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.