title: The impact of aging and chronic disease on use of hospital and outpatient services in a large HMO: 1971-1991.
abstract: OBJECTIVE
  To examine overall and diagnosis-specific trends in the use of inpatient and outpatient medical services (1970-1988) among older members of a large HMO.
  
  
  METHODS
  Two cohorts of approximately 3000 persons aged 65 or older in 1971 and 1980 were compared for hospital and outpatient utilization during 9-year follow-up periods (1971-79 and 1980-88). All subjects were evaluated for vital status throughout the follow-up period as well.
  
  
  METHODS
  All 6057 subjects were members of the Northern California Kaiser Permanente Medical Care Program in 1971 or 1980. The study sample was sex-age stratified (65-69,70-79,80+) at baseline.
  
  
  METHODS
  Data on demographics, outpatient health services utilization, categories of outpatient utilization and disease diagnoses were obtained from membership lists or medical chart review; inpatient utilization, including admitting and discharge diagnosis, length of stay, and number of hospital days was assessed from computerized hospitalization records.
  
  
  RESULTS
  Hospital discharge rates (sex-age adjusted) increased by 12% between cohorts, with the largest increases at the oldest ages. There was a 25% increase among women and a 9% increase among men. Length of stay decreased by 20%. Hospitalization for ischemic heart disease decreased by 17%. Congestive heart failure (CHF) discharge rates (sex-age adjusted) were 92% higher in the 1980-88 cohort. For diagnoses related to nursing home institutionalization and frailty, discharge rates were significantly higher in the 1980-88 cohort: pneumonia (+34%), urinary tract infections (+104%), dehydration (+110%), osteoarthritis (+64%), syncope (+246%), leg cellulitis (+70%). In-hospital survival improved, but overall percent of readmissions also increased by 4%; readmissions for CHF increased by 13% and those for conditions of frailty by 120%. Overall outpatient visits increased by 17%. Use of laboratory tests (+57%) and outpatient surgeries (+99%) increased for all age strata in 1980-88 compared with 1971-79.
  
  
  CONCLUSIONS
  While overall outpatient and inpatient utilization has largely decreased over the past 30 years, as a result of economic factors and improved treatments for some major diseases, there has been an increase in utilization among older people. Hospitalization for diagnoses associated with end-stage cardiovascular disease (CHF), musculoskeletal disease, frailty and iatrogenic aspects of institutionalization are clearly increasing substantially. The largest impact of aging on health care may be the result of institutionalization and its sequelae. Improved treatment for cardiovascular disease may also be leading to increased utilization at later stages in the disease process.
authors.affiliation: Department of Epidemiology and Preventive Medicine, University of California, Davis 95616, USA.
authors.forename: M N
authors.initials: MN
authors.lastname: Haan
authors.forename: J V
authors.initials: JV
authors.lastname: Selby
authors.forename: C P
authors.initials: CP
authors.lastname: Quesenberry
authors.forename: J A
authors.initials: JA
authors.lastname: Schmittdiel
authors.forename: B H
authors.initials: BH
authors.lastname: Fireman
authors.forename: D P
authors.initials: DP
authors.lastname: Rice
mesh_terms: D000368:Aged; D000375:Aging; D000553:Ambulatory Care / Q000706:statistics & numerical data*; D002140:California; D002908:Chronic Disease; D005260:Female; D006279:Health Maintenance Organizations; D006760:Hospitalization; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D010343:Patient Admission; D012189:Retrospective Studies