Impact of Psychiatric Comorbidities on Health Care Costs Among Patients With Cancer

Background: Psychiatric disorders are common in cancer patients and impact outcomes. Impact on cancer care cost needs study to develop business case for psychosocial interventions. Objective: To evaluate the impact of preexisting psychiatric comorbidities on total cost of care during 6 months after cancer diagnosis. Methods: This retrospective cohort study examined patients diagnosed with cancer between January 1, 2009, and December 31, 2014, at one National Cancer Institute-designated cancer center. Patients who received all cancer treatment at the study site (6598 of 11,035 patients) were included. Patients were divided into 2 groups, with or without psychiatric comorbidity, based on International Classification of Diseases, Ninth Revision (ICD-9) diagnosis codes. Total costs of care during the first 6 months of treatment were based on standardized costs adjusted to 2014 dollars, determined by assigning Medicare reimbursement rates to professional billed services and applying appropriate cost-to-charge ratios. Quantile regression models with covariate adjustments were developed to assess the effect of psychiatric comorbidity across the distribution of costs. Results: Six hundred ninety-eight ( 10.6%) of 6598 eligible patients had at least one psychiatric comorbidity. These patients had more nonpsychiatric Elixhauser comorbidities (mean 4 vs. 3). Unadjusted total cancer care costs were higher for patients with psychiatric comorbidity (mean [standard deviation]: $51,798 [$74,549] vs. $32,186 [$45,240]; median [quartiles]: $23,871 [$10,705-$57,338] vs. $19,073 [$8120-$38,230] ). Quantile regression models demonstrated that psychiatric comorbidity had significant incremental effects at higher levels of cost: 75th percentile $8629 (95% confidence interval: $3617-13,642) and 90th percentile $42,586 (95% confidence interval: $25,843-59,330). Conclusions: Psychiatric comorbidities are associated with increased total cancer costs, especially in patients with very high cancer care costs, representing an opportunity to develop mitigation strategies.