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Colloquium SCINSCAN PAAMOST dr. N.W. de Jong Erasmus MC Rotterdam
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Topics Factors influencing skin test Literature Erasmus MC Demonstration Cut-off value Distribution
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Factors influencing skin prick test result Allergen: quantity potency quality Design of lancet: Needle hight needle thickness Shape of shoulder Drawing of the wheal: Performance Pen thickness Ink diffusion in skin and adhesive tape Performance: Pressure Angle Time Histological features: Density of mast cells IgE on mast cells Thickness of skin Density of receptors Area determination: Plus signs (1+ - 5+) Mean diameter L + W /2 Area calculation: π x (D mean/2) 2 L.K. Poulsen, C. Bindslev- Jensen, H.J. Malling Clun. Exp. Allergy 1993,23;61-8
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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
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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 Literature scanning method
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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
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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
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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
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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
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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 Software 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
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Scanning method Wohrl S, Vigl K, Binder M, Stingl G, Prinz M. Exp Dermatol. 2006 Feb;15(2):119-24 a.Original image b.Blue color to grey c.Increase contrast d.Wheal’s contour middle e.Close gaps f- isuperimposition of reconstruction
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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.
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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%
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Skinscan Demonstration
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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
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Chapter 7: Optimization of Skin testing, evaluation of cut-off values Optimally cut-off value using mean wheal diameter: ICT 0.7, SPT 0.4 Predictive value: ICT: RAST 83%; Anamnesis 77% SPT: RAST 77%; Anamnesis 86% Examples: ICT Histamine 8 mm; grass pollen 5 mm: 5/8 = 0.62 (negative) or 6/8 = 0.75 (positive) SPT Histamine 7 mm; peanut 3 mm: 3/7 = 0.42 (positive) Skin test reagent in the diagnosis of atopic disease N.R. Niemeyer; thesis 1996
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n = 1500 6 different inhalation allergens: D. pteronyssius Birch Grass Mugwort Kat Dog Determination of cut-off values using skin test area HEIC index: Histamine Equivalent Intracutanous index Area versus diameter HEIC Cut off value X (diameter) = 0.7; Y (AREA) = 0.55
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HEP Cut off value X (diameter) = 0.4; Y = (AREA) = 0.21 Determination of cut-off values using skin test area HEP index: Histamine Equivalent Prick index Area versus diameter n = 1200 10 different Food allergens: Scrimp Curry Egg- white Cows milk Peanut Soy Peach Wheat Celery Tomato
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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 valuesmore research on predictive values Statistical analysisvia access, statistics are easily done Future:Dutch data bank skin test results
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St. Elisabeth ziekenhuis, Tilburg Leids Universitair Medisch, Centrum Universitair Centrum, Maastricht Universitair Medisch Centrum, Groningen Maasstad, Rotterdam Diakonessenhuis, Utrecht Diakonessenhuis, Voorburg Scinscan distribution
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Colloquium SkinScan PAAMOST Dept. of Information and Technology: Ed Hoorn Nico Drost Dept of Epidemiology & Biostatistics: Paul Mulder Dept. of Allergology: Nicolette de Jong Ilse Groenendijk Hans de Groot Roy Gerth van Wijk
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