Effect of dementia diagnosis on receipt of postoperative colon cancer chemotherapy.

Abstract

769 Background: Colon cancer and dementia have a high risk of co-occurrence. Prior studies found that patients with dementia have higher mortality than non-demented counterparts, mostly from non-cancer causes. We hypothesized that a dementia diagnosis using an improved algorithm would be associated with reduced use of postoperative therapy. Methods: In addition to the claims-based algorithm for dementia published by Centers for Medicare and Medicaid Services that uses SEER-Medicare Medicare Provider Analysis and Review, Carrier Claims, Home Health Agencies, and Outpatient files, we developed a medication-based algorithm using the part D file based on prescription for any of the five FDA-approved dementia drugs (donepezil, galantamine, memantine, rivastigmine, tacrine). We measured agreement between the two diagnostic algorithms with k-statistics. Using each algorithm and a final combined algorithm, we used multivariable logistic regression adjusting for demographics and disease characteristics to examine the effect of dementia on the use of post-operative colon cancer chemotherapy. Parallel analyses restricted the population to later-stage cancer patients (stage III/IV). Results: 46,126 patients diagnosed between 2007 and 2009 were identified. 20% had dementia by either of the algorithms. 9% of the dementia cases were identified through Part D data. The two algorithms showed moderate agreement (k>0.49, p=0.007). After surgery, those patients with dementia by the combined algorithm were less likely to receive chemotherapy (OR = 0.641, 95% CI: 0.597-0.688). Those with dementia identified by part D data were even less likely to receive chemotherapy than those identified by the claims algorithm (OR=0.617, 95% CI: 0.466-0.816 for medication; OR=0.767, 95% CI: 0.684-0.860 for claims). A similar pattern was detected when restricting to stage III/IV patients (OR=0.667, 95% CI: 0.457-0.973). Conclusions: Part D data increases the sensitivity for identifying dementia cases in SEER-Medicare. Patients with dementia are significantly less likely to receive post-operative chemotherapy. Thus, reduced postoperative colon cancer therapy among patients with dementia may contribute to higher cancer-related mortality.