Validation of Sleep Questionnaires in the Down Syndrome Population

Specific Aims:

1. Demonstrate the criterion validity of the Sleep-Related Breathing Disorder subscale of the PSQ as a screening tool for the diagnosis of OSA in children with Down Syndrome, using polysomnography as the gold standard.

Hypothesis: Compared to the published threshold for a positive screen in the general pediatric population (≥ 7 of 22 positive responses), the threshold for a positive screen that corresponds to an optimal sensitivity and specificity in the Down syndrome population will be significantly different.

2. Demonstrate the construct validity of the OSA-18 as a scale to assess sleep-related quality of life in children with Down Syndrome by comparing OSA-18 scores to an objective measure of disease burden (polysomnography) and a generic quality of life instrument (the Pediatric Quality of Life inventory, PedsQL).

Hypothesis: OSA-18 scores will be significantly associated with the Apnea-Hypopnea Index assessed by polysomnography and the PedsQL Total Score, Physical Health, and Psychosocial Health summary scores.

Background:

1. Obstructive Sleep Apnea and Down Syndrome: Obstructive sleep apnea (OSA) affects 1-5% of children in the US and has been associated with a myriad of health consequences including cardiovascular complications, behavioral disturbances, and neurocognitive dysfunction. In contrast, there is a reported OSA prevalence of 31-79% in children with Down Syndrome due to traits that predispose to OSA including hypotonia, obesity, and craniofacial anatomy such as midfacial and mandibular hypoplasia which can lead to pharyngeal crowding. With increased risk of congenital cardiovascular defects in the Down Syndrome population, it is possible that these children are also at risk of the most serious complications of OSA including pulmonary hypertension.

OSA has also been shown to have a significant impact on quality of life. Behavioral problems associated with OSA include reduced attention, hyperactivity, irritability and problems with peers. Previous studies in the general pediatric population have shown similar quality of life scores in children with symptoms of OSA as children with asthma and rheumatoid arthritis. In children with Down syndrome, reduced sleep has been associated with reduced cognitive function, memory, poor communication skills, and poor self-help skills. Furthermore, parents of children with sleep disordered breathing often suffer from sleep deprivation themselves which can result in negative impacts on family life, decreased ability to care for their children and higher levels of maternal stress.

2. Subjective Measures of Sleep Disordered Breathing and Obstructive Sleep Apnea: Overnight polysomnography (PSG) is the gold standard for diagnosing OSA in children. However, due to cost and inconvenience, only a minority of patients being evaluated for OSA undergo PSG prior to adenotonsillectomy. One survey study conducted among pediatric otolaryngologists showed that 31% of respondents said they referred children suspected of OSA for PSG "rarely" or "never." In a separate study, 75% of pediatric otolaryngologists surveyed referred for PSG in less than 10% of children with suspected OSA. Commonly cited factors for this include cost of obtaining PSG and delay in obtaining PSG due to availability. In addition, a substantial proportion of patients referred for PSG are either lost to follow-up or experience significant delays in treatment due to testing. As a result, alternative methods of screening for or diagnosing OSA have been explored that are cheaper and less burdensome. This includes a variety of questionnaires that were designed to screen the pediatric population for symptoms of sleep disordered-breathing (SDB) and assess its impact on quality of life within a clinic setting. The Sleep-Related Breathing Disorders subscale of the Pediatric Sleep Questionnaire (SRBD-PSQ) was developed to screen for SDB using 3 categories: daytime sleepiness, snoring, and behavioral disturbances.3 This has previously been validated in children aged 2-18 within the general pediatric population. The OSA-18 is a survey that measures the impact of SDB or OSA on disease-specific quality of life in children by assessing common manifestations of the disease including sleep disturbance, emotional distress, daytime function, and caregiver concerns. This questionnaire has been validated in children ages 6 months to 12 years. Validated subjective measures like these capture different aspects of the disease experience than objective measures like PSG. They can also be used to assess large numbers of patients with far less burden and expense than PSG which frequently has long wait times due to limited capacity.

3. No Validated Screening instruments or OSA-related QOL measures in Down Syndrome: Despite the high prevalence of OSA in the Down syndrome population and the availability of widely used questionnaires for SDB, screening for SDB is generally inconsistent in this population. Even when parental report of symptoms of SDB is solicited, multiple studies have demonstrated poor diagnostic accuracy of parental history compared to PSG. A recent study investigating parental assessment of the symptoms of SDB found that 66% of Down syndrome patients had frequent symptoms consistent with SDB including snoring, witnessed apnea, and restless sleep. However, there was no association between the frequency of these symptoms and diagnosis with OSA. Other studies have similarly demonstrated poor diagnostic accuracy of parental history with respect to PSG findings. For this reason, the most recent American Academy of Pediatrics (AAP) guideline regarding management of Down syndrome patients has recommended routine screening for OSA using PSG in all patients by the age of 4, regardless of symptomatology. There are currently no validated instruments for screening for OSA or assessing OSA-related quality of life in the Down syndrome population.