This study showed that nearly 30% of children and adolescents with chronic pain presenting for tertiary care had constant pain and an alarming, median maximum pain intensity of 9 (NRS 0–10). Disturbing as this may be it is only the tip of the iceberg. The impact of the pain, like that previously found in adults [29
], was prominent with children scoring highly for pain-related disability. Many children were no longer participating in normal every day activities, one quarter were missing more than 25% of school and emotional distress was high with clinically significant scores for depression (24%) and anxiety (19%).
The children in this study experienced a much higher negative impact from the pain with elevated levels of pain intensity [4
] and pain frequency [30
] in contrast to findings from epidemiology studies that included children with recurrent or permanent pain during the past 3
months. This study population also displayed significant interference in daily life, school attendance and emotional well-being. The presence of pain in different parts of the body has been previously illuminated [4
] and this study delved further into the subject of co-morbid diagnoses, discovering a large number of children with a chronic pain disorder with somatic and psychological factors (43%) or more than one distinct pain diagnosis (55%). Additionally, children were experiencing elevated symptoms of anxiety and depression, 19% and 24% respectively.
Importantly, and as previously shown in other clinical and epidemiological findings [4
], the study population was dominated by female patients (61%) with this increase manifesting from the age of 13
years possibly suggesting an effect of pubertal development [33
]. These findings, as previously suggested [4
], underline adolescent girls as a very vulnerable group. Treatment studies also show that adolescent girls have a worse treatment outcome compared to boys [23
]. Regarding pain location in this study, adolescent girls suffered from more musculoskeletal pain and pain in more than two locations. Sex differences with regards to pain location were not found in other age groups. This is in contrast to a recent German epidemiological study which investigated the location of the most bothersome pain. Girls reported this to be the head or the abdomen more often than boys [6
]. Further studies in school children with chronic pain showed that girls experience more abdominal pain; boys more limb pain [4
]. Sex difference in pain intensity found in school children with chronic pain, where girls report more intense pain compared to boys [4
], could also not be replicated in our group of highly impaired children. In line with recent epidemiological findings [5
], boys and girls in this sample did not differ in pain-related disability. Discrepancies between findings in epidemiological research and our sample can be interpreted in two ways: Either pain characteristics in highly impaired children with a chronic pain are different from school children who report the symptom of pain or differences are caused by a systematic effect of treatment seeking.
Over all, even though girls are more prominent in this tertiary care sample, group comparisons indicate age differences, rather than sex differences, as being implicated in pain severity and extremely high impairment in this sample. In this sample both pain intensity and pain-related disability increase with age. Epidemiological studies have not found these associations [4
]. Arguably, the association between age and severity of pain, detected in this study of children with high impairment from chronic pain, was the most important finding. This may be partially explained by the worrying discovery that adolescents entering specialist management had had pain for a longer period of time, no matter the sex, compared to younger children. This kind of delay has the potential to increase developmental stasis, or even regression, in children of any age. Furthermore, extremely high levels of impairment were associated with previous hospital stays, increased depression and pain in several locations.
This level of complexity, along with the striking number of unsuccessful prior hospital stays would suggest problems with identification and referral of unsatisfactorily managed children and adolescents with chronic pain in the primary and secondary health care system. It is intended that patients seek treatment at a primary care level before calling upon tertiary treatment. Treatment in primary care will be sufficient in a large number of affected children. The elevated time since pain onset in our sample (median: 19
months, range: 1–193) may suggest that the referral to a pain specialist is carried out too late. With regards to our data, this interpretation would imply that this effect gets stronger the older the child; the average time from pain onset until receiving tertiary treatment in 15
year-old children is 4
Since we did not control for pain severity in the past, an alternative interpretation of these findings could be developmental changes in the pain condition during adolescence. Adolescence is a vulnerable period of life. It may aggravate a preexisting pain problem and other associated problems (e.g. problems in school, emotional distress) thereby becoming a condition that requires treatment. Further research will be required to investigate this further.
Two diagnostic groups, in our study, that may highlight an insufficient knowledge in the primary care sector were adolescents with abdominal pain classified as chronic pain disorder with somatic and psychological factors (more than 10% of the children older than 10
years) and younger children diagnosed with migraine (48% of the children younger than 11
years). The prevalence of functional abdominal pain in the community is known to be more common in younger children [35
] while prevalence data for migraine in the community suggests an increase with age [36
]. Bhatia et al. [37
] revealed a lack of knowledge of pediatricians and physicians in treating children with chronic pain in primary care which might be specifically prominent in these two groups. This lack of knowledge and earlier referrals to a tertiary pain service for children with more complicated diagnoses could be improved by a comprehensive advanced training program in chronic pain for primary pediatricians.
Improvement is not only needed in the primary care sector. Tertiary care structures for highly impaired children with chronic pain are scarce [1
]. Children are often referred to specialized centers according to the location of pain i.e. to headache clinics [38
], pediatric gastroenterologists [40
] or institutions specialized in musculoskeletal pain [1
]. However, this would seem inadequate given the findings that 55% of the children analyzed in this study have more than one distinct pain diagnosis partially affecting different parts of the body and nearly 20% of children reported pain in more than two locations.
The discrepancy between services offered and needed [2
] makes planning for services based on demand unfeasible. One obvious reality stands out with the current situation; there is a lack of specialized clinics available to meet patient demand. It is of desperate interest to know why health care for this vulnerable group of children is so sparse and extensive investigation is crucial to identify the issues and, as a consequence rectify the situation.
Another worrying outcome of the study was the high number of children on analgesics (76%) without an evidence based indication for the analgesic used in 43%; that is a total of 33% of the sample taking analgesics without indication. This suggests medication use was inadequate for a sizable number of children. Misuse of analgesics may have detrimental effects such as the exacerbation of pain and disability caused by analgesic rebound headache following the overuse of analgesics in children with chronic headache [41
Results of this study have to be seen in the light of some limitations. First, this study has the standard limitations of any retrospective analysis and any findings of significance can only reflect a correlation not a causal relationship. Second, the described sample aims to reflect the characteristics of children with a severe chronic pain condition, in keeping with referrals to a tertiary center. However, it is probable that not all children who could have benefited from involvement with the service during the study period were seen due to certain restrictions such as financial or distance barriers [42
] or, indeed, inadequate referral patterns. And last, it has to be noted that parent proxy reports for pain characteristics were used in case of missing child report. Data for this study was gathered retrospectively from the clinical letters, where missing values from children are automatically replaced by parent reports. We examined the data of 529 children, who presented in the pain clinic between July 2009 and June 2010 (Wager et al., in prep.). In this subsample only 2% of missing child data on pain intensity was replaced by parent information.