In a large nationally representative sample of adolescents, we found that self-reported chronic pain was associated with increased risk of suicide ideation and attempts. These findings are similar to observations among adults48,22,37,5
. This association did not vary as a function of age and gender, indicating that suicidality is increased in both boys and girls of all ages who suffer from chronic pain. We also observed that pain was associated with an increase in suicidal thoughts and behaviors 1 year later. Thus, pain is associated with both increased likelihood of suicidal thoughts and attempts in the last year, as well as increased suicidal thoughts and behavior in the subsequent year. More studies are needed to determine if chronic pain plays a causative role in the development of suicide ideation and thoughts.
Pain and suicidal thoughts or ideation may not be directly linked. Underlying factors could explain the co-occurrence of both. One such a factor is depression. Depression is an important risk factor for suicidality, and co-morbid depression is common in pain patients. We found that chronic pain, and specifically chronic headache, was associated with suicide ideation
after controlling for depression. This is in accordance with previous studies which have found that chronic pain in adults is associated with increased suicide ideation/attempt independently of depression25, 28
. In contrast, suicide attempts
among youth with chronic pain were largely associated with the presence of depression. Thus, youth with co-morbid pain and depression maybe at heightened risk for suicide attempt. Even though we did not find an independent effect of pain on suicide attempts in this large sample, clinicians working with individual cases
should be open to the possibility that youth with pain but no depression may still confer a risk for suicide attempt. Previous studies have found that although depression is a main risk factor for suicide, not all suicide attempts occur in the presence of depression2
. Indeed, all patients reporting thoughts of wanting to kill themselves should be closely monitored by their physicians. However, the current findings do imply that the presence of depression among individuals with chronic pain is significantly related to increased risk of suicide attempts. Clinicians should be especially vigilant in monitoring risk among young patients with chronic pain and depression, and in helping these young patients receive appropriate treatment for both their pain and their depression.
The present study does not allow us to investigate why chronic pain and suicidality are related. A recent review by Tang and Crane51
identified 8 risk factors for suicidality in chronic pain divided into general risk factors (family history of suicide, previous suicide attempt, being female and co-morbid depression) and pain-specific factors (pain location, intensity, duration and co-morbid insomnia). In our current study, we didn’t find an effect of general risk factors such as gender and age. Furthermore, as discussed above, the relationship of headache pain to future suicide ideation and both headache and stomachache pain to previous year’s suicide ideation and attempts was largely independent of depression. It is possible that pain-specific factors, such as duration/intensity and control over the pain, may explain why some young pain patients are at increased risk for suicidality. Moreover, pain and suicide may share similar biological pathways that can explain their association. For example, serotonin has been implicated in both pain and suicide ideation/attempt but so far the overlap has not been studied10,31
To our knowledge, this is the first study to observe an association between chronic pain and suicide ideations/attempts in a population-based sample of adolescents. This is an important age period because there is an increased risk of suicidality; suicide is one of the major causes of death in adolescence and for every death, there are 100–200 attempts leaving many adolescents prone to self-inflicted injury11
. Rates of suicide attempt in our study and others range form 4–6% in this age group and suicide ideation is 2 to 3 times more common7
. Increased ability to recognize those adolescents who are at risk for suicide and offering appropriate care can make an important difference in the lives of many.
The strength of the current study is the large nationally representative sample of youth in the United States and the longitudinal design allowing us to look at the association of pain with suicide ideation/attempt over time. However, it also has some weaknesses which should be acknowledged. First, all data are based on self-reports, which may be subject to issues of recall. Memory bias may have varied across the variables of interest as pain and suicide ideation/attempt were based on a 12-month recall and depressive symptoms were measured in the past week. Moreover, current depression could increase recall of pain and/or suicide ideation/attempt in the past year. Second, despite the longitudinal design of the study, no inference can be made about causality: even if pain is associated with suicidality 1 year later, other factors than pain may explain this link. Third, since this is an existing dataset, the timing of assessing chronic pain, depression and suicide ideation/attempt may not be optimal to understand the temporal relation to each other. And last, the dataset is limited by the amount of medical information related to pain. The subjects in the study reported that they have suffered from at least weekly episodes of pain in the past year, but the dataset does not contain information about the causes of pain or its severity. For most chronic pain, no illness or injury is found upon medical examination that would explain the pain symptoms 3,45
. In this context, it appears that most of the chronic pain reported in this study would be consistent with the definition of chronic pain as set forth by the International Association for the Study of Pain, namely: “pain that persists beyond the usual course of an acute illness or injury or beyond what is the usual time for recovery”1,21
. In the case of abdominal pain, non-painful conditions may also have been included. Subjects were asked about both “stomachaches” and “upset stomach”. The last may have included stomach discomfort such as bloating, nausea or early satiety. These symptoms may or may not be associated with pain and thus a minority of patients may have been included who had non-painful stomach discomfort. Considering that non-painful conditions are included in our abdominal pain group, the association between abdominal pain and suicide ideation/attempt is probably under-estimated
in this study. To supplement the findings from this population study, data from clinical samples are needed, in which cause and treatment of pain and temporal ordering of pain relative to depression and suicide ideation/attempt are available,.
In sum, 25–50% of youth in our study and other population studies suffer from chronic pain41,32
. Chronic pain in youth is associated with significant psychiatric comorbidity, reduced quality of life, restrictions in daily living, increased days missed of school, medical consultation for the pain and continued functional impairments into adulthood 41,34,33,18,19,6
. Not only does severe chronic pain result in tremendous suffering, but medical treatment provides only marginal relief. However, the seriousness of chronic non-malignant pain is often not recognized because it doesn’t directly affect morbidity or mortality of the patient. The current study underlines the need for clinicians to be alert to suicide ideation and attempt in this at-risk population and to address psychiatric co-morbidities vigilantly.