Treatment Seeking Nitrous Oxide Users in Addiction Care: A Comparison with Cocaine Users on Clinical and Treatment Characteristics

Introduction: Over the past decade, frequent use of large quantities of nitrous oxide (N2O) has become more common in the Netherlands. Although N2O poses several negative health consequences for a subgroup of problematic N2O users, there is a lack of knowledge on what characterizes these intensive users. This study therefore aims to provide the demographic and substance use characteristics and experiences during treatment of treatment seeking problematic N2O users and to compare this with a matched group of treatment-seeking problematic cocaine users. Methods: A retrospective chart review was performed of patients who were referred for treatment of problematic N2O use at a large Dutch addiction care facility from January 2020 to September 2022, extracting demographics, pattern of use and follow-up data. Additionally, a subgroup of N2O users was propensity-score matched (1:1) with a subgroup of treatment seeking problematic cocaine users, both groups excluding users with substance use disorders or frequent use of substances other than N2O and cocaine, respectively. Results: 128 patients with a N2O use disorder were included in the total sample and a subgroup of 77 N2O-only users was propensity-score matched on age and sex to 77 cocaineonly users. N2O users were typically young (mean age 26.2 years), male (66.4%), unmarried (82.9%), with a low education level (59.0%) and born in the Netherlands (88.2%), with parents born in Morocco (45.3%). N2O was used intermittently (median 10 days/month, IQR 4.0-17.5 days) and often in very large quantities (median 5 kg [ca. 750 balloons] per average using day, IQR 2-10 kg). Compared to the patients with a cocaine use disorder, matched N2O users were lower educated, more often from Moroccan descent, and less likely to be alcohol or polysubstance users. Despite receiving similar treatments, N2O users were twice as likely to discontinue treatment before completion compared to cocaine users (63 vs. 35%, p = 0.004). Conclusion: Treatmentseeking problematic N2O users are demographically different from treatment-seeking problematic cocaine users and are much more likely to dropout from psychological treatment. Further research is needed into the needs and other factors of problematic N2O users that relate to poor treatment adherence in problematic N2O users.