Abstract
PURPOSE:
This exploratory study demonstrates the application of functionally relevant physical exercises (FRPE) to objectively assess physical functioning among children with chronic pain. Intensive interdisciplinary pain treatment (IIPT) focuses on functional improvements as a primary outcome. FRPEs aim to enhance clinical assessments and monitoring by providing relevant data for physical and occupational therapies.
METHODS:
Children enrolled in three weeks of IIPT provided data for study. They completed two self-report measures of functioning (Lower Extremity Functioning Scale [LEFS] and Upper Extremity Functioning Index [UEFI]), measure of pain intensity, and six separate FRPEs (box carry, box lifts, floor to stand, sit to stand, step ups, and modified six-minute walk test). Data from 207 participants aged 8–20 years old were analyzed.
RESULTS:
Upon admission, over 91% of children could perform each FRPE at some level to provide clinicians with a baseline assessment of functional strength. Following IIPT, all children were able to complete FRPEs. Overall, children reported statistically significant gains in functioning on all subjective reports and FRPEs (p’s < 0.001). Spearman correlations demonstrated that LEFS and UEFI were weakly to moderately correlated to all FRPEs at admission (r’s between.43–.64, p’s < 0.001 and.36–.50, p’s < 0.01 respectively). Correlations between all subjective and objective measures were comparatively lower at discharge.
CONCLUSION:
FRPEs appear to serve as good objective measures of strength and mobility for children with chronic pain, measuring variability across patients and change over time, which is unique from subjective data gathered via self-report. Due to face validity and objective measurement of functioning, from a clinical practice perspective, FRPEs provide meaningful information to support initial assessment, treatment planning, and patient monitoring. This study offers initial support for a novel measurement method that is easily administered and replicated to effectively measure functional improvement in children with chronic pain.
Keywords
Abbreviations
IIPT Intensive Interdisciplinary Pain Treatment
LEFS Lower Extremity Functional Scale
UEFI Upper Extremity Functional Index
FRPE Functionally Relevant Physical Exercise
Introduction
Chronic pain is defined as persistent or recurring pain lasting longer than three months. Although most children who report chronic pain can perform day-to-day activities, it has been found that 3–5% [1–3] experience severe functional impairments, such as inability to attend school, decreased socialization, avoidance of physical activity, and subsequent deconditioning. Due to prolonged deficits across multiple domains of functioning, children with chronic pain and associated dysfunction often require intensive inpatient pain treatment (IIPT) to regain age-appropriate functioning. These interventions have been replicated across treatment sites to support their efficacy [1, 4–6]. Physical and occupational therapies play a critical role in children’s consistent physical functioning, as there is consistent evidence that exercise has a clinically relevant effect on pain when compared to no intervention or conservative therapies [7]. Despite reported positive outcomes of IIPT programs, many do not report objective physical functioning data as part of peer-reviewed outcomes [8, 9].
As one example, physical self-report measures [10–12] have helped to demonstrate subjective changes in independent functioning and assess perceived functional gains in pediatric pain rehabilitation [13–15]. While these tools have proven useful as outcome measures, subjective reports are limited by potentially confounding psychological factors, such as perceived self-efficacy, a global sense of impairment, and/or poor insight [16, 17]. Objective measurement isolates the child’s actual physical performance (e.g., posture, balance, joint mobility, motor function, muscle strength, gait) from psychological constructs or self-perception. Therefore, including objective tools in clinical assessment helps to create a holistic assessment of physical functioning and identify clinical therapy targets for treatment and monitoring of progress.
The complicating factor in objective assessment involves the selection, application, and scoring of functioning, particularly in an intensive program with varied pain conditions and restricted time, space, and staffing. Due to extreme differences in age, diagnosis, and levels of physical functioning at the time of admission, it is challenging to find a single set of established objective measures to support chronic pain rehabilitation. Also, children with chronic pain, regardless of diagnosis, often demonstrate limited or inconsistent deficits in several areas, particularly in day-to-day functional domains. For example, a child may demonstrate appropriate strength via manual muscle testing yet struggle with the functional application during sit-to-stand or floor-to-stand transitions. While research on objective physical functioning/impairment is on the rise, it can be difficult to quantify [1, 18] in a way that is clinically meaningful and practically applicable in IIPT.
Existing standardized objective tools present several limitations for use with children with chronic pain. As one example, the Bruininks-Oseretsky Test of Motor Proficiency (BOT-2) [19] can gather valuable information related to fine and gross motor skills and coordination; however, it involves a lengthy assessment and scoring period and strict assessment protocol, and it does not directly reflect common gross motor skills used in daily physical functioning. Anecdotal evidence suggests that children in chronic pain do not tolerate long structured assessments, nor do they present with sufficient energy or stamina to complete them, leading to an artificial floor effect. It is also argued that psychosocial variables (e.g., self-efficacy, fear of pain, low motivation) show greater potential influence in assessments requiring sustained effort.
This aim of this study was to demonstrate the application of functionally relevant physical exercises (FRPEs) as a potential enhancement to evaluate functional strength, endurance, and mobility for children with chronic pain. The practical benefit of FRPEs as applied in this clinical population were: 1) easy to administer in variable settings, 2) well-tolerated by children with chronic pain upon evaluation, 3) relevant to day-to-day function, and 4) sensitive to measuring change across three weeks of intensive rehabilitation. It was hypothesized that children’s objective physical functioning using FRPEs would be similar but distinct from subjective measures of functioning, yielding weak to moderate correlations between subjective and objective measures. It was also hypothesized that FRPEs would capture clinical improvement in physical functioning following IIPT, similar to prior reports of clinical improvement using subjective measures.
Methods
Participants
Children ranging in age from 8–20 years and admitted to an IIPT due to severe functional impairments resulting from chronic pain were included in this study. As seen in Table 2, they presented with a range of diagnoses, including headache/migraine, back pain, abdominal pain, amplified musculoskeletal pain syndrome (AMPS), postural orthostatic tachycardia syndrome (POTS), Ehlers-Danlos syndrome (EDS), and complex regional pain syndrome (CRPS). Data was collected on the entire cohort as part of standard clinical care. Data from 40 children were excluded from data analysis for the following reasons: left the program early, withdrew consent, did not obtain data during either admission or discharge, or remained in the program for more than four weeks. Out of the 247 children initially included in the study, 207 met inclusion and exclusion criteria.
Participant demographics including age, sex, diagnosis, and chronicity of pain
Participant demographics including age, sex, diagnosis, and chronicity of pain
Children completed a standard three-week IIPT, consisting of 3–4 hours daily of physical and occupational therapy and 6 hours per week of psychology, and supplemented by other therapeutic programming for 8–9 hour days (e.g., recreation therapy, school services, music therapy). The program focused on gradually increasing functional activities and using appropriate self-directed coping and pain management skills in order to return to age-appropriate daily life activities after discharge [4, 20]. Relevant to this study, physical and occupational therapies target isolated strengthening of appropriate musculature, endurance, proprioceptive, and sensory training techniques; improved body mechanics and posture during exercises; and skills that specifically facilitate a return to the highest level of function in daily life activities. Further details of this program have been published in previous studies. The positive clinical outcomes of this program are similar to other IIPTs [4, 21].
Data collection
A retrospective review was conducted using data collected upon admission and on the day of discharge, as part of standard clinical assessment and care. FRPEs were also completed weekly in a group setting under therapist supervision and guidance. They were not directly or intentionally integrated into treatment sessions to prevent a practice effect that would impact clinical assessment.
Data collection has been approved by the hospital Institutional Review Board and is on the clinical database registry. All patients are provided information on the registry with an option to opt out of including data in research.
Measures
Self-report measures
Lower Extremity Functioning Scale (LEFS) [10] and Upper Extremity Functioning Index (UEFI) [11]: The LEFS and UEFI are separate 20-item self-report measures about perceived ability to perform everyday tasks with lower or upper extremities. Individuals rated each item on a 0–4 Likert scale (0 = extreme difficulty or cannot perform and 4 = no difficulty). Scores were summed for a possible score of 0 to 80. The LEFS and UEFI have demonstrated strong internal consistency (α=.96 and.94, respectively) as well as test-retest reliability (r = .86 and.95, respectively). Both are sensitive to change in functioning; a minimum detectable change score of nine points is considered clinically important. Depending on age and cognition, staff assisted with reading and rating self-report scales.
Pain: A single-item measure evaluated pain severity in the previous 24 hours using a numerical rating scale (NRS) from 0 (no pain) to 10 (worst pain) [22, 23].
Objective measures
FRPEs: Physical and occupational therapists, each with extensive chronic pain experience, designed exercises based upon recurring themes identified when reviewing self-report data (LEFS and UEFI) from children previously in IIPT. From this list, therapists developed a set of FRPEs to measure clinical impairment and functional improvement. These exercises were deemed face valid as functionally relevant given the frequency at which children would complete these movements while attending school or completing housework or chores. These FRPEs are summarized in Table 1 and included box carry, box lift (floor to waist), box lift (waist to eye), floor to stand, sit to stand, step-ups, and a six-minute walk test. Each FRPE was a single-item measure; therefore it could be examined separately. All exercises were novel for adolescents except for the six-minute walk and the one-minute sit-to-stand, which have been supported in previous research. The six-minute walk test used here was similar to the traditional six-minute walk test [24]; however, minor modifications were employed to make the activity more age-appropriate and function-based, including walking with peers in the same areas and listening to music. The one-minute sit-to-stand test was modified from the original protocol: a standard chair was used rather than adapting the chair height to the individual height of the child [25]. All activities were able to be completed in under 30 minutes with no further clinical time required for scoring the assessment.
Details of Functionally Relevant Physical Exercise (FRPE) as objective measures
Details of Functionally Relevant Physical Exercise (FRPE) as objective measures
*Five pound weight if younger than 12 years old; eight pound weight if 13 years or older.
During FRPE assessment, focus was placed on body awareness, avoiding compensatory strategies and facilitating proper alignment and muscle activation [26]. Specifically, the child was asked to attempt the activity but to discontinue the trial if significant variations occurred. The therapist kept track of time and provided prompting to improve alignment and body mechanics. Children were asked to self-count and track information to demonstrate a more independent role as would be done in a school setting and as part of their home exercise program [26, 27]. If the activity was significantly modified, it was coded as “0” repetitions.
Data was entered in a REDCap database [28], then converted to an SPSS 22.0 dataset for analyses. Initial analyses (ANOVA) were conducted to assess if a large number of outcome variables or a pattern of variance in outcomes could be attributed to diagnosis groups, age, or sex, to be statistically controlled in later analyses if needed. Change scores were also calculated by subtracting the admission data from the discharge data. To test the first hypothesis that FRPEs would yield weak to moderate correlations with subjective reports (LEFS, UEFI), Spearman correlation coefficients were calculated both at admission and discharge. To test the second hypothesis that children completing pain rehabilitation would demonstrate functional gains as measured by established subjective reports and novel objective FRPEs, the Wilcoxon signed rank test evaluated change in physical functioning measures (LEFS, UEFI, FRPEs) as well as pain over time.
Results
Participants
Those included in the study were primarily females (71%) and averaged 15 years of age. Children had various diagnoses and chronicity of pain as seen in Table 2. There were some differences in functioning that could be attributed to diagnosis groups, age, and sex; however, the number of significant effects was minimal and yielded no clear pattern. Younger age appeared to be correlated with greater improvements in lower extremity functioning from admission to discharge. Compared to females, males had greater changes from admission to discharge in the LEFS. Diagnosis appeared to differentiate functioning using the UEFI only. On the whole, each subgroup demonstrated an improvement in functioning from admission to discharge. Therefore, it was determined appropriate to continue analyses on the entire dataset as one group of children with chronic pain.
Data distribution
Subjective data at admission and discharge are reported in Table 3. Complete data at admission and discharge was missing respectively for two and three patients for some FRPEs and for 100 and 102 patients for two FRPE items introduced later as part of standard clinical care. Data was normally distributed for pain (both time points); however, data was not normally distributed for lower extremity functioning (LEFS) at discharge and upper extremity functioning (UEFI) at admission and discharge.
Means and standard deviation (SD) of subjective and objective measures at admission and discharge
Means and standard deviation (SD) of subjective and objective measures at admission and discharge
* p < .05; **p < .01; ***p < .001; +Number of children who scored 0 on this exercise at admission.
Objective data for FRPEs are reported in Table 3. Data was normally distributed for only one item at both time points: box lift from waist to eye. For all FRPEs, more than 91% of children completed a score greater than 0 upon admission, suggesting that, as a group, a floor effect was not identified to influence results. At discharge, 100% of children attempted each item and held a score greater than 0.
Results of non-parametric correlations for all variables are in Table 4. To test the first hypothesis that FRPEs would measure functioning in children completing pain rehabilitation in a manner similar, but separate, from subjective measures of functioning, the strength of association between self-report measures of functioning and FRPEs was examined. Spearman correlations demonstrated that the LEFS correlated weakly to moderately to all FRPEs at admission (r’s between.43–.64; p’s < 0.001) with weak correlations at discharge (r’s between.23–.33; p’s < 0.01). The UEFI demonstrated weak to moderate correlations with all FRPEs at admission (r’s between.36–.50; p’s < 0.001) with weak correlations at discharge (r’s between.15–.27; p’s < 0.001).
Spearman correlations of objective and subjective data at admission and discharge
Spearman correlations of objective and subjective data at admission and discharge
*p < .05; **p < .01; ***p < .001; LEFS: Lower Extremity Functional Scale. UEFI: Upper Extremity Functional Index.
To further differentiate subjective and objective methods of data collection, two additional results are worth noting. First, all correlations between FRPEs and the two subjective measures (LEFS and UEFI) were weaker than the strong direct correlation between the two subjective measures (LEFS and UEFI) both at admission (r = .813) and discharge (r = .816; p’s < 0.001). Second, all correlations between objective FRPEs and the single subjective measure of pain were weaker than the correlations between subjective measures of LEFS and UEFI with pain at both time points.
Results of Wilcoxon signed rank tests for self-report data are presented in Table 3. To test the second hypothesis, change scores of self-reported functioning and FPREs were examined. As often seen with IIPT [21] over a short period of time, there was no significant reduction in numerical pain rating. However, as expected and similar to previous reports, children reported a statistically significant improvement in the LEFS and UEFI (all p-values<0.001) over the course of rehabilitation. Also, as hypothesized and similar to subjective data, children undergoing IIPT demonstrated statistically significant improvement in objective measures of functioning as measured by FRPE scores (all tests significant at p < 0.001).
Discussion
Children with chronic pain can suffer from severe impairments impacting age-appropriate functioning and day-to-day tasks. The primary goal of pediatric chronic pain rehabilitation is to improve daily functioning for these children, often over the course of intensive interdisciplinary pain treatment programs. While studies demonstrate overall improvement following IIPT programs [1, 29], reported outcomes do not typically isolate objective physical functioning from subjective assessment methods. More recently, there has been an attempt to increase the resources available to collect and monitor physical functioning more objectively [14, 18].
A primary aim of this study was to enhance clinical assessment and monitoring of children with chronic pain by providing practically measurable and clinically relevant objective data of physical functioning (i.e., strength, endurance, and mobility) using FRPEs. The FRPEs used in this study were readily administered, easily interpreted, and relevant to treatment planning and clinical monitoring. They also did not present with floor effect and demonstrated a range of performance across children assessed. As hypothesized, FRPEs functioned in a similar manner to subjective measures of functioning: all captured clinical improvements following intensive rehabilitation treatments. In addition, FRPEs yielded weak (r’s 0.3 to 0.5) to moderate (r’s 0.5 to 0.7) correlations with subjective measures at both admission and discharge, suggesting that objective measurement captures a related but distinct aspect of physical functioning. This aligns with previously reported limitations of subjective measurement, which may be confounded by psychosocial factors such as self-efficacy, a global sense of impairment, and/or poor insight. This study highlights the possibility, and potential benefit, of isolating objective performance from subjective assessment.
This study adds to existing research by examining and reporting objective FRPEs as a practical method to enhance assessment and goal setting for chronic pain. FRPEs were designed to be easily administered in variable settings, seemingly well tolerated by children with chronic pain when initiating treatment, relevant to day-to-day function, and sensitive to measuring change over three weeks. FRPEs provided a meaningful observation of the child’s functioning by closely resembling functional tasks, offering increased perception of physical functioning and improved understanding of functional gains in rehabilitation. These FRPEs also seemed to be the appropriate challenge level, as more than 91% children could complete at least one repetition of the exercise during the initial evaluation. Finally, the FRPEs demonstrated practical benefits of using several single-item FRPEs instead of a lengthy standardized method (e.g., BOT-2), as FRPEs could be completed as separate tests, allowing rest breaks or other modifications that naturally occur during a busy pediatric rehabilitation environment. As a set, these exercises objectively captured both existing deconditioning at admission and functional gains at discharge.
Other points of discussion were observed in the data. First, correlations were strongest between FRPEs and the LEFS, which intuitively makes sense, as most functional exercises involved lower body strength and mobility. Further, correlations between subjective measures of functioning were very strong, suggesting that both capture a larger general construct of functional impairment. In addition, correlations were relatively weaker at discharge, suggesting that subjective perceptions may not change at the same rate or in the same manner as objective functioning. For example, a child with chronic pain may struggle to lift a gallon of milk prior to rehabilitation; after rehabilitation, this same child may clearly increase their ability to lift a gallon of milk but may or may not subjectively report improved functioning on the UEFI. These subjective measures with embedded psychosocial constructs are still important as indicators of improvement. In sum, both subjective and objective measures uniquely contribute to clinical assessment and monitoring of clinical improvement.
While not directly related to the hypothesis, it is often helpful to monitor self-reported pain in conjunction with other study variables in studies of chronic pain in children. A substantial change in self-reported pain severity was not observed over the three weeks of IIPT. Given that intervention occurred over only three weeks and that the therapy focus was to initially improve functioning across multiple domains for sustained gains after discharge, it was not common to see large decreases in pain level during the program. However, post hoc analyses showed that subjective report of pain was more highly correlated with subjective measures of functioning.
Further research in this area could expand the understanding and utility of FRPEs. As one example, in this study, children demonstrated clinically meaningful increases in subjective assessment of lower and upper extremity functioning. They also demonstrated an approximately 50% increase on all objective tools except for the six-minute walk (35%). As with studies on the LEFS and UEFI, future research could examine what amount of gain on FRPEs is not just statistically significant but shows clinically meaningful change. Additional research could isolate measures of strength and mobility from measures of endurance (e.g., six-minute walk) to clarify their independent role in measuring improvement. It is likely that strength and mobility gains occur before (and possibly influence) later gains in endurance. Further development of FRPEs may include simple versus complex movement-based tasks to better see variability in the level of impairment. In addition, other established functional exercises such as the two-minute step test, two-minute walk test, 10-meter walk test, stair climb test, chair stand test, and timed up and go test could be studied in the future [30–32].
Limitations
Limitations in this study also point to future research directions. First, while children completed these activities individually during their initial evaluation, they did not complete them independently for discharge. Instead, they completed them alongside peers, which is reflective of real-life application. How much of the objective functional gain could be influenced by social factors was not able to be evaluated. Future research could examine the influence of social factors (e.g., presence/absence of peers) on measurement of FRPEs. Second, this study did not utilize a control group (e.g., wait-list control) to isolate whether the observed change was due directly to the IIPT intervention. Future research could examine a group comparison to further validate treatment gains or create a normative dataset to compare individuals and groups. Third, there was no measure of feasibility, efficiency, or child satisfaction, which could further validate the utility of FRPEs. Lastly, assessment of meaningful change [33] would have added to the validity and utility of objective measures in pediatric chronic pain rehabilitation.
Conclusion
Children with chronic pain often have impaired physical abilities. Current subjective measures of functioning do not isolate objective performance, and some objective measures have practical limitations. The use of FRPEs provides objective data reflecting strength, endurance, and mobility that is practical to administer, easy to score, and clinically meaningful as an addition to chronic pain rehabilitation programming. FRPEs add to clinical care by isolating objective measures of performance from perceptions or self-reports, appropriately capturing functional deconditioning at admission and functional gains at discharge. Pairing subjective self-report measures with FRPEs provides a pragmatic and meaningful way to assess overall physical functioning and track progress in chronic pain rehabilitation. The use of these function-based physical exercises may improve therapists’ understanding of functional strength and how it may facilitate or limit overall outcomes. In addition, objective measurement using these exercises allows clinicians to easily monitor a child’s progress, bringing attention to the importance of day-to-day tasks. Future research on FRPEs in pediatric chronic pain will further strengthen the understanding of these conditions and children’s response to rehabilitation. In sum, objective FRPEs offer a practical and meaningful addition to the assessment and treatment of childhood chronic pain.
Footnotes
Acknowledgments
This author would like to acknowledge Rachel Heines, PT, and Lauren Nelson, OT, for assistance in developing the reported functionally relevant physical exercises as well as data collection as part of evaluations, discharges, and follow ups. This research could not have been done without them.
Conflict of interest
The authors have no conflicts of interest to report.
Ethical considerations
Data collection has been approved by the Institutional Review Board and is on the clinical database registry (IRB# 16-790).
Funding
The authors have no funding to report.