Risk of Suicide in Patients With Major Depressive Disorder and Comorbid Chronic Pain Disorder: An Insight From National Inpatient Sample Data.

BACKGROUND

Approximately 17.3 million adults in the United States have had a minimum of one major depressive episode. Comorbidity of depression and pain can affect individuals of any age, but is more prevalent in the elderly affecting up to 13% of people in the elderly population. Given that depression and suicidal ideation (SI) pose a considerable burden resulting in enormous suffering, there is a need to understand the factors of the relationship between chronic pain (CP), depression, and SI.

OBJECTIVES

Our primary objective in this study was to compare suicidality (SI/attempt [SA]) between patients with major depressive disorder (MDD) and CP and a matched control group. The secondary objective was to compare length of stay, total hospital costs, and discharge disposition in these populations.

STUDY DESIGN

The National Inpatient Sample (NIS) dataset developed by the Healthcare Cost and Utilization Project was used for this study. The NIS is a database of hospital inpatient stays derived from billing data submitted by hospitals to statewide data organizations across the United States. We obtained patient records from the NIS dataset for the years 2006 to 2017. All data were de-identified so Institutional Review Board approval was waived.

METHODS

We used mean and standard error to describe continuous data and counts (percentage) to describe categorical data. Categorical data were compared using Rao-Scott adjusted chi-square tests and continuous data were compared using Student's t tests. Matching was performed using propensity scores in random order with a caliper size of 0.001. To assess predictors associated with suicidality, logistic regression analysis was performed.

RESULTS

A total of 393,481 patients having MDD with CP (MDD+CP) were included in the analysis. The mean age was 49.4 years, and 54.9% of patients were women. Overall, rate of composite outcome of SI/SA was more prevalent in MDD+CP group (51% vs 41%, P < 0.001). Rate of SI was 48% vs 39% (P < 0.001) in the MDD+CP and MDD without CP (MDD-CP) groups, respectively. MDD+CP was one of the strongest predictors of suicidality, responsible for 48% more risk of SI/SA compared to MDD-CP group. In comparison to non-Whites, the rate of suicidality was 7.5% less in White population. Alcohol abuse and substance abuse were associated with 17% and 8% greater risk of SI/SA, respectively. For women, the odds of having SI/SA was 1.20 greater compared to men.

LIMITATIONS

No information was available on the causal relationship between MDD+CP disorder and SI/SA. Retrospective studies are susceptible to recognition, reporting, and coding bias. There is no information available on medications use or the duration and severity of CP and bipolar disorder, which can all be confounding factors.

CONCLUSIONS

Psychiatrists and other physicians must be cognizant of the presence of CP and the risk of suicide, especially when patients present with depressive symptoms. The treatment plan for this patient population should include routine screening for pain symptoms and risk assessment for SI.