title: Comorbidity, age, race and stage at diagnosis in colorectal cancer: a retrospective, parallel analysis of two health systems.
abstract: BACKGROUND
  Stage at diagnosis plays a significant role in colorectal cancer (CRC) survival. Understanding which factors contribute to a more advanced stage at diagnosis is vital to improving overall survival. Comorbidity, race, and age are known to impact receipt of cancer therapy and survival, but the relationship of these factors to stage at diagnosis of CRC is less clear. The objective of this study is to investigate how comorbidity, race and age influence stage of CRC diagnosis.
  
  
  METHODS
  Two distinct healthcare populations in the United States (US) were retrospectively studied. Using the Cancer Care Outcomes Research and Surveillance Consortium database, we identified CRC patients treated at 15 Veterans Administration (VA) hospitals from 2003-2007. We assessed metastatic CRC patients treated from 2003-2006 at 10 non-VA, fee-for-service (FFS) practices. Stage at diagnosis was dichotomized (non-metastatic, metastatic). Race was dichotomized (white, non-white). Charlson comorbidity index and age at diagnosis were calculated. Associations between stage, comorbidity, race, and age were determined by logistic regression.
  
  
  RESULTS
  342 VA and 340 FFS patients were included. Populations differed by the proportion of patients with metastatic CRC at diagnosis (VA 27% and FFS 77%) reflecting differences in eligibility criteria for inclusion. VA patients were mean (standard deviation; SD) age 67 (11), Charlson index 2.0 (1.0), and were 63% white. FFS patients were mean age 61 (13), Charlson index 1.6 (1.0), and were 73% white. In the VA cohort, higher comorbidity was associated with earlier stage at diagnosis after adjusting for age and race (odds ratio (OR) 0.76, 95% confidence interval (CI) 0.58-1.00; p = 0.045); no such significant relationship was identified in the FFS cohort (OR 1.09, 95% CI 0.82-1.44; p = 0.57). In both cohorts, no association was found between stage at diagnosis and either age or race.
  
  
  CONCLUSIONS
  Higher comorbidity may lead to earlier stage of CRC diagnosis. Multiple factors, perhaps including increased interactions with the healthcare system due to comorbidity, might contribute to this finding. Such increased interactions are seen among patients within a healthcare system like the VA system in the US versus sporadic interactions which may be seen with FFS healthcare.
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, USA. yousuf.zafar@duke.edu
authors.forename: S Yousuf
authors.initials: SY
authors.lastname: Zafar
authors.forename: Amy P
authors.initials: AP
authors.lastname: Abernethy
authors.forename: David H
authors.initials: DH
authors.lastname: Abbott
authors.forename: Steven C
authors.initials: SC
authors.lastname: Grambow
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Marcello
authors.forename: James E
authors.initials: JE
authors.lastname: Herndon
authors.forename: Krista L
authors.initials: KL
authors.lastname: Rowe
authors.forename: Jane T
authors.initials: JT
authors.lastname: Kolimaga
authors.forename: Leah L
authors.initials: LL
authors.lastname: Zullig
authors.forename: Meenal B
authors.initials: MB
authors.lastname: Patwardhan
authors.forename: Dawn T
authors.initials: DT
authors.lastname: Provenzale
mesh_terms: D000367:Age Factors; D000368:Aged; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000208:ethnology / Q000473:pathology / Q000503:physiopathology; D015897:Comorbidity; D003695:Delivery of Health Care; D055088:Early Detection of Cancer; D018588:Fee-for-Service Plans; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D044469:Racial Groups; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology; D014493:United States Department of Veterans Affairs