There is a frequent occurrence of gambling disorder (GD) in patients with major depressive disorder (MDD). Psychiatric comorbidities can present more severely in patients diagnosed with pathological gambling. There is limited information on symptom trends in MDD patients with GD, particularly in association with suicidality.
Our primary aim was to compare baseline characteristics in MDD patients with and without a GD diagnosis. The secondary aim was to assess the rate of suicidality (suicidal ideation/attempt) between groups and evaluate any predictors that may be associated with an increased risk of suicidal behavior. In addition, we also assessed the variation in gambling trends in MDD patients over several years.
Data for the study were obtained retrospectively from the Nationwide Inpatient Sample (NIS) dataset for the years 2006-2017. Our primary patient cohort was composed of patients age ≥ 18 years; admitted to the hospital with a primary diagnosis of MDD and a secondary diagnosis of GD. For baseline characteristics and suicidality, we compared these patients to MDD patients without a GD diagnosis. In addition, we also assessed the trends of baseline characteristics in MDD patients with GD over the years.
A total of 6646 patients were included in the MDD with GD group, and compared with 4,021,063 MDD patients without a GD diagnosis. More patients in MDD with GD group were older, white, and male. Alcohol abuse and obesity were seen more commonly in the GD group. In the outcome analysis, suicidal ideation (45.4% vs. 39.5%, p < 0.001), suicide attempt (7.2% v. 4.5%, p < 0.001) and composite of suicidal ideation/attempt (50.7% vs. 43.1%, p < 0.001) were more common in MDD with GD group compared to MDD without GD. In the multivariate analysis, GD was associated with higher odds of suicidality (Odds Ratio: 1.42 (1.35-1.49), p < 0.001). For the in-hospital trend analysis, we observed that, out of all MDD related admissions, comorbid GD related admissions decreased from 0.20% in 2006-2008 to 0.12% in 2015-2017. Among MDD patients with GD, there was an upward trend of inpatient admissions for non-white race, and Southern part of the United States (US) and a downward trend white race, and Western part of the US.
There is a higher risk of suicide, with an upward trend over the years in MDD patients with GD when compared to MDD patients without GD. Also, the prevalence of alcohol abuse was high in the GD group. Increased resource allocation and efforts to raise awareness campaigns for suicide prevention are needed to address the morbidity in this vulnerable patient population.

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