Impact of comorbid depression or anxiety on patterns of treatment and economic outcomes among patients with diabetic peripheral neuropathic pain.

OBJECTIVE: The objective of this retrospective analysis was to assess the correlation of comorbid depression and/or anxiety to patterns of treatment, healthcare utilization, and associated costs among diabetic peripheral neuropathic pain (DPNP) patients, employing a large US administrative claims database. RESEARCH DESIGN AND METHODS: Patients under age 65 with commercial insurance and patients aged 65 and older with employer-sponsored Medicare supplemental insurance were selected for the study if they had at least one diagnosis of DPNP in 2005. The first observed DPNP claim was considered the 'index date.' All individuals had a 12-month pre-index and 12-month follow-up period. For both populations, two subgroups were constructed for individuals with depression and/or anxiety (DPNP-DA cohort) or without these disorders (DPNP-only cohort). Patients' demographic characteristics, clinical characteristics, and medication use were compared over the pre-index period. Healthcare expenditures and resource utilization were measured for the post-index period. Two-part models were used to examine the impact of comorbid depression and/or anxiety on healthcare utilization and costs, controlling for demographic and clinical characteristics.
RESULTS: The study identified 11,854 DPNP-only and 1512 DPNP-DA patients in the Medicare supplemental cohort, and 11,685 and 2728 in the commercially insured cohort. Compared to DPNP-only patients over the follow-up period, a significantly higher percentage of DPNP-DA patients were dispensed pain and DPNP-related medication. All components of healthcare utilization, except home healthcare visits and physician office visits, were more likely to be provided to DPNP-DA patients versus the DPNP-only cohort (all p < 0.01). Controlling for differences in demographic and clinical characteristics, DPNP-DA patients had significantly higher total costs than those of DPNP-only patients for Medicare ($9134, p < 0.01) and commercially insured patients ($11,085, p < 0.01). LIMITATIONS: Due to the use of a retrospective administrative claims database, limitations of this study include the potential for selection bias between study cohorts, mis-identification of DPNP and/or depression, and inability to assess indirect costs as well as use and cost of over-the-counter medications.
CONCLUSIONS: These findings indicate that the healthcare costs were significantly higher for DPNP patients comorbid with depression and/or anxiety relative to those without such disorders.