4008 — Chronic hypoxia is a marker of suicide risk in veterans

Lead/Presenter: Natalie Riblet,  White River Junction VA Medical Center
All Authors: Riblet N (White River Junction VA Medical Center, Geisel School of Medicine at Dartmouth), Gottlieb DJ (White River Junction VA Medical Center, The Dartmouth Institute), , Watts BV (National Center for Patient Safety, Geisel School of Medicine at Dartmouth), Cornelius SL (White River Junction VA Medical Center), Fan VS (VA Puget Sound, University of Washington), Shi X (Dartmouth College), Shiner B(White River Junction VA Medical Center, Geisel School of Medicine at Dartmouth)

Objectives:
Patients with chronic hypoxia may be at increased risk for death of suicide, possibly through of the role of oxygen on serotonin synthesis. There has been limited study of the relationship between three key markers of chronic hypoxia (altitude, smoking and chronic obstructive pulmonary disease (COPD)) and suicide risk.

Methods:
Using the Veterans Affairs (VA) national administrative database, we carried out a population-based, retrospective cohort study to evaluate the association between three markers of chronic hypoxia (altitude, smoking, and COPD) and suicide. Eligible patients were over 18 years old and accessed VA healthcare services at any time during 2005 and 2014. Patients entered the cohort in their first year with a documented healthcare encounter and remained in the cohort until their death or the end of the study period. We used generalized estimating equation (GEE) methodology to evaluate the relationship between suicide and altitude, smoking, and COPD. We summarized results using odds ratio (OR) and 95% confidence intervals (CI). We adjusted for age, gender, ethnicity, rurality and VA use in each year.

Results:
9,620,944 patients met inclusion criteria. There were 22,403 suicide deaths. Patients living at elevations above sea-level were at significant increased risk for suicide (OR [1500meters or greater]: 1.36, 95%CI: 1.23, 1.40). The odds of suicide were greater among patients with COPD versus without COPD (OR: 1.52, 95%CI: 1.46, 1.57). Current smokers had a nearly two times greater odds of dying by suicide compared with never smokers. The odds of suicide among patients with all three markers of chronic hypoxia was almost four times that of patients who had no markers (OR 3.96, 95%CI: 3.47 - 4.52).

Implications:
Chronic hypoxia is a risk factor for suicide and having multiple indicators of hypoxia confers a greater risk for suicide, indicating a dose-response relationship.

Impacts:
Our study highlights possible levers for suicide prevention in the VA health system. Veterans with chronic hypoxia may not only require closer follow-up, but also specialized treatments. Studies are needed that use ecologic and experimental methods to ascertain effective, targeted interventions that can decrease suicide risk in patients with chronic hypoxia.