The first aim of this survey was to provide data on intensity, frequency and localization of adolescent spinal pain as well as its consequences on daily life [9]. Pain intensity was reported on average as moderate, which is in line with former studies using the VAS for pain quantification [14,25], but higher than in a study that assessed pain intensity by six faces as suggested in the Young Spine Questionnaire [9] and rescaled it to a 0–10 scale [26]. Which of these two approaches to assess pain intensity in adolescents is preferable however needs further investigation as it might be dependent on age. Nevertheless, all these studies consistently found a linear relation between pain frequency and pain intensity [14,25,26]. In the present study, about one quarter of those adolescents with back pain indicated frequent pain of moderate or severe intensity, which is slightly more than in the study by Aartun et al. [26]. Although these results are not directly comparable due to methodological differences in the assessment of pain intensity (VAS versus faces) and pain frequency (one month versus one week recall period), these results indicate that about every fourth or fifth adolescent back problem might be serious. Additionally, the present study revealed that 13% of all participants, including the pain-free adolescents, suffered from pain in more than one spinal area. These adolescents also reported significantly higher pain intensity and pain frequency and undertook more changes in daily life than those who complained about pain in only one spinal area. These results indicate that adolescents who report pain in multiple areas should receive special attention as they may be at risk of developing a serious back problem in adulthood. This is supported by the findings of a review by Roth-Isigkeit [3] and is further supported by the finding of this study that sleep disorders are one of the predictors for pain in multiple spinal areas. Sleep disorders in childhood occur together with several psychiatric disorders, predict anxiety/depression disorders later in life [27] and are a feature of widespread pain [8]. The adolescents with pain in more than one spinal area might thus correspond to the ‘LBP and depression/anxiety disorders cluster’ by Beales et al. [8], which was characterized by increased probability for headaches and sleep disorders in addition to LBP. In the present study, sleep disorders co-existed, in tendency, with moderate or severe frequent pain. They were also a strong predictor for those adolescents who complained about frequent and at least moderate pain in more than one spinal area. In contrast, headache, particularly in combination with abdominal pain, emerged from this study as the main predictor for experiencing intense pain, while sleep disorders did not predict pain intensity. Similarly, moderate or severe, but occasional pain co-existed with headaches and abdominal pain, but not with sleep disorders. Thus, adolescents with intense, but only occasional pain might represent the ‘spinal cluster’ by Beales et al. [8], which was featured by a high probability of LBP and increased probability of headaches, but absence of sleep disorders. Although these clusters were defined for LBP only and their significance needs to be followed into adulthood, it might be hypothesized that adolescents of the ‘LBP and depression/anxiety disorders cluster’, in whom back pain represents a multidimensional health problem, should be carefully monitored.

Regarding pain frequency, parental back pain was, apart from age, the only significant risk factor for occasional back pain regardless of intensity and there was a tendency for it to co-exist with mild occasional back pain. Therefore the adolescents with mild occasional back pain might be regarded as healthy [7] and correspond to the ‘healthy individuals cluster’ in the study by Beales et al. [8]. While several studies reported spinal pain in at least one parent to be a risk factor for adolescent spinal pain [14,28], this study revealed that this applies only for the appearance of occasional, but not of frequent back pain. Thus, the impact of the parental role model seems to be of less importance than previously suggested. Frequent spinal pain was predicted, similarly to pain in more than one spinal area, by headache (particularly combined with abdominal pain) and with a tendency for sleep disorders. Interestingly, impaired single leg stance with closed eyes was a further predictor for frequent back pain. This parameter also emerged as the only physical parameter which distinguished pain-free adolescents from those with the more serious back problem (frequent and at least moderate pain in more than one spinal area). Reduced postural stability, predominantly with visual obstruction, has been shown in adults with LBP [21] and neck pain [29], regardless of pain duration. Reduced proprioceptive input due to neurological adaptations or acute pain inhibition was proposed as a possible explanation for this phenomenon [21]. About the causative factors for the observed deficiency in single leg stance in the present study can only be speculated. Neurological adaptations due to chronic pain are less probable in adolescents, and acute pain (point prevalence) was not asked for. Reduced balance control, mainly in visual and somatosensory conflict situations, was reported in adolescent with idiopathic scoliosis at the disease onset [30]. Alternatively, the observed impairment in single leg stance could be an indicator of a general coordinative clumsiness. Regardless of etiology, the importance of balance deficits under visual restriction for the development of back problems in adolescence needs further investigation. Furthermore, the reliability of the chosen balance test needs to be determined in adolescents and the center of pressure sway should be measured in those adolescents with severe and frequent pain in more than one spinal area.

Regardless of pain localization, pain intensity increased in parallel with pain frequency and was the only predictor of whether the experience of spinal pain had an impact on the adolescents’ daily life. This corroborates the finding that for adolescent pain in general, pain intensity is the most robust predictor for functional impairment [31]. Furthermore, changes in daily life might indeed be proxy measures for pain intensity [9]. However, whether they have, in combination with a measure for pain intensity, the potential to distinguish between trivial and significant pain as suggested in literature [9], remains debatable. Based on the results of this study, data on pain intensity need to be complemented by data on pain frequency and pain localization in order to give a comprehensive picture of the severity of an adolescent back problem. Milanese and Grimmer identified in their review three categories of LBP in literature, namely general LBP (no characterization of LBP), chronic/recurrent LBP (characterized by a measure of recurrence) and severe/disabling LBP (characterized by a measure of severity), that might have different risk factors [32]. The results of this study suggest that these categories also need to be studied in combination. In terms of the description of adolescent spinal pain in general, particularly pain localization in more than one spinal area should be recorded.

Limitations

The main limitation of the present study was that it used a non-validated questionnaire. The ‘Young Spine Questionnaire’ (YSQ), which has meanwhile been developed [9], has so far been tested on children in the age of 9 to 11 years and is available only in English and Danish. Therefore, it was not chosen for this study. However, the composition of the questionnaire used in this study was similar in terms of dividing the three spinal regions neck, mid back and lower back and illustrating them by means of a manikin. The main differences were that the YSQ asked for the 1-week period prevalence, whereas the present study used the 1-month period prevalence as recommended by other studies [7,11]. Nevertheless, to compare results, the 1-week period prevalence may be used in the future. Furthermore, similar to the YSQ, the questionnaire should include a question on point prevalence (pain today). A second major limitation was that the participants were volunteers, which implies a selection bias. Therefore, the results of the study may not be generalized to the whole Swiss adolescent population. Furthermore, although the total number of participants was high, the sample size of some categories became rather small, which might have increased the risk for not detecting some associations (type II error).