The quality of life in Chinese juvenile idiopathic arthritis patients: psychometric properties of the pediatric quality of life inventor generic core scales and rheumatology module

Juvenile idiopathic arthritis (JIA) is a systemic chronic inflammatory disease occurred in children below 16 years, featured on chronic joint synovitis and extra articular organs’ damages. It is the most common type of rheumatic diseases in children with prevalence varies from 4.01 to 70 ‰ [1]. During the active period of JIA, children may suffer from high fever, general malaise, joint swelling and pain, and limited daily activities every day [2]. Although there are already great progress on the treatment of JIA in recent years, it is still a chronic persistent disease and have high recurrence rate, even in remission period it still needs drug maintenance therapy, and some severe cases cannot able to be cured. The pain, disability, psychological pressure and treatment discomfort caused by long-term joint and muscle damage all have impact on the physiological, psychological and self-awareness of patients [3, 4]. Some children are even out of school, depressed, and with declined social adaptability, all of which seriously affects their quality of life (QoL) [5]. So, for JIA patients, traditional evaluation indexes such as mortality, remission rate and effective rate cannot fully evaluate the effect of intervention measures, and cannot meet the new requirements of people for health. Therefore, the evaluation of QoL has become one of the indispensable evaluation contents in the study of chronic diseases such as rheumatism.

The QoL scale for JIA patients and related studies were very mature in many countries [3‐5], but there are few researches on that in China. The Pediatric Quality of Life Inventory (Peds QL) developed by Varni contains a series of scales and is the most widely used scale for children's QoL until now. Among which, the PedsQL4.0 Generic Core Scales (PedsQL 4.0-GC) can be applied to all children, and the PedsQL3.0 Rheumatology Module (PedsQL3.0-RM) was specifically tailored for pediatric rheumatology [6]. These two scales have both been translated into Chinese version [7, 8], but their application on JIA was hardly seen in China. So, in this study, we applied the Chinese version of PedsQL 4.0-GC and PedsQL3.0-RM, to evaluated the status and influencing factors of the QoL in Chinese JIA children, and explored the psychometric properties of these two scales in these children, and provide basis for further research and improvement on the QoL of JIA children.

A total of 180 JIA children (102 boys and 78 girls) aged 8 ~ 18 years participated in this survey. The general information such as age, onset age of disease, course and drug application was showed in Table 1.

The QoL of JIA children is worse than healthy children, and those in active period is significantly worse than those in remission period especially in dimensions of physiological function, school function and pain. In this study, the average score of PedsQL 4.0-GC scale is 82.85, the score of school function dimension is 74.28, which are lower than the scores of healthy children (87.36 and 81.29) in previous survey [11]. This is due to the impact of JIA on children's physical and psychosocial functions: the pain and different disability caused by JIA greatly limits children's daily activities, leading to their social activities decreased [12]; long-term therapy of immunosuppressant and glucocorticoid resulted in growth retardation, changes of children’s face and body shape, all of these induced a series of negative emotions such as inferiority, anxiety and depression [13]. Also, it may lead to memory decline and attention loss, seriously affect patients' academic performance and even lead to children dropping out of school. A global multicenter cohort study also found that the QoL of JIA children was significantly reduced especially the physical dimension, disability and pain were the most important factors affecting the physical dimension and psychosocial dimension respectively [14], and serious activity of JIA was the risk factor for poor QoL of children [15]. Feng's research also confirmed that the most important factors affecting the QoL of JIA children are physical pain and high-intensity exercise restriction, and the QoL damage is more serious in the active period of disease, which is consistent with clinical observation and previous studies [16‐18].

The type of disease also can affect the QoL of JIA children. The QoL of patients in Oligoarticular type is the best, followed by patients in Polyarticular type, and those in systemic type is the worst. Table 3 showed that, the scores of PedsQL 4.0-GC and PedsQL3.0-RM scale in systemic JIA were 77.05 and 89.41, which were significantly lower than that of Oligoarticular JIA (87.12 and 93.71), and there were all significant differences between three types in five dimensions of physiological function, social interaction, school, treatment and communication. Bouchra amine also confirmed that compared with polyarticular and systemic JIA, the Oligoarticular JIA patients has better motor function, less psychosocial dysfunction and clinical symptoms, so their QoL were significantly better than other types [19]. The possible reasons are patients in polyarticular and systemic type suffered from more joints and systemic symptoms, which lead to limb pain, limited activity and reduced social participation. In addition, pain, rigidity and fatigue are the main reasons affect children's enrollment rate and social activity participation [12], and all these factors lead to a significant reduction in the QoL of children in systemic JIA.

For children with older onset age of JIA, their QoL were better than those with younger onset age. This is confirmed by the fact that the QoL score of children with onset age older than 12 years are significantly higher than other groups (Figs. 1, 2), suggesting that the younger the onset age is, the worse the prognosis of JIA and their QoL. There are inconsistent conclusions about the effect of course on the QoL of JIA children. Some studies considered short course is a risk factor for poor QoL [20], while others found the longer course lead to the worse QoL [19]. Our study does not find the effect of course on QoL of JIA children. These different conclusions may affected by other confounding factor such as disease activity, disability degree and disease type. Another important factor is the large-scale use of biological agents in recent years, which greatly reduces the risk of children's disability and limited activity due to long course of disease, ensures children's participation in social activities, all above comprehensively improve the QoL of JIA patients. However, for early-onset systemic JIA, the disease recurrence rate is relatively high, so early diagnosis and treatment is still one of the most important measure to improve their long-term QoL [21].

The reliability and validity of PedsQL 4.0-GC and PedsQL3.0-RM scale for Chinese JIA patients are all satisfactory, so can be used in clinical and scientific evaluation. The Cronbach's αcoefficient of these two scales is both greater than 0.7, which suggest greater inter consistencies. In PedsQL 4.0-GC scale, the correlation coefficients of 18 items and their dimensions is greater than 0.7, the other 4 items is between 0.5 and 0.7, only one item "I lost three and dropped four" is 0.406. In PedsQL3.0-RM scale, the correlation coefficient of all items and their dimensions is greater than 0.5, which suggest a good validity. At the same time, more and more people believe that it is necessary to evaluate the QoL of JIA children. Besides pain and disability, many factors such as age, cognitive level, understanding of JIA, parents' attitudes, family’s financial burden, school and social’s support may all affect the QoL of JIA children. For example, the long course of disease, higher recurrences and the biological agents therapy have brought great economic burden to families and society (A study of 162 JIA children in Europe shows that the medical cost per person per year ranges from 18,913 to 36,396 Euro [22]), and children may attacked by feelings of inferiority and guilt, even close or abandon themselves and lost their labor force, which will lead to greater socio-economic loss. Therefore, we need a standardized evaluation tool to accurately evaluate the QoL of JIA children. According to the results, we can give psychological intervention, exercise, social support and other combined interventions, and provide a comprehensive, multidisciplinary and practical individualized treatment plan for every JIA children.

In conclusion, the QoL of JIA children in China is worse than their healthy peers, especially in physiological function and school function. The activity and type of JIA are important factors affecting those children’s QoL. The reliability and validity of PedsQL 4.0-GC and PedsQL3.0-RM scale in Chinese JIA children are satisfactory, and can be used in clinical and scientific research. This may help pediatric rheumatologist to pay more attention to the QoL of children when they treating their basic diseases, and provide basis for development of multi-disciplinary individual intervention programs in order to practical improve the QoL of JIA children in China.