Wednesday, May 22, 2013

Another Study Links Chronic Pain and Suicide

SuicideSuicide is the 10th most common cause of death in the United States and a growing body of scientific literature suggests that chronic pain is associated with suicidal ideation, attempts, and mortality. However, there have been limited data on the extent to which specific pain conditions might be linked to suicides. New research suggests that back pain, migraine, and psychogenic pain may be of greatest concern.

In this new study, Mark A. Ilgen, PhD — of the U.S. Veterans Affairs (VA) Serious Mental Illness Treatment Resource and Evaluation Center, Ann Arbor, Michigan — and colleagues examined associations between clinical diagnoses of chronic noncancer pain conditions and suicide in a very large population of patients served by the VA Healthcare System (Ilgen et al. 2013). The researchers retrospectively identified 4,863,036 individuals who received services in fiscal year 2005 and were alive at the start of fiscal year 2006.

During a 3-year followup period (spanning fiscal years 2006-2008), there were 2,838 suicides in patients with pain conditions. The data were examined for associations between baseline clinical diagnoses of arthritis, back pain, migraine, neuropathy, headache or tension headache, fibromyalgia, and psychogenic pain and subsequent suicide death recorded in the National Death Index. At baseline, 92% of the patients were male and the vast majority (81%) were aged 50 years or older — more than a third (38%) were older than 70 years of age.

In the total population sample, arthritis was the predominant pain condition (43%), followed by back pain (23%), headache of any type (5%), neuropathy (5%), fibromyalgia (1.6%), and psychogenic pain (<1%). Using a traditional measure of statistical significance — ie, a p-value <0.05 — all of the chronic noncancer pain conditions were significantly associated with suicide mortality.

However, writing in an early online edition of JAMA Psychiatry, the researchers report that they also controlled for select demographic and contextual factors — age, sex, and Charlson Comorbidity Index score — and used a higher level of significance (p<0.01) in view of the very large sample size. In this analysis, elevated suicide risks were observed for each pain condition except for arthritis and neuropathy; hazard ratios ranged from 1.33 (99% Confidence Interval, 1.22-1.45) for back pain to 2.61 (99% CI, 1.82-3.74) for psychogenic pain.

When the analyses were further controlled for concomitant psychiatric conditions, the associations between pain conditions and suicide death were reduced. Significant associations only remained for A) back pain (hazard ratio, 1.13; 99% CI, 1.03-1.24), B) migraine (HR 1.34; 99% CI, 1.02-1.77), and C) psychogenic pain (HR 1.58; 99% CI, 1.11-2.26). In other words, compared with patients without the pain conditions during a 3-year period, the suicide risk was on average 13% greater in those with back pain, 34% greater with migraine, and 58% greater with psychogenic pain.

Ilgen et al. conclude that this is the largest and most comprehensive study to date of associations between noncancer pain and suicide mortality, and the findings indicate that links between pain and suicide differ by the specific pain condition. The most common condition, arthritis, had a modest association with suicide that did not remain significant after controlling for psychiatric comorbidity and other factors; whereas, back pain and some less common conditions — including migraines and psychogenic pain — were significantly associated with increased risk.

Healthcare providers treating patients with these conditions should be aware of the increased suicide risk, they propose, and note that this risk may be independent of mental health disturbances. It may be useful to conduct a suicide risk assessment in these patients and attend to other potential indicators of risk in those with chronic pain, such as hopelessness and suicidal ideation.

COMMENTARY: The association of chronic noncancer pain and suicide is not a new discovery, and it emphasizes that these pain conditions can become life-threatening if not adequately treated. Previous Pain-Topics UPDATES [here], [here], [here], [here], and [here] have discussed this topic, and many comments to those articles from readers have stressed that suicide is frequently considered as a last-resort option — especially when sufficient pain care is unavailable.

In many past studies attempts have been made to implicate opioid analgesics in the suicides, using biased distortions of data to portray greater risks when these medications are prescribed for pain. However, Ilgen and colleagues found that, for the overall group of VA patients with pain, most suicides involved the use of a firearm (68% of deaths), with poisoning as a distant second most common method (17% of suicides, but specific agents were not specified).

A limitation of this data-mining study was its focus on older men, and the researchers further note that reliable information on race/ethnicity, employment status, marital status, and level of social support were unavailable in the VA database — any of these factors could have played significant roles affecting suicide. Fibromyalgia, reported in only 1.6% of the sample, was probably underrepresented due to the relatively small percentage of females. Also, pain severity and the extent to which it was adequately treated via pharmacotherapy or other means is unknown, and these could have been critical factors influencing suicide.

Of particular concern in this study is the “psychogenic pain” category, which had been diagnosed in only 0.4% of the total sample, or 18,145 patients, but had an estimated increased suicide risk of from 11% to 126% (as reflected in the 99% Confidence Interval). Almost all patients (>95%) with psychogenic pain had an additional pain-condition diagnosis; although, analyses that controlled for other pain conditions and psychiatric comorbidity still found the greatest suicide risk associated with psychogenic pain. Yet, it is feasible that, despite the statistical manipulations, psychogenic pain remained confounded by and conflated with mental health problems and/or the presence of other diagnosed pain disorders.

Psychogenic pain has its own ICD-9-CM code within the International Classification of Diseases, but is otherwise undefined in the study by Ilgen et al. Many published definitions generally consider this disorder, also called “psychalgia,” as physical pain caused, increased, or prolonged by mental, emotional, or behavioral factors. There is no specific definition referencing the disorder by name in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV-TR), but some of the medical literature refers to chronic psychogenic pain under the umbrella of persistent somatoform pain disorder or functional pain syndrome.

Ilgen and colleagues suggest that the ambiguity related to the causes and treatments of psychogenic pain may be a core part of the relationship between this diagnosis and increased suicide risk. They state…

“It is possible that the burden of having a significant pain condition with an ambiguous cause is particularly difficult for patients, thus increasing their hopelessness, frustration, and risk for suicide. In addition, when treatment providers believe that a patient has pain without a clear cause or that they attribute mostly to a psychiatric problem, they may be less likely to provide active pain treatment in the form of pharmacologic or behavioral interventions. This undertreatment of pain could also increase the risk of suicide over time.”

More than anything, this suggests that a “psychogenic pain” or “psychalgia” diagnosis can be a medical euphemism for “it’s all in the patient’s mind” and the diagnosis probably should be eschewed. It is surprising that so many patients in the VA Healthcare System had this diagnosis noted in their records, which may have hindered effective pain management for those patients just as it might have confounded some of the analyses in this study.

REFERENCE: Ilgen MA, Kleinberg F, Ignacio RV, et al. Noncancer Pain Conditions and Risk of Suicide. JAMA Psychiatry. 2013 (May 22), online ahead of print [abstract here].

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