title: The direct and indirect effects of cost-sharing on the use of preventive services.
abstract: OBJECTIVE
  To test empirically a model for estimating the direct and indirect effects of different forms of cost-sharing on the utilization of recommended clinical preventive services. DATA SOURCES/SETTINGS: Stratified random sample of 10,872 employees, 18-64 years, who had belonged to their plan for at least one year, from seven large companies that were members of the Pacific Business Group on Health (PBGH) in 1994.
  
  
  METHODS
  The 1994 PBGH Health Plan Value Check Survey. 1994 PBGH data on requirements for employee out-of-pocket patient cost-sharing for 52 different health plans.
  
  
  METHODS
  Five equations were derived to estimate the direct and indirect effects of two forms of cost-sharing (copayments and coinsurance/deductibles) in two forms of managed care (HMOs and PPO/indemnity plans) on four clinical preventive services: mammography screening, cervical cancer screening, blood pressure screening, and preventive counseling. Probit models were used to estimate elasticities for the indirect and direct effects.
  
  
  RESULTS
  Both forms of cost-sharing in both plan types had negative and significant indirect effects on preventive counseling (from -1 percent to -7 percent). The direct effect of cost-sharing was negative for preventive counseling (-5 percent to -9 percent) and Pap smears (from -3 percent to -9 percent) in both HMOs and PPOs, and for mammography only in PPOs (-3 percent to -9 percent). The results of the effects on blood pressure screening are inconclusive.
  
  
  CONCLUSIONS
  Both the direct and indirect effects of cost-sharing negatively affected the receipt of preventive counseling in HMOs and PPOs. As predicted, the direct negative effect of cost-sharing was greater than the indirect effect for Pap smears and mammography. Eliminating cost-sharing for these services may be important to increasing their utilization to recommended levels.
authors.affiliation: Center for Health and Public Policy Studies, University of California, Berkeley, School of Public Health 94720-7360, USA.
authors.forename: G
authors.initials: G
authors.lastname: Solanki
authors.forename: H H
authors.initials: HH
authors.lastname: Schauffler
authors.forename: L S
authors.initials: LS
authors.lastname: Miller
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D015982:Bias; D002140:California; D017047:Cost Sharing / Q000191:economics*; D004180:Direct Service Costs / Q000706:statistics & numerical data*; D005260:Female; D006264:Health Benefit Plans, Employee / Q000191:economics / Q000706:statistics & numerical data; D006279:Health Maintenance Organizations / Q000191:economics*; D006291:Health Policy; D006302:Health Services Research; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011237:Predictive Value of Tests; D011243:Preferred Provider Organizations / Q000191:economics*; D011314:Preventive Health Services / Q000191:economics* / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires