Design
This is an explorative and descriptive study with a cross-sectional design. The study was approved by the Regional Ethics Committee for Medical Research (Dnr 2018/175-31) in accordance with the Helsinki declaration [21].
Participants and procedure
A consecutive sample of Swedish-speaking parents of children between 3 and 10 years old with no major health problems were asked to participate when visiting child health care centres and public dental services for the child’s regular health check-up. To achieve a representative population, we selected health care centres and public dental clinics with catchment areas from large cities as well as small towns at the countryside in two regions in South Eastern Sweden. It is not known how many parents the staff excluded due to language difficulties or health problems or how many parents declined to participate. After providing informed consent, the parents answered the Pediatric Insomnia Severity Index (PISI) and KIDSCREEN-27 proxy version for their children. In cases where the parent had more than one child between 3 and 10 years old, they were asked to fill out the questionnaires for the siblings as well. The coded, completed forms were placed in a postage-paid envelope and returned to the authors. Data were collected between September 2018 and January 2019.
Measurements
Sleep was estimated by the six-item Swedish version of the PISI, a parent-proxy questionnaire for children between 3 and 10 years old. The items follow the ICSD-II general criteria for insomnia, including difficulties falling asleep, difficulties maintaining sleep, and daytime impairment. Five of the items are scored on a six-point Likert-type scale (0 = never, 5 = always), and total hours of sleep on most nights are rated on a six-point scale (0 = 11–13 hours, 5 = less than 5 hours). Higher values indicate more sleep problems. The questionnaire refers to the children´s sleep over the last week and consists of two dimensions of sleep difficulties: sleep onset problems (SOP) and sleep maintenance problems (SMP). The PISI is validity and reliability tested with good results for brief screening of insomnia [22,23]. The validity and reliability test of the Swedish version of PISI was calculated on this sample with good results and have been formerly presented in Angelhoff et al. [23].
To measure various aspects of HRQoL in healthy children, we sought a general HRQoL instrument available in the Swedish language, with a reasonable number of items with a salutogenetic perspective, developed in accordance with the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) Patient Reported Outcomes (PRO) Good Research Practices Task Force Report (25,25). KIDSCREEN-27 was developed as a self-report measurement applicable for healthy and chronically ill children and adolescents aged from 8 to 18 years in an intercountry collaboration network including 13 European countries; created after literature reviews, consultations with experts, and discussions in focus groups with children, and thereafter adjusted and tested as a proxy-version [26-28]. According to the developers of KIDSCREEN-27, obtaining responses via self-reports may not be practicable in very young children, but HRQoL may be ascertained via proxy reports [26]. Therefore, the proxy-version of KIDSCREEN-27 was considered to be appropriate for this study of children 3-10 years old.
The 27 items are scored on a five-point Likert-type scale (1 = no agreement at all, 5 = total agreement). The generic questionnaire includes five dimensions of HRQoL: physical well-being (level of physical activity, energy, and fitness), psychological well-being (positive emotions and satisfaction with life), autonomy and parent relation (perceived level of autonomy, interaction between child and parent, and feeling loved and supported), social support and peers (interaction between child and peers), and school environment (perception of cognitive capacity, learning, concentration, and feelings about school). The questions refer to the children´s HRQoL over the last week. Higher values indicate better HRQoL, and T-scores of 50 and SD ± 10 are regarded as normal. The measurement has acceptable reliability (Pearson´s r 0.61–0.74) and validity, as well as internal consistency (Cronbach’s α 0.79–0.84), in analyses including several European languages [27,28]. In this sample, Cronbach’s α was 0.94. Availability and permission to utilize the Swedish version of KIDSCREEN-27 was granted by the copyright holder [27].
Statistical analysis
Rasch measurement analysis was used for all five KIDSCREEN-27-dimensions and thereafter transformed to T-values, according to the manual [26]. Descriptive statistics are presented as means (m), standard deviations (SD), medians, interquartile range (Q1, Q3), frequencies (n), and percentage (%). Nonparametric tests were used, as both the PISI and KIDSCREEN-27 include qualitative variables. The Mann–Whitney U-test was performed to calculate differences between genders. Spearman’s rho (ρ) was used for comparison of dimensions of HRQoL and dimensions of sleep problems, gender, and age. A two-samples t-test was conducted to compare KIDSCREEN-27 between our sample and the European reference population, consisting of >8000 children 8-18 years old, used in Ravens-Sieberer et al. [27].
All reported p-values were two-sided, and a p-value of <0.05 was considered statistically significant. Data were processed using IBM SPSS statistics version 25.