Comorbid problem gambling in substance users seeking treatment

Pathological and problem gambling refer to a class of impulse control or addictive disorders that may be common comorbidities in substance use treatment. This class of disorders include those meeting criteria for a psychiatric diagnosis of ‘pathological gambling’, and others comprising a broader spectrum of severity defined by significant personal and social harm, and described in terms of ‘problem gambling’. This project was comprised of two parts and was intended to address limitations of existing evidence. It was also intended to: (a) provide rigorous estimates of the prevalence of pathological and problem gambling in treatment for substance use problems; and (b) explore data on associations between gambling comorbidities in substance use treatment and clinical covariates.
Part A of the project comprised a systematic review of studies of the prevalence of gambling disorders in substance use treatment. This review identified 26 eligible studies, which were based mostly in the United States (US) and considered treatment contexts including inpatient or residential services, methadone maintenance therapy (MMT), and general outpatient treatment for alcohol and illicit drug use. Results from 25 studies (total n = 11,470) suggested around 14% of patients that demonstrated comorbid pathological gambling. Results from 18 studies (total n = 8,089) suggested approximately 23% that suffered conditions along the spectrum of problem gambling. The analyses also identified high levels of statistical heterogeneity across studies, suggesting estimates of pathological gambling that varied meaningfully across studies and contexts. Although there were trends suggesting potential differences across studies according to
clinical factors (e.g., studies of MMT tended to produce higher estimates than studies of inpatient or general outpatient settings) and methodological factors (e.g., studies relying on self-report tools tended to produce higher estimates than studies using the Diagnostic and Statistical Manual of Mental Disorders (DSM) based interviews), these differences were not statistically significant. As
such, the observed variability across studies remains unexplained. Funnel plots produced tentative evidence of publication bias in results, such that studies reporting lower estimates were seemingly less likely to be observed in the published literature. This suggests that available studies may
provide an upwardly bias selection of findings.
Part B comprised a secondary analysis of data from wave 1 (2000-2001) and wave 2 (2004-2005) of the US National Epidemiological Survey on Alcohol and Related Conditions (NESARC). Analyses were based on data from n = 272 participants reporting past year treatment for substance use problems, and considered links between symptoms of pathological gambling and
various outcomes including mental and physical health, substance usage and psychosocial difficulties. Results failed to support expected associations with symptoms of pathological gambling and current Axis I disorders, as well as overall mental and physical health status, substance usage and healthcare utilisation. Rather, the findings suggested more specific associations with certain
lifetime Axis I disorders (e.g., major depression) and Axis II disorders, as well financial and interpersonal difficulties. Symptoms of pathological gambling were associated prospectively with subsequent diagnoses of major depression.
Overall, results highlight limitations of available evidence, including unexplained heterogeneity across published studies, and a dearth of empirical data from outside the US. Notwithstanding a concomitant need for caution when interpreting the findings, this project provides evidence to suggest that gambling disorders comprise a prevalent class of comorbidities in substance use treatment. It suggests that where pathological gambling symptoms are observed in substance use treatment they may reflect a pervasive form of underlying psychopathology which manifests through development of multiple psychiatric problems across the lifetime. These may include gambling problems as well as affective and personality disturbances. Although pathological gambling symptoms may have modest independent associations with many clinical covariates (given high levels of psychiatric severity that define treatment seeking samples overall), there are
specific psychosocial difficulties associated with pathological gambling. These include interpersonal problems at work and financial crises, which can exacerbate pre-existing mental health problems like major depression. This report concludes with a discussion of strategies for identifying and responding to pathological and problem gambling in the context of substance use treatment.