Sleep Disordered Breathing in Early Childhood: Quality of Life for ...

SDB IN EARLY CHILDHOOD: QUALITY OF LIFE FOR CHILDREN AND FAMILIES http://dx.doi.org/10.5665/sleep.3116

Sleep Disordered Breathing in Early Childhood: Quality of Life for Children and Families Angela R. Jackman, PhD1; Sarah N. Biggs, PhD2; Lisa M. Walter, PhD2; Upeka S. Embuldeniya, DPsych2; Margot J. Davey, MBBS2,3; Gillian M. Nixon, MD2,3; Vicki Anderson, PhD1,4; John Trinder, PhD1; Rosemary S. C. Horne, PhD2 1 Melbourne School of Psychological Sciences, The University of Melbourne, Melbourne, Australia; 2The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Australia; 3Melbourne Children’s Sleep Centre, Monash Children’s, Monash Medical Centre, Melbourne, Australia; 4Critical Care and Neurosciences, Murdoch Children’s Research Institute, Melbourne, Australia

Objectives: To characterize health-related quality of life (QOL) in preschool children with sleep disordered breathing (SDB) and their families compared with nonsnoring control patients in the community. It was hypothesized that children with SDB and their families would have poorer QOL than control children, that a relationship would be found between SDB severity and QOL, and that even children with mild SDB and their families would have reduced QOL. Participants and Methods: A clinical sample of preschool children (3-5 y) with SDB diagnosed by gold standard polysomnography (primary snoring, PS = 56, mild obstructive sleep apnea, OSA = 35, moderate/severe OSA = 24) and control children recruited from the community (n = 38) were studied. Parents completed health-related QOL and parenting stress questionnaires. Results: Children and families in the PS and mild OSA groups had consistently poorer QOL than control children (both P < 0.05-0.001), based on parent ratings, and parents of children with PS had elevated stress ratings relative to control children (P < 0.05-0.001). The moderate/severe OSA group differed from the control group on select measures of parent and family QOL (worry, P < 0.001 and total family impact, P < 0.05). Conclusions: Our findings demonstrate that sleep disordered breathing is associated with reduced quality of life in preschool children and their families. These results support previous quality of life findings in older children and in samples with broader age ranges. Furthermore, clinically referred preschool children with mild forms of sleep disordered breathing may be at greatest risk. Keywords: Apnea, parenting stress, pediatrics, preschool children, quality of life, sleep, sleep disordered breathing, snoring Citation: Jackman AR; Biggs SN; Walter LM; Embuldeniya US; Davey MJ; Nixon GM; Anderson V; Trinder J; Horne RSC. Sleep disordered breathing in early childhood: quality of life for children and families. SLEEP 2013;36(11):1639-1646.

INTRODUCTION Snoring is very common in childhood, and is a symptom of obstructive sleep apnea (OSA), a condition characterized by snoring, apneas and/or hypopneas, hypoxia, hypercarbia, and/or frequent arousals from sleep. The spectrum from primary snoring (PS, snoring without gas exchange abnormality or sleep disruption) to severe OSA can be termed sleep disordered breathing (SDB). SDB is particularly prevalent during the preschool years1,2 and may affect up to one third of preschool children.1 Clear links have been established between pediatric SDB across wide age ranges and poor outcomes in a number of functional domains, including health-related quality of life (QOL).3-12 This association exists regardless of disease severity4,9,11-14 or the presence of obesity,9 and may persist even after the symptoms of SDB remit.6 SDB in children has also been associated with changes in parents’ emotional well-being and problems within the family.3,11,13 Despite the high prevalence of SDB during the preschool years and the developmentally vulnerable status of young children, few studies have described QOL specifically in preschoolaged children with snoring or SDB.5,15,16 Taken together, these

reports lack a focus on polysomnographically (PSG)-diagnosed SDB, comparison of affected children with control children, and substantial data regarding family effects. Such information would be highly valuable to clinicians making complex management decisions, which often relate to invasive surgical intervention. The current study aimed to characterize QOL in a clinical sample of preschool children with PSG-diagnosed SDB and their families. The hypotheses tested were that children with SDB and their families would have poorer QOL than nonsnoring control children and their families, and although a dose-response relationship would exist between SDB severity and QOL, even children with mild SDB and their families would have reduced QOL. METHODS This study was part of a larger project examining sleep quality, cardiovascular function, and neurobehavioral outcomes in preschool children with SDB. Sleep, cognitive, and behavioral data have been described previously.17-19 The Southern Health, Monash University, and University of Melbourne Human Research Ethics Committees provided ethical approval. Written informed consent was obtained from parents and informal oral assent was obtained from children.

Submitted for publication November, 2012 Submitted in final revised form March, 2013 Accepted for publication March, 2013 Address correspondence to: Professor Rosemary SC Horne, The Ritchie Centre, Level 5, Monash Medical Centre, 246 Clayton Road, Clayton, Victoria, Australia 3168, Tel: +61 3 9594 5100; Fax: +61 3 9594 6811; E-mail: [email protected] SLEEP, Vol. 36, No. 11, 2013

Participants A clinical sample of 3- to 5-year-old children was recruited from the Melbourne Children’s Sleep Centre between July 2008 and May 2011. Children had no comorbid conditions known to affect sleep, breathing (excluding asthma), or blood pressure, and were not taking medications known to affect sleep. 1639

Quality of Life in Snoring Preschool Children—Jackman et al

Nonsnoring control children age 3-5 y were recruited from the community during the same time period via poster and email advertisements at the participating hospital and universities, local day care centers and kindergartens, and other community publications. No financial incentive was provided for participation.

Item scores were linearly transformed to a scale of 0-100, with higher scores representing better QOL. Mean scores for four subscales and two summary scales (Psychosocial Health Summary Score, inclusive of emotional, social, and school functioning scales; and total score) were calculated, and agestandardized z-scores were derived using published normative data.30 This questionnaire has been previously used to assess QOL in children with SDB.9 The effects of children’s health on the QOL of their parents and families were assessed using the 36-item PedsQL™ 2.0 – Family Impact Module.31 Three summary scores are derived from eight subscales: Parent Health-Related Quality of Life (HRQOL; inclusive of physical, social, emotional, and cognitive functioning scales), family functioning (daily activities and family relationships scales), and total (all subscales). Item scores were transformed as for the PedsQL™ 4.0 Generic Core Scales. Raw scores were analyzed because age-standardized normative data were not available. The Parenting Stress Index, Third Edition–Short Form (PSI/ SF)32 parent report questionnaire is composed of 36 items that are summed into three subscales and a total stress score, with higher scores indicating greater stress. Raw scores were used for analyses because age group percentile conversions were not available.

Procedure All children underwent standard pediatric overnight clinical PSG. Medical histories were taken and physical examinations were conducted by pediatricians prior to PSG studies. Each child’s height and weight were measured and body mass index (BMI) z-scores were calculated.20 Parents (predominantly mothers) completed demographic and behavioral questionnaires on the night of the study. QOL and parenting stress questionnaires were completed by parents during home visits conducted 1 to 3 weeks after the PSG study, at which time cognitive assessments were performed.19 Sleep diaries were completed by parents during the week prior to each home visit. Measures Sleep Assessment

Full details of PSG parameters, sleep staging, and arousal and respiratory event scoring have been described previously.19 The obstructive apnea-hypopnea index (OAHI) was defined as the total number of obstructive and mixed apneas and obstructive hypopneas per hour of total sleep time (TST), and SDB severity was defined as: OAHI ≤ 1 event/h = PS; OAHI > 1- ≤ 5 events/h = mild OSA; OAHI > 5-10 events/h = moderate OSA; OAHI > 10 events/h = severe OSA.21 Moderate and severe OSA groups were subsequently collapsed into one moderate/severe (MS) OSA group. Control subjects had an OAHI ≤ 1, did not snore on the night of the study, and were not reported to snore by parents.

Statistical Procedure Statistical analyses were conducted using IBM® SPSS® Statistics, Version 20 (SPSS, Inc., Chicago, IL). Sex ratios were compared between diagnostic groups using the Pearson chi-square test. All other demographic, sleep, and respiratory variables were first tested for normality of distribution and homogeneity of variance. Group differences were tested using one-way analysis of variance with Tukey honestly significant difference post hoc tests (when normality assumptions were met) or Kruskal-Wallis tests with Mann-Whitney U post hoc tests using the Holm sequential Bonferroni method to correct for multiple comparisons. Group differences on behavior and QOL measures were tested using one-way analysis of covariance (ANCOVA) with pairwise post hoc tests and Bonferroni correction, covarying for SRI. The relationships of all sleep, respiratory, and index-level behavioral variables with summary-level QOL and parenting stress variables (PedsQL™ 4.0 Generic Core Scales Total Score; PedsQL™ 2.0 Family Impact Module total, parent HRQOL, and family functioning scores; and PSI/SF total stress) were explored for the entire sample using two-tailed Spearman rank correlations for nonnormally distributed data. Data are presented as mean ± standard error unless otherwise specified. A P value < 0.05 was used as the threshold for significance, and adjusted P values are reported when corrections were used for multiple post hoc pairwise comparisons.

Demographics

The social risk index (SRI)22 was used to quantify sociodemographic information and takes into account family structure, highest education completed by a primary caregiver, employment status and occupation of primary income earner, language spoken at home, and maternal age at birth of child. Higher SRI scores indicate greater social risk (range: 0-12). Maternal education was also rated 1-6 according to highest level completed (primary through postgraduate degree), and maternal occupations were converted into occupational status scores according to the Australian Socioeconomic Index 200623 (range: 0-100), with higher scores indicating greater status.

Behavior

The Behavior Rating Inventory of Executive Function – Preschool Version (BRIEF-P)24 and the Child Behavior Checklist 1.5-5 (CBCL/1.5-5)25 were completed by parents to identify problem behaviors, as previously described.19 Higher scores indicate more problem behaviors.

RESULTS A total of 160 clinically referred children were recruited for the larger project. Of these, 115 (56 PS, 35 mild OSA, 24 MS OSA) participated in both the PSG and home assessments and had adequate PSG data for analysis (> 4 h of sleep overnight to enable clinical diagnosis). Of 42 nonsnoring children recruited, 38 met control group criteria and had adequate data for inclusion.

Quality of Life

The Pediatric Quality of Life Inventory™ (PedsQL™) 4.0 Generic Core Scales26-29 Parent Report is a 21-item (for those aged 2-4 y) or 23-item (for those aged 5 y) questionnaire. SLEEP, Vol. 36, No. 11, 2013

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Table 1—Demographic, respiratory, and sleep characteristics of control and sleep disordered breathing groups Age (y) Males, n (%) BMI z-score Maternal education Maternal occupation Social risk index OAHI RDI SpO2 nadir Total Arousal Index TST, min Sleep efficiency, % NREM 1, %TST NREM 2, %TST NREM 3, %TST NREM 4, %TST NREM 3/4, %TST Total NREM, %TST REM, %TST Sleep diary, h

Control (n = 38) 4.3 (0.2) 18 (47%) 0.6 (0.2) 5.0 (0.2) 74.0 (3.0) 0.5 (0.1) 0.1 (0.0) 1.0 (0.1) 92.4 (0.5) 12.1 (0.7) 453.3 (5.3) 88.3 (1.0) 8.6 (0.6) 41.9 (0.9) 4.2 (0.2) 22.5 (0.7) 26.8 (0.7) 77.2 (0.7) 22.8 (0.7) 10.6 (0.2)

PS (n = 56) 4.2 (0.1) 34 (61%) 0.9 (0.1) 4.2 (0.2)** 59.2 (2.4)** 1.4 (0.3)* 0.3 (0.0)** 1.9 (0.2)** 92.2 (0.6) 12.4 (0.6) 440.3 (5.4) 88.6 (0.9) 9.0 (0.6) 41.0 (0.9) 4.9 (0.3) 25.4 (0.9) 30.4 (1.0)* 80.3 (0.5)** 19.7 (0.5)** 9.9 (0.2)*

Mild OSA (n = 35) 4.6 (0.1) 25 (71%) 1.0 (0.3) 4.4 (0.2) 55.3 (3.4)** 1.5 (0.3)** 2.8 (0.2)**,## 4.9 (0.4)**,## 90.9 (0.8) 14.6 (0.7)*,# 441.1 (8.0) 88.6 (1.1) 9.9 (0.7) 41.2 (1.2) 5.0 (0.4) 23.4 (1.0) 28.4 (1.1) 79.5 (0.7) 20.5 (0.7) 9.9 (0.2)

MS OSA (n = 24) 4.0 (0.2)‡ 15 (63%) 0.4 (0.3) 4.8 (0.2) 68.9 (3.1)‡ 1.1 (0.2) 13.2 (1.7)**,##,‡‡ 16.1 (1.8)**,##,‡‡ 87.6 (1.2)**,##,‡ 25.3 (1.8)**,##,‡‡ 431.3 (9.9) 88.0 (1.5) 12.6 (1.0)**,# 40.8 (1.3) 5.5 (0.6) 21.4 (0.6)## 26.8 (1.0)# 80.2 (0.8)* 19.8 (0.8)* 9.8 (0.3)

Unless otherwise specified, data presented as mean (standard error). BMI, body mass index; NREM, nonrapid eye movement; OAHI, obstructive apneahypopnea index; OSA, obstructive sleep apnea; PS, primary snoring; RDI, respiratory disturbance index; REM, rapid eye movement; SpO2, oxygen saturation; TST, total sleep time; sleep diary, average nightly sleep duration reported by parents (minimum of 5 nights; control = 33; PS = 49; mild OSA = 32; MS OSA = 19). *Versus control, P < 0.05. **P < 0.01. #Versus PS, P < 0.05. ##P < 0.01. ‡Versus mild OSA, P < 0.05, ‡‡P < 0.01.

Table 2—Problem behavior index scores and analysis of covariance results, controlling for social risk index Control M (SE) BRIEF-P, n (%) Inhibitory self-control Flexibility Emergent metacognition Global executive CBCL/1.5-5, n (%) Internalizing problems Externalizing problems Total problems

PS M (SE)

Mild OSA M (SE)

MS OSA M (SE)

P

Partial η2

0.001 0.001 0.001 0.001

0.10 0.19 0.13 0.16

0.001 0.02 0.001

0.19 0.06 0.19

38 (100) 44.9 (1.4) 42.9 (1.0) 43.5 (1.3) 43.1 (1.2)

56 (100) 55.0 (1.9)** 55.5 (1.7)*** 56.0 (2.0)*** 56.2 (1.9)***

34 (97) 55.5 (2.4)** 54.9 (2.0)*** 53.2 (2.2)* 54.9 (2.3)**

23 (96) 49.0 (2.1) 48.3 (2.0)# 47.7 (2.4) 47.0 (2.1)#

37 (97)

55 (98)

35 (100)

23 (96)

41.9 (1.8) 45.2 (1.5) 43.1 (1.6)

56.1 (1.4)*** 53.1 (1.7)* 56.8 (1.4)***

54.2 (2.3)*** 52.2 (2.0) 54.4 (2.1)***

50.3 (2.0)* 48.7 (2.0) 50.0 (2.0)

Age-adjusted, normalized T scores presented, with higher scores indicating greater dysfunction. Means and standard errors calculated before covariate adjustments. BRIEF-P, Behavior Rating Inventory of Executive Function – Preschool Version; CBCL/1.5-5, Child Behavior Checklist 1.5-5; M (SE), mean (standard error); OSA, obstructive sleep apnea; PS, primary snoring. *Versus control, P < 0.05. **P < 0.01. ***P < 0.001. #Versus PS, P < 0.05. Bold values indicate overall questionnaire results.

Demographic data are presented in Table 1. The MS OSA group was slightly younger than the mild OSA group (P < 0.05). Group differences were also found for maternal education, maternal occupation, and SRI. Both the PS and mild OSA groups had significantly greater cumulative social risk (SRI scores) than the control group (P < 0.05 and 0.01, respectively). Respiratory and sleep characteristics are also presented in Table 1. Groups differed as expected on measures reflecting SDB severity, as previously described.19 The PS and MS OSA groups SLEEP, Vol. 36, No. 11, 2013

spent a smaller percentage of TST in rapid eye movement (REM) sleep than the control group (P < 0.01 and 0.05, respectively) and the PS group spent a larger percentage of TST in nonrapid eye movement sleep stages 3 and 4 than the control group (P < 0.05). The PS group also had a shorter habitual sleep duration than the control group (P < 0.05) according to sleep diaries. We have previously published detailed behavioral evaluation of this cohort,19 and these results are presented in brief in Table 2 given the relevance of children’s behavior to QOL 1641


Figure 1—Unadjusted z-scores and analysis of covariance results, controlling for social risk index. School functioning relates to daycare, preschool, or kindergarten (control = 38; PS = 48; mild OSAS = 33; MS OSAS = 22). *Versus control, P < 0.05; **P < 0.01; ***P < 0.001; #Versus PS, P < 0.05.

Figure 2—Unadjusted scores and analysis of covariance results, controlling for social risk index. HRQOL, health-related quality of life; OSA, obstructive sleep apnea; SE, standard error. *Versus control, P < 0.05; **P < 0.01; ***P < 0.001; #Versus PS, P < 0.05.

and parental stress. After controlling for SRI, the PS and mild OSA groups had consistently elevated problem behavior index scores relative to the control group, and the PS group occasionally had elevated scores relative to the MS OSA group. In contrast, the MS OSA group had significantly higher scores than the control group only on the CBCL/1.5-5 Internalizing Problems scale (P < 0.05). Subscale results showed a similar pattern, and the MS OSA group’s score was elevated relative to control children only on the CBCL/1.5-5 Sleep Problems subscale (P < 0.05). No group differences were found on the CBCL/1.5-5 Attention Problems subscale. No main effects SLEEP, Vol. 36, No. 11, 2013

of SRI or interactions of SRI with group were found for any behavioral variable. PedsQL™ 4.0 Generic Core Scales z-scores, PedsQL™ Family Impact Module scores, PSI/SF scores, and ANCOVA results are presented in Figures 1, 2, and 3, respectively. Parents of two children did not complete QOL or stress questionnaires and parents of two additional children did not complete the PSI/ SF. After controlling for SRI, significant group effects were found for all subscales and summary scales of each questionnaire. With regard to children’s QOL (PedsQL™ 4.0 Generic Core Scales ratings; Figure 1), the PS group had significantly poorer 1642


Figure 3—Unadjusted scores and analysis of covariance results, controlling for social risk index. OSA, obstructive sleep apnea; SE, standard error. *Versus control, P < 0.05; **P < 0.01; ***P < 0.001; #Versus PS, P < 0.05.

scores than control patients for each scale (P < 0.05-0.001), and poorer scores than the MS OSA group for the Psychosocial Health Summary and Total scales (both P < 0.05). Children with mild OSA also had poorer scores than control patients for all scales except social functioning (P < 0.05-0.001). Scores of the MS OSA group did not differ significantly from those of the control group. The group effect size was strongest for emotional functioning (partial η2 = 0.18), but when the “trouble sleeping” item was excluded from this scale the non age-standardized effect size (0.12) approximated that of physical functioning (0.14). A parallel pattern was found for parent and family QOL (PedsQL™ 2.0 Family Impact Module ratings; Figure 2). Parents of children with PS rated their QOL as significantly poorer than parents and families of control children on each scale (P < 0.010.001), and poorer than parents of children with MS OSA on the physical functioning and parent HRQOL scales (both P < 0.05). The mild OSA group’s scores were significantly lower than those of control parents (P < 0.05-0.01) for all but four scales (social functioning, cognitive functioning, communication, and family relationships). Parents of children with MS OSA reported greater worry (P < 0.001) and had lower total scores (P < 0.05) than parents of control children. Significant main effects of SRI were found for all but two scales (social functioning and worry). No other main effects of SRI or interactions of SRI with group were identified for QOL or stress scales. Results of the parenting stress measure (PSI/SF; Figure 3) showed significantly more stress in parents of children with PS than parents of control children in each domain (P < 0.01-0.001), and more stress in parents of children with PS than parents of children with MS OSA in the area of parent-child dysfunctional Interaction (P < 0.05). Parents of the PS group also had a mean total stress rating (81.7) approaching the threshold for clinical significance (86; 85th percentile). Parents of children with mild and MS OSA did not report more stress than parents of control children for any scale. SLEEP, Vol. 36, No. 11, 2013

Correlations of sleep and respiratory variables with summary level QOL and parenting stress variables showed significant associations between poorer ratings on all outcome measures and smaller %TST in REM sleep (rs absolute values: 0.19-0.24; P < 0.05-0.01). A greater %TST in slow wave sleep (NREM stages 3 and 4) was also associated with poorer QOL in children (rs: -0.018; P < 0.05). Shorter habitual sleep duration was associated with poorer QOL in children (rs: 0.22; P < 0.05), parent HRQOL (rs: 0.24; P < 0.01), family functioning (rs: 0.20; P < 0.05), and family impact total (rs: 0.22; P < 0.05) scores, but not with elevated parental stress. Higher RDIs were associated with lower family functioning scores (rs: -0.17; P < 0.05), but no other significant relationships were found between respiratory variables and outcome measures. All index level behavioral variables were highly correlated with all summary level QOL and parenting stress variables (rs absolute values: 0.39-0.65), with PSI/SF total stress scores being most strongly related to children’s behavior (0.52-0.65). DISCUSSION This study is the first to examine QOL specifically in a group of preschool-aged children with varying severities of PSGdiagnosed SDB and their families in comparison with nonsnoring community control children and families. In support of our hypothesis, preschool children with SDB and their families had poorer QOL than control children and families. In contrast to expectations, our results showed consistently poorer QOL in the mild SDB (PS and mild OSA) groups compared to control groups, and even on some scales in the PS group compared to the MS OSA group, whereas the MS OSA group only differed from the control group on one subscale (parental worry) and one summary scale (family impact module total). The PS group also had elevated parenting stress compared to both control patients and the MS OSA group. Reduced QOL on all scales of the PedsQL™ 4.0 Generic Core Scales Parent Report within the current sample of preschool 1643


children with SDB is consistent with previous findings in an older cohort.9 This study also reported that the degree of reduction in QOL in children with SDB substantially exceeded that reported in children with chronic health conditions.9,27 Stewart and colleagues33 similarly found some aspects of QOL (related to emotional effect, behavior, and parental effect of the child’s disease) in children aged 2-16 y with tonsil and adenoid disease to be more impaired than in children with juvenile rheumatoid arthritis and asthma. The reduction in parent-reported QOL in the current sample generally did not exceed that reported in chronically ill children,27 however, suggesting that SDB may be more psychosocially burdensome in older children or that the psychosocial effect of SDB increases over time. The association between all severities of SDB and poor psychosocial outcomes has been described previously in pediatric samples with broad age ranges,4,9,11-14 though reports of poorer QOL in children with mild SDB compared with more severe SDB are few. Mitchell and colleagues10 did find that children with milder SDB made greater QOL gains after adenotonsillectomy than children with a moderate degree of SDB, but these gains were smaller than those made by children with more severe SDB. Stewart and colleagues12 also found poorer ratings of emotional or behavioral role/social limitations in children with a history of snoring compared to children with OSA, though the groups’ scores in all other QOL respects were similar. In light of our behavioral data, the pattern of QOL and parenting stress findings is not surprising. Reduced QOL and elevated parental stress in the mild SDB groups could be mediated by behavioral impairments in these children and/or associated caregiving burden. Although a degree of shared variance is accounted for by common respondents, the strong correlations between our BRIEF-P and QOL data are consistent with previous findings that behaviors reflective of executive dysfunction in children relate to psychosocial difficulties and problems with parent and family functioning.34 Our previously reported finding of more problem behaviors in the milder SDB groups19 was also unexpected. Reports of greater behavioral impairment in milder SDB are uncommon but not unprecedented in the literature on school-aged children.35-38 Responsible physiological mechanisms are uncertain but it is possible that different pathological mechanisms predominate in PS (e.g., sleep fragmentation at some level, even if undetected) versus OSA (e.g., hypoxia).9,18,19 A recent report by our group demonstrated evidence to suggest that enhanced sleep pressure and impaired restorative sleep function may account for deficits identified in children with PS.18 The correlations found between our outcome measures and sleep diary reports also suggest that sleep duration is an important contributor to reduced QOL in preschool children with SDB, though we acknowledge the low strength of these correlations and that sleep diary data are less convincing than objective measures. Furthermore, reduced REM and increased slow wave sleep, as observed in the PS group, is the pattern typically seen in sleep deprivation. It is therefore possible that the observed pattern of behavioral and QOL findings reflects the effect of inadequate sleep. This explanation would be in agreement with the known developmental relevance of sleep in early childhood and is consistent with literature demonstrating broad negative SLEEP, Vol. 36, No. 11, 2013

effects of sleep disturbance in early life,15,39 including effects on parental fatigue and stress.40 As highlighted by Crabtree and colleagues,9 sleep disturbance associated with snoring may lead to fatigue in children, which may lead to impairments in daily functioning and ultimately interfere with multiple aspects of a child’s life, including peer and family relationships. The current findings add to mounting evidence challenging the use of the OAHI or AHI as the optimal outcome parameter in pediatric SDB. Several studies have found weak or nonexistent relationships between traditional severity indices such as AHI and psychological outcome measures,12,41-43 suggesting that alternative parameters such as snoring frequency should be considered.43-45 Another possible explanation for the QOL differences between the mild SDB and MS OSA groups is referral bias. Parents of children with milder symptoms of SDB may be more likely to present their children for investigation if they have concurrent behavioral or psychosocial problems than SDB symptoms in isolation.35 Features of history are not reliable enough to distinguish PS from OSA,46 but we cannot exclude the possibility that parents were more worried by less severe symptoms in the presence of other daytime challenges. Such difficulties are inherent in clinical samples but may be overcome by studying population-based samples. Despite this, our findings have clinical relevance as they draw attention to associations of milder SDB that may not be due to the condition itself and may thus be less likely to improve with treatment. A strength of the study is the generic QOL measures used. Disease-specific QOL questionnaires are widely used7,47,48 and have the benefit of highly relevant items, but may result in artificially enhanced relationships between SDB and QOL. Conversely, it is a limitation of the study that most control subjects were recruited through advertisements to staff at the hospitals and universities collaborating in the study. The consistent similarities between the control and MS OSA groups, however, suggest that the control group is reasonably representative of the general population. CONCLUSIONS Our findings demonstrate that sleep disordered breathing is associated with reduced quality of life in preschool children and their families, as reported in older children and in samples with broader age ranges. Furthermore, clinically referred preschool children with mild forms of sleep disordered breathing may be at greatest risk. These data support accumulating evidence that primary snoring is not a straightforward, benign condition. The nature of the relationship between sleep disordered breathing and psychosocial function in these young children is of particular concern given the substantial proportion of preschool children at risk of sleep disordered breathing, most of whom will have mild forms. Clinicians may be inclined to treat these mild forms in the presence of adverse psychosocial indicators in light of evidence linking sleep disordered breathing to adverse neurocognitive and behavioral outcomes. The pattern of our findings, however, raises the possibility that such outcomes may not be due entirely to the condition itself, and that the child’s sleep duration should also be considered. Further research comparing quality of life in clinically referred versus community samples would assist in clarifying the potential role of referral bias, and 1644


studies of sleep disordered breathing treatment outcomes will continue to be vital in informing treatment guidelines.

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