title: Initial weight loss as a predictor of response to obesity drugs.
abstract: BACKGROUND
  Initial weight loss has been used as a predictor of long-term response to obesity drugs. Discontinuation of drugs has been recommended if weight loss is not > or =1.81 kg (4 lb) in the first month of treatment.
  
  
  OBJECTIVE
  We compared the weight loss response at 6 months of patients losing > or =1.81 kg (responders) vs. < 1.81 kg (non-responders) in the first month of treatment with the combination of fenfluramine and phentermine.
  
  
  METHODS
  Outcomes at 6 months in 975 patients treated in a comprehensive program of phentermine (15-30 mg/d) d,l-fenfluramine (20-60 mg/d), were compared for responders vs. non-responders.
  
  
  RESULTS
  In the total population, first month weight loss highly correlated with % reduction in body mass index (BMI) after 6 months of treatment (P<0.001). The reduction in baseline BMI after 6 months treatment was greater for the responders (15.9% vs. 10%, P<0.02). However, the North American Association for the Study of Obesity (NAASO) guidelines for drug treatment of obesity state that a 5% weight loss produces significant health benefits, and may be used as a criteria for success. At 6 months, 76%, 37% and 14% of the non-respondents had lost > or = 5%, > or = 10% and > or = 15% of baseline BMI, respectively. After 6 months treatment the reductions in serum cholesterol, triglycerides and LDL-cholesterol were 0.55, 0.31 and 0.42 mmol/L, respectively, (P< or =0.006), for the non-responders. Adverse effects after 6 months of treatment and the dropout rates after 1 y of treatment were not significantly different for the two groups.
  
  
  CONCLUSIONS
  Although, the first month weight loss predicted the long-term response to phen-fen treatment, it was inadequate in identifying the non-responders and may unnecessarily preclude potential beneficiaries of the treatment.
authors.affiliation: University of Wisconsin Medical School, Madison 53706, USA.
authors.forename: N V
authors.initials: NV
authors.lastname: Dhurandhar
authors.forename: R C
authors.initials: RC
authors.lastname: Blank
authors.forename: D
authors.initials: D
authors.lastname: Schumacher
authors.forename: R L
authors.initials: RL
authors.lastname: Atkinson
mesh_terms: D000328:Adult; D019440:Anti-Obesity Agents / Q000627:therapeutic use*; D001067:Appetite Depressants / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005260:Female; D005277:Fenfluramine / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000188:drug therapy*; D010645:Phentermine / Q000627:therapeutic use*; D011237:Predictive Value of Tests; D016896:Treatment Outcome; D015431:Weight Loss
chemical_list: D019440:Anti-Obesity Agents; D001067:Appetite Depressants; D005277:Fenfluramine; D010645:Phentermine