Psychosomatics 45:291-296, August 2004
© 2004 The Academy of Psychosomatic Medicine
PTSD and Somatization in Women Treated at a VA Primary Care Clinic
Rodrigo Escalona, M.D.,
Georgiana Achilles, Ph.D.,
Howard Waitzkin, M.D., Ph.D., and
Joel Yager, M.D.
Received Sept. 25, 2002; revision received Aug. 4, 2003; accepted Aug. 15, 2003. From the New Mexico VA Health Care System; and the Departments of Psychiatry, Psychology, and Community Medicine, University of New Mexico School of Medicine, Albuquerque. Address reprint requests to Dr. Escalona, VA Medical Center, 116A, 1501 San Pedro Dr. S.E., Albuquerque, NM 87108; pescalona{at}salud.unm.edu (e-mail).
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ABSTRACT
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The authors examined the association between trauma, posttraumatic stress disorder (PTSD), and somatization in 264 women attending a Department of Veterans Affairs primary care clinic. Using a structured computerized interview (Composite International Diagnostic Interview), they found that traumatic events were reported by 81% of the women. The lifetime prevalence of PTSD was 27%; for somatization it was 19%. PTSD was the best predictor of somatization after control for demographic variables, veteran status, and other mood and anxiety disorders. Psychological numbing symptoms of PTSD emerged as a particularly strong predictor of somatization. The link between PTSD and somatization deserves further study.
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INTRODUCTION
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Somatization (bodily symptoms for which organic causes are not found) is a common occurrence in primary care settings. These multiple unexplained symptoms result in substantial disability, add to the cost of health care, and often lead to therapeutic disappointment.1 The etiology of these unexplained symptoms remains unknown, although there is general consensus that psychological factors play an important role. Several psychiatric conditions have been associated with somatization, including mood and anxiety disorders.2 Psychological trauma and abuse have been associated with somatization as well, but this relationship remains poorly understood. Patients suffering from posttraumatic stress disorder (PTSD), associated with both civilian and combat-related traumas, have shown disproportionately high rates of unexplained somatic symptoms.3 To our knowledge, the association between PTSD and somatization has not been examined together with other possible predictors, such as other anxiety and mood disorders.
Since women are twice as likely as men to suffer from both PTSD and somatization4 and since women in the military have reportedly experienced high rates of sexual and other violent traumas and their consequences, women who have served in the military may merit particular investigation.
The present study explores further the association between trauma, PTSD, and somatization in women attending a primary care clinic at a Department of Veterans Affairs (VA) medical center. In this group, containing both veteran and nonveteran women, we examined trauma history and mood and anxiety disorders as potential predictors of somatization. We also examined whether specific PTSD symptom clusters differed in their association to somatization.
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METHOD
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Subjects
Female patients scheduled for an appointment to visit a VA-based primary care women's health clinic were approached at the clinic or by telephone and asked to participate in the study. Our goal was to recruit a group of approximately half veterans and half nonveterans (i.e., spouses of veterans) who were eligible for care in the VA system. Exclusion criteria were limited to the presence of psychosis and/or severe acute medical illness.
The human subjects institutional review board at the University of New Mexico approved the project. The nature and purpose of the study were described to patients who agreed to participate, and the subjects' informed consent was obtained. The protocol included a computerized structured diagnostic interview and paper-and-pencil questionnaires chosen to measure current overall health and severity of current PTSD symptoms. Participating subjects were compensated for their time with $20.
Assessment
The Composite International Diagnostic Interview,5 version 2.1, was used to elicit demographic information, trauma history, and information regarding past and present psychiatric diagnoses according to ICD-106 and DSM-IV7 criteria. This structured computerized instrument was developed by the World Health Organization and the U.S. Alcohol, Drug Abuse, and Mental Health Administration for use as a diagnostic tool in primary care psychiatric research.5 The interview was developed after the NIMH Diagnostic Interview Schedule8 (DIS) and has been fully validated and used in both national and international studies.9–12
Demographic information
The Composite International Diagnostic Interview provided key demographic information; supplemental data were obtained by questionnaire.
Trauma
Trauma is operationally defined as any stressful life event that is either outside the range of normal human everyday experience or poses a serious threat to the physical integrity of oneself and/or significant others (DSM-IV). During administration of the Composite International Diagnostic Interview, participants were asked whether they had ever experienced nine different types of trauma, including direct combat experience in a war; involvement in a life-threatening accident; involvement in a fire, flood, or other natural disaster; witnessing someone being badly injured or killed; experiencing rape, sexual molestation, or a serious attack or assault; being threatened with a weapon, held captive, or kidnapped; and being tortured or the victim of terrorists. Respondents were also asked to report any other extremely stressful or upsetting event and whether they had ever suffered a great shock because one of the events listed happened to someone close to them.
PTSD
Respondents were asked during the Composite International Diagnostic Interview to indicate the "most upsetting" traumatic event they had experienced, and specific PTSD symptom responses were queried according to the event indicated. Consistent with DSM-IV, symptoms of PTSD were characterized by 1) intense fear, helplessness, or horror, 2) persistent re-experiencing of the event, 3) persistent avoidance of trauma-related stimuli and numbing of general responsiveness, and 4) persistent symptoms of increased arousal.
Somatization
We assessed each of the 35 symptoms used in DSM-IV to diagnose somatization disorder. When a somatic symptom was reported during the Composite International Diagnostic Interview, a series of probes determined 1) the severity of the symptom, 2) whether it could be explained by physical illness, injury, or the use of medications, alcohol, or drugs, 3) whether the symptom had interfered with daily functioning, and 4) the onset and recency of each somatic symptom. A positive symptom score, based on the DSM-IV criteria, indicated that the symptom was not likely to be due to a physical disorder. For the purpose of this study, patients meeting the abridged somatization criteria of Escobar et al.13 (four unexplained somatic symptoms for men and six unexplained somatic symptoms for women) were classified as "somatizers." The somatization items of the Composite International Diagnostic Interview were used to determine an abridged diagnosis, as well as the number of somatic symptoms (range=0–35) or tendency to report somatic symptoms.
Other psychiatric disorders
Lifetime diagnoses of depression, generalized anxiety disorder, panic disorder, and phobias were also determined by the Composite International Diagnostic Interview. For the purpose of this study, the designation of depression reflects recurrent cases (mild, moderate, and severe).
Statistical Analysis
SPSS 8.0 for Windows (Chicago, SPSS, 1997) was the statistical package used in the analysis of the data. Logistic regression generated odds ratios and confidence intervals (CIs). These values were used to determine associations between the predictor variables and abridged somatization.
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RESULTS
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Subjects
Of 601 eligible patients approached between June 1998 and September 2000, 334 agreed to participate and scheduled an appointment. The findings reflect completed data for 264 respondents, 134 veterans and 130 nonveterans. Subject ages ranged from 23 to 85 years. Ethnicity was predominately white of non-Hispanic origin (46%), and the remaining participants were identified as Hispanic white (30%), American Indian or Alaskan Native (3%), black of non-Hispanic origin (3%), Asian or Pacific Islander (2%), and Hispanic black (1%) (data for 15% not reported). Frequency of ethnicity by veteran status differed significantly for Hispanics, who were more prevalent among nonveterans than veterans ( 2=22.05, df=1, N=80, p<0.0001). Ethnicity of participants and nonparticipants did not differ significantly, but the average age of nonparticipants was significantly higher than that of participants (F=25.9, df=1, 264, p<0.0001).
Prevalence of Trauma and Psychiatric Disorders
The experience of some type of trauma was reported by 81.1% of the subjects, with 73.9% reporting self-experienced traumas (Table 1). Of those reporting self-experienced trauma, 24.6% reported one trauma only, 17.4% reported two traumas, and 58.1% reported three or more. An additional 7.2% reported suffering a great shock resulting from a trauma experienced by someone close to them.
The lifetime prevalences of psychiatric disorders, including somatization, PTSD, recurrent depression, generalized anxiety disorder, and panic disorder, are displayed in Table 2.
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TABLE 2. Lifetime Prevalence of Somatization and Other Common Psychiatric Disorders Among Female Patients in a VA Primary Care Clinic
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Associations Between Trauma, PTSD, and Somatization
Data collected on lifetime prevalence of psychiatric diagnoses indicated a significant relationship between PTSD and abridged somatization. In a stepwise logistic regression equation, abridged somatization was entered as the outcome variable with two levels: negative or positive diagnosis. The model controlled for demographic variables by including veteran status, age, and prevalent ethnic groups (Hispanics, 29%, and whites, 48%) in the first step. Next, trauma (self-experienced) was entered with two levels: no reported trauma or at least one reported trauma. The models and individual factors were not significant. Results are presented in Table 3.
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TABLE 3. Logistic Regression (Stepwise) Showing Associations Between Trauma, PTSD, and Abridged Somatization Among 234 Female Patients in a VA Primary Care Clinica
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When history of PTSD diagnosis (positive or negative) was added, the model attained significance (2=20.12, df=6, N=227, p=0.003). Individuals with a history of PTSD were significantly more likely to meet the criteria for abridged somatization (odds ratio=3.23, 95% CI=1.53–6.85). The strength of the association did not vary by age, veteran status, or ethnicity.
PTSD, Other Common Psychiatric Disorders, and Somatization
Next, the relative strength of associations between abridged somatization and PTSD, versus other common psychiatric disorders, was examined. Again, demographic variables were controlled for in the first step of a logistic regression. Next, depression, generalized anxiety disorder, and panic disorder were added, and the model attained significance (2=14.92, df=7, N=226, p=0.04). However, depression was the only single variable significantly associated with abridged somatization (odds ratio=2.36, 95% CI=1.13–4.91). When PTSD was added, the change in the model was significant (change in 2=8.62, df=1, N=234, p=0.003). Depression did not retain significance in the model, and PTSD emerged as the only significant predictor of abridged somatization (odds ratio=3.09, 95% CI=1.46–6.52). Thus, subjects with a history of depression were more likely than subjects with generalized anxiety or panic disorder to meet the criteria for abridged somatization, but subjects with a history of PTSD showed an even greater likelihood of meeting the criteria for abridged somatization (see Table 4).
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TABLE 4. Logistic Regression (Stepwise) Showing Associations Between PTSD, Other Common Psychiatric Disorders, and Abridged Somatization Among 234 Female Patients in a VA Primary Care Clinica
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PTSD and PTSD Symptom Clusters as Predictors of Abridged Somatization
Finally, the relative strengths of trauma-related predictors (PTSD diagnosis, PTSD symptom clusters) of abridged somatization were examined. As before, demographic variables were controlled for in the first step of the model. When PTSD was included, the model attained significance (2=12.78, df=5, N=145, p=0.03) and PTSD was a significant predictor in the model (odds ratio=3.28, 95% CI=1.44–7.48).
Next, the four PTSD symptom clusters (numbing, hyperarousal, intrusion, avoidance) were added to the model individually, in stepwise fashion. When the numbing symptom cluster was included, the change in the model was significant (change in 2=8.75, df=1, 151, p=0.003). It was interesting that PTSD did not retain significance when numbing symptoms were included. When each symptom cluster was subsequently added to the model, none of the inclusions significantly added to the outcome variance. Therefore, when PTSD and all four symptom cluster categories were included as predictors, only the numbing symptom cluster was significantly associated with abridged somatization (odds ratio=1.80, 95% CI=1.21–2.69) (see Table 5).
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TABLE 5. Logistic Regression (Stepwise) Showing Associations Between PTSD, PTSD Symptom Clusters, and Abridged Somatization Among 151 Female Patients in a VA Primary Care Clinica
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Important to note is the high correlation between symptom clusters, suggesting that the numbing cluster did not offer unique predictive information. Rather, clusters other than numbing and the PTSD diagnosis overall did not offer predictive power above and beyond that which was accounted for by the numbing symptom cluster alone.
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DISCUSSION
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Our results confirm previous findings of very high rates of reported exposure to traumatic events in women attending a primary care clinic, particularly sexual assault in the veteran group. The lifetime prevalence rates of PTSD (27.3%) and somatization (19.3%) were both high. The two conditions were significantly associated, and PTSD was the best predictor of abridged somatization after demographic characteristics, veteran status, and other mood and anxiety disorders were controlled for in our logistic regression model.
The emergence of PTSD as the best predictor of somatization is in agreement with the findings by Andreski et al.,3 who prospectively studied a large group of patients in a health maintenance organization. In that study, subjects with PTSD developed significantly more somatization symptoms over a period of 5 years than comparison subjects. Previous large epidemiological studies of somatization using an older version of the Composite International Diagnostic Interview did not include a module for PTSD.2 This may explain why mood and anxiety disorders were equally good predictors of somatization in those studies. Our data and those of others suggest that PTSD must be included in studies of somatization. Among the PTSD symptom cluster, numbing symptoms (excluding avoidance) were the best predictors of somatization. It has been suggested that numbing symptoms are independent of active avoidance and that they might have a different neurobiology.14 To our knowledge, this is the first report to directly link numbing symptoms specifically to somatization. It is conceivable that numbing symptoms reflect social or emotional disengagement, causing increased awareness of and focus on internal sensory perception. It is also possible that some of the numbing symptoms of PTSD overlap with the alexithymia construct, which is known to be associated with somatization. If confirmed and replicated, the finding could lead to a new model for conceptualizing and studying somatization in the traumatized population.
Veteran status did not appear to be a significant predictor of somatization. The female veterans in our study reported more traumatic events, but the lifetime prevalence of PTSD was about the same in both groups (no significant difference).
Contrary to what we expected, rates of somatization did not vary with ethnicity. This finding differs from previous reports that suggested that Hispanic patients tend to somatize more.15 This may reflect the level of acculturation of the Hispanics in the military and particularly in New Mexico.
Our study has some limitations, including the relatively low response rate and the lack of comprehensive data from the nonparticipant group. The use of lifetime prevalence rates for both somatization and PTSD makes it impossible to determine the temporal relationship of the association. However, the results deserve further investigation.
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ACKNOWLEDGMENTS
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Supported by NIMH grant 1R2-MH-58404-01.
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REFERENCES
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- World Health Organization: Composite International Diagnostic Interview, version 2.1. Geneva, WHO, 1997
- World Health Organization: The International Statistical Classification of Diseases and Related Health Problems, 10th revision (ICD-10). Geneva, WHO, 1993
- American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, 4th ed (DSM-IV). Washington, DC, APA, 1994
- Robins LN, Helzer JE, Croughan J, Ratcliff KS: The National Institute of Mental Health Diagnostic Interview Schedule: its history, characteristics, and validity. Arch Gen Psychiatry 1981; 38: 381–389
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- Wittchen HU, Lachner G, Wunderlich U, Pfister H: Test-retest reliability of the computerized DSM-IV version of the Munich-Composite International Diagnostic Interview (M-CIDI). Soc Psychiatry Psychiatr Epidemiol 1998; 33:568–578[CrossRef][Medline]
- Wittchen HU, Robins LN, Cottler LB, Sartorius N, Burke JD, Regier D: Cross-cultural feasibility, reliability and sources of variance of the Composite International Diagnostic Interview (CIDI). Br J Psychiatry 1991; 159:645–653[Abstract/Free Full Text]
- Escobar JI, Waitzkin H, Silver RC, Gara M, Holman A: Abridged somatization: a study in primary care. Psychosom Med 1998; 60:466–472[Abstract]
- Foa EB, Riggs DS, Gershuny BS: Arousal, numbing, and intrusion: symptom structure of PTSD following assault. Am J Psychiatry 1995; 152:116–120[Abstract/Free Full Text]
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ABSTRACT
INTRODUCTION
