Clinical Markers Associated With Risk of Suicide or Drug Overdose Among Individuals With Smoking Exposure: A Longitudinal Follow-up Study of the COPDGene Cohort

Abstract

Studies have shown that COPD and smoking are associated with increased suicide risk. To date, there are no prospective studies examining suicide risk among individuals with smoking exposure along a spectrum of pulmonary diseases ranging from normal spirometry to severe COPD. Which clinical variables predict death by suicide or overdose of indeterminate intent in a large cohort of individuals with smoking exposure within the Genetic Epidemiology of COPD (COPDGene) study? We studied data from 9,930 participants involved in COPDGene, a multisite, prospective cohort study of individuals with smoking exposure. Primary cause of adjudicated deaths was identified by using death certificates, family reports, and medical records. Time to death by suicide/overdose was examined as the primary outcome in Cox regression models including age, sex, race, BMI, pack-years, current smoking status, airflow limitation (FEV1 %predicted), dyspnea (modified Medical Research Council scale score≥ 2), 6-min walk distance, supplemental oxygen use, and severe exacerbations in the prior year with time-varying covariates and other causes of death as a competing risk. The cohort was 47%female and 33%Black (67%White); they had a mean ± SD age of 59.6 ± 9.0 years and a mean FEV1 %predicted of 76.1 ± 25.5. Sixty-three individuals died by suicide/overdose. Factors associated with risk of suicide/overdose were current smoking (hazard ratio [HR], 6.44; 95%CI, 2.64-15.67), use of sedative/hypnotics (HR, 2.33; 95%CI, 1.24-4.38), and dyspnea (HR, 2.23; 95%CI, 1.34-3.70). Lower risk was associated with older age (per-decade HR, 0.45; 95%CI, 0.31-0.67), higher BMI (HR, 0.95; 95%CI, 0.91-0.99), and African-American race (HR, 0.41; 95%CI, 0.23-0.74). Severity of airflow limitation (FEV %predicted) was not associated with suicide risk. In this well-characterized cohort of individuals with smoking exposure with and without COPD, risk factors for suicide/overdose were identified that emphasize the subjective experience of illness over objective assessments of lung function.