title: Pain during photodynamic therapy is associated with protoporphyrin IX fluorescence and fluence rate.
abstract: BACKGROUND
  Pain during photodynamic therapy (PDT) is a considerable problem that needs to be studied to improve this otherwise attractive treatment of skin diseases.
  
  
  OBJECTIVE
  To compare pain during PDT using two different fluence rates, and also to evaluate the association between pain and protoporphyrin IX (PpIX) fluorescence, lesion type, lesion preparation and lesion localization.
  
  
  METHODS
  Twenty-six patients with actinic keratoses (AKs) in different localizations and 34 patients with facial acne vulgaris were treated with methyl aminolaevulinate-PDT. Patients with acne were illuminated using two different fluence rates. Pain score during PDT and PpIX fluorescence prior to illumination were measured.
  
  
  RESULTS
  The study showed that pain during illumination was associated with the PpIX fluorescence in the treatment area (P = 0.0003, R(2) = 0.31). When using a fluence rate of 34 mW cm(-2) patients with acne had a pain score of 6 [interquartile range (IQR) 5-7] compared with 8 (IQR 6-10) when using a fluence rate of 68 mW cm(-2) (P = 0.018). After correcting the pain score for PpIX fluorescence no differences in pain scores were found between first and second acne treatment, locations of AK lesions or between the two types of lesions.
  
  
  CONCLUSIONS
  Pain during PDT was correlated with the PpIX fluorescence in the treatment area prior to illumination. Pain was reduced using a lower fluence rate during PDT of acne.
authors.affiliation: Department of Dermatology, Bispebjerg Hospital, University of Copenhagen, Bispebjerg Bakke 23, Copenhagen NV, Denmark. SRW01@bbh.regionh.dk
authors.forename: S R
authors.initials: SR
authors.lastname: Wiegell
authors.forename: J
authors.initials: J
authors.lastname: Skiveren
authors.forename: P A
authors.initials: PA
authors.lastname: Philipsen
authors.forename: H C
authors.initials: HC
authors.lastname: Wulf
mesh_terms: D000152:Acne Vulgaris / Q000150:complications / Q000188:drug therapy*; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007642:Keratosis / Q000150:complications / Q000188:drug therapy*; D008297:Male; D010146:Pain / Q000209:etiology*; D010147:Pain Measurement / Q000379:methods; D010778:Photochemotherapy / Q000009:adverse effects*; D011237:Predictive Value of Tests; D011524:Protoporphyrins / Q000008:administration & dosage / Q000009:adverse effects*; D012867:Skin / Q000187:drug effects
chemical_list: D011524:Protoporphyrins; C028025:protoporphyrin IX