The main finding was that pain was present in almost all children, regardless of OI-type, sex, and age group. In addition, pain interfered in children’s everyday life, which was associated with children’s self-perceived health status.
Almost all children reported presence of pain and the intensity was consistent with previous studies including children with OI [19, 20]. However, many children with OI have experienced pain from an early age and might have adjusted their life by avoiding activities in order to reduce pain or have adapted to a certain level of chronic pain, and therefore some children might have underestimated their level of pain . Children reported presence of pain several times per week. The findings are in line with results from the UK, where a random sample of 35 children with OI, aged 5–18 years was included . Concerning pain location, the present study showed that the back and feet were most common. Zack et al. also described the back as the most common location, together with the chin and front of the thighs . In the present study children reported the probable causes of pain, of which the most frequent were walking long distances, followed by walking, exercise, football, jumping and after injuries. However, many children further explained that prolonged sedentary positions caused pain. Confirming results were reported by Zack and colleagues, where 43% of the participants described minor traumas, recent exercise, or prolonged poor positions as painful situations . In the present study, pain interfered in children’s everyday lives, and affected participation in various activities. Since physical activity is a key factor for decreasing bone resorption and rebuilding bone mass, this information is essential. If children avoid physical activities because of fear of pain, or due to pain, it might cause a vicious circle of inactivity, which further decreases bone density and increase the risk of fractures, additional pain and further inactivity [13, 22].
Many children reported pain interference during sleep, which has been described earlier in an integrative review concerning pain experiences in children and adolescents with OI . Zack et al. reported that the impact of pain was most frequent in participants when they were trying to fall sleep . Altogether, these results indicate that sleep is a topic that should be further investigated, since sleep deprivation affects school performance, emotional status, relationships, and by increase the pain experience itself [5, 23, 24].
In our sample, pain interference during schoolwork was associated with anxiety, depressive symptoms, fatigue, and less social support from friends. Confirmatory results were described from the UK . The frequency of children reporting school absence due to pain was high in our group of children. Many previous studies have used “school absence”, to evaluate children´s ability to participate in school-related activities, since they are considered to be the most important activities for children, due to social, cognitive, emotional, and physical aspects .
Self-perceived health status was investigated, and mobility was reduced in the total sample, and the lowest mobility was detected in children with type III, while a positive trend was that many children reported results similar to the general population in other domains, findings consistent with previous research [26, 27]. Confirming results were also presented in a review concerning QoL in children and adults with OI, where the authors concluded that physical QoL appeared to be lower than in the general population, while the mental and psychosocial QoL was equal or better . Both low physical and social scores in HRQoL were detected in a Brazilian prospective cross-sectional study, including 52 children and adolescents with OI, aged 5–17 years; however, significant differences were detected between the OI types . A lower HRQoL in children with OI than children in the general population, and especially those with severe OI-types, was reported in a Chinese cross-sectional study, including 138 children with OI, aged 2–18 years . No difference between sexes was found in the present study, which could imply that the self-perceived health status might be similar for boys and girls within the Swedish OI population, a finding consistent with the Chinese study . In our group of children, a high correlation was detected between children’s self-perceived health status and pain interference in everyday life, a discovery emphasising the importance of finding optimal possibilities for treatments. The results are in line with previous research .
A limitation in this study was the small sample included, and a reason is that at our clinic a high number of children are below the age of six years, and in addition small sample is to be expected in single-site studies of children with rare diseases . A further limitation was the use of the five structured questions in the interview, that had not previously undergone psychometric testing. A strength was that the representation of OI-types was consistent with the prevalence in the Swedish population . Further strengths were that only one child declined to participate, that the response rate in the questionnaires was high, and that the same researcher (KL) conducted all interviews. The use of PII, a psychometric tested index, considered as an adequate tool to assess pain interference in children and adolescents, was a further strength . Another strength was the use of PROMIS-25, since it offers possibilities for comparison with the general population.
In conclusion almost all children experienced pain, which interfered in children’s everyday lives, affected participation in various activities and was associated with reduced self-perceived health status. If children avoid physical activities because of pain, it might cause a vicious circle of inactivity, which further decreases bone density and increase the risk of fractures. The results emphasize the importance to offer adequate pain reducing interventions.