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Abstract

No data are available on the prevalence or incidence of paediatric chronic pain in Australia, and only limited data exist on the functional limitation that chronic and recurrent pain has on affected children, their parents and siblings.¹

Specialised integrated pain management clinics that offer cognitive behavioural therapy programs are successful in the management of adults with chronic pain,² but few programs exist for children and adolescents in Australia.

As no Australian epidemiological or demographic data exist for children and adolescents with chronic pain, I performed a prospective, descriptive study to investigate the demography, clinical characteristics, treatment, functional limitations and outcomes of patients referred to a paediatric multidisciplinary pain clinic.

Methods

Patient population

The Royal Children's Hospital is a tertiary paediatric referral centre servicing Victoria. A multidisciplinary clinic for children and adolescents with chronic pain, the Children's Pain Management Clinic, was established in March 1998. From March 1998 to March 2000, patients aged 0-18 years of age were prospectively and consecutively included in the analysis. The Statistical Local Areas defined by the Australian Bureau of Statistics³ were used to classify residential location as rural or metropolitan Victoria.

Interviewers

All patients were assessed by one of three paediatric anaesthetists. The initial interview involved taking a full medical and social history and physical examination of the patient in the presence of one or both parents. One or more allied health professionals (physiotherapist, occupational therapist or clinical psychologist) also assessed the children.

Interview

The interview followed a structured format. Responses to questions were obtained from both child and parent(s), unless the child was cognitively impaired, in which case the parent(s) or carer provided information.

The questions related to diagnostic information (nature, site and intensity of the pain), functional disability (time off school, inability to partake in sporting activities) and sleep dysfunction.

Definitions

• Chronic pain was defined as "pain persisting beyond the time of healing or pain which is persistent or near constant for three months or longer".⁴

• Complex regional pain syndrome (CRPS) Types I and II were diagnosed according to previously published criteria.⁵ CRPS is a condition in which pain and disability are sustained, out of proportion to an initiating noxious event, by mechanisms that are still incompletely understood. Diagnosis is based on clinical findings, including allodynia (non-painful stimulus eliciting pain) or hyperalgesia (exaggerated sensitivity to pain) beyond the territory of a single peripheral nerve, oedema, skin blood flow abnormality (colour and/or temperature change) or abnormal sudomotor (sweating) activity. CRPS Type I is distinguished from Type II in that Type II follows nerve injury.

• Pain intensity was assessed by a pain assessment tool appropriate for the patient's age and cognition: Eland pain diagram; visual analogue scale; verbal numerical rating (1-10) scale; Wong-Baker faces; and parental or carer report in the case of non-verbal patients, toddlers and those with cognitive impairment.

• Outcomes were recorded as:

  Good: Marked reduction in the intensity of pain (no or minimal pain) and marked functional improvement (return to school and sport where applicable, and resumption of normal sleep pattern);

  Moderate: Partial reduction in pain intensity and/or some functional improvement (return to school or sport where applicable or resumption of normal sleep pattern); or

  Poor: No improvement in pain intensity or functional activity.

  Outcome was classified as unknown if there was no follow-up.

The frequency and duration of follow-up were as clinically indicated.

Over the two-year study period, 207 patients aged 1-18 years were referred to the Children's Pain Management Clinic (Box 1). Most patients (57%) were referred by orthopaedic surgeons.

Medical conditions and associated disability

Concomitant medical conditions (Box 2) were present in 106 (51%) patients. The disease process, its treatment, complications of the disease or side effects of the treatment accounted for the pain experienced by 93 of these 106 patients.

A clear organic precipitant to the pain was identified in 39 of the 101 patients with no pre-existing medical condition. The cause of pain in these patients was neuropathic (nerve injury, nerve entrapment or neuroma) in 20 patients, soft tissue injury in 14, bone- or joint-related in four, and renal colic in one. In 62 of these 101 patients, no clear aetiology was found. The abdomen (10 patients) was the most common single site of presenting pain in this group, followed by headache or facial pain (9), multiple sites of pain (9), and pain in the foot (9), hand or forearm (8), knee (7), leg (5), back (2), shoulder (1), chest (1) and neck (1).

CRPS was diagnosed in 44 of the 207 patients (Type I, 40 patients; Type II, 4 patients). Females (33 patients) and the lower limb (33 patients) were predominantly affected. Mean age was 13.7 (range, 9-17) years. CRPS was precipitated by minor trauma in 18 patients, and lower-limb surgery in six patients. No precipitant was identified in nine patients.

Overall, 105 patients (95% of school attenders) missed at least five days of school because of pain (independent of medical appointments) (Box 3).

There were 147 (71%) patients with impaired ability to participate in sport because of their pain. Of the remaining 60 patients, 43 were unable to participate in sport because of their concomitant condition, and 17 had no such inability on presentation.

Overall, 146 patients (71%) suffered daily or almost daily sleep disruption attributable to pain. Of this group, 140 (96%) patients woke up three times or less. Parents of children with cerebral palsy, cognitive impairment or intellectual disability reported sleep disruption in 16 of 22 patients. Waking each night in these patients was more frequent and difficult to manage.

Interventions

Medications prescribed are listed in Box 4, and interventions are listed in Box 5. Individuals may have received one or more of these simultaneously or consecutively. No medication was prescribed in 75 of 207 (36%) patients; however, this group may have received any one or more of the interventions listed. The median duration of follow-up was four months (range, 2 weeks to 16 months).

Patients diagnosed with CRPS were treated as inpatients (26 patients) or outpatients (18 patients) depending on the severity of their condition. Inpatients underwent a more intense and structured rehabilitation program tailored to their individual requirements. This involved cognitive behavioural therapy, physiotherapy (with graded return to physical activity) and re-integration into school and social activities. The median length of hospital stay was five days.

Outcomes

Outcome was good in 134 (65%) patients, moderate in 32 (15%), poor in 16 (8%) and unknown in 25 (12%). Box 6 shows the outcomes for patients diagnosed with CRPS.

Of the 29 patients who had missed more than 40 days of school because of pain, 23 began attending school regularly once treatment for their pain syndrome commenced. Ten successfully underwent a graded return-to-school program coordinated in conjunction with the school, the Royal Children's Hospital Education Institute and the Children's Pain Management Clinic. Of the 76 patients who had missed between five and 40 days of school and who completed follow-up, 70 attended school regularly after intervention.

Of the 147 patients who had impaired ability to participate in sport because of pain, 129 (88%) regained the ability after treatment.

Sleep disturbance was successfully managed in 129 of 146 patients (88%). Most (122 patients or their parents) reported uninterrupted sleep as a result of either analgesic intervention or successful use of relaxation techniques. The remaining seven patients (or their parents) reported marked improvement in the frequency of waking and less troublesome return to sleep when they woke during the night.

Twelve (6%) of the 207 patients died of their underlying terminal condition or its complications.

There were three complications related to therapy for pain. Two were epidural-related in patients with cerebral palsy and CRPS: both developed back pain and fever. One had an epidural infection and the other paraspinous myositis with possible osteomyelitis. One patient developed paraesthesiae after lumbar sympathetic nerve block. All three patients recovered with no long-term sequelae.

Discussion

In my study, chronic pain in children and adolescents was associated with considerable functional limitation, most commonly school absenteeism, sleep disturbance and inability to perform sporting activities. The duration of school absenteeism was significant and could be expected to affect school performance, although this was not specifically recorded. Previous studies from other countries have reported on the incidence of functional disability in relation to specific painful sites or conditions.¹ In our patients, chronic pain, irrespective of aetiology or site, commonly resulted in significant functional disability.

More females than males were referred in all age brackets. CRPS, headache, fibromyalgia, recurrent abdominal pain and somatoform pain all occur more frequently in females than in males aged less than 18 years.⁶

More than a third of all patients referred were aged 12 years or less. Recurrent abdominal pain is commonly reported in this age group.⁷ However, only 11% of children in this age group referred to our clinic complained of abdominal pain, whereas half presented with limb pain. This may indicate that recurrent abdominal pain is successfully dealt with and understood by paediatricians, whereas limb pain is more likely to be referred.

Patients from rural Victoria accounted for 29% of all referrals, in keeping with the population distribution in Victoria.³ This has implications regarding the provision of education of general practitioners and services to rural areas.

CRPS was diagnosed in 21% of patients referred. The lower limb was more commonly involved than the upper, and females were more often affected than males. Previous studies from the United States⁸ and Sweden⁹ have shown a similar ratio of limb involvement. In these studies, females were more commonly affected than in this study (5 and 13 times more often than males, respectively). Unlike in those studies, in which a large percentage of girls with CRPS were active in sports, gymnastics, skating and dance, this was true for only 10% of our patients.

Children and adolescents with cerebral palsy made up the largest single group of patients with a concomitant condition. Locating the source of pain can be difficult in this group,¹⁰ especially in those with cognitive impairment. Hip and/or back pain was the source in 55%. Spasticity itself can cause pain¹¹ and contributes to deformity, subluxation, dislocation, capsulitis and osteoarthritis in these regions. Sleep disruption was more frequent and problematic in these children, both overall and on a nightly basis. Addressing pain resulted in most patients sleeping uninterrupted through the night. Eliminating or minimising sleep disruption is of obvious benefit to the child and carers.¹²

The nature and management of chronic pain in children and adolescents differs from that in adults. Bullying, sexual or physical abuse, marital disharmony and difficulties at school may all contribute to abnormal pain behaviour in children. Family therapy may be indicated, as family situations can contribute to exacerbating and maintaining pain behaviour in children. Parents as well as afflicted children often need to be taught behavioural modification and pain-coping strategies.

Abolition of pain, particularly in patients with chronic conditions, is not always achievable. The diverse aetiologies which manifest as pain behaviour necessitate a coordinated, multidisciplinary approach. My results support this multidisciplinary approach and focus on regaining function and minimising pain behaviour. The lack of a psychologist (a psychologist was initially a team member, but only for three months) and psychiatrist as integral team members may have contributed to the poor outcomes observed in some patients. Poor outcome was commonest in patients from chaotic family environments or in those with moderate intellectual disability. The latter are least likely to respond to cognitive behavioural techniques. Behavioural modification is better suited to this group, but may be difficult and time consuming to implement.

A recent unpublished survey of tertiary paediatric hospitals in Australia and New Zealand, conducted by the Paediatric Pain Working Party of the Faculty of Pain Medicine, Australian and New Zealand College of Anaesthetists, revealed that only three centres in Australia and New Zealand have chronic pain management services which meet their minimum requirements for multidisciplinary staffing.¹³ Given the magnitude of functional disability demonstrated in our population, the provision of funding for paediatric chronic pain services requires urgent attention.

The socioeconomic cost of chronic pain in children and adolescents is considerable. Although not specifically addressed in this study, it was apparent that there were implications for the child (education, self-esteem, friendships), the parents (time off work caring for the child and attending appointments, cost of medication, hospitalisation and complementary therapies) and the healthcare system (medical care, including serial referrals to multiple specialists, medication and hospitalisation and allied healthcare costs).

Future studies should address the prevalence and epidemiology of pain in Australian children and adolescents, the early identification of those in whom significant functional disability exists and the cost-benefits of establishing multidisciplinary paediatric pain centres. Future directions should include education programs for GPs, paediatricians, schoolteachers and counsellors and allied health professionals to recognise early warning signals such as school absenteeism, frequent sick bay attendances, failure to respond to treatment, and poor school sports participation.

References

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Authors' details

The Royal Children's Hospital, Melbourne, VIC.
George A Chalkiadis, DA, FANZCA, Anaesthetist, and Co-ordinator Pain Management.

Reprints will not be available from the author.
Correspondence: Dr GA Chalkiadis, Royal Children's Hospital, Flemington Road, Parkville, VIC 3052.
chalkiagATcryptic.rch.unimelb.edu.au

©MJA 2001
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