ALLERGY SKIN TEST ROUND 1 CRECER

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ALLERGY SKIN TESTROUND 1CRECER
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ROUND 1 CHARACTERISTICS

• Dates 7/07/06-10/12/06
• Total of 536 children enrolled
• 10 subjects did not complete interview
• 526 Children completed interview
• 189 (36) control homes
• 154 (29) new homes
• 183 (35) plancha homes

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Approach to analysis

• Hypothesis variable early lifetime exposure
  (birth to 18 months) to smoke is associated with
  allergic sensitization.
• In raw data base subjects in 3 groups
• new homes (n), control homes (c) and plancha
  homes (p)
• For this analysis subjects grouped into 2 groups
  based on stove type from birth to 18 months
• Open fire homes children from new homes (n) and
  control homes (c)
• Plancha homes children from plancha homes (p)

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Baseline characteristics
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Procedure

• 6 allergens tested mixed tree, dog, cat,
  cockroach, D. Pteronyssinus, D. Farinae
• 2 controls saline (negative), histamine
  (positive)
• Raw data wheals measured along long axis and
  perpendicular axis
• Calculated mean wheal size out of these two
  numbers

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Wheal measurements per allergen in all subjects
and by stove type
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Wheal measurements per allergen

• Wheal measurements available for 525 subjects for
  most allergens except for cat, D. Ptery, and D.
  Farinae
• Symbols in preceding table to specify the number
  (n) of subjects with measurements for specific
  allergens within stove sub-group
• n341
• n275
• n182
• n145

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Determining positive skin test

• Calculated the difference between the mean wheal
  size of the allergen the mean wheal size of the
  negative control. (continuous variable)
• Determined skin test if this difference was gt
  3mm. (dichotomous outcome)

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Fischer Exact Test to compare proportions of
positive skin tests
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Unpaired t-test to compare mean wheal difference
(allergen-control)
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Intrepretation

• In round 1, no significant association between
  early lifetime (birth to 18 months) smoke
  exposure (using stove type as surrogate) and
  positive allergy skin tests.