title: Adverse selection and the effect of health insurance on utilization of prescribed medicine among patients with chronic conditions.
abstract: OBJECTIVE
  To examine the effects of health insurance types on the use of prescribed medication that treat patients with hypertension, diabetes, and asthma. The study distinguishes between individuals with private health maintenance organization (HMO) plans and private non-HMO plans. The study also distinguishes between people with health insurance and drug coverage and people with health insurance and no drug coverage.
  
  
  METHODS
  Joint discrete factor models are estimated to control for endogeneity of each type of coverage.
  
  
  RESULTS
  The main findings suggest that the effect of health insurance varies across patients with different conditions. The strongest and most significant effect is evident among patients with hypertension while the weakest and least significant is among patients with asthma. These findings suggest that patients with asymptomatic conditions are more likely to exhibit moral hazard than patients with conditions that impose immediate impairment. Additional results suggest that, relative to the uninsured and people with health insurance but no drug coverage, patients with drug coverage are more likely to initiate drug therapy and to consume more medications.
  
  
  CONCLUSIONS
  The results of the study indicate that moral hazard of drug utilization is condition specific. The variation in "silence" of conditions' symptoms could be a key reason for difference in insurance effects among patients with hypertension, diabetes, and asthma.
authors.affiliation: Social and Scientific System, Agency for Healthcare Research and Quality, Rockville, MD, USA.
authors.forename: Yuriy
authors.initials: Y
authors.lastname: Pylypchuk
mesh_terms: D000293:Adolescent; D000328:Adult; D002908:Chronic Disease / Q000188:drug therapy*; D005260:Female; D006279:Health Maintenance Organizations; D006801:Humans; D019458:Insurance Coverage; D007348:Insurance, Health / Q000145:classification*; D007356:Insurance, Pharmaceutical Services; D008297:Male; D008875:Middle Aged; D017059:Models, Econometric; D010349:Patient Compliance; D004364:Pharmaceutical Preparations; D014481:United States; D055815:Young Adult
chemical_list: D004364:Pharmaceutical Preparations