Walking capacity and its association with quality of life among children with down syndrome in Saudi Arabia

For this cross-sectional study, we recruited Arabic-speaking children aged 6–12 years using a convenience sampling method from August to November 2021. After sending the participants an invitation letter outlining the purpose of the study, we accepted children with parents or guardians who voluntarily agreed to have them participate. All children were divided into two groups: those who do not have Down syndrome (n = 38) and those who have Down syndrome (n = 30). The group who did not have Down syndrome consisted of 38 children of the same age with no medical issues or recent injuries recruited from two randomly selected local schools. The other group included 30 children who have Down syndrome, who were recruited from randomly selected various associations and organizations in Riyadh, Saudi Arabia. The numerous organizations included the King Khalid University Hospital, the Saudi Association for Special Education, the Efada Center for Down Syndrome, the National Center for Early Intervention, and support groups for families and children who have Down syndrome.

We selected children for recruitment from Riyadh because it is one of Saudi Arabia’s major cities and has a population that is typical of the country’s cities in terms of socioeconomic diversity. Children who have Down syndrome were excluded if they had undergone any lower limb surgery in the past, used a walking aid, had moderate to severe cardiac problems, or had any other condition or injury that might have affected their physical function (such as cerebral palsy). Children from both groups were excluded from the study if they did not complete the accelerometer-wearing period [16].

The 6-Minute Walk Test (6MWT) was utilized to evaluate each child’s walking capacity. It is a practical test that measures a person’s walk distance in six minutes and is used to evaluate functional exercise capacity in several cardiopulmonary conditions, including Down syndrome [17]. This test, which also serves as a predictor of morbidity and death, has been widely employed in rehabilitation programs to assess walking capacity [18]. The 6MWT was carried out over a minimum of a 12-meter-long open area, including corridors and the schoolyard, following defined procedures [19] and wheel-measuring equipment protocols [20]. Before beginning the 6MWT, the participants rested for 10 min. The researcher then took their vital signs to rule out any conditions that may make the 6MWT hazardous, such as a heart rate > 120 beats per minute, blood pressure > 180 mm Hg +/− diastolic 100, or oxygen saturation > 85% [17]. Pulse oximetry was used to measure heart rate and blood oxygen saturation [21]. In pediatrics, blood pressure is measured with a digital arm sphygmomanometer [22].

The children and their parents were instructed to sit on a chair with a back and armrests. The arm used to take the measurement was supported at the sternum. Along the walking course, a measuring tape with a cone at each end (to indicate the turning point) was set up at 1-meter intervals. The participants were instructed to move around these cones as naturally and easily as possible. Throughout the exam, the researcher followed each individual closely and recorded each round that was completed. After the test session, the data were reported to the nearest meter. A stopwatch and trundle wheel were used for this test to measure the distance traveled. The 6MWT is a reliable and valid test with an interclass correlation coefficient of 0.84 for individuals with Down syndrome [17].

The Pediatric Quality of Life (PedsQL) inventory scale [23], which has an Arabic translation, was used to assess how a child or parent perceived the quality of their child’s life on four general core scales (domains): physical functioning (PF, 8 items), emotional functioning (EF, 5 items), social functioning (SF, 5 items), and school functioning (ScF, 5 items). There are two Arabic versions of the PedsQL for children aged 5–7 [24] and 8 or 12 years old [23]. Each version contained two sections: one to be completed by the child (in a parallel child self-report format) and the other by the child’s parents (in a parent proxy report format). In both groups, each child was represented in this study by their parents.

There were some minor differences between the versions and sections. The version for children aged 5‒7 years has three choices for each item, where the answer represents 4 (“almost always”), 2 (“sometimes”), and 0 (“not at all”). The other versions have five choices for each item (0 = “never a problem,” 1 = “almost never a problem,” 2 = “sometimes a problem,” 3 = “often a problem,” and 4 = “almost always a problem”). In addition, there is a difference in the simplicity of wording to suit the target age group, despite the similarity of meaning between them. The results of both versions are converted to a score of 0–100. The score for each domain is calculated using the following formula: the sum of the items is divided by the number of items answered by the participant. The overall quality of life score is calculated by summing all the items reported in all domains, where 100 represents the best quality of life. The quality of life scores (PedsQL) were categorized into three groups: worst (< 0.50), moderate (0.50‒0.80), and high (> 0.80) [25]. The PedsQL scale is a reliable (good internal consistency of alpha = 0.9) and valid (Spearman’s rho range between 0.27 and 0.70) instrument for assessing the quality of life of children with Down syndrome [26].

The researcher used a screening sheet to gather demographic data. The child’s weight was determined while they were wearing minimal clothing and no shoes. The Eufy Body Sense Smart Scale was used twice to measure the weight to the closest 0.1 kg. With the headset in the Frankfurt plane and heels firmly planted against a wall, height was measured twice and recorded to the nearest 0.1 cm using a wall-mounted stadiometer. Weight in kg divided by height squared (m²) is the formula for calculating body mass index (BMI).

Using the G*POWER statistical software (version 3.1.9.4; Universitat Kiel, Germany), the minimum required sample size was determined to be 70 children (35 for each group), with a medium effect size of 0.5 (based on Cohen’s d) and a significance level of 0.05. and a power level of 0.80, with the addition of 10% to account for the likelihood of drop-off [27].

The Kolmogorov–Smirnov test was used to determine the normality of the continuous variables [28]. The participants’ sociodemographic and anthropometric characteristics were summarized using means and standard deviations for continuous data, while frequencies and percentages were used for categorical data. Significance differences between groups (those who have and those who do not have Down syndrome) were examined using the chi-squared test for categorical data and the independent t-test, analysis of variance, and post hoc test for continuous data.

The difference in 6MWT scores between children who have and who do not have Down syndrome was assessed using an independent t-test. The Pearson correlation coefficient was used to examine the correlations and collinearity of age, height, weight, and BMI with quality of life, PF, EF, SF, and ScF. The correlation coefficient scores were defined as high (> 0.70), moderate (0.50–0.69), low (0.30–0.49), and negligible (< 0.30) [29].

The Declaration of Helsinki’s principles guided the conduct of this study. The King Saud University College of Medicine’s ethical committee approved this study (No. 20/0673). Before collecting data, each eligible child and their parent or legal guardian signed an informed consent form regarding their participation.