. (N = 120)

The use of the skinscan program to calculate skin test areas in scientific research. Coefficient of variation

Chapter 7: Optimization of Skin testing, evaluation of cut-off values

Optimally cut-off value using mean wheal diameter: ICT 0.7, SPT 0.4Predictive value: ICT: RAST 83%; Anamnesis 77%SPT: RAST 77%; Anamnesis 86%

Examples: ICTHistamine 8 mm; grass pollen 5 mm:5/8 = 0.62 (negative) or 6/8 = 0.75 (positive)

SPTHistamine 7 mm; peanut 3 mm: 3/7 = 0.42 (positive)

Skin test reagent in the diagnosis of atopic diseaseN.R. Niemeyer; thesis 1996

n = 1500

6 differentinhalationallergens:

D. pteronyssiusBirchGrassMugwortKatDog

Determination of cut-off values using skin test areaHEIC index: Histamine Equivalent Intracutanous index Area versus diameter

HEIC Cut off value X (diameter) = 0.7; Y (AREA) = 0.55

HEP Cut off value X (diameter) = 0.4; Y = (AREA) = 0.21

Determination of cut-off values using skin test areaHEP index: Histamine Equivalent Prick indexArea versus diameter

n = 120010 different

Food allergens: Scrimp

Curry

Egg- white

Cows milk

Peanut

Soy

Peach

Wheat

Celery

Tomato

totalen hep diameter < 2.0

y = 0,6362x2 + 0,2738xR2 = 0,9506

0,00

0,50

1,00

1,50

2,00

2,50

3,00

3,50

4,00

0,00 0,50 1,00 1,50 2,00 2,50

hep diameter

hep

area

Skinscan

Advantages

Reproducibility: low CV intra, inter & day to day Accuracy: low CV SPT & ICT Efficiency: fast, easy, cheap Digital: step forward to electronic dossier Cut-off values more research on predictive values Statistical analysis via access, statistics are easily done Future: Dutch data bank skin test results

St. Elisabeth ziekenhuis, Tilburg

Leids Universitair Medisch, Centrum

Universitair Centrum, Maastricht

Universitair Medisch Centrum, Groningen

Maasstad, Rotterdam

Diakonessenhuis, Utrecht

Diakonessenhuis, Voorburg

Scinscan distribution

ColloquiumSkinScan PAAMOST

Dept. of Information and Technology:

Ed HoornNico Drost

Dept of Epidemiology & Biostatistics:

Paul Mulder

Dept. of Allergology:

Nicolette de JongIlse GroenendijkHans de GrootRoy Gerth van Wijk