title: When does an episode of care for cancer begin?
abstract: BACKGROUND
  Little is known about the medical care resources devoted to diagnosing and treating cancer-related symptoms before a definitive cancer diagnosis. Previous research using SEER-Medicare data to measure incremental costs and utilization associated with cancer started with the date of diagnosis. We hypothesized that health care use increases before diagnosis of a new primary cancer.
  
  
  METHODS
  We used a longitudinal case-control design to estimate incremental medical care utilization rates. Cases were 121,293 persons enrolled between January 2000 and December 2008 with ≥1 primary cancers. We selected 522,839 controls randomly from among all health plan members who had no tumor registry evidence of cancer before January 2009, and we frequency matched controls to cancer cases on a 5:1 ratio by age group, sex, and having health plan eligibility in the year of diagnosis of the index cancer case. Utilization data were extracted for all cases and controls for the period 2000 to 2008 from standardized distributed data warehouses. To determine when and the extent to which patterns of medical care use change preceding a cancer diagnosis, we compute hospitalization rates, hospital days, emergency department visits, same-day surgical procedures, ambulatory medical office visits, imaging procedures, laboratory tests, and ambulatory prescription dispensings per 1000 persons per month within integrated delivery systems.
  
  
  RESULTS
  One- to 3-fold increases in monthly utilization rates were observed during the 3 to 5 months before a cancer diagnosis, compared with matched noncancer control groups. This pattern was consistent for both aged and nonaged cancer patients. Aged cancer patients had higher utilization rates than nonaged cancer patients throughout the year before a cancer diagnosis.
  
  
  CONCLUSIONS
  The prediagnosis phase is a resource-intensive component of cancer care episodes and should be included in cost of cancer estimates. More research is needed to determine whether reliable prognostic markers can be identified as the start of a cancer episode before a pathology-based diagnosis.
authors.affiliation: The Center for Health Research, Kaiser Permanente Northwest, Portland, OR 97227-1110, USA. mark.c.hornbrook@kpchr.org
authors.forename: Mark C
authors.initials: MC
authors.lastname: Hornbrook
authors.forename: Paul A
authors.initials: PA
authors.lastname: Fishman
authors.forename: Debra P
authors.initials: DP
authors.lastname: Ritzwoller
authors.forename: Jennifer
authors.initials: J
authors.lastname: Elston-Lafata
authors.forename: Maureen C
authors.initials: MC
authors.lastname: O'Keeffe-Rosetti
authors.forename: Ramzi G
authors.initials: RG
authors.lastname: Salloum
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003120:Colorado; D003695:Delivery of Health Care / Q000191:economics* / Q000706:statistics & numerical data*; D017050:Episode of Care; D005260:Female; D006801:Humans; D007348:Insurance, Health / Q000706:statistics & numerical data*; D008297:Male; D008824:Michigan; D008875:Middle Aged; D009369:Neoplasms / Q000175:diagnosis* / Q000628:therapy*; D009922:Oregon; D016032:Randomized Controlled Trials as Topic; D013997:Time Factors; D014861:Washington; D055815:Young Adult