Effect of managed care on preventable hospitalization rates in California.
BACKGROUND
Hospitalization rates for ambulatory care-sensitive (ACS) conditions have emerged as a potential indicator of health care access and quality. The effect of managed care on reducing these potentially preventable hospitalizations is unknown.


OBJECTIVE
To ascertain whether increases in managed care penetration were associated with changes in hospitalization rates for ACS conditions.


METHODS
Longitudinal analysis between 1990 and 1997 of all California hospitalizations for ACS conditions aggregated to 394 small areas.


METHODS
Association of change in ACS hospitalization rate with change in managed care penetration.


RESULTS
In unadjusted analysis there was no association between the change in managed care penetration and the change in hospitalization rates for ACS conditions over time. However, in a multivariate model that controlled for changes in area demographics and hospitalization rates for marker conditions that were assumed to be stable over time, the change in managed care penetration was negatively associated with a small but statistically significant change in the ACS hospitalization rate. Each 10-point increase in percentage private managed care penetration was associated with a 3.1% decrease in the ACS hospitalization rate (95% CI, -5.4% to -0.8%)


CONCLUSIONS
Overall, in California, an increase in the penetration of private managed care in a community was associated with a decrease in ACS admission rates. Additional research is needed to determine if the observed association is causal, the mechanism of the effect and whether it represents an improvement in patients' health outcomes.
Backus
Lisa
L
Department of Medicine, Primary Care Research Center, San Francisco General Hospital, 1001 Potrero Avenue Ward 95, San Francisco, CA 94110, USA.
Moron
Marie
M
Bacchetti
Peter
P
Baker
Laurence C
LC
Bindman
Andrew B
AB
D000328:Adult; D000553:Ambulatory Care / Q000706:statistics & numerical data / Q000639:trends; D002140:California; D005260:Female; D006297:Health Services Accessibility / Q000639:trends*; D006300:Health Services Misuse / Q000706:statistics & numerical data*; D006760:Hospitalization / Q000706:statistics & numerical data* / Q000639:trends; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008329:Managed Care Programs / Q000706:statistics & numerical data*; D015999:Multivariate Analysis; D019984:Quality Indicators, Health Care; D012044:Regression Analysis