Participants included 219 pediatric chronic pain patients (70.8% female (n=155) with a mean age of 14.34 years (range = 7 years 9 months – 18 years 3 months, SD=2.49) presenting for treatment at a multidisciplinary, tertiary clinic specializing in pediatric chronic pain. The current sample was obtained from patients with initial clinic visits between February 2003 and October 2007. Presenting pain diagnoses were (percentages add to more than 100% due to multiple diagnoses): 44.7% headaches (n=98) (migraines; myofascial, vascular, tension, stress-related or any other type), 37% functional neurovisceral pain disorder (n=81) (functional bowel, uterine, or bladder disorder), 35.2% myofascial pain (n=77) (excluding headaches), 10% fibromyalgia (n=22), 7.3% complex regional pain syndrome (CRPS) (n=16), and .9% arthritis (n = 2). Average duration of pain symptoms was 45 months (SD=48.32). Almost a third of patients (29.7%, n=65) presented with multiple pain diagnoses.
Total child ethnic/racial composition was .9% (n=3)American Indian/Alaskan Native, 2.2% (n=5) Asian/Native Hawaiian/Pacific Islander, 3.6% (n=8) Black/African American, 13.3% (n=30) Latino/Hispanic, 64.9% (146) Caucasian, and 12.4% (n=28) Other. Further demographic information is presented in .
Descriptive characteristics of clinic sample, including ethnic, sex and age differences
For analyses comparing ethnic differences, participants were identified as either Caucasian or non-Caucasian (minority status).
Parent-reported marital status was 76.1% married, 11% divorced, 4.8% separated, 4.3% single living alone, 2.9% widowed, 1% single living with a companion. Parents were relatively educated; 3.4% had not completed high school, 5.9% had attained high school education, 34.7% completed some college, 22.4% completed college and 28.3% had a postgraduate qualification. Chi square tests categorizing education into three levels (high school or less, partial or completed college and postgraduate schooling) revealed significant differences between parents of Caucasian and minority children; parents of minority children reported significantly less education than parents of Caucasian children (Chi square = 15.95, p = .00).
The study received ethical approval by the University of California, Los Angeles (UCLA) Institutional Review Board (IRB). Written informed consent was completed by parents, and children provided written assent.
Prior to patients’ initial clinic visit and following verbal consent obtained by telephone, questionnaires were mailed to the home. Questionnaires assessed demographic and health information including measures of the child’s pain and functioning. Only questionnaires pertaining to this study’s aims were included in analyses and discussed below. Questionnaires were completed at home prior to clinic visit without assistance, and questionnaire packets and written informed consent were collected at the clinic intake appointment. All questionnaires were then reviewed by a research assistant and by the evaluating physician during the initial visit in order to ensure completion and clarify ambiguous responses.
A subset of 78 parents were administered additional measures, including the Functional Disability Inventory (FDI) (described below), as well as items about the child’s sleep, and current level of pain. These measures were included in the packet sent to clinic patients with intake dates after August 2005. This subset did not significantly differ from the overall group in age (t = −1.118, p > .05), sex (?2 = .140, p > .05), ethnicity (?2 = 2.553, p > .05), pain duration (t = −.848, p > .05), or parent education (?2 = 2.338, p > .05). The subset included 57 Caucasian subjects and 21 minority subjects. Composition of the minority subset included American Indian/Alaskan Native (n=2), Asian/Native Hawaiian/Pacific Islander (n=2), African American (n=2), Latino/Hispanic (n=12), and Other (n=3).
Demographic Information Questionnaire
An author developed demographic information questionnaire was completed by parents, assessing information such as child age, sex, and race/ethnicity. Parents were asked about their level of education and their child’s current schooling situation, including whether the child is in regular full-time school. Responses were categorized according to levels (no high school, some high school, completed high school, some college, college degree and post-graduate degree), and were transformed to continuous variables for regression analyses. Parents also reported on the number of hours their child had slept the previous night.
Information regarding duration of pain symptoms, number and type of pain diagnoses, and psychological diagnoses were obtained from patients’ medical records via chart review. Additionally, information was obtained about school absenteeism and type of schooling (e.g. home or at school, independent study, etc.). These items were obtained from the child and parent during clinic intake interviews and recorded in the assessment portion of the initial evaluation report by the evaluating physician. A standard evaluation form was used to assess all new patients, so that the same group of questions was asked of each patient.
Child Health Questionnaire, Parent Report (CHQ PF-28)
The CHQ PF-28 is designed to assess parents’ measurement of their child’s physical and psychosocial well-being. It has acceptable reliability and validity. The CHQ parent form is comprised of a number of sub-scales. For the purposes of assessing children’s pain and health status, we focused on the bodily pain and global health sub-scales. The bodily pain sub-scale asks about intensity and frequency of child general pain and discomfort and higher scored indicate better functioning, i.e. less pain. The global health sub-scale assesses the parent’s report of the child’s general health status, ranging from excellent to poor, with higher scored indicating better health.
Children’s Somatization Inventory (CSI) – Parent Report
The CSI contains 35 psychophysiological symptoms rated on 5-point scales: 0= not at all; 1= a little; 2= somewhat; 3= pretty much; and 4= very much. Parents indicated the extent to which their children experienced each symptom over the past two weeks. Symptoms include gastrointestinal (e.g. “nausea/upset stomach”), pseudoneurological (e.g. “seizures”), cardiovascular (e.g. “heart beats too fast”), and pain (e.g. “pain in arms or legs”) complaints. Total score can be computed by summing the score across all items. Higher scores indicate higher levels of somatic complaints. Good internal consistency and test-retest reliability have been reported (P=.001) (11
Functional Disability Inventory (FDI) – Parent report
The FDI is a 14-item questionnaire measuring children’s difficulty in physical and psychosocial functioning due to their physical health during the past two weeks. Parents rated the severity of their child’s functional disability in daily activities including walking, chores, social activities, eating and sleeping. Respondents rate the level of difficulty their child has performing each of the items and total scores are computed by summing the ratings for each item. Higher scores indicate greater disability. The FDI has been documented as valid, stable, and sensitive to change (12
). This measure was completed by the subset of 78 patients.
Children were asked to rate their pain on a 10-cm Visual Analogue Scale (VAS) representing a continuum from no pain to worst pain possible. The VAS has been established and widely used as a reliable and valid measure of pain intensity with children. This method measured the amount of pain currently experienced by the child and was completed by the subset of 78 patients.
Bivariate analyses were initially conducted to examine relationships among the study variables prior to multivariate analyses. One sample t-tests for continuous data and chi-square tests for categorical data were used to examine mean differences between the present sample and national norms for the CHQ global health and pain subscales, as well as the child’s school attendance. Chi square tests and t-tests were also used to examine sociodemographic differences on: child pain diagnosis, pain duration, hours slept, CSI, CHQ pain, CHQ global health, FDI, and pain VAS. These measures were tested for differences based on race/ethnicity (Caucasians versus minority status individuals), sex (boys versus girls), and age (children; i.e., participants younger than 12 years, 11 months versus teens; i.e., participants aged 13 – 18 years).
Confirmatory multivariate analyses were conducted on the health and pain-related variables shown to differ based on race/ethnicity in the bivariate analyses. The use of multivariate analyses was intended to assess the relative impact of the child socio-demographic variables on pain and health status, and to determine the relative contribution of minority status to pain and health status after controlling for parent education, as well as child sex and age. Using sequential multiple regression analyses, the independent variables were entered in two steps: the first step consisted of parental education (categorized as a continuous variable), and the second step consisted of age (entered as a continuous variable), sex (boys coded as 0, girls coded as 1) and ethnicity (Caucasian coded as 0; minority status, coded as 1). This regression model was tested for each of the following dependent variables separately: CHQ global health, CSI scores, number of hours slept, FDI scores and VAS pain intensity.