title: Patch test results with metals and meteorological conditions.
abstract: BACKGROUND
  Nickel, cobalt and chromium are some of the most common causes of type IV sensitizations and subsequent allergic contact dermatitis. Accurate diagnosis of contact sensitization to these metal salts is made possible through standardized patch testing; however, patch tests with metal allergens may be influenced by meteorological conditions at the time of testing. We aimed to investigate how patch test reactions to these metals relate to outdoor temperature and humidity at the time of testing.
  
  
  METHODS
  Clinical patch test results from 61,435 patients tested at Austrian and German dermatology departments participating in a contact sensitization surveillance network (www.ivdk.org) from 1993 through 2001 were evaluated with weather data measured near the testing location and at the time of testing. Test reactions and ambient temperature and humidity were examined with multinomial logistic regression models.
  
  
  RESULTS
  The odds of irritant and doubtful reactions to all 3 ionized metals increased during cold/arid conditions, and the odds of weak allergic (positive) reactions to nickel and cobalt also increased during cold/dry weather. Strong allergic reactions were essentially independent of weather conditions.
  
  
  CONCLUSIONS
  The increase in irritant and doubtful reactions coinciding with decreasing temperature and humidity may be the result of an overall increase in skin irritation brought about by these ambient conditions. The observed increases in erythematous and infiltrated ('weak allergic') reactions may be due to doubtful reactions increasing in intensity and being (falsely) classified as positive during colder and drier conditions.
authors.affiliation: Department of Medical Informatics, Biometry and Epidemiology, Friedrich-Alexander University Erlangen-Nurnberg, Erlangen, Germany.
authors.forename: Janice
authors.initials: J
authors.lastname: Hegewald
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Uter
authors.forename: Birger
authors.initials: B
authors.lastname: Kranke
authors.forename: Axel
authors.initials: A
authors.lastname: Schnuch
authors.forename: Olaf
authors.initials: O
authors.lastname: Gefeller
authors.forename: Annette
authors.initials: A
authors.lastname: Pfahlberg
mesh_terms: D000328:Adult; D000485:Allergens / Q000009:adverse effects / Q000276:immunology*; D002857:Chromium / Q000009:adverse effects / Q000276:immunology; D003035:Cobalt / Q000009:adverse effects / Q000276:immunology; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis* / Q000453:epidemiology; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D006813:Humidity; D016015:Logistic Models; D008297:Male; D019216:Metals, Heavy / Q000009:adverse effects / Q000276:immunology*; D008875:Middle Aged; D009532:Nickel / Q000009:adverse effects / Q000276:immunology; D010328:Patch Tests / Q000379:methods*; D013696:Temperature
chemical_list: D000485:Allergens; D019216:Metals, Heavy; D002857:Chromium; D003035:Cobalt; D009532:Nickel