Objective
We sought to determine the relationship among a history of physical or sexual abuse, pain experience, and depressive symptoms among women with chronic pelvic pain (CPP).
Study Design
This was a cross-sectional study of women who presented to a tertiary referral center for evaluation of CPP (N = 273). All participants completed standardized questionnaires to assess a history of physical or sexual abuse, pain severity, pain disability, and depressive symptoms. Subjects were grouped by abuse category and compared to CPP participants without history of abuse. Multinomial logistic regression models were used to determine the association between adolescent or adult and childhood physical or sexual abuse with pain intensity, pain-related disability, and depressive symptoms.
Results
Logistic regression analyses indicated that, after controlling for age and education, none of the abuse categories was associated with pain severity. However, adolescent or adult sexual abuse predicted greater pain-related disability (odds ratio, 2.39; 95% confidence interval, 1.05–5.40), while both adolescent or adult physical and sexual abuse were associated with higher levels of depression (both P < .05). Level of education was significantly associated with pain intensity, pain disability, and depression.
Conclusion
For our sample of women with CPP, a history of abuse during childhood or adulthood was not associated with differences in pain intensity, but adolescent or adult sexual abuse was associated with greater pain-related disability. A history of physical abuse or sexual abuse appears to hold a stronger relationship with current depressive symptoms than pain experience for women with CPP. Educational achievement holds a robust relationship with pain morbidity and depression for this population.
Many women with chronic pelvic pain (CPP) suffer from pain-related disability without a definitive medical diagnosis. Early clinical reports asserted a causal role for childhood sexual abuse in explaining persistent pelvic pain in the absence of a definitive diagnostic workup. Later comparative studies found a high rate of sexual abuse among women with CPP and in comparison to women without pelvic pain. Evidence from community-based surveys further strengthened the perceived association between a history of sexual or physical abuse and a higher prevalence of pain symptoms among women with CPP. Recently, Fenton proposed a model of limbic sensitization as a mechanism for explaining CPP without obvious medical etiology that invoked childhood sexual abuse as a primary trigger for the development of a reverberating cycle of pain and central nervous system sensitization.
More recently, a number of critical reviews have questioned the empirical evidence for a specific and direct association between abuse history and the development of CPP. These authors note that the majority of relevant studies fail to adequately control for potential confounding factors, such as the presence of chronic pain, in considering the association of abuse history and CPP. For example, only 2 previous studies examining the relation of CPP and abuse have included a nonabused sample of CPP patients as a control, and both found no differences between the groups for pain severity. Further, when women with CPP are compared with other chronic pain populations for a history of abuse, the results have been equivocal or negative for observing comparatively more severe pain experience for women with CPP who have been abused.
A second methodological criticism of this literature concerns the lack of clarity for case definition across studies. The issue of case definition is important as a history of abuse as a risk factor for pain can vary in terms of the type and timing of abuse (eg, sexual vs physical, childhood vs adult), and these dimensions of abuse are frequently collapsed in analyses, which questionably assumes heterogeneity across groups. Moreover, childhood sexual or physical abuse rarely occurs in isolation from other forms of abuse or severe family disturbance during childhood, and childhood abuse is known to significantly predict adulthood abuse.
This study examined the association between a history of abuse and pain experience and depressive symptoms among women with CPP. The study compared a sample of women with CPP and a history of abuse to women with CPP with no history of abuse, thus controlling for the influence of chronic pain and pain diagnosis on the relation between a history of abuse and both pain and depressive symptoms. To further examine any differences due to timing and type of abuse, history of abuse was stratified across 4 categories–childhood vs adolescent or adulthood, and sexual vs physical–and each subcategory was compared to CPP patients without a history of abuse. In addition, a measure of depressive symptoms was included as a variable of interest due to previous evidence suggesting an association between CPP and depression and to determine whether women with CPP who have experienced various types of abuse report more severe depressive symptoms.
Materials and Methods
Participants (N = 273) comprised a convenience sample of consecutive women with CPP seen for evaluation and treatment in a university hospital CPP referral clinic from March 2006 through September 2007. The mean age of the sample was 34.8 years (SD 11.3). Participants had a mean duration of pain of 67.6 months (SD 86.2). The sample included a heterogeneous group of women with a combination of various pain disorders including but not limited to endometriosis, adenomyosis, pelvic adhesions, ovarian remnants, vulvodynia, interstitial cystitis, irritable bowel syndrome, and abdominal and pelvic floor myofascial pain.
Prior to the first appointment, a packet of questionnaires was mailed to the participant and collected at the evaluation appointment. Participants received the questionnaires as part of routine medical care. The packet included both a general questionnaire soliciting relevant sociodemographic information (eg, age, marital status, educational achievement) and medical history, in addition to standardized inventories that assessed pain experience, depressive symptoms, and a history of abuse. The number of patients who reported CPP but did not receive or declined to complete the questionnaire as part of their routine medical care was not recorded in the medical record. The study was approved by the University of Michigan Medical School Institutional Review Board.
To assess pain experience, subjects completed the Brief Pain Inventory (BPI) short form (SF), a self-administered questionnaire that assesses pain severity and functional interference from persistent pain. Subjects are asked to rate the severity of their pain and the degree to which pain interferes with a variety of life activities during the past week. The BPI-SF provides 2 summary measures of pain experience: (1) subjective rating of pain intensity (BPI Severity, range, 0–10); and (2) pain interference (BPI Interference, range, 0–10), which is defined as the degree to which a subject reports functional and activity-related disability attributed to pain. Higher scores indicate more severe pain intensity and pain interference. Several studies support the validity of the BPI-SF for a heterogeneous group of chronic pain patients.
Participants also completed the Center for Epidemiological Studies Depression (CES-D) scale, an inventory that examines self-reported mood and behavior during the previous week. Higher scores (range, 0–60) indicate greater depressive symptoms. Internal consistency of the CES-D is .85 for the community and .90 in a patient population. The CES-D possesses good validity for predicting major depression in a chronic pain population.
A history of sexual and/or physical abuse was obtained from the Sexual and Physical Abuse History Questionnaire, a standardized screening measure previously validated with a CPP population. Physical abuse is defined as incidents separate from sexual abuse indicating a life-threatening physical attack with intent to kill or seriously harm, or less severe physical assaults such as being beaten, kicked, bit, or other attacks outside of normal parenting or interpersonal engagement. Sexual abuse is defined as the touching of private body parts by a perpetrator, making the subject similarly touch the perpetrator, or making the subject have vaginal or anal intercourse, with these actions occurring within a context of threat or harm. For individual items, separate prompts are used to assess abuse in childhood or adulthood. Separate measures are calculated for the physical abuse and sexual abuse scores, and both measures are stratified into childhood (≤13 years) and adolescent or adult (≥14 years) age brackets. Age brackets were defined according to the same age limits described by Leserman et al. Test-retest reliability coefficients for both the physical abuse (0.81) and sexual abuse (0.77) scales are high, and the measures demonstrate adequate construct validity. In the current study, abuse was categorized as having occurred or not occurred (eg, nonabused) if a subject endorsed any (or no) item in each category.
Statistical analyses
Group differences were examined separately for the BPI Pain Severity, BPI Pain Interference, and CES-D scores by the various groups with a history of abuse compared to subjects who reported no history of abuse. The abuse categories were arranged in a 2 × 2 design, with the dimensions of history of physical abuse and history of sexual abuse each divided into childhood and adolescent or adulthood groups. Independent samples t tests were used to examine whether mean differences between the group comparisons were statistically significant. A correction was made to the test when the sample variances were not equivalent.
Multinomial logistic regressions were conducted to examine the relative contribution of each type of history of abuse to the prediction of pain intensity, pain interference, and depressive symptoms. Age and level of education were entered as control variables along with the 4 types of abuse. As the use of logistic repression requires categorization of the dependent variables, BPI Severity pain scores were categorized in relation to those subjects with no pain (0), mild or moderate pain (>0-6.99), and severe pain (≥7). To examine differences in pain-related disability, a median split was performed of the BPI Interference scale (the median was 5). For depression, we examined the incidence of clinically significant depression on the CES-D in each abuse category, defined as a score of ≥16. Low scores were coded as 1 and treated as the reference category, whereas high scores were coded as 0. Presence of history of abuse in any category was coded as 0, while absence of abuse was coded as 1 and treated as the reference category. The overall model fit of each regression was assessed using a χ 2 test, which examines whether the model with predictors fits better as a whole compared to a model with no predictors. The significance of the contribution of each type of abuse to the dependent variable was assessed using the Wald test statistic. Adjusted odds ratios, along with 95% confidence intervals (CIs), are also reported.
Results
Of the 273 total subjects, a subset had missing data on the questionnaires. Missing responses varied by the particular measure examined. Therefore, the sample sizes are reported in the tables along with the mean and SD of each sample. For the regressions, the total sample size is reported in the footnote. The characteristics of the sample are reported in Table 1 . The frequency of each category of abuse in the sample ranged from 23.8–32.6%.
| Variable | Mean ± SD or frequency (%) |
|---|---|
| Age, y | 34.8 ± 11.3 |
| Marital status | |
| Single | 97 (35.5) |
| Married | 139 (50.9) |
| Divorced | 23 (8.4) |
| Other | 14 (5.2) |
| Educational level | |
| <High school | (4) |
| High school graduate | (17) |
| Some college | (36) |
| Associate degree | (13) |
| Bachelor degree | (16) |
| Postgraduate training | (14) |
| BPI pain composite | 4.95 ± 2.3 |
| BPI interference composite | 4.95 ± 3.0 |
| CES-D total score | 17.0 ± 11.5 |
| History of child physical abuse | 65 (23.8) |
| History of child sexual abuse | 77 (28.2) |
| History of adolescent or adult physical abuse | 81 (29.7) |
| History of adolescent or adult sexual abuse | 89 (32.6) |
The means, sample sizes, and SD of the BPI Severity scores, BPI Interference scores, and CES-D scores for each of the abuse groups compared to their nonabused cohorts, are reported in Tables 2, 3 , and 4 , respectively. There was no difference in pain severity scores when comparing CPP patients with a history of abuse relative to those without a history of abuse ( Table 2 ). However, women with CPP and a history of physical abuse as an adolescent or adult reported significantly higher pain-related disability (BPI Interference) when compared to patients reporting no abuse in these categories [t (225) = 1.99, P < .05] ( Table 3 ). Furthermore, women with CPP who reported a history of child physical abuse [t (240) = 2.68, P < .01] or child sexual abuse [t (234) = 3.52, P < .01] reported significantly more depressive symptoms compared to respondents who reported no history of child abuse in these categories ( Table 4 ). The findings were similar for those reporting history of adolescent or adult abuse, as patients reporting a history of physical abuse [t (243) = 4.25, P < .001] or sexual abuse [t (236) = 3.86, P < .001] both reported significantly more depressive symptoms compared to persons reporting no history of abuse in these categories.
| Category of abuse | BPI pain severity | |
|---|---|---|
| Abuse (n, SD) | No abuse (n, SD) | |
| Physical abuse, child | 5.08 (57, 2.30) | 4.91 (167, 2.31) |
| Physical abuse, adolescent or adult | 5.15 (71, 2.37) | 4.86 (155, 2.27) |
| Sexual abuse, child | 5.09 (69, 2.38) | 4.95 (148, 2.27) |
| Sexual abuse, adolescent or adult | 5.17 (75, 2.36) | 4.83 (143, 2.30) |
| Category of abuse | BPI pain interference | |
|---|---|---|
| Abuse (n, SD) | No abuse (n, SD) | |
| Physical abuse, child | 5.01 (56, 3.10) | 4.98 (168, 2.90) |
| Physical abuse, adolescent or adult a | 5.54 (70, 2.88) | 4.70 (157, 2.95) |
| Sexual abuse, child | 5.12 (67, 3.01) | 4.92 (151, 2.91) |
| Sexual abuse, adolescent or adult | 5.43 (76, 3.14) | 4.78 (143, 2.84) |
| Category of abuse | CES-D | |
|---|---|---|
| Abuse (n, SD) | No abuse (n, SD) | |
| Physical abuse, child a | 20.82 (61, 13.77) | 15.68 (181, 10.28) |
| Physical abuse, adolescent or adult a | 21.46 (77, 11.56) | 14.96 (168, 10.88) |
| Sexual abuse, child a | 20.93 (73, 20.93) | 15.37 (163, 10.68) |
| Sexual abuse, adolescent or adult a | 21.16 (83, 12.38) | 15.01 (155, 10.31) |
Multinomial logistic regression models were used to evaluate the influence of a history of abuse on pain severity, pain-related disability, and depression, while controlling for age and educational level. When considering any adult abuse compared to CPP without history of abuse, any childhood abuse compared to CPP without prior abuse, or any form of abuse (either adult or childhood) compared to CPP without prior abuse, the combined effects of abuse were not significantly associated with pain severity, pain-related disability, or depression (data not shown). However, when considering the individual impact of each abuse subcategory on pain severity, pain-related disability, and depression, all model fits were statistically significant ( Tables 5-7 ). For example, Table 5 presents the logistic regression analysis examining the influence of type of abuse history on pain severity, controlling for age and educational level. Overall, the model fit was statistically significant [χ 2 (6) = 26.9, P < .001]. Education was the only variable significantly associated with pain severity in an inverse fashion ( P < .001). History of adolescent or adult sexual abuse was marginally associated with a higher likelihood of having severe pain ( P = .082), although this did not reach statistical significance.
| Variable | B | Wald | P value | aOR | 95% CI |
|---|---|---|---|---|---|
| Age | −.03 | 2.81 | .09 | 0.97 | 0.93–1.01 |
| Education | −.67 | 15.77 | < .001 | 0.51 | 0.37–0.71 |
| History of child physical abuse | −.57 | 1.20 | .27 | 0.57 | 0.20–1.57 |
| History of child sexual abuse | −.22 | 0.18 | .67 | 0.80 | 0.29–2.24 |
| History of adolescent or adult physical abuse | .34 | 0.46 | .50 | 1.40 | 0.53–3.68 |
| History of adolescent or adult sexual abuse | .90 | 3.03 | .08 | 2.45 | 0.89–6.73 |
| Variable | B | Wald | P value | aOR | 95% CI |
|---|---|---|---|---|---|
| Age | −.03 | 4.41 | .04 | 0.97 | 0.94–1.0 |
| Education | −.29 | 6.84 | .009 | 0.75 | 0.61–0.93 |
| History of child physical abuse | −.20 | 0.24 | .63 | 0.82 | 0.37–1.82 |
| History of child sexual abuse | −.55 | 1.64 | .20 | 0.58 | 0.25–1.34 |
| History of adolescent or adult physical abuse | .55 | 1.91 | .17 | 1.73 | 0.80–3.74 |
| History of adolescent or adult sexual abuse | .87 | 1.35 | .04 | 2.39 | 1.05–5.40 |
| Variable | B | Wald | P value | aOR | 95% CI |
|---|---|---|---|---|---|
| Age | −.01 | 0.15 | .70 | 1.00 | 0.97–1.02 |
| Education | −.40 | 13.77 | < .001 | 0.67 | 0.55–0.83 |
| History of child physical abuse | −.29 | 0.50 | .48 | 0.75 | 0.33–1.69 |
| History of child sexual abuse | −.08 | 0.04 | .84 | 0.92 | 0.41–2.07 |
| History of adolescent or adult physical abuse | .92 | 5.39 | .02 | 2.51 | 1.15–5.47 |
| History of adolescent or adult sexual abuse | .94 | 5.51 | .02 | 2.55 | 1.17–5.58 |
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