Pain in persons with cerebral palsy: extension and cross validation¹ ☆

Article Outline

• Abstract
• Methods
  • Participants
  • Procedures
  • Measures
    • Demographic and CP-related questions
    • Presence of pain problem
    • Pain intensity
    • Pain interference
    • Other pain-related variables
    • Psychologic functioning
    • Significance of pain problem
    • Satisfaction with pain management care
• Results
  • Demographics and CP-related measures
  • Pain reports
  • Pain interference
  • Significance of the pain problem and satisfaction with pain management
  • Psychologic status
• Discussion
• Conclusion
• References
• Copyright

Abstract 

Engel JM, Jensen MP, Hoffman AJ, Kartin D. Pain in persons with cerebral palsy: extension and cross validation. Arch Phys Med Rehabil 2003;84:1125–8.

Objective:

To cross-validate and extend the assessment of pain in persons with cerebral palsy (CP).

Design:

Standardized in-person interviews.

Setting:

University medical clinics and local residential and community housing for persons with developmental disabilities.

Participants:

One hundred adults with CP.

Interventions:

Not applicable.

Main Outcome Measures:

Measures of pain intensity, pain interference in daily activities, psychologic function, significance of pain problem, and satisfaction with pain treatment.

Results:

Sixty-seven (67%) subjects reported 1 or more chronic pain problem(s). Low back, hip, and leg pain were most common. Twenty-four percent reported constant pain; 19% reported that pain occurred daily. Mean pain intensity ± standard deviation over the previous week on an 11-point scale (0, no pain; 10, pain as bad as could be) was 4.08±2.25. Minor interference (2.55±3.03; scale range, 0–10) from pain with routine daily activities was reported. Responses to the Satisfaction with Life Scale (n=63) indicated only moderate life satisfaction (18.44±8.34; scale range, 5–35) among those with 1 or more pain problem(s). Responses to the Rand Mental Health Inventory (n=65; mean score, 60.65±20.36) revealed relatively high levels of psychologic distress in those with chronic pain. Consumer satisfaction with pain management care varied, with 32.8% of the subjects reporting dissatisfaction.

Conclusions:

The study findings are consistent with earlier findings concerning pain problems in adults with CP and provide further evidence that pain problems may be overlooked and undertreated in this population.

Keywords:  Cerebral palsy, Pain, Rehabilitation

THE STUDY OF CHRONIC PAIN in the cerebral palsy (CP) population has only recently begun to be addressed in detail in the literature.1, 2, 3, 4, 5 In 1993, Tenuta et al6 investigated the long-term effects of triple arthrodesis surgery in 27 adults with CP who had the procedure on their feet as children (mean time since surgery, 19y 9mo). Medical records were reviewed, and patients completed a questionnaire regarding surgical outcome. They found that 11 (41%) of the patients reported continued pain as adults, and that patient satisfaction with the procedure was most highly related to reported pain intensity levels and distance limitations.6 More recently, Turk et al4 interviewed 63 community-residing adult women with CP. Eighty-four percent of the sample reported pain in at least 1 area. For 56% of the entire sample, pain was reported to limit activity. In our initial survey study of adults with CP,3 we found that 67% of the sample reported 1 or more areas of chronic pain, and that 53% of those with pain indicated that their pain was of moderate to severe pain intensity. Over 56% of the subjects reported their pain occurred on a daily basis.

The purpose of our study was to cross-validate and extend the findings of our earlier survey study with an additional 100 adults with CP.

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Methods 

Participants 

One hundred adults were recruited from medical and rehabilitation clinics at the University of Washington Medical Center and from local residential and community-based treatment facilities for persons with developmental disabilities. Inclusion criteria were (1) primary diagnosis of CP, (2) documented intelligence quotient of at least 70 or clinical judgment of health care provider or interviewer of no more than mild cognitive impairment, and (3) chronologic age of 18 years or older. Augmentative communication devices, such as communication boards and Dyna Vox, were used as needed to facilitate the accuracy of the interview data. Of 116 potential subjects approached for the study, 5 chose not to participate and 11 were ineligible (8 subjects did not actually have CP, 2 had cognitive limitations exceeding the inclusion criteria, 1 subject did not speak English).

Procedures 

After informed consent was obtained, data were collected in face-to-face interviews by using a standardized protocol that included questions about demographics, CP, pain intensity, pain interference, and psychologic functioning. To determine the frequency of chronic pain in this population, interviews were conducted with all eligible subjects whether or not they had pain complaints. If subjects did not report at least 1 pain problem of at least 3 months in duration, only basic demographic and CP-related information were obtained.

Measures 

All subjects were asked to provide demographic and CP-related information. Subjects were asked to report their gender, age, marital status, educational level, employment status, and ethnicity. They were also asked about severity and type of CP.

Subjects were asked to indicate whether they experienced a pain problem during the past 3 months. Only those who responded affirmatively to this item were asked to respond to the remainder of the interview protocol, which included measures of pain, pain impact, psychologic functioning, pain treatments received, and satisfaction with pain treatments.

Current and worst, least, and average pain intensity over the previous week were assessed by using an 11-point numeric rating scale, with 0 equal to no pain and 10 equal to pain as bad as could be.7

Interference of pain with routine activities of daily living was assessed over the same 1-week time frame by using the 3 interference items from the Chronic Pain Grade.7 The first item asks subjects to rate how much pain interferes with daily activities on an 11-point scale, with 0 equal to no interference and 10 equal to unable to carry out any activities. The second item asks subjects how much pain interferes with their ability to take part in recreational, social, and family activities. The third item asks subjects how much pain interferes with their ability to work (including housework and volunteer work). The latter 2 items ask about interference on an 11-point scale, with 0 equal to no interference and 10 equal to complete interference.

Subjects were asked to indicate in which, if any, of 17 body sites they experienced pain (eg, head, leg, back). Subjects were also asked to indicate the date of pain onset and to rate the average pain intensity (scale range, 0–10) at each location. Finally, the intensity of the most frequent pain complaint was assessed by using the 11-point pain intensity scale described previously.

Subjects were administered the Satisfaction with Life Scale8 (SWLS) and the Rand Mental Health Inventory9 (MHI-5). The SWLS is a 5-item scale designed to measure global life satisfaction. Diener et al8 showed that the SWLS assesses a single factor, and that it shows excellent test-retest stability over a 2-month period (.82) as well as excellent internal consistency (.87). Subsequent validation research has replicated the high internal consistency of the measure (α coefficients in 2 samples were .83 and .85), high 1-month test-retest stability (.84), and convergent validity through its strong associations with other self- and peer-reported measure of life satisfaction.10

Subjects were also asked to respond to the MHI-5. This measure contains 5 items that assess emotional well-being and is also a part of the Medical Outcomes Study 36-Item Short-Form Health Survey,11 a common measure of quality of life (QOL). The MHI-5 has shown adequate to excellent internal consistency coefficients across a variety of patient populations (Cronbach α range, .67–.95), as well as validity through its significant associations with measures of general health and QOL.11 In addition, the scale’s validity as a measure of emotional well-being has been confirmed through its ability to screen for major depression and other affective disorders.9

Subjects were asked to select 1 of 5 statements to describe how much pain is a problem for them. Statements ranged from “The pain I have is not a problem for me” to “My pain is the most significant problem I have.”

Subjects rated their satisfaction with their pain management care on a 6-point scale, with 1 being “I am completely satisfied with my pain management care” to 6 being “I am completely dissatisfied with my pain management care.”

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Results 

Demographics and CP-related measures 

Subject demographics of the current sample are provided in table 1, and are listed along with the characteristics of the sample from our previous survey study.3 As can be seen, no significant differences existed between the 2 samples on any demographic or CP-related variables other than age (t₁₉₈=−2.11, P<.05), indicating minimal differences between the 2 samples overall.

Table 1. Subject Demographics

Abbreviations: GED, General Educational Development; SD, standard deviation.

Pain reports 

Sixty-seven percent (n=67) of the 100 subjects reported 1 or more chronic pain sites. Low back (n=47, 72.3% of those with pain), hip (n=41, 63.1%), and leg pain (n=35, 53.8%) were the most common. The mean pain duration in months for these sites was 13.10±10.81, 17.06±15.06, and 16.87±12.56 months, respectively. Other pain sites, in descending order of frequency, were hand and wrist (n=35, 53.8%), neck (n=33, 50.8%), shoulder (n=30, 46.2%), arm (n=27, 41.5%), upper back (n=23, 35.4%), feet and ankle (n=26, 40.6%), head (n=21, 32.3%), abdominal and pelvic (n=14, 21.9%), buttocks (n=13, 20.0%), and chest (n=11, 16.9%). Subjects with at least 1 pain problem reported a mean of 5.68±3.30 pain locations with a range of 1 to 14 sites.

Twenty-four percent of the subjects reported constant pain. Nineteen percent of subjects with pain reported that they had some pain-free periods, but that their pain occurred on a daily basis with a mean average pain intensity of 4.08±2.25 over the previous week on the 11-point scale (0, no pain; 10, pain as bad as could be). Among all the respondents with at least 1 pain problem, the current mean pain intensity rating was 3.28±2.74 (range, 0–10). Most of the subjects with pain rated their average pain as mild (43.8%) to moderate by (32.8%) using the Serlin et al12 classification of pain severity (eg, on 11-point scale: 1–4, mild; 5–6, moderate; 7–10, severe pain). Fourteen percent (14.1%) of subjects with pain rated their average pain in the severe range.

Pain interference 

Overall, subjects reported only minor interference with routine daily activities because of pain, as measured by the pain interference ratings. Among the 67 subjects who reported pain, mean pain interference with daily activities was 2.55±3.03 (range, 0–10) during the previous week, with 29% of these subjects reporting no interference of pain with their daily activities. Sixty percent of those with pain reported some interference with their social activities (mean interference rating ± standard deviation [SD], 1.77±2.90), and 64% of subjects reported that pain interfered with work activities (mean interference rating, 1.97±3.09). The correlation between average pain intensity and pain interference as measured by a composite of these interference ratings was r equal to .49 (P<.01).

Significance of the pain problem and satisfaction with pain management 

Forty-nine percent of subjects reported that pain was only a minor problem for them. Forty-three percent reported that their pain was either a problem or a significant problem for them. Only 4.6% of the sample that reported pain also reported that pain was not a problem for them. On the other hand, only 3.1% of the sample reported that pain was their most significant problem.

Consumer satisfaction with pain management care varied. Only 18% of the respondents with pain were either completely satisfied (8.2%) or very satisfied (9.8%) with pain management care. Approximately one third (36.1%) of subjects with pain indicated they were satisfied with pain treatment. However, another third (32.8%) reported dissatisfaction; and 13.19% were either very dissatisfied (11.5%) or completely dissatisfied (1.6%) with pain management. In addition, average pain intensity was significantly, albeit only moderately, correlated with level of dissatisfaction (r=.32, P<.05).

Psychologic status 

Sixty-three subjects with pain completed the SWLS; their mean score was 18.44±8.34. We were unable to obtain complete responses from 4 subjects because of communication difficulties. Participant responses ranged throughout the entire possible range of the SWLS (5–35), and the average response to the SWLS items on the 1 to 7 scale was 3.69, which translates to feeling very slightly dissatisfied with life overall (3, slightly disagree; 4, neither agree nor disagree). The SWLS scores from this sample were significantly lower than those of a group of older volunteers from a community sample10 (mean age ± SD, 74±8.97y; mean SWLS score, 24.44±6.99; t₁₀₀=3.75, P<.001) and also from a group of 136 students enrolled in a course on personality research (mean SWLS score, 23.37±6.53; t₁₉₇=4.52, P<.001). Thus, our sample of persons with CP reports relatively lower general satisfaction with life than 2 samples of other people in the community. The SWLS score in this sample, however, was not significantly associated with average pain intensity, as measured by the 11-point scale (r=.10, P=.42).

Sixty-five subjects completed the MHI-5; their a mean score was 60.65±20.36. Scores ranged from 4 (poor emotional well-being) to 100 (excellent emotional well-being). Although these scores were statistically significantly lower than those of the general US population (US population normative mean, 74.74±18.05; t_2,537=6.19, P<.001), the MHI-59 scores showed only a weak to moderate association with average pain (r=−.22, P=.08).

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Discussion 

The results of this study replicate and extend our earlier findings3 that chronic pain is a substantial problem in some, but not all, adults with CP. In our initial survey study, we found that 67% of the sample reported experiencing pain for more than 3 months,3 precisely the same percentage found in our current sample of different adults with CP. In both samples, back, hip, and lower extremity were the most common pain locations.

Some differences, however, did emerge in severity of pain reports in the 2 samples. For example, 43% percent in our current study compared with 56% of subjects in the previous study reported that their pain occurred on a daily basis. In addition, the average pain intensity was significantly higher in our current study (4.08±2.25) compared with the previous study (3.16±2.45; t₁₂₆=−2.22, P<.05) on the 11-point scale of 0 (no pain) to 10 (pain as bad as could be). On the other hand, only a slightly larger number of respondents reported that they had constant pain in the earlier study (39%) than in our current study (24%). The reasons for the discrepancy between the 2 studies are not known. It is interesting to note, however, that more subjects in the previous study (84%) compared with current study (74%) were classified as having quadriplegic type CP (although this difference was not statistically significant), suggesting a greater degree of physical impairment in the previous sample. It is possible that having less physical impairment is associated with greater efforts at mobility and subsequent increases in daily pain associated with these efforts. Future research is needed to examine this possibility further.

Overall, subjects in both studies tended to report only minor interference of the pain on their activity levels and social or work functioning, despite frequent reports of mild to moderate intensity pain. On average, subjects who reported chronic pain indicated that their mean interference with daily activities was only 2.03±2.50 (range, 0–10) in the initial survey3 and 2.55±3.03 (range, 0–10) in our current study. This relatively minor activity interference, on average, may reflect the low functional level common for many persons with CP who have multiple impairments. In both samples, however, there were some individuals who reported substantial (ie, >7 on the 0–10 scale) interference with daily activities, 18% in the initial study and 14% in the current study. These findings indicate that there is a subgroup of adults with CP who experience a large negative impact from pain on their functioning. An important question concerns whether these individuals are receiving adequate treatment for their pain to address this impact. In our current study, data on consumer satisfaction with pain management were gathered retrospectively. These data suggest that many persons with CP-related pain were not satisfied with pain treatment and suggests that many persons with CP may not be getting adequate pain treatment.1

Psychologic distress appears to be a common difficulty among persons experiencing CP-related pain. Both in terms of global satisfaction with life, and in terms of self-rated emotional well being, the subjects in this sample of adults with CP reported lower levels of psychologic functioning than adults without CP or other illnesses or disabilities. This finding is consistent with our earlier work.13 The weak associations between the measures of psychologic functioning and pain intensity in this sample, however, suggest that pain does not play a large role in the psychologic functioning of most of the study subjects. However, a larger association between pain intensity and the measures of psychologic functioning may have been found had participants with no pain been asked to respond to the measures of psychologic functioning and been included in the correlational analyses. Future research can examine this possibility further by obtaining all measures in both pain and pain-free participants.

It is important to consider the limitations of our current study. First, many of the study participants were recruited from treatment facilities and residential centers. It is possible that these individuals may have had a greater likelihood of having medical problems, including pain, than others individuals with CP who lived in the community. If so, it is possible that our findings overrepresent the incidence of pain problems in the CP population as a whole. In addition, all of the data collected for this study were self-reported. Although many of the dimensions assessed (eg, pain experience, mood) require self-report, other important pain-related variables (eg, observed pain behaviors, pain treatments received, efficacy of pain treatments) can be obtained from someone who knows the participant well. Future research in this area would be improved with the inclusion of such data.

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Conclusion 

Despite the limitations of the study, the findings are generally consistent with our earlier research and that of others. Chronic pain is common in many adults with CP, and it may contribute to disability among some, but not all, persons with CP. Among those with chronic pain, many report relatively low satisfaction with the assistance they receive for pain management. Further research is needed to better understand the nature and scope of pain in this population. For example, clarification is needed regarding the true incidence of the frequency of types of pain (eg, constant versus chronic) in persons with CP, because our current research reports rates that vary somewhat from our initial survey. Future research should also examine more closely the efficacy of pain interventions that are being recommended and used for CP-related pain. To the extent that such research contributes to more effective management of pain, then it will contribute to improved QOL in persons with CP.

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References 

1. Engel JM, Kartin D, Jensen MP. Pain treatment and health care in persons with cerebral palsy (frequency and helpfulness). Am J Phys Med Rehabil. 2002;81:291–296
   • View In Article
   • MEDLINE
   • CrossRef
2. Murphy KP. Medical problems in adults with cerebral palsy (case examples). Assist Technol. 1999;11:97–104
   • View In Article
   • MEDLINE
   • CrossRef
3. Schwartz L, Engel JM, Jensen MP. Pain in persons with cerebral palsy. Arch Phys Med Rehabil. 1999;80:1243–1246
   • View In Article
   • Abstract
   • Full-Text PDF (568 KB)
   • CrossRef
4. Turk MA, Geremski CA, Rosenbaum PF, Weber RJ. The health status of women with cerebral palsy. Arch Phys Med Rehabil. 1997;78:10–17
   • View In Article
5. Tyler E, Jensen MP, Engel JM, Schwartz L. The reliability and validity of pain interference measures in persons with cerebral palsy. Arch Phys Med Rehabil. 2002;83:236–239
   • View In Article
   • Abstract
   • Full Text
   • Full-Text PDF (40 KB)
   • CrossRef
6. Tenuta J, Shelton YA, Miller F. Long-term follow-up of triple arthrodesis in patients with cerebral palsy. J Pediatr Orthop. 1993;13:713–716
   • View In Article
   • MEDLINE
   • CrossRef
7. Von Korff M, Ormel J, Keefe FJ, Dworkin SF. Grading the severity of chronic pain. Pain. 1992;50:133–149
   • View In Article
   • Abstract
   • Full-Text PDF (2161 KB)
   • CrossRef
8. Diener E, Emmons RA, Larsen RJ, Griffin S. The Satisfaction with Life Scale. J Pers Assess. 1985;49:71–75
   • View In Article
   • MEDLINE
   • CrossRef
9. Berwick DM, Murphy JM, Goldman PA, Ware JE, Barsky AJ, Weinstein MC. Performance of a five-item mental health screening test. Med Care. 1991;29:169–176
   • View In Article
   • MEDLINE
   • CrossRef
10. Pavot W, Diener E, Colvin CR, Randall C, Sandvik E. Further validation of the Satisfaction with Life Scale (evidence for the cross-method convergence of well-being measures). J Pers Assess. 1991;57:149–161
    • View In Article
    • MEDLINE
    • CrossRef
11. Ware JE, Snow KK, Kosinski M. SF-36 Health Survey (manual and interpretation guide). Lincoln (RI): QualityMetric Inc; 2000;
    • View In Article
12. Serlin RC, Mendoza TR, Nakamura Y, Edwards KR, Cleeland CS. When is cancer pain mild, moderate or severe? Grading pain severity by its interference with function. Pain. 1995;61:277–284
    • View In Article
    • Abstract
    • Full-Text PDF (735 KB)
    • CrossRef
13. Engel JM, Schwartz L, Jensen MP, Johnson DR. Pain in cerebral palsy (the relation of coping strategies to adjustment). Pain. 2000;88:225–230
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (70 KB)
    • CrossRef

• 1 No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.