Limitation: The results probably underrepresent the true percentage of suicide decedents who had chronic pain, given the nature of the data and how they were captured.
Conclusion:Chronic pain may be an important contributor to suicide. Access to quality, comprehensive pain care and adherence to clinical guidelines may help improve pain management and patient safety.
Primary Funding Source: None.
More than 25 million adults (11.2%) in the United States have some level of daily pain; 10.5 million (4.6%) have considerable pain every day (
1). Chronic pain costs $600 billion annually in medical care and lost productivity, exceeding the costs associated with heart disease, cancer, or diabetes. Despite this societal toll, these statistics do not describe the effect of chronic pain on each person who has a diminished quality of life. The burden of chronic pain is difficult and imprecise to measure and often is undervalued in research, management, prevention, and policy development.
Suicide has been increasing since 1999 and is now the 10th leading cause of death in the United States. Recent findings suggest that chronic pain is associated with suicide and patients with chronic pain commonly have risk factors for suicide, including comorbid psychiatric conditions (such as depression and anxiety) and access to opioids used to treat chronic pain. However, previous studies primarily examined nonfatal suicidal behaviors rather than suicide deaths associated with chronic pain or the characteristics of such deaths. The purpose of our analysis was to better understand the burden of chronic pain among suicide decedents, thereby providing an indication of one effect that chronic pain may have on individuals and their quality of life.
Methods
Data Sources: We analyzed data from 18 states participating in the National Violent Death Reporting System (NVDRS) for at least 1 year from 1 January 2003 to 31 December 2014. The NVDRS, described elsewhere, is an active, state-based surveillance system that links data on violent deaths (including suicides) from death certificates, coroner or medical examiner reports, and law enforcement reports into a single incident record. Information is abstracted by using standard coding guidance developed by the Centers for Disease Control and Prevention (CDC). The NVDRS defines suicide as a death resulting from the intentional use of force against oneself, classified by the International Classification of Diseases, 10th Revision, cause-of-death codes X60 to X84, Y87.0, and U03. Statewide NVDRS data have been collected in Maryland, Massachusetts, New Jersey, Oregon, South Carolina, and Virginia since 2003; Alaska, Colorado, Georgia, North Carolina, Oklahoma, Rhode Island, and Wisconsin since 2004; Kentucky, New Mexico, and Utah since 2005; Ohio since 2011; and Michigan since 2014.
More than 600 standard variables are coded in the NVDRS, including circumstances identified as directly contributing to the death (such as a physical health problem). Data on these precipitating circumstances often originate from investigators’ interviews with informants who knew the decedent. In addition, the NVDRS abstractors enter separate narratives based on reports from both coroners or medical examiners and law enforcement officers to summarize the events of the fatal incident and other pertinent information, including health conditions affecting the decedent.
Case Selection: We included decedents aged 10 years or older who died by suicide during 2003 to 2014 in this analysis. We identified cases with evidence of chronic pain by using keyword searches for 120 medical conditions and 9 pain types (allowing for common misspellings) in the coroner or medical examiner and law enforcement narratives. We selected these keywords on the basis of medical conditions and pain types associated with chronic pain from the American Chronic Pain Association (ACPA).
We selected cases 3 ways. First, we selected cases that reported at least 1 medical condition primarily associated with chronic pain (such as “fibromyalgia”), pain classified by anatomical location (such as “back pain”) or organ system (such as “musculoskeletal pain”), or pain type consistent with chronic pain (such as “persistent pain”) (group 1). Second, we selected cases with medical conditions frequently associated with chronic pain, but not necessarily as the primary symptom (such as “sickle cell”), if the keyword “pain” (excluding “emotional” and “acute” pain) also was present and a contributing physical health problem was endorsed (group 2). Third, we selected cases with the keyword “pain” (excluding “emotional” and “acute” pain) and a contributing physical health problem (group 3) to maximize the capture of decedents with chronic pain. “Contributing physical health problem” is a standard NVDRS variable indicating that any physical health condition, such as terminal disease, debilitating condition, or chronic pain, was determined to be a contributing factor. This variable alone is too broad for defining cases of chronic pain but was used in groups 2 and 3 to increase specificity. We separately categorized pain by anatomical structure and medical condition by organ system by using a pain taxonomy prepared by the American Pain Society. Decedents may have had more than 1 medical condition in more than 1 pain category.
We reviewed the narratives of randomly selected decedents (n = 100 each from groups 1, 2, and 3) by using an iterative approach to further refine and validate our keyword search. Criteria for chronic pain cases were met if the decedent had any of the ACPA medical conditions or pain types described earlier, or if the narrative specifically indicated chronic pain. Cases were excluded if the pain duration was documented as less than 3 months, the described pain referred exclusively to emotional pain, or the condition or pain type described applied to someone other than the decedent. Rater pairs conducted a final review of 216 randomly selected cases (2.0%). Interrater agreement ranged from 92.6% to 96.2% (κ range, 0.63 to 0.65); discrepancies were discussed and coded to consensus. In this analysis, 199 decedents (92.1%) were true cases of chronic pain.
We also reviewed narratives of a random sample of 200 decedents with chronic pain who left suicide notes to determine whether the notes offered insights regarding the role of pain in precipitating suicide. Pain was determined to be a contributing factor if the suicide note included documentation that the decedent’s decision to die by suicide was because of pain.
Measures: We assessed the percentage of suicide decedents with chronic pain over time as well as the subset who died of prescription or illicit opioid overdose. We examined suicide decedents with and without chronic pain by demographic characteristics, mechanism of death, toxicology results, and precipitating circumstances.
Statistical Analysis: We examined the percentage of suicide decedents with evidence of chronic pain over time and used descriptive statistics to examine characteristics of suicide decedents with and without chronic pain across 12 data years (2003 to 2014). We used U.S. Census population data to calculate crude suicide rates per 100 000 persons by age group. Because of small sample sizes during 2003 to 2004, resulting in unstable rates, all reported rates represent annualized averages across 10 data years (2005 to 2014). We used SAS, version 9.3 (SAS Institute), for all analyses.
Role of the Funding Source
This study used data collected as part of routine injury surveillance and was not funded.
Results
During 2003 to 2014, the NVDRS identified 123 181 suicide decedents aged 10 years or older, 10 789 (8.8%) of whom had evidence of chronic pain. The percentage of decedents with chronic pain increased from 7.4% in 2003 to 10.2% in 2014, but the percentage who died by opioid overdose remained low overall (<2.0%)
