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Three Part Question

In [children with Down's syndrome] is [pulse oximetry effective in diagnosing obstructive sleep apnoea] when compared with [polysomnography]?

Clinical Scenario

In community paediatric clinic you review a 4 year old boy with Down’s syndrome with attention difficulties. Parents report no concern with his sleep. At a recent meeting you remember a respiratory physician discussing screening for OSA in children with Down’s syndrome. Polysomnography is difficult to access in your area, you wonder whether overnight pulse oximetry would be an appropriate alternative.

You realise you require three main questions answered:
1. What is the baseline prevalence of OSA in children with Down’s syndrome?
2. How accurate is pulse oximetry in diagnosing OSA in children with Down’s syndrome?
3. What is the post-test probability of OSA using pulse oximetry in my patient with Down’s syndrome?

Search Strategy

Medline (clinical queries)



1. child down syndrome AND sleep apnea: 116 studies
Those studies that were recruited from sleep investigation centres were dismissed.

2. pulse oximetry AND sleep apnea children AND Down syndrome (diagnosis) = 4

pulse oximetry AND sleep apnea children (diagnosis) = 161

Search Outcome

1. This search strategy retrieved a total of 116 articles, of which 6 were appropriate.

2. This search strategy retrieved a total of 165 articles, 1 of which was identified as able to answer the question of how accurate pulse oximetry was in all children, not specifically children with Down’s syndrome.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Ng DK et al. Obstructive sleep apnoea in children with Down syndrome. Singapore Med J. 2006 Sep;4 2006 Singapore	22 children with Down’s syndrome (mean age 10 +/- 5.9) recruited Down’s Syndrome Association matched with controls with habitual snoring referred to sleep disorder service	Case-control	Detailed clinical evaluation overnight polysomnography (PSG).	Prevalence of OSA was 59% in children with Down’s syndrome. 40% of these children were asymptomatic	potential selection bias
de Miguel-Diez J, Villa-Asensi JR, Alvarez-Sala JL. 2003 Spain	108 consecutive unselected children with Down’s syndrome (mean age, 7.9 years; range, 1-18 years)	Case-control	1.History and physical examination 2.Lateral radiographs of the nasopharynx 3.Overnight cardiorespiratory polygraphy	Prevalence of sleep-disordered breathing was 54.6%
Dahlqvist A, Rask E, Rosenqvist CJ, Sahlin C, Franklin KA. 2003 Sweden	21 children with Down’s syndrome from a geographically defined area were invited aged 2-10, with their siblings acting as controls. 17/21 Down’s syndrome and 21 controls completed the study.	Population based study: case control	1. Overnight polysomnography 2. Echocardiography	No increase in rate of OSA in Down’s syndrome when compared with controls. Snoring, restless sleep and hypertrophy of the tonsils were common among children with Down's syndrome but not OSA.
Dyken ME, Lin-Dyken DC, Poulton S, Zimmerman MB, Sedars E. 2003 United States	19 children with Down’s syndrome who were seen for routine developmental assessment. Mean age 9.1yrs +/- 4.7	Case control	1. Standard overnight polysomnography.	Prevalence of OSA was 79%
Marcus C, Keens T, Bautista D, et al. 1991 United States	53 children recruited from Down’s syndrome parents association and specialty clinics including 17 referred by physician for clinically suspected OSA . Mean age 7.4 +/- 1.2 years	Case-control	1.Parental history 2. All had 1-2 hr nap polysomnography 3. 16 children had night-time polysomnography	Prevalence of obstructive sleep apnoea was 45%. Nap studies were found to underestimate abnormalities compared to overnight studies Parental history alone was not a significant test for OSA	Possible selection bias
Stebbens VA, Dennis J, Samuels MP, Croft CB, Southall DP. 1991 United Kingdom	36 children with Down's syndrome under the age of 5 from a geographically defined area invited. 34/36 completed study. Median age 1.4	Case-control	1.Parental questionnaire 2.Overnight tape recordings of arterial oxygen saturation (Sao2) and breathing movement 3.Clinical assessment	Prevalence of upper airway obstruction was 31%
Brouillette RT, Hanson D, David R, et al. 1984	349 children between the ages of 6 months and 18 years who were referred to their sleep laboratory with suspected OSA. Six out of the total population had Down’s syndrome. The overall pre-test probability of this population was 60%, the incidence of OSA in the study population.	case-control	1. polysomnography 2. pulse oximetry	The results confirm that pulse oximetry is highly specific (97%) and most useful when it is positive. The sensitivity is relatively low (43%) which means that a negative test does not effectively rule out OSA – not ideal in a screening test. The likelihood ratio for a positive test was 19.4; a negative test 0.58.

Comment(s)

OSA is common in children with Down’s syndrome and the complications of undiagnosed and unmanaged are significant, potentially affecting the child’s general health and developmental potential. The challenge to clinical practice is finding a safe, cost-effective method of assessing children with Down’s syndrome. Polysomnography is the gold standard for diagnosing OSA but is time-consuming, expensive and often not accessible. Pulse oximetry has many benefits, including reduced cost and potential for home monitoring. However while oximetry is useful when positive in confirming OSA in the general childhood population, a negative oximetry result cannot be used to rule out OSA therefore limiting its role in screening for OSA.

Clinical Bottom Line

Clinical bottom-line: • Obstructive sleep apnoea is common in children with Down syndrome with estimated prevalence between 31-79% • Polysomnography is the gold standard for diagnosing OSA • Positive pulse oximetry increases the probability of OSA to ~ 90% • Negative pulse oximetry decreases the probability of OSA to ~ 40%

References

1. Ng DK et al. Obstructive sleep apnoea in children with Down syndrome. Singapore Med J. 2006 Sep;47(9):774-9
2. de Miguel-Diez J, Villa-Asensi JR, Alvarez-Sala JL. Prevalence of sleep-disordered breathing in children with Down syndrome: polygraphic findings in 108 children. Sleep 2003;26:1006-9.
3. Dahlqvist A, Rask E, Rosenqvist CJ, Sahlin C, Franklin KA. Sleep apnea and Down's syndrome. Acta Oto-Laryngologica. 2003;123:1094-7.
4. Dyken ME, Lin-Dyken DC, Poulton S, Zimmerman MB, Sedars E. Prospective polysomnographic analysis of obstructive sleep apnea in Down syndrome. Arch Pediatr Adol Med. 2003;157:655-60.
5. Marcus C, Keens T, Bautista D, et al. Obstructive sleep apnea in children with Down syndrome. Pediatrics. 1991;88:132.
6. Stebbens VA, Dennis J, Samuels MP, Croft CB, Southall DP. Sleep-related upper airway obstruction in a cohort with Down’s syndrome. Arch Dis Child 1991; 66: 1333–8.
7. Brouillette RT, Hanson D, David R, et al. A diagnostic approach to suspected obstructive sleep apnoea in children. J Pediatr. 1984;105:10-14