title: Placebo response in asthma: a robust and objective phenomenon.
abstract: BACKGROUND
  Placebos are hypothesized to exert positive effects on medical conditions by enhancing patient expectancies. Recent reviews suggest that placebo benefits are restricted to subjective responses, like pain, but might be ineffective for objective physiologic outcomes. Nevertheless, mind-body links and placebo responsivity in asthma are widely believed to exist.
  
  
  OBJECTIVE
  We carried out a randomized, double-blind investigation to (1) determine whether placebo can suppress airway hyperreactivity in asthmatic subjects, (2) quantify the placebo effect, (3) identify predictors of the placebo response, and (4) determine whether physician interventions modify the placebo response.
  
  
  METHODS
  In a double-blind, crossover design investigation, 55 subjects with mild intermittent and persistent asthma with stable airway hyperreactivity were randomized to placebo or salmeterol before serial methacholine challenges. Subjects were additionally randomized to physician interactions that communicated either positive or neutral expectancies regarding drug effect.
  
  
  RESULTS
  Placebo bronchodilator administration significantly reduced bronchial hyperreactivity compared with baseline (the calculated concentration of methacholine required to induce a 20% decrease in FEV(1) nearly doubled); 18% of subjects were placebo responders by using conservative definitions. Experimental manipulation of physician behavior altered perceptions of the physician but not the magnitude or frequency of the placebo response.
  
  
  CONCLUSIONS
  Objective placebo effects exist in asthma. These responses are of significant magnitude and likely to be meaningful clinically. The placebo response was not modulated by alterations in physician behavior in this study.
  
  
  CONCLUSIONS
  The placebo response in patients with asthma is important in understanding the limitations of clinical research studies and in maximizing safe and effective therapies. This article confirms the existence of a strong placebo response in an objective and clinically relevant measure of disease activity.
authors: University of California, San Francisco, Calif., USA.
authors: Margaret E
authors: ME
authors: Kemeny
authors: Lanny J
authors: LJ
authors: Rosenwasser
authors: Reynold A
authors: RA
authors: Panettieri
authors: Robert M
authors: RM
authors: Rose
authors: Steve M
authors: SM
authors: Berg-Smith
authors: Joel N
authors: JN
authors: Kline
mesh_terms: D000293:Adolescent; D000328:Adult; D000420:Albuterol / Q000008:administration & dosage / Q000031:analogs & derivatives; D001249:Asthma / Q000175:diagnosis / Q000188:drug therapy* / Q000523:psychology; D016535:Bronchial Hyperreactivity / Q000517:prevention & control / Q000523:psychology; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010819:Physician's Role / Q000523:psychology; D015990:Placebo Effect; D010919:Placebos; D011237:Predictive Value of Tests; D000068299:Salmeterol Xinafoate; D016037:Single-Blind Method
chemical_list: D010919:Placebos; D000068299:Salmeterol Xinafoate; D000420:Albuterol