Review of methods used to measure comorbidity in cancer populations: No gold standard exists
ABSTRACT This article reviews methods used to measure comorbidity in the context of cancer; summarizing methods, identifying contexts in which they have been used, and assessing the validity, reliability, and feasibility of each approach.
Studies describing methods to measure comorbidity in epidemiological studies related to cancer were identified. Data relating to content, face, and criterion validity, reliability, and feasibility were collected.
Two thousand nine hundred seventy-five abstracts were reviewed and 21 separate approaches identified. Content and face validity varied but tended to be higher for measures developed for cancer populations. Some evidence supporting criterion validity of all approaches was found. Where reported, reliability tended to be moderate to high. Some approaches tended to score well on all aspects but were resource intensive in terms of data collection. Eight indices scored at least moderately well on all criteria, three of which demonstrated usefulness in relation to non-site specific cancer (Charlson Comorbidity Index, Elixhauser approach, and National Cancer Institute [Combined] Index).
No gold standard approach to measuring comorbidity in the context of cancer exists. Approaches vary in their strengths and weaknesses, with the choice of measure depending on the study question, population studied, and data available.
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ABSTRACT: Studies from Norway and other countries have shown that the unmarried have poorer cancer survival than the married, given age, tumor site and stage at diagnosis. The objective of this investigation was to assess the importance of comorbidities for this difference, using disease indicators derived from the Norwegian Prescription Database (NorPD) and information on cancer and sociodemographic characteristics from various other registers, all of which cover the entire Norwegian population. Discrete-time hazard models for cancer mortality up to 2007 were estimated for all 22,925 men and 21,694 women diagnosed with 13 common types of cancer in 2005-7. There were 4898 cancer deaths among men and 4187 among women. Controlling for sociodemographic factors and tumor characteristics, the odds of dying from cancer among never-married men relative to the married was 1.56 (CI 1.41-1.74). The corresponding estimates for widowed and divorced were 1.16 (CI 1.05-1.28) and 1.27 (CI 1.15-1.40). For women, the odds ratios for these three groups were 1.47 (CI 1.29-1.67), 1.10 (CI 1.01-1.20) and 1.14 (CI 1.02-1.27). Several of the 24 indicators of diseases in the year before diagnosis were associated with cancer survival, but their inclusion reduced the excess mortality of the unmarried by only 1-5 percentage points, or about 10% as an overall relative figure. Similar results were found when the four most common cancers were analyzed separately, though there were some differences between them in the role played by the comorbidities. It is possible that important comorbidities are inadequately captured by the included indicators, and perhaps especially for the unmarried. Such concerns aside, the results suggest that the marital status differences in cancer survival to little extent are due to comorbidities (and the few disease risk factors that are also captured), but rather to various other "host factors" or to treatment or care.Social Science [?] Medicine 03/2013; 81:42-52. DOI:10.1016/j.socscimed.2013.01.012 · 2.56 Impact Factor
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ABSTRACT: We investigated temporal changes in overall survival among prostate cancer (PC) patients and the impact of comorbidity on all-cause mortality. We conducted a population-based cohort study in the Central Denmark Region (1.2 million inhabitants). Using medical registries, we identified 7,654 PC patients with first-time PC diagnosis within the period 2000-2011 and their corresponding comorbidities within 10 years prior to the PC diagnosis. We estimated 1- and 5-year survival in four consecutive calendar periods using a hybrid analysis and plotted Kaplan-Meier survival curves. We used Cox proportional hazards regression to compute 1- and 5-year age-adjusted mortality rate ratios (MRRs) for different comorbidity levels. All estimates are reported with their corresponding 95% confidence intervals (CI). The annual number of PC cases doubled over the 12-year study period. Men aged <70 years accounted for the largest proportional increase (from 33% to 47%). The proportion of patients within each comorbidity category remained constant over time. One-year survival increased from 82% (CI: 80%-84%) in 2000-2002 to 92% (CI: 90%-93%) in 2009-2011, while 5-year survival increased from 43% (CI: 40%-46%) to 65% (CI: 62%-67%) during the same time intervals. Improvements in 5-year survival were most prominent among patients aged <80 years and among those with no comorbidity (from 51% to 73%) and medium comorbidity (from 32% to 54%). Improvements in survival were much smaller for those with high comorbidity (from 33% to 39%). The 1-year age-adjusted MRR for patients with high comorbidity (relative to patients with no comorbidity) increased over time from 1.84 (CI: 1.19-2.84) to 3.67 (CI: 2.49-5.41), while the 5-year age-adjusted MRR increased from 1.73 (CI: 1.34-2.23) to 2.38 (CI: 1.93-2.94). Overall survival of PC improved substantially during 2000-2011, although primarily among men with low comorbidity. All-cause mortality was highest among PC patients with high comorbidity, and their relative 1- and 5-year mortality increased over time compared to those without comorbidity.Clinical Epidemiology 11/2013; 5(Suppl 1):47-55. DOI:10.2147/CLEP.S47153
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ABSTRACT: Effect of comorbidity on the treatments that patients receive is not clear, as healthy elderly patients and the elderly with less comorbid diseases are included in the studies. In the present study, the effect of comorbidity on the survival was evaluated using Charlson Comorbidity Index (CCI) and Cumulative Illness Rating Scale (CIRS). The general features and comorbid diseases of the pancreatic cancer patients were retrospectively screened from the patient files using the automated system. CCI and CIRS were used as the comorbidity indices. A total of 106 patients with pancreatic cancer were included in the study. The median overall survival rate was 9.0 [95 % confidence interval (CI): 6.7-11.3] months. The median overall survival rate was found as 9.4 (95 % CI: 6.7-12.1) months in the patients whose CCI score was ≤ 2 and was found as 6.2 (95 % CI: 4.0-8.3) months in the patients with CCI scores ≥ 3 (p = 0.05). The median overall survival rate was calculated as 9.8 (95 % CI: 6.3-13.4) months in the patients with CIRS scores ≤ 2 and was calculated as 8.3 (95 % CI: 6.0-10.6) months in the patients with CIRS scores ≥ 3 (p = 0.51). When surgery, radiotherapy, grading, and CCI score were evaluated using multivariate analysis, it was observed that only the treatment modality had a significant effect on the survival rate. The results on the use of comorbidity indices are contradictory for the cancers with lower survival rates such as pancreatic cancer. New prognostic scales might be developed for this patient group by considering the side effects of chemotherapy.Wiener klinische Wochenschrift 11/2013; 126(1-2). DOI:10.1007/s00508-013-0453-9 · 0.79 Impact Factor