Session Type: Abstract Submissions (ACR)
Patients with rheumatoid arthritis (RA) have greater risk of non-Hodgkin lymphoma (NHL) than the general population. A previous two-center study suggested that the rates of progression and relapse of patients with NHL and antecedent RA were better than those of patients with NHL alone, but that the overall risk of mortality was increased. The objective of this study was to conduct a population-based study of Medicare beneficiaries to compare the survival of patients with NHL and prior RA with that of patients with NHL alone.
We used for this study population-based data that links patients with cancer in the State of Texas (Texas Cancer Registry) with Medicare data in beneficiaries 65 years and older. The datafile has a case capture of over 95%. We included all Medicare-linked cases in the registry diagnosed with NHL (B cell, T cell, or not otherwise specified/unknown lineage) between 2001 and 2010. We classified each patient into one of three groups based on RA Medicare claims during the year prior to cancer diagnosis (International Classification of Diseases ICD 9, code 714): (i) 1-RA (having least one RA claim), (ii) 2-RA (having at least 2 hospital or outpatient claims, 6 or more months apart), and (iii) no-RA (having no claims related to RA). Cox proportional hazards regression models were used to compare overall survival among groups. Covariates included demographic variables, stage at diagnosis and comorbidity burden estimated using the Charlson’s comorbidity index.
8,858 NHL patients were included, of whom 2.5% (n=226) had 1-RA claim and 2.3% (n=203) had 2-RA claims. Overall median survival for the cohort was close to 4 years. The hazard ratio (HR) for patients in the 1-RA group was 1.14 (95% CI, 0.95-1.37), and that for the 2-RA group was 1.04 (95% CI, 0.85-1.27), compared to that of patients without RA after controlling for demographics, and stage. The risk did not significantly change after including comorbidity in the models: 1-RA group HR=1.13, 95% CI, 0.94-1.36, and 2-RA group HR=1.04, 95% CI, 0.85-1.26. Comorbidity was an independent factor significantly associated with mortality such that having one additional comorbidity increased risk by 20% HR=1.20, (95% CI, 1.12-1.29), and having 3 or more comorbidities increased risk by more than 2 fold, HR=2.31 (95% CI, 2.01-2.43).
Having antecedent RA does not confer an independent mortality risk in NHL Medicare beneficiaries. However, patients with RA and NHL with other comorbidities can have decreased survival. Additional research should evaluate the risk associated with specific comorbid conditions, and whether this potential detrimental effect is from disease burden or differential use of cancer therapies.
Z. Abou Zahr,
M. E. Suarez-Almazor,
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