George F. Kroker, MD FACAAI

1. Tools of the Allergist:A review of diagnostic techniques George F. Kroker, MD FACAAI

2. Tools of the Allergist • Skin Tests • Scratch • Skin Prick Test • Intradermal (ID, IDT) • In Vitro Tests • Specific IgE • RAST (radioallergosorbent test) • ELISA (enzyme-linked immunosorbent assay) • Total IgE, other immunological tests

3. Test Preferences—Vary by Specialty • Board Certified Allergist • Skin Prick Test (SPT) • Intradermal Test (ID) • In Vitro Specific IgE • ENT Allergist • Intradermal Dilutional Test (IDT) • Modified Quantitative Test (MQT) • In Vitro Specific IgE

4. Annals of Allergy 101:580-592, 2008

5. The Importance of the History • “The clinical history drives the diagnosis of human allergic disease…the clinical history makes the critical link between the allergy skin or blood test results and the allergic disease” Pearls and pitfalls of allergy diagnostic testing: report from the ACAAI/AAAAI Specific IgE Test Task Force Annals of Allergy 101:580-592, 2008

6. The Importance of History (cont.) • “Diagnostic tests should be used to support or exclude a diagnosis of specific allergies based on the history. They should almost never be used as a substitute for a careful history…neither skin tests nor serum IgE tests should be either requested or interpreted outside the context of the clinical history and physical examination…” Pearls and pitfalls of allergy diagnostic testing: report from the ACAAI/AAAAI Specific IgE Test Task Force Annals of Allergy 101:580-592, 2008

7. The La Crosse Method Perspective We recognize that various allergy testing techniques have their rightful place Our ultimate goal is to deliver SLIT treatment at the optimum therapeutic level in a streamlined manner Our testing protocols have been developed to provide a high degree of quantification of the patient’s sensitivities as efficiently as possible

8. Where are we now? • Optimized IDT: streamlined to reduce patient’s time in the office • Selective use of In Vitro testing • Determine which specific SLIT protocol is best suited for the patient • Treat at the therapeutic dose • Retest allergens being treated to monitor effectiveness of current dose

9. How did we get here? Brief review of skin testing techniques History of skin testing techniques Types of techniques Principles applicable to all techniques Advantages & disadvantages of each technique

10. History of the Skin Test Charles Blackley, MD 1820-1900 Daily Pollen Counts May 28-Aug 1, 1866

11. Types of Skin Tests Epicutaneous Scratch Prick-puncture Modified prick Intradermal Single strength Intradermal Dilutional Titration (IDT)

12. Skin Testing: A Common Goal

13. Factors influencing skin test reactivity Age: Reactivity progressively increases throughout childhood to about age 20-30, then gradually declines until age 50, after which the decline is more rapid Menstrual cycle: Reactions to allergen & histamine larger at midcycle Seasonal: Reactions to a seasonal allergen are greater just after the allergy season is finished Sun Damage: Affects skin mast cell number

14. Factors influencing skin test reactivity Site tested: Upper back > lower back> forearm Clinical status on day of testing: Heavy allergen exposure immediately before testing can enhance reactivity Other diseases: cancer, etc. Medications: Antihistamines, tricyclic antidepressants, H2 antagonists reduce reactivity

15. Wait time for testing after med d/c

16. Epicutaneous: Scratch Test • Method: Knife blade or allergen abrades an area of skin in linear fashion, producing a superficial scratch. Allergen extract applied. • Advantage: • Time • Safety • Disadvantage: • Lack of uniformity of abrasion • Uncomfortable & traumatic • Increased false pos & false neg compared to prick/puncture

17. Epicutaneous: Puncture Test Method: Drop of extract is placed on the skin Testing device (lancet, bifurcated needle) placed perpendicular to the skin Device is tapped gently through the drop of extract, and held on the skin with pressure for about 1 second

18. Epicutaneous: Modified Prick Test Method: Drop of extract placed on skin Needle is introduced laterally into skin at an angle, through the drop Skin is lifted up with no downward pressure introducing a minute amount of extract into the skin

19. Stand-Alone Skin Prick Tests Stand-alone SPT favored by many allergists for its specificity, safety, and efficiency Reactions are graded based on wheal size, presence of pseudopods, and in comparison to pos/neg controls Results graded from 1+ to 4+ Multi-prong device may be used to speed application and provide consistency

20. Epicutaneous Skin Testing The skin prick test: “more than meets the eye” David Bernstein MD Ann Allergy 92: 587-588, June 2004 (editorial) “Despite its widespread adoption as the premier method used in clinical practice, many characteristics of the skin prick or puncture test are poorly defined…it is concerning that a standard protocol for skin prick testing has yet to be universally adopted. Arcane systems are still being used to grade skin prick test wheal-and-flare responses (i.e., grade 1 to 4+) which greatly impedes communications of results between different clinics.”

21. Intradermal: Single-strength Allergy: Principles & Practice, 5th ed 1998 E. Middleton Ed. “The value of prick tests is limited by low potency extracts producing false negative results.” “Infrequently, an intradermal test will reveal a clinically relevant reaction in the case of a negative prick test.”

22. Intradermal: Single-strength Joint Task Force on Practice Parameters for the Diagnosis and Treatment of Asthma Ann Allergy Asthma Immunol 75:543-625, 1995. “Intracutaneous testing may be useful and should be pursued if the prick/puncture test is negative or equivocal to allergens strongly suggested by the patient’s history or exposure.”

23. Intradermal: Single-strength Method: Testing performed with disposable tuberculin syringe and small gauge needle A small amount (.02ml) of dilute extract is injected into the superficial layers of the skin, making wheals approximately the same size

24. Intradermal: Single-strength • Advantage • More sensitive than prick test • Disadvantage • Less specific than prick test • Rate of systemic reactions, <0.5% • Can cause large local reactions • First fatality reported 1922 fish ID injection

25. Epicutaneous Skin Testing Jay Portnoy, Ann Allergy 89: 335-336, Oct 2002. • What do allergy skin tests really mean? • “Categorization of skin test results from 0 to 4+ is analogous to recording the results of a CBC and differential as a moderate white count with 2+ neutrophils, 3+ lymphocytes, and 1+ bands. One could argue that if we are only concerned about white blood cell counts that either are very low or very high, such categorization should be adequate. Even so, most physicians prefer to review the actual numbers so they can interpret the results themselves. Why should we not do the same for skin test results?”

26. History of IDT 1911: Leonard Noon injected allergy patients with pollen extracts (to induce production of pollen “antitoxin”) Attempted to determine degree of sensitivity of his pts by making various dilutions of antigens and instilling them into the patient’s conjunctiva Leonard Noon MD 1878-1913

27. History of IDT Noon quantified a patient’s sensitivity by instilling drops of different-strength pollen extracts into the conjunctiva of a known hay fever patient The strength of extract required to produce a minimal reaction would then represent the patient’s “resistance”: i.e., if a dilution of four “units” was required to institute a reaction, the patient’s “resistance” was rated as 4 These quantified responses could then be used in selecting the appropriate dose for injection therapy

28. Noon’s Quantified Results

29. History of IDT “Three quarters of a century later, a large percentage of the allergy world uses basically non-quantitative techniques of diagnosis and treatment…there is also considerable disagreement regarding an appropriate starting dose for therapy. It has been observed that should William Osler be returned to life, he would be unable to recognize most of the technology in use. If Leonard Noon returned, he could resume his practice as he left it with little difficulty. He would probably continue to seek better quantification.” Hueston King, MD Otolaryngologic Clinics of North America, 18: p 703, 1985

30. History of IDT French K. Hansel MD 1893-1981 Herbert J. Rinkel MD 1896-1963

31. History of IDT (cont.) 1930: French Hansel was the first to perform skin tests using multiple-strength individual extracts instead of single-concentration extracts He used intradermal injections of antigens in serial 1:10ratiosof varying strengths while measuring the response He demonstrated that eachantigen has a uniqueresponse in a given patient He found the strength of a response to different antigens is not the same for all the antigens encountered by a given individual

32. History of IDT (cont.) Hansel concluded that multiple intradermal skin tests using individual allergens with varying doses produced greater accuracy of information regarding the degree of the patient’s sensitivity 1937: Herbert Rinkel, an allergist working with Hansel, found that an antigenic dilution ratio of 1:5 administered in progressively increasing increments was qualitatively and quantitativelysuperior in measuring allergic skin reactivity. The response was constant through 3 or 4 dilutions in 72% of patients

33. Goals of IDT Reliably identify an inhalant sensitivity by skin testing Determine a safe starting point at which to initiate therapy (the “threshold dose”) Allow treatment to be started during patient’s peak allergy season Treat a variety of allergens of different degrees of sensitivity in a single mix by varying the concentration of individual antigens according to the skin test rxns (“Multi-antigen threshold therapy”)

34. Principles of IDT IDT is based upon the interpretation of the skin response to the injection of weak (nonreacting) dilutions of antigen, proceeding to stronger (reacting) dilutions of the antigen The first test producing a wheal 2 mm larger than the preceding non reacting wheal is considered the endpoint of the reaction Treatment based on the endpoint responseis within a safe and therapeutic range

35. IDT: Standard Technique Allergenic extracts are prepared using 5-fold serial dilutions (Concentrate to a #6)

36. LCM Serial Dilutions

37. LCM Concentrates & No 1 dil

38. IDT: Standard Technique The antigen is injected intradermally, creating a demarcated 4mm wheal containing approx .01 ml of the appropriate dilution The number 6 dilution of each antigen is administered The response is measured at 10 min

39. IDT: Technique

40. IDT: Standard Technique The wheal will normally grow to 5mm within 10 minutes If less than 2mm growth, the result is interpreted as negative and a stronger dilution is applied The first dilution to establish a 7mm wheal is considered the “endpoint” Confirmation: show a clear progression of wheal size of 2mm over 3 consecutive dilutions

41. IDT: Typical Std Titration Results # 6 # 5 #4 #3 #2 #1 4 5 9 4 7 Endpoint 5 5 7 9 Endpoint

42. IDT: Std Titration

43. IDT: Standard Technique This process may take several hours and/or 2 or more sessions depending on the number of allergens being tested, the severity of reactions, abnormal skin or whealing responses, etc.

44. La Crosse Method: Optimized IDT Technique of administration of antigens is identical to standard titration, except for starting dilution In contrast to giving a number 6 starting dilution for all antigens, varying-strength starting dilutions are used for different antigens, based on clinical experience and the patient’s own history Goal: to find 2 mm wheal growth response (i.e, 7mm wheal in 10 minutes) with further confirmation by giving additional selected test dilutions as needed

45. Optimized IDT Screening Dilutions Normal Degree of Clinical Sensitivity Moderate Degree of Clinical Sensitivity: DROP BACK 1 DILUTION High Degree of Clinical Sensitivity DROP BACK 2 DILUTIONS

46. IDT Technique: Advantages of Optimized vs. Standard IDT testing Speeds up testing process Minimizes the number of skin tests & patient’s discomfort Minimizes testing expense Allows better workflow so that more patients can be tested in the same amount of time

47. Modified Quantitative Testing (MQT) Krouse JH, et al Otolaryngology Clinic N Am (2003) 855-868 Skin Prick Test (SPT) is first used as a rapid screening measure of reactivity, then selective IDT testing done based on SPT results Using the Multi-Test II device is estimated to yield a skin response equivalent to a 1:1500 w/v IDT, this first step is similar to a #3 dilution

48. Multi-Test Device allows consistent application of multiple tests to screen initial sensitivity Rapid, with minimum patient discomfort

49. Modified Quantitative Testing (MQT) Krouse JH, et al Otolaryngology Clinic N Am (2003) 855-868 • SPT is used in combination with IDT • If SPT negative, a single stronger IDT may be administered • If SPT positive, a single weaker IDT may be administered • The combination of SPT with IDT yields an efficient, rapid estimate of the strength of the allergic response that can be interpreted and used in treatment vial preparation

50. MQT Algorithm Summary Krouse JH, et al Otolaryngology Clinic N Am (2003) 855-868 • SPT Wheal Size: > 9mm, No ID, Interpret as #6 EP • SPT Wheal Size: 3-8 mm, Apply #5 ID • If ≤5mm, Interpret as #4 EP • If 7-9mm, Interpret as #5 EP • If ≥9mm, Interpret as #6 EP • SPT Wheal Size: <3mm, Apply #2 ID • If ≤6mm, Interpret as NEG • If ≥ 7mm, Interpret as #3 EP