Chronic pain frequently coexists with psychiatric symptoms in patients diagnosed with complex regional pain syndrome (CRPS). Previous studies have shown a relationship between CRPS and the risk of suicide. The purpose of this study was to assess risk factors for suicidal ideation in patients with CRPS.
Based on criteria established by the International Association for the Study of Pain, 39 patients diagnosed with CRPS Type 1 or Type 2 were enrolled in this study. Suicidal ideation was assessed using item 3 of the Hamilton Depression Rating Scale (HAMD), and symptoms of pain were evaluated using the short form of the McGill Pain Questionnaire (SF-MPQ). Psychiatric symptoms were assessed in using the Structured Clinical Interview for DSM-IV Disorders (SCID-I, SCID-II), the HAMD, the Hamilton Anxiety Rating Scale (HAMA), the Global Assessment of Functioning Scale (GAF), and the Pittsburgh Sleep Quality Index (PSQI).
Twenty-nine patients (74.4%) were at high risk and 10 (25.6%) were at low risk for suicidal ideation. Risk factors significantly associated with suicidal ideation included depression (p=0.002), severity of pain (p=0.024), and low scores on the GAF (p=0.027). No significant correlations were found between suicidal ideation and anxiety or quality of sleep.
Significant risk factors for suicidal ideation in patients with CRPS include severity of pain, depressive symptoms, and decreased functioning. These results suggest that psychiatric evaluation and intervention should be included in the treatment of CRPS.
Pain is associated with higher risk of suicide.
Although it may be difficult to determine whether a mental disorder is a preexisting condition or is subsequent to chronic pain, comorbidity significantly increases the risk of suicide.
Complex regional pain syndrome (CRPS) is a medical condition whose primary symptom is chronic distressing pain and it has been subdivided into type I (reflex sympathetic dystrophy) and type II (causalgia).
Although CRPS has properties similar to those of other conditions involving peripheral neuropathy, it also has several distinct characteristics. For example, the subjective experience of pain in CRPS is accompanied by sudomotor and vasomotor dysfunction (i.e., changes in skin color and/or temperature).
It is prudent for clinicians to include a thorough suicide risk assessment in medical examinations of patients with CRPS given their apparent vulnerability due to functional impairments and severe pain and to the possibility of psychiatric symptoms associated with depression and other psychological diagnoses. Lohnberg's review
The primary aim of this study was to identify clinical factors related to suicidal ideation in patients with CRPS. Secondarily, we evaluated psychiatric comorbidity in this population. Results indicated an association between suicidal ideation and various psychiatric symptoms. We hypothesized that lifetime comorbid psychiatric symptomatology would increase the risk for suicidal ideation among individuals with CRPS.
The subjects were outpatients at the Pain Clinic of Seoul National University Hospital. Patients included in the study met the following criteria: 1) aged 18 years or older; 2) presentation with CRPS symptoms; and 3) voluntary provision of informed consent for participation in the study. Exclusion criteria consisted of 1) younger than 18 years of age, 2) fewer than 6 months of CRPS treatment, 3) a medical history of neurological disease, 4) a history of substance abuse, and 5) previous treatment for any type of neuropsychiatric condition.
After obtaining approval to conduct the study from the Institutional Review Board, the procedures used in the study were fully explained to all subjects, who then provided informed consent to participate. The patient subjects were evaluated by physicians to confirm the presence of CRPS as defined by the International Association for the Study of Pain (IASP). Each subject was subsequently assessed by neuropsychiatric specialists who were blind to each patient's clinical profile to determine the presence and nature of any psychiatric symptoms.
The Structured Clinical Interview for DSM-IV Disorders (SCID) is a diagnostic tool used to identify DSM-IV Axis I
Psychiatric characteristics were assessed with Hamilton Rating Scale for Depression (HAMD)
The low-suicidal ideation (SI) group included those with scores of 1 or below on HAMD item 3 (0=suicide ideation absent, 1=feels that life is worth living), and the high-SI group included those with HAMD item 3 scores above 1 (2=wishes he were dead or any thoughts of possible death to self; 3=suicidal ideas or gesture; 4=attempts at suicide). This cutoff value has been commonly used in previous studies.
The PSQI
The short form of the McGill Pain Questionnaire (MPQ-SF)
Between-group comparisons involving categorical data were performed using the chi-square statistic corrected for continuity; between-group comparisons involving continuous data (age and socio-economic status) were calculated using Student's t-test. Pearson's correlation analysis was used to assess correlations between suicidal ideation and other variables.
The sample included 39 patients with CRPS; 33 (84.6%) were diagnosed with CRPS Type 1, and six (15.4%) were diagnosed with CRPS Type II. Males accounted for 61.5% (n=24) of the patients, and females 38.5% (n=15). The mean age of the patients at their initial evaluation at the pain clinic was 37.87 (±11.94) years, and the mean number of years of education was 12.49 (±2.68) years. Patients reported having CRPS symptoms for a mean of 2.84 years (±2.49) at the time of evaluation and had been prescribed 4.28 (range, 0-7) different kinds of medications on average. The most frequently used medications were anticonvulsants and antidepressants. We found no significant differences between the two groups in terms of demographic characteristics and medications (
Anxiety was not a significant predictor of suicide risk, but depressive symptoms were. The HAMD average score of high-SI group (25.00±6.94 SD) was significantly higher than that of the low-SI group (14.03±9.49; F=1.67, t=-3.35, df=37, p=0.002).
The average pain intensity for each year after symptom onset was 5.50 (SD=2.3). The high-SI group reported greater pain intensity (6.90±2.81) than did the low-SI group (5.02±1.93; t=-2.36, df=37, p=0.02). The low-SI group also had significantly higher GAF scores (53.38±14.56) than did the high-SI group (44.90±7.68; t=2.33, df=30.2, p=0.03). No differences were found with regard to sleep quality, but the majority of patients reported poor sleep quality (13.64±4.22). Significant correlations were found between suicidal ideation and HAMD (r=0.72, p=0.00), HAMA (r=0.58, p=0.00), PSQI (r=0.43, p<0.01), and GAF (r=-0.56, p=0.00) scores.
This cross-sectional study gathered data about patients with CRPS who had no previous psychiatric symptoms using neuropsychiatric scales administered by a psychiatric specialist at a tertiary university-based pain center. To the best of our knowledge, this is the first study to assess predictors of suicide risk in patients with CRPS. The strengths of this study include its use of a structured interview (SCID) to diagnose mental disorders.
In terms of mental health-related variables, although we found no significant differences in the SCID results for the two groups, the HAMD scores were significantly higher in the high-SI than in the low-SI group, and we found a positive correlation between suicidal ideation and depressive symptoms. Little research has assessed the causal relationship between suicidal ideation and depression in patients with CRPS, but several studies on chronic pain have revealed that the presence of pain may hinder the detection and treatment of depression, and patients in pain are in a high risk for suicide.
Pain severity strongly distinguished the high-SI from the low-SI group and was significantly correlated with suicidal ideation. Previous studies have suggested that persistent pain is associated with elevated rates of suicide-related behaviors. Ratcliffe et al.
We did not control for the interaction between pain and depression in our analysis of the predictive value of the factors under examination. However, several studies have shown a causal association between depression and pain in patients with CRPS. Kroenke et al.
No difference was found between the high- and low-SI groups in terms of anxiety. This result is similar to those of other studies that reported that symptoms of anxiety were relatively less significant predictors of SI severity compared with depression.
The two SI groups differed significantly in their scores on the GAF, which assesses patients' 1-year psychological, social, and occupational functioning and has been accepted as stronger predictor psychiatric symptoms.
Although we found no significant difference with regard to suicidal ideation, most patients (97%) reported higher than 5 in PSQI total score (mean±SD=13.64±4.22) which means poor quality of sleep and we found a significant correlation between suicidal ideation and PSQI total scores (r=0.28, p=0.00). Several previous surveys about chronic pain suggested that various etiologies significantly interfere with sleep.
Similar with other chronic pain conditions, biological, psychological, and social factors are important in treatment of CRPS. Previous studies reported that chronic pain brings about disability, emotional arousal which in turn aggravates pain severity.
Several limitations of this study should be considered when interpreting the findings. First, because the present study is cross-sectional, these results may not be generalizable to all CRPS patients. Although longitudinal investigations are necessary to replicate these findings, this study should assist patients with CRPS who may be at risk for suicidal ideation by underscoring the importance of regular assessment and psychological treatment. Second, the sample size was relatively small, which may have resulted in a selection bias. Several epidemiologic studies have reported a female to male ratio ranging from 2:1 to 4:1
CRPS is recognized as one of the most difficult conditions to treat among pain syndromes. This study found that the factors most strongly associated with suicide in patients with CRPS were depression, pain severity, and general functioning. Taken together, these results should reinforce the importance of psychiatric evaluations and multidisciplinary approach in the treatment of patients with CRPS.
This study was supported by the Original Technology Research Program for Brain Science through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012-0006587).
Comparison of symptoms profiles for patients with CRPS between high SI and low SI. *p<0.05. HAMD: Korean version of the Hamilton Depression Rating Scale, HAMA: Korean version of the Hamilton Anxiety Rating Scale, VAS (MPQ-SF): Visual Analogue Scale, PSQI (Total): Pittsburgh Sleep Quality Index, GAF: Global Assessment of Functioning, SI: suicidal ideation.
Demographic and clinical characteristics of patients
Continuous variables: Mean±SD. *independent sampled t-test, †chi-square test. SD: standard deviation, CRPS: Complex Regional Pain Syndrome, SI: suicidal ideation
Psychiatric co-morbidities assessed by SCID I and II
†chi-square test. SCID: Structured Clinical Interview for DSM-IV, PD: personality disorder, SI: suicidal ideation, NOS: not otherwise specified