title: The impact of comorbid disease history on all-cause and cancer-specific mortality in myeloid leukemia and myeloma - a Swedish population-based study.
abstract: BACKGROUND
  Comorbidity increases overall mortality in patients diagnosed with hematological malignancies. The impact of comorbidity on cancer-specific mortality, taking competing risks into account, has not been evaluated.
  
  
  METHODS
  Using the Swedish Cancer Register, we identified patients aged >18 years with a first diagnosis of acute myeloid leukemia (AML, N = 2,550), chronic myeloid leukemia (CML, N = 1,000) or myeloma (N = 4,584) 2002-2009. Comorbid disease history was assessed through in- and out-patient care as defined in the Charlson comorbidity index. Mortality rate ratios (MRR) were estimated through 2012 using Poisson regression. Probabilities of cancer-specific death were computed using flexible parametric survival models.
  
  
  RESULTS
  Comorbidity was associated with increased all-cause as well as cancer-specific mortality (cancer-specific MRR: AML = 1.27, 95 % CI: 1.15-1.40; CML = 1.28, 0.96-1.70; myeloma = 1.17, 1.08-1.28) compared with patients without comorbidity. Disorders associated with higher cancer-specific mortality were renal disease (in patients with AML, CML and myeloma), cerebrovascular conditions, dementia, psychiatric disease (AML, myeloma), liver and rheumatic disease (AML), cardiovascular and pulmonary disease (myeloma). The difference in the probability of cancer-specific death, comparing patients with and without comorbidity, was largest among AML patients <70 years, whereas in myeloma the difference did not vary by age among the elderly. The probability of cancer-specific death was generally higher than other-cause death even in older age groups, irrespective of comorbidity.
  
  
  CONCLUSIONS
  Comorbidities associated with organ failure or cognitive function are associated with poorer prognosis in several hematological malignancies, likely due to lower treatment tolerability. The results highlight the need for a better balance between treatment toxicity and efficacy in comorbid and elderly AML, CML and myeloma patients.
authors.affiliation: Division of Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. mohammad.mohammadi@ki.se.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Mohammadi
authors.affiliation: Institute of Environmental Medicine, Unit of Biostatistics, Division of Epidemiology, Karolinska Institutet, Stockholm, Sweden. yang.cao@ki.se.
authors.forename: Yang
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Department of Medicine, Clinical Epidemiology Unit, Solna, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden. Ingrid.glimelius@onkologi.uu.se.|Department of Immunology, Genetics and Pathology, Unit of Oncology, Uppsala University, Uppsala, Sweden. Ingrid.glimelius@onkologi.uu.se.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Glimelius
authors.affiliation: Institute of Environmental Medicine, Unit of Biostatistics, Division of Epidemiology, Karolinska Institutet, Stockholm, Sweden. matteo.bottai@ki.se.
authors.forename: Matteo
authors.initials: M
authors.lastname: Bottai
authors.affiliation: Department of Medicine, Clinical Epidemiology Unit, Solna, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden. Sandra.eloranta@ki.se.
authors.forename: Sandra
authors.initials: S
authors.lastname: Eloranta
authors.affiliation: Department of Medicine, Clinical Epidemiology Unit, Solna, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden. Karin.ekstrom.smedby@ki.se.|Hematology Center, Karolinska University Hospital, Stockholm, Sweden. Karin.ekstrom.smedby@ki.se.
authors.forename: Karin E
authors.initials: KE
authors.lastname: Smedby
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002423:Cause of Death / Q000639:trends; D015897:Comorbidity / Q000639:trends; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000453:epidemiology*; D015470:Leukemia, Myeloid, Acute / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000453:epidemiology*; D011159:Population Surveillance; D012042:Registries; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult