Background Alcohol Use Disorder is associated with suicide and suicide attempts, and addiction treatment services have a role in suicide prevention. We aimed to identify risk factors for suicide attempt among a cohort of community-based alcohol treatment service users. Methods Linked data from 4415 adults accessing secondary addiction services for alcohol treatment between 2006 and 2019 in London, UK, were used to identify risk factors for suicide attempt. Cox proportional hazards regression estimated the relative increase or decrease in hazard associated with each risk factor on a composite outcome event; death by suicide or contact with emergency psychiatric care within one year of starting treatment. Findings There were 468 (10.5%) crisis care contact events, and <10 suicide deaths. After adjustment, factors associated with increased hazard of crisis care contact or death by suicide were history of suicide attempt (HR 1.83[1.43-2.33]), poor mental health (HR 1.81[1.41-2.32]), current suicidal ideation (HR 1.65[1.18-2.31]), use of drugs other than cocaine, cannabis and opiates (HR 1.41[1.02-1.95]), female sex (HR 1.34[1.10-1.65]) and social isolation (HR 1.24[1.02 - 1.51]). Factors associated with reduced hazard of crisis care contact or death by suicide were alcohol abstinence (HR 0.51[0.31-0.83], ref>30 units), drinking 1-15 units (HR 0.64[0.49-0.85], ref>30 units), Black ethnicity (HR 0.61[0.45-0.83]) and living with children (HR 0.74[0.56-0.99]). Interpretation The identified risk factors for suicide attempt can help risk formulation and safety planning among patients accessing alcohol treatment services. Funding National Institute for Health Research Biomedical Research Centre at South London and Maudsley NHS Foundation Trust, King's College London.

The authors have declared no competing interest.

This work was supported by a PhD studentship from King's College London (JR), and used data provided by the Clinical Record Interactive Search (CRIS) platform funded and developed by the National Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London, and a joint infrastructure grant from Guy's and St Thomas' Charity and the Maudsley Charity (grant number BRC-2011-10035).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ethical approval for the study was granted via the Oxford C Research Ethics Committee, reference (18/SC/0372), which covers all uses of CRIS as an anonymised database for secondary analysis. Specific approval from the CRIS oversight committee was granted under Project 20-030 'The impact of alcohol treatment on suicidal crisis and use of emergency psychiatric care'. All patient identifiable information was removed prior to use by the CRIS application. All data remained within the NHS firewall during analysis. Frequencies fewer than 10 are suppressed in this manuscript as per CRIS guidelines.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

The ethical approval to access CRIS data (Oxfordshire Research Ethics Committee C (18/SC/0372)) requires the data to be stored behind an NHS firewall with access governed by a patient-led oversight committee. For this reason, the data cannot be made available in the manuscript, Supporting Information files or a public repository. However, subject to approval from the oversight committee, data access for research purposes is encouraged. Further information is available from cris.administrator@slam.nhs.uk.