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Stewart MG, Glaze DG, Friedman EM, Smith EO, Bautista M. Quality of Life and Sleep Study Findings After Adenotonsillectomy in Children With Obstructive Sleep Apnea. Arch Otolaryngol Head Neck Surg. 2005;131(4):308–314. doi:10.1001/archotol.131.4.308
Copyright 2005 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.2005
To assess polysomnogram (PSG) results and global and disease-specific quality of life (QOL) in children with obstructive sleep apnea (OSA), before and after adenotonsillectomy, and to assess the association between PSG findings and QOL.
Prospective observational study. We performed overnight PSG using standardized techniques and assessed disease-specific and global QOL using validated instruments. Follow-up was assessed at 1 year. We compared QOL outcomes between children who underwent adenotonsillectomy and children who did not.
A large tertiary care children’s hospital.
Children with sleep-disordered breathing who were suspected of having OSA.
Main Outcome Measures
We evaluated PSG parameters, disease-specific QOL, and global QOL.
We enrolled 47 children, 31 of whom met PSG criteria for OSA. Disease-specific and global QOL were not significantly different between children with OSA and children without. Global QOL was significantly worse for children with OSA than healthy children on several subscales: general health perception, behavior, and parental impact–emotional. Children who underwent adenotonsillectomy had significant improvements in QOL scores and PSG parameters (apnea-hypopnea index, P = .004; minimum saturation, P = .004). We found significantly larger QOL changes in children who underwent surgery compared with children without surgery (subscales: infections, P = .01; airway, P = .002; swallowing, P = .02; and behavior, P = .03). No strong association was identified between QOL scores and PSG parameters.
Children with OSA and sleep-disordered breathing have significantly worse QOL than healthy children. However, the association between PSG findings and QOL was only moderate. Children with OSA treated with adenotonsillectomy demonstrated large improvements in disease-specific and global QOL as well as PSG parameters.
Adenotonsillectomy is a commonly performed procedure in the pediatric population, and in recent years there has been an increased frequency of surgery based on hypertrophy and sleep breathing disturbance rather than infectious pharyngitis.1,2 Several studies have found that obstructive sleep apnea (OSA) is improved or cured in most children after adenotonsillectomy, using different criteria for success including sleep study findings.3-8 In addition, some disease-specific quality-of-life (QOL) instruments have been developed for children with sleep breathing disturbance,9-11 and studies of disease-specific QOL in children with OSA have identified significant improvements after adenotonsillectomy.12-14 Furthermore, global QOL is significantly impaired in children with tonsil and adenoid disease, including children with sleep breathing disturbance and hypertrophy.15
Despite this recent evidence indicating the benefit of adenotonsillectomy, no prospective study has assessed sleep study parameters, disease-specific QOL, and global QOL in the same group of patients. Our prospective study reports QOL and sleep study findings from a group of children with a diagnosis of OSA indicated by a sleep study; most children had tonsil and adenoid hypertrophy and underwent adenotonsillectomy during the study period.
As part of a prospective study on the neuropsychological and cognitive effects of OSA in children, we assessed global and disease-specific QOL as well as polysomnogram (PSG) findings in these children. This study was approved by the institutional review board at Baylor College of Medicine. Children were enrolled based on suspicion of sleep breathing disturbance from a history and/or audiotaped evidence of loud snoring, sleep breathing disturbance, or witnessed apnea. After enrollment, all children underwent a comprehensive overnight multichannel PSG in the Children’s Sleep Center at Texas Children’s Hospital (Houston). Children were studied in the company of a parent or guardian for 8 to 12 hours in a quiet, darkened room with an ambient temperature of approximately 24°C.
The following parameters were measured. Airflow at the nose was assessed with a pressure transducer airflow sensor (PTAF 2, model 1287; Pro-Tech Services, Mukilteo, Wash); airflow at the mouth was assessed by oral thermocouple. End-tidal carbon dioxide levels were assessed with a sidestream end-tidal capnograph interfaced with the pressure transducer airflow sensor and/or oral thermocouple providing breath-by-breath assessment of end-tidal carbon dioxide levels (BCI Capnocheck Plus, model 58550A4; Smiths Medical PM, Inc, Waukesha, Wis). Arterial oxygen saturation was assessed by pulse oximetry (model 3012; Nonin Medical, Inc, Plymouth, Minn). Chest and abdominal wall movement were measured by piezo bands (CT 2 Piezo Respiratory Effort Sensor, model 1585; Pro-Tech Services), and heart rate was measured by electrocardiogram. Bilateral electrooculograms, 6 channels of electroencephalograms, and chin electromyograms were also obtained, and bilateral leg and foot movement (Periodic Limb Movement Sensor, model 1697; Pro-Tech Services) and body position (by observation of technologist) were continuously monitored. Snoring was assessed by a sensor (Piezo Snore Sensor, model 1696; Pro-Tech Services) placed over the trachea. All measures were digitized using a commercially available PSG system (Rembrandt sleep software, version 7; Medcare Diagnostics, Buffalo, NY).
Sleep architecture was assessed by standard techniques.16 Central, obstructive, and mixed apneic events were scored. Obstructive apnea was defined as the absence of airflow with continued chest wall and abdominal movement for a duration of at least 10 seconds. Hypopnea was defined as a decrease in nasal flow of at least 50% with a corresponding decrease in oxygen saturation of at least 3%, an arousal, or both. The obstructive apnea-hypopnea index (AHI) was defined as the number of obstructive apneas and hypopneas per hour of total sleep time. A composite severity score to describe the severity of sleep-disordered breathing was derived from the total of scores (0-4) assigned to the AHI, respiratory arousal index, minimum oxygen saturation value, number of drops of oxygen saturation below 90% associated with obstructive apneic or hypopneic events, and maximum end-tidal carbon dioxide value (Table 1). The range of composite severity scores was 0 (least severe) to 20 (most severe).
A complete multichannel PSG was repeated 1 year after study entry. All sleep studies were funded by the grant from the National Institutes of Health (Bethesda, Md) that supported this study. Extensive neuropsychological testing was also performed, but those data are not reported in this article.
There was no randomization or treatment assignment in this study. Each child was evaluated by a pediatric otolaryngologist (E.M.F.), and adenotonsillectomy was recommended if the child had adenoid and tonsil hypertrophy. Although not all children who were recommended for surgery actually underwent adenotonsillectomy during the study period for various reasons, such as parental preference, there was no systematic reason why children did not undergo surgery. All parents were contacted for QOL assessment of their child 6 months and 1 year after surgery, or after PSG testing was completed for patients who did not have surgery. Patients were defined as having OSA if they had an AHI of 1 or more per hour, which is the accepted diagnostic standard for pediatric OSA. Eligible children who did not meet this criterion on the PSG still received follow-up. Exclusion criteria were as follows: non–English-speaking parent or child; chronic medical conditions such as asthma or cardiac disease; a diagnosis of attention-deficit/hyperactivity disorder; patient receiving any kind of stimulant, such as methylphenidate hydrochloride; genetic disorder; neurologic disorder including mental retardation, degenerative or metabolic disorder, or epilepsy; prior adenotonsillectomy; and craniofacial abnormalities.
In addition, we collected QOL data from the caregiver parent at study entry and 6 months and 1 year after study entry. Global QOL was assessed using the Child Health Questionnaire–version PF28,17 which is a validated and widely used instrument. This questionnaire is made up of multiple subscales representing different constructs of global QOL. Disease-specific QOL was assessed using the Tonsil and Adenoid Health Status Instrument, which is also fully validated.11 The instrument is scored into subscales based on different types of problems caused by tonsil and adenoid disease: infections, airway and breathing, behavior, swallowing, health care utilization, and cost of care.
Statistical analysis was performed using SPSS version 10.0 statistical software (SPSS Inc, Chicago, Ill). Associations between variables were assessed using the nonparametric Spearman correlation coefficient; a significant correlation was considered to be 0.40 or greater. For other comparisons, because an underlying normal distribution of the data could not be assumed, nonparametric statistical analysis was used. Analysis of changes in score over time was performed using the Wilcoxon signed rank test, and comparisons between groups were performed by calculating change scores and using the Mann-Whitney test. Comparisons between multiple groups were performed using the Kruskal-Wallis test. Statistical significance was set at P≤.05.
Forty-seven children entered the study with a clinical history of sleep-disordered breathing. There were 32 (68%) boys and 15 (32%) girls; 23 (49%) were white, 13 (28%) were Hispanic, 8 (17%) were African American, and 3 (6%) were Asian or other. Mean age was 8.0 years and median age was 7.5 years, with a range from 6 to 12 years.
Of those 47 children, 31 had OSA according to PSG criteria: 22 (71%) boys and 9 (29%) girls. Ethnic distribution was similar to the overall group. Age distribution for the OSA group was also very similar, with a mean of 8.1 years, a median of 7.5 years, and a range from 6 to 12 years. Mean body mass index at enrollment (calculated as weight in kilograms divided by height in meters squared) was 20.0, with a range from 12 to 35.7. Overall, 29 of 31 parents completed an extensive set of QOL and other neuropsychological instruments 6 months after enrollment, for a follow-up rate of 94%. Only 19 children (61%) returned for a repeated PSG and comprehensive psychometric and QOL testing at 1 year.
For the enrollment group, which had a complete set of data, baseline global QOL subscale scores at study entry are shown in Table 2, divided into groups: OSA by PSG and no OSA by PSG. Almost all mean subscale scores were not significantly different between groups. Data from the disease-specific Tonsil and Adenoid Health Status Instrument are shown in Table 3. Again, there were no significant differences in subscale scores between groups. Mean scores from both instruments were compared by ethnicity, and there were no significant differences in mean score between ethnic groups.
Table 4 shows the comparison of global QOL data for healthy children and the group with OSA. We compared the 2 groups using the 2-sample t test, and scores were significantly different for 8 of 12 subscales, with scores always worse in the OSA group. Subscales with notably large differences included role/social limitations due to physical problems, bodily pain, behavior, general health perceptions, and parental impact–emotional.
Of the 31 children with OSA, 29 returned for follow-up at 6 months. Of that group, 24 had undergone adenotonsillectomy, and 5 had not. As mentioned previously, there was no treatment assignment or randomization in this study; all children were recommended for surgery, and there was no systematic reason why children did not undergo surgery. However, we wanted to explore the possibility of an actual difference between groups, even if unintentional. Therefore, we tested for differences between the 2 groups (surgery vs no surgery) by comparing baseline global QOL and disease-specific QOL, and there were no significant differences between subscales on either instrument.
As noted earlier, only 19 children returned for testing 1 year after treatment or enrollment. We compared QOL subscale scores between the 6-month follow-up and 1-year follow-up periods, and there were no significant differences identified between mean scores for any subscale on either the global instrument or the disease-specific instrument. Therefore, since the sample size was larger for the 6-month group, we used that group for further analysis of the QOL data.
Table 5 shows the change scores on the global and disease-specific QOL instruments at 6 months, with statistical comparison between the 2 groups using the Mann-Whitney test. Despite the small sample size, significantly larger improvements were seen in the surgery group for several subscales on the disease-specific instrument as well as the behavior and parental impact–emotional subscale of the global instrument. These changes remained significant after an analysis to control for baseline effects.
In addition to calculating statistical significance, we assessed clinical significance by calculating the raw change scores and standardized response means for subscale scores. Since scores on QOL instruments are not intuitive and can be difficult to compare with changes on objective testing, it is important to assess clinical magnitude so that the numeric change in score on a QOL instrument can be compared with an understandable change in clinical status. As a rule of thumb, a minimally detectable change in clinical status on a health status instrument is usually about 7 points on a 100-point scale. Beyond the minimally detectable change, to assess the relative size of a numeric change, the standardized response mean (SRM) is often used. An SRM of 0.5 or greater indicates a moderate change in status, and an SRM of 0.80 or greater indicates a large change in status. The SRMs for the Tonsil and Adenoid Health Status Instrument were as follows: utilization, 0.63; infections, 0.72; airway, 1.17; cost of care, 0.68; and behavior, 0.75. Therefore, the change on the airway subscale was large, and changes on the behavior and infections subscales approached the accepted threshold for a large change. The SRMs for the global QOL instrument were generally larger than a minimally detectable change.
The PSG data for the children with OSA were as follows. Baseline mean AHI was 14.8 with a range from 1.0 to 75.8, mean minimum oxygen saturation was 82% with a range from 46% to 94%, and mean number of desaturations per hour was 12.9 and ranged from 0 to 109. The mean composite severity score at baseline was 8.32 with a range from 0 to 20. For children who completed the PSG 1 year after enrollment, the mean AHI was down to 3.16 (range, 0-24.1), mean minimum oxygen saturation was up to 91% (range, 83%-96%), mean number of desaturations per hour was 1.9 (range, 0-24.1), and mean composite severity score was 3.94 (range, 0-13.0). Using the Wilcoxon signed rank test to compare results at baseline and 1 year, differences were statistically significant for 3 of 4 variables (AHI, P = .004; minimum saturation, P = .004; number of desaturations, P = .11; and composite severity index, P = .007). Nine (53%) of 17 children who completed a PSG at 1 year were cured (AHI<1.0), and 15 (88%) of 17 children had a decrease in their AHI.
We next explored associations between the PSG findings and QOL scores on both the global and disease-specific instrument. Table 6 shows the correlations at baseline between PSG findings and QOL subscale scores for the children with OSA. Most correlations are nonsignificant.
Because the airway subscale had reasonable correlation with PSG findings and logically it was the subscale most likely to be predictive of OSA, we explored those data to see if the instrument subscale scores could be used to predict the presence of OSA. All 47 children with sleep-disordered breathing, even those who did not meet PSG criteria for OSA, were used for this analysis. A cross-tabular evaluation revealed that of the 8 children with an AHI of 0, none had an airway score of 0; scores ranged from 12.5 to 93.8 with a mean score of 47.7 and a median of 46.9. We performed further analysis by creating strata of children with similar AHIs; the mean airway score data are shown in Table 7. As indicated by the correlation coefficient, children with higher AHIs tended to have higher airway subscale scores, but the range was very wide. Even children with a low AHI had fairly high airway scores. Statistical analysis comparing the groups revealed no significant difference (Kruskal-Wallis test, P = .63). From these data, we conclude that airway subscale scores should not be used as a screen for the presence of OSA.
Adenotonsillectomy continues to be a commonly performed procedure in the pediatric population, and the prevalence of surgery performed for hypertrophy and sleep breathing disturbance has been increasing significantly in recent years.1,2 There has been increased recognition of the importance of snoring, sleep breathing disturbance, and sleep apnea in children, and several studies have found that OSA is improved or cured in most children after adenotonsillectomy.3-8
The definition of OSA syndrome in children is a “disorder of breathing during sleep characterized by prolonged partial upper airway obstruction and/or intermittent complete obstruction (obstructive apnea) that disrupts normal ventilation during sleep and normal sleep patterns.”8(p705) The PSG is the gold standard for diagnosis of OSA. It is well known that pediatric sleep studies should be evaluated using different criteria from those of adult sleep studies, including the definitions of apnea and hypopnea.18
Several disease-specific QOL instruments have been developed for children with sleep breathing disturbance.10-12 These instruments have allowed the assessment of changes in QOL after adenotonsillectomy, and different studies of children with OSA have identified significant improvements in disease-specific QOL.12-14 In addition to disease-specific QOL, a recent study found that global QOL was significantly impaired in children with tonsil and adenoid disease, including children with sleep breathing disturbance and hypertrophy.15 Although these studies have generally identified good outcomes after surgery, no study has assessed PSG data, disease-specific QOL, and global QOL in the same group of patients who were treated for OSA with adenotonsillectomy. The American Academy of Pediatrics guideline for OSA noted that “adenotonsillectomy is the first line of treatment for most children.”8(p705) In its comprehensive review of the literature, it noted multiple studies that found snoring, clinical symptoms, PSG findings, behavior, growth, and other outcomes improved after adenotonsillectomy—in some cases, even in children who were morbidly obese. The role of adenoidectomy alone was less well defined. However, the review noted that the methodologic quality of the available studies was variable and that results and methods were sometimes difficult to interpret.
An early prospective study of 60 children with OSA6 found that in a subset of children who underwent adenotonsillectomy, their apnea was basically resolved according to PSG criteria. Another prospective study with preoperative and postoperative PSG data3 found that 26 of 26 children who underwent adenotonsillectomy for OSA had a reduction in their AHI after surgery. A third prospective study evaluated changes in PSG criteria following either adenoidectomy or adenoidectomy with tonsillectomy and found that all 24 patients with OSA pretreatment had resolution of OSA.4
A retrospective study evaluated changes in PSG and other clinical parameters19 after adenotonsillectomy and uvulopalatopharyngoplasty in children with neurologic impairment; 12 of 14 children had improvement in sleep quality and minimum oxygen saturation. A retrospective survey study20 of the parents of 80 children found that 100% of parents were pleased with the overall outcome of adenotonsillectomy 1 year after surgery, and 63% of parents felt that their child’s sleeping pattern was improved. A retrospective study from Japan assessed 50 children with upper airway obstruction with PSG before and after surgery, and 93% of patients had a decrease in apnea index.5
Two other studies have used validated instruments to assess changes in QOL after adenotonsillectomy in children with obstructive sleep breathing disorder.12,14 One prospective study used the OSD-6,9 which is a validated 6-item instrument completed by the parent or caregiver. In that study, 101 children (mean age, 6.2 years) from 7 tertiary care pediatric otolaryngology practices were enrolled. The diagnosis of obstructive sleep disorder was made using a combination of history, physical examination, nasopharyngoscopy, sleep audiotape, sleep study, and an orocraniofacial scale; only 8 children had a preoperative PSG study. Postoperative PSG data were not reported. After surgery, the authors found that 88% of children had improvement in disease-specific QOL; 75% of them had a large improvement, and 6% had moderate improvement. Direct comparison of the QOL changes before and after surgery was also performed, and differences were highly significant.
The second prospective QOL study14 used the OSA-18 instrument10 and another validated instrument that assessed children’s behavior. Sixty-four children with sleep breathing disturbance underwent adenotonsillectomy. Improvements in QOL were statistically significant and clinically large, as assessed by a standardized change score, and behavior after adenotonsillectomy was improved significantly.
A recent pilot study on radiofrequency tonsil reduction in children (n = 10) with sleep-disordered breathing found that several parameters improved after tonsil reduction.13 Improvement was noted at the 3-month follow-up visit and persisted at 12 months of follow-up on both the OSA-18 instrument and a subjective daytime sleepiness score.
To our knowledge, our study is the first to report both PSG data and disease-specific and global QOL data from the same group of patients who underwent adenotonsillectomy. In addition, we report long-term follow-up data 1 year after surgery. Our study included a representative sample of children of different ethnicity, body mass, and OSA severity. We had excellent follow-up 6 months after enrollment but poorer compliance at 1 year. The reasons for this are not entirely clear, but the 1-year visit required a repeated sleep study and another battery of instruments. Many parents reported that their children’s sleep problems were clearly resolved and that they did not want to undergo another sleep study because the child was doing so well. A large number of instruments were used in this study (not all findings are in this report), and the respondent burden was fairly high. The parents had already completed a battery of instruments twice, so many did not want to complete the battery again at 1 year.
In this study, we found that baseline global QOL was significantly impaired in children with sleep study–proven OSA. However, QOL was also impaired in children with sleep-disordered breathing who did not have OSA according to PSG criteria. These findings indicate that even in the absence of OSA, sleep-disordered breathing has a significant impact on QOL. In addition, we found that global and disease-specific QOL improved after adenotonsillectomy. Other QOL studies used different instruments, and not all children had OSA proven by sleep study.9,14 This study confirms that when using a different validated instrument, disease-specific QOL improves after adenotonsillectomy. The improvements in QOL were seen 6 months after surgery and were sustained at 1 year. Even though not all children were cured of OSA (using PSG parameters), the improvement in QOL was nevertheless significant. This indicates that some effects of sleep-disordered breathing on QOL are not measured by the PSG.
As expected, the largest improvement was in the airway subscale of the disease-specific instrument. Improvement in the behavior subscale was also expected. Interestingly, the infections subscale showed postoperative improvement. Although this was not anticipated because we did not exclude children who had a history of recurrent infections, it is likely that the improvement seen in the infections subscale was due to a reduction in infections after surgery. The overall magnitude of improvement in the airway subscale after surgery was quite large, whereas the magnitude of improvement in other subscales was moderate. The magnitude of changes on the global instrument subscales was moderate; this finding is consistent with those from other outcomes research, in which global instruments are often less sensitive to change than disease-specific instruments.
We also evaluated the associations between global QOL, disease-specific QOL, and PSG parameters. We believed that if we could identify a reliable proxy for the PSG findings, it would be clinically helpful to the practicing physician. Unfortunately, we identified no consistent associations, although some associations achieved statistical significance. Thus, there was some shared variance, but clearly much of the variability in each construct was not explained by variability in the other construct. This finding is fairly consistent in QOL research, including studies on adults with OSA.21-23 There is some association between objective, hard measures and the patient’s subjective assessment, but many other factors are not explained solely by values from objective tests.
Although we attempted to construct a severity gradient using the airway subscale, there was too much variability between patients to use the subscale score as a predictor of PSG findings. This finding tells us that PSG data and QOL data are related but complementary and that they assess different but associated constructs. Whereas children with more severe apnea tended to have higher airway subscale scores, much of the variability in QOL was not explained by apnea severity.
In summary, children with OSA treated with adenotonsillectomy demonstrated large and sustained improvements in QOL, both on disease-specific and global QOL instruments. In addition, there were marked improvements in PSG findings after surgery. Although these changes in QOL were associated with improvements in PSG findings, the association between QOL and PSG findings was only moderate.
Correspondence: Michael G. Stewart, MD, MPH, The Bobby R. Alford Department of Otorhinolaryngology & Communicative Sciences, One Baylor Plaza, NA-102, Houston, TX 77030 (firstname.lastname@example.org).
Submitted for Publication: September 27, 2004; final revision received October 19, 2004; accepted December 16, 2004.
Funding/Support: This study was supported by grant R01HL62404-01 from the National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Md.
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