Temporal order of diagnosis between gambling disorder and substance use disorders: Longitudinal results from the Norwegian Patient Registry

INTRODUCTION: Previous research has established co-occurrence between substance use disorders (SUDs) and gambling disorder (GD). Less well understood is the temporal sequencing of onset between these disorders, and in particular whether SUD is a risk factor for GD. The present study examined the temporal order between registered diagnoses of SUD and GD, stratified by sex. METHODS: A study with a longitudinal design using objective registry data drawn from the Norwegian Patient Registry was carried out. Among the patients with a registered diagnosis of GD between 2008 and 2018 (N = 5,131; males = 81.8%), those (who in addition) had a registered diagnosis of any SUD (n = 1,196; males = 82.1%) were included. The measures included a registered diagnosis using the ICD-10 of both GD (code F63.0) and SUDs (codes F10-F19) by a health care professional. Binomial tests were used to identify the temporal order between SUD(s) and GD. Co-occurring cases (i.e., cases diagnosed within the same month) were removed in the main analyses. RESULTS: Results showed a significant directional path from SUD to GD but no support for the reversed path (i.e., from GD to SUD). This finding was similar overall for (i) both males and females, (ii) when different SUDs (alcohol, cannabis, sedatives, and polysubstance) were examined individually, and (iii) when specifying a 12-month time-lag between diagnoses. CONCLUSIONS: The findings suggest that experiencing SUD(s) is a risk marker for GD given the temporal precedence observed for patients in specialised healthcare services seeking treatment. These results should be considered alongside screening and prevention efforts for GD.