HRQOL in patients with a spine deformity decreased for several reasons, especially in adolescents [14, 15]. For example, AIS can lead to physical, psychological, and social impairments that eventually impact HRQOL . Besides, conservative treatment of scoliosis with a rigid brace can be harmful to affect their QOL .
In this study, patients in the brace-treated group took X-rays both with and without the brace. We measured Cobb angle from X-rays without the brace, and strictly chose patients with Cobb angle ranging between 20 and 40 degrees, making the sample included in the study fitted the indications for braces for AIS. When evaluating the effect of brace treatment, the changes in the radiologic measurements and in the QOL must be considered . In turn, QOL is closely related to patients’ compliance with brace treatment and depends on the conservative treatment effect [17, 18].
ISYQOL questionnaire designed to evaluate the HRQOL of adolescents with idiopathic scoliosis. Some papers perceived the need to use a disease-specific questionnaire Instead of a generic questionnaire [19,20,21]. From the total questionnaire score, 0 % of patients scored at the floor and 0 % scored at the ceiling, showing no floor and ceiling effects.
Cronbach’s alpha is the most commonly applied statistical parameter for showing the internal consistency of an instrument . The SC-ISYQOL had a high value of Cronbach’s alpha coefficient (0.88 and 0.75), both the brace-treated and the no-treated groups, exceeding the minimum recommended value of 0.70 and indicating satisfactory internal consistency as a factor of acceptable reliability of the SC-ISYQOL.
Intraclass correlation coefficients(ICC)of the SC-ISYQOL assessed using of the test–retest method was 0.72 in the no-treated group and 0.80 in the brace-treated group, showing good temporal stability.
There are some questions designed for wearing the brace in the ISYQOL questionnaire. ISYQOL measure can convert scores to standard measurement, which is used to compare the total score of the no-treated and the brace-treated groups. It is suitable for evaluating the changes of HRQOL before and after brace treatment.
Criterion validity is the correlation of a scale with a valid, accepted universally acknowledged measure of the trait or disorder under study. The outcome measures for construct validity adopted the SRS-22, most widely used as a reference standard in the past, to evaluate the relationship with another patient-oriented questionnaire not focused on brace therapy. The results of the current study showed that a strong relationship existed between the ISYQOL measure and SRS-22 scores (rho = 0.62; p < 0.01), reflecting the high validity of the questionnaires. And get the same strong relationship in every subgroup (p < 0.01). This relationship was also found in the study by Caronni al. , with rho = 0.71 and p < 0 0.01.
There is no difference in HRQOL between the brace-treated group and the no-treated group, whether through the ISYQOL or the SRS-22. Earlier reports reported that braces affecting HRQOL may occur due to factors such as stiffness of brace , but it did not appear in this study. That may be related to the new-design brace applied in the hospital. The brace is light and custom-made by 3D printing, having good fit and comfort. No difference may also due to part-time brave wearing (16 h per day on average). Although the impact of the brace on HRQOL is dose-independent, other influencing factors (such as avoiding school wearing) mixed, so the conclusion cannot be drawn. Caution in the interpretation is needed. That is a cross-sectional study with a different sample of the 2 groups. This view needs to be followed up and compared by the same person’s QOL score before and after brace treatment. Perhaps the daily wear time is long enough, and the patient’s adaptation and acceptance of the brace will increase. It also needs to be confirmed by further research. There was also no statistical difference in gender and age, which may be related to the consistent disease situation.
The advantage to using the ISYQOL instead of SRS-22 or other questionnaires is that it included specific questions targeting patients who were using the brace . In that way, the questionnaire is more targeted and individual. Thanks to the Rasch analysis, it is possible to compare the ISYQOL measure with other questionnaire scores even if they are different . ISYQOL measure also used to compare the HRQOL of patients before and after using the brace, which is not in other questionnaires targeted to patients wearing the brace .
The weakness of ISYQOL is that it is not as widespread as the former questionnaires. There are limited versions in different languages and has not confirmed in a wide range of population .
In our study, there are limitations, such as the single clinical center available in the cross-cultural adaptation process. Further test will evaluate the reliability, construct validity, and responsiveness in the Rasch framework. The ISYQOL questionnaire needs to be promoted and applied in clinical and research, and multi-center cooperation has been obtained for further confirmation.