title: Early application of low-level laser may reduce the incidence of postherpetic neuralgia (PHN).
abstract: BACKGROUND
  Postherpetic neuralgia (PHN) is difficult to treat, and currently there are no available treatments that effectively reduce its incidence. Low-level laser therapy (LLLT) has been proposed for indirect virus deactivation in treating recurrent herpes simplex infections.
  
  
  OBJECTIVE
  This study seeks to investigate whether LLLT could reduce the incidence of PHN.
  
  
  METHODS
  We retrospectively reviewed the incidence of PHN at the first, third, and sixth months after rash outbreak in 3 groups: the acute group of patients who received LLLT during the first 5 days; the subacute group of patients who received LLLT during days 6 to 14 of the eruption; and the control group of patients who did not receive LLLT.
  
  
  RESULTS
  There were 48, 48, and 154 patients in the acute, subacute, and control groups, respectively. After adjusting for confounding factors, including age, sex, and use of famciclovir, the incidence of PHN was significantly lower in the acute group versus the control group after 1 month (odds ratio [OR] 0.21, P = .006, 95% confidence interval [CI] 0.068-0.632), 3 months (OR 0.112, P = .038, 95% CI 0.014-0.886), and 6 months (OR 0.123, P = .021, 95% CI 0-0.606). The subacute group only had a lower incidence (OR 0.187, P = .032, 95% CI 0.041-0.865) after 3 months when compared with the control group.
  
  
  CONCLUSIONS
  This is a retrospective study lacking double-blind randomization, and the placebo effect may be a major concern. Lack of standardized and prospective evaluation measures is also a limitation of this study.
  
  
  CONCLUSIONS
  Applying LLLT within the first 5 days of herpes zoster eruption significantly reduced the incidence of PHN. LLLT may have the potential to prevent PHN, but further well-designed randomized controlled trials are required.
authors.affiliation: Department of Dermatology, Wan Fang Hospital, Taipei, Taiwan, Republic of China; Department of Dermatology, Shuang Ho Hospital, Taipei, Taiwan, Republic of China; School of Public Health, College of Public Health and Nutrition, Taipei, Taiwan, Republic of China.
authors.forename: Yu-Tsung
authors.initials: YT
authors.lastname: Chen
authors.affiliation: Department of Dermatology, Wan Fang Hospital, Taipei, Taiwan, Republic of China.
authors.forename: Hsiao-Han
authors.initials: HH
authors.lastname: Wang
authors.affiliation: Department of Ophthalmology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, Republic of China; Department of Ophthalmology, Taipei Medical University Hospital, Taipei, Taiwan, Republic of China.
authors.forename: Tsung-Jen
authors.initials: TJ
authors.lastname: Wang
authors.affiliation: Department of Dermatology, Wan Fang Hospital, Taipei, Taiwan, Republic of China.
authors.forename: Yu-Chuan
authors.initials: YC
authors.lastname: Li
authors.affiliation: Department of Dermatology, Wan Fang Hospital, Taipei, Taiwan, Republic of China; Department of Dermatology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, Republic of China. Electronic address: paladerm@yahoo.com.tw.
authors.forename: Ting-Jui
authors.initials: TJ
authors.lastname: Chen
mesh_terms: D015075:2-Aminopurine / Q000031:analogs & derivatives / Q000627:therapeutic use; D000328:Adult; D016022:Case-Control Studies; D000077595:Famciclovir; D005260:Female; D005500:Follow-Up Studies; D006562:Herpes Zoster / Q000150:complications* / Q000175:diagnosis* / Q000188:drug therapy; D006801:Humans; D016015:Logistic Models; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D051474:Neuralgia, Postherpetic / Q000517:prevention & control* / Q000532:radiotherapy*; D010147:Pain Measurement; D011379:Prognosis; D012016:Reference Values; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015075:2-Aminopurine; D000077595:Famciclovir
keywords: herpes zoster; low-level laser therapy; postherpetic neuralgia