title: Predictors of outpatient mental health utilization by primary care patients in a health maintenance organization.
abstract: OBJECTIVE
  The authors examined the volume and predictors of outpatient mental health utilization among primary care patients in a large staff-model health maintenance organization (HMO).
  
  
  METHODS
  Consecutive primary care patients (N = 1,810) were screened by using the 12-item General Health Questionnaire, and a stratified random sample (N = 373) completed the 28-item General Health Questionnaire and Composite International Diagnostic Interview. Telephone interviews and computerized records were used to examine use of mental health services inside and outside the HMO over the following 3 months.
  
  
  RESULTS
  Over 3 months, 6.7% of the screened patients used mental health services within the HMO. Utilization increased with higher General Health Questionnaire score (2.9% among those scoring 0, 22.3% among those scoring 8 or more) and decreased with higher out-of-pocket cost for mental health visits (7.5% for those with no change, 3.3% for those paying $30/visit). Among the interviewed subjects, 5.1% used mental health services within the HMO (mean = 2.92 visits) and 8.9% used outside mental health services (mean = 8.86 visits). Use of outside services was more strongly related to sociodemographic factors, and use of inside services was more related to severity of psychological disorder.
  
  
  CONCLUSIONS
  Among these subjects, use of mental health care was high and services purchased outside the HMO exceeded those inside the HMO. Increasing copayment levels progressively reduced demand without respect to severity of illness. Attempts to control outpatient mental health costs must address equity and clinical need.
authors.affiliation: Center for Health Studies, Group Health Cooperative of Puget Sound, Seattle, WA 98101.
authors.forename: G E
authors.initials: GE
authors.lastname: Simon
authors.forename: M
authors.initials: M
authors.lastname: VonKorff
authors.forename: M L
authors.initials: ML
authors.lastname: Durham
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000553:Ambulatory Care / Q000191:economics / Q000706:statistics & numerical data; D017047:Cost Sharing; D004522:Educational Status; D004651:Employment; D005260:Female; D006279:Health Maintenance Organizations / Q000191:economics / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008297:Male; D017533:Marital Status; D001523:Mental Disorders / Q000175:diagnosis / Q000628:therapy*; D008605:Mental Health Services / Q000191:economics / Q000706:statistics & numerical data*; D008875:Middle Aged; D011320:Primary Health Care / Q000191:economics / Q000706:statistics & numerical data; D011336:Probability; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D012720:Severity of Illness Index