SLEEP Articles

Ethical Integrity is the Sine Qua Non of Scientific Reporting

If You Weigh Too Much, Maybe You Should Try Sleeping More

Commentary on Watanabe et al. Association of short sleep duration with weight gain and obesity at 1-year follow-up: a large-scale prospective study. SLEEP 2010;33:161-167.

Predicting Sleep/Wake Behavior for Model-Based Fatigue Risk Management

Commentary on Darwent et al. Prediction of probabilistic sleep distributions following travel across multiple time zones. SLEEP 2010;33:185-195.

Impaired Nocturnal Cerebral Hemodynamics during Long Obstructive Apneas: The Key to Understanding Stroke in OSAS Patients?

Commentary on Pizza et al. Nocturnal cerebral hemodynamics in snorers and in patients with obstructive sleep apnea: a near-infrared spectroscopy study. SLEEP 2010;33:205-210.

The Prevalence of Short Sleep Duration by Industry and Occupation in the National Health Interview Survey

Study Objectives: To explore whether employment in industries likely to have non-standard work schedules (e.g., manufacturing and service) and occupations with long work-weeks (e.g., managerial/ professional, sales, and transportation) is associated with an increased risk of short sleep duration.
Design: Cross-sectional epidemiologic survey.
Setting: Household-based face-to-face survey of civilian, non-institutionalized US residents.
Participants: Sample adults interviewed for the National Health Interview Survey in 1985 or 1990 (N = 74,734) or between 2004 and 2007 (N = 110,422). Most analyses focused on civilian employed workers interviewed between 2004 and 2007 (N = 66,099).
Interventions: N/A
Measurements and Results: The weighted prevalence of self-reported short sleep duration, defined as ≤6 h per day, among civilian employed workers from 2004-2007 was 29.9%. Among industry categories, the prevalence of short sleep duration was greatest for management of companies and enterprises (40.5%), followed by transportation/warehousing (37.1%) and manufacturing (34.8%). Occupational categories with the highest prevalence included production occupations in the transportation/warehousing industry, and installation, maintenance, and repair occupations in both the transportation/warehousing industry and the manufacturing industry. In the combined sample from 1985 and 1990, 24.2% of workers reported short sleep duration; the prevalence of short sleep duration was significantly lower during this earlier time period compared to 2004-2007 for 7 of 8 industrial sectors.
Conclusions: Self-reported short sleep duration among US workers varies by industry and occupation, and has increased over the past two decades. These findings suggest the need for further exploration of the relationship between work and sleep, and development of targeted interventions for specific industry/occupation groups.
Keywords: Sleep duration, occupational groups, work

Association of Short Sleep Duration with Weight Gain and Obesity at 1-Year Follow-Up: A Large-Scale Prospective Study

Study Objectives: To investigate the association between short sleep duration and elevated body mass index (BMI) and obesity in a large sample of Japanese adults over a short period
Design: Prospective design with baseline in 2006 and 1-year follow-up
Setting: Workplaces of an electric power company in Japan
Participants: 35,247 company employees (31,477 men, 3,770 women) distributed throughout Japan
Measurements and Results: Measured weight and height and self-reported sleep duration were obtained at annual health checkup in 2006 and 2007. Weight change was defined as the difference in body mass index (BMI) between the baseline and 1 year later. Relative to the reference category (sleep duration 7-8 h), short sleep duration (< 5 and 5-6 h) and long sleep duration ≥ 9 h were associated with an increased risk of weight gain among men after adjustment for covariates. Of the non-obese (BMI < 25) men at baseline, 5.8% became obese (BMI ≥ 25) 1 year later. Higher incidence of obesity was observed among the groups with shorter sleep duration. Adjusted odds ratios for the development of obesity were 1.91 (95%CI 1.36, 2.67) and 1.50 (95%CI 1.24, 1.80) in men who slept < 5 and 5-6 h, respectively. No significant association between sleep duration and weight gain or obesity was found for women.
Conclusions: Short sleep duration was associated with weight gain and the development of obesity over 1 year in men, but not in women.
Keywords: Sleep duration, obesity, body mass index, weight gain, occupational health

Validation of the ICSD-2 Criteria for CSF Hypocretin-1 Measurements in the Diagnosis of Narcolepsy in the Danish Population

Study Objectives: The International Classification of Sleep Disorders (ICSD-2) criteria for low CSF hypocretin-1 levels (CSF hcrt-1) still need validation as a diagnostic tool for narcolepsy in different populations because inter-assay variability and different definitions of hypocretin deficiency complicate direct comparisons of study results.
Design and Participants: Interviews, polysomnography, multiple sleep latency test, HLA-typing, and CSF hcrt-1 measurements in Danish patients with narcolepsy with cataplexy (NC) and narcolepsy without cataplexy (NwC), CSF hcrt-1 measurements in other hypersomnias, neurological and normal controls. Comparisons of hypocretin deficiency and frequency of HLA-DQB1*0602-positivity in the Danish and eligible NC and NwC populations (included via MEDLINE search), by (re)calculation of study results using the ICSD-2 criterion for low CSF hcrt-1 (<30% of normal mean).
Measurements and Results: In Danes, low CSF hcrt-1 was present in 40/46 NC, 3/14 NwC and 0/106 controls (p < 0.0001). Thirty-nine of 41 NC and 4/13 NwC patients were HLA-DQB1*0602-positive (p < 0.01). Hypocretin-deficient NC patients had higher frequency of cataplexy, shorter mean sleep latency, more sleep onset REM periods (P < 0.05) and more awakenings (NS) than did NC patients with normal CSF hcrt-1. Across populations, low CSF hcrt-1 and HLA-DQB1*0602-positivity characterized the majority of NC (80% to 100%, p = 0.53; 80% to 100%, p = 0.11) but a minority of NwC patients (11% to 29%, p = 0.75; 29% to 89%, p = 0.043).
Conclusion: The study provides evidence that hypocretin deficiency causes a more severe NC phenotype. The ICSD-2 criterion for low CSF hcrt-1 (<30% of normal mean) is valid for diagnosing NC, but not NwC. HLA-typing should precede CSF hcrt-1 measurements because hypocretin deficiency is rare in HLA-DQB1*0602-negative patients.
Keywords: Hypocretin-1, HLA-DQB1*0602, narcolepsy with cataplexy, narcolepsy without cataplexy, ICSD-2

Habitual Sleep Duration and Insomnia and the Risk of Cardiovascular Events and All-cause Death: Report from a Community-Based Cohort

Study Objectives: To investigate the relationship between sleep duration and insomnia severity and the risk of all-cause death and cardiovascular disease (CVD) events
Design: Prospective cohort study
Setting: Community-based
Participants: A total of 3,430 adults aged 35 years or older
Intervention: None
Measurements and Results: During a median 15.9 year (interquartile range, 13.1 to 16.9) follow-up period, 420 cases developed cardiovascular disease and 901 cases died. A U-shape association between sleep duration and all-cause death was found: the age and gender-adjusted relative risks (95% confidence interval [CI]) of all-cause death (with 7 h of daily sleep being considered for the reference group) for individuals reporting ≤ 5 h, 6 h, 8 h, and ≥ 9 h were 1.15 (0.91-1.45), 1.02 (0.85-1.25), 1.05 (0.88-1.27), and 1.43 (1.16-1.75); P for trend, 0.019. However, the relationship between sleep duration and risk of CVD were linear. The multivariate-adjusted relative risk (95% CI) for all-cause death (using individuals without insomnia) were 1.02 (0.86-1.20) for occasional insomnia, 1.15 (0.92-1.42) for frequent insomnia, and 1.70 (1.16-2.49) for nearly everyday insomnia (P for trend, 0.028). The multivariate adjusted relative risk (95% CI) was 2.53 (1.71-3.76) for all-cause death and 2.07 (1.11-3.85) for CVD rate in participants sleeping ≥9 h and for those with frequent insomnia.
Conclusions: Sleep duration and insomnia severity were associated with all-cause death and CVD events among ethnic Chinese in Taiwan. Our data indicate that an optimal sleep duration (7-8 h) predicted fewer deaths.
Keywords: Sleep, cohort study, cardiovascular disease

Prediction of Probabilistic Sleep Distributions Following Travel Across Multiple Time Zones

Study Objectives: To parameterize and validate a model to estimate average sleep times for long-haul aviation pilots during layovers following travel across multiple time zones. The model equations were based on a weighted distribution of domicile- and local-time sleepers, and included algorithms to account for sleep loss and circadian re-synchronization.
Design: Sleep times were collected from participants under normal commercial operating conditions using diaries and wrist activity monitors.
Participants: Participants included a total of 306 long-haul pilots (113 captains, 120 first officers, and 73 second officers).
Measurement and Results: The model was parameterized based on the average sleep/wake times observed during international flight patterns from Australia to London and Los Angeles (global R² = 0.72). The parameterized model was validated against the average sleep/wake times observed during flight patterns from Australia to London (r² = 0.85), Los Angeles (r² = 0.79), New York (r² = 0.80), and Johannesburg (r² = 0.73). Goodness-of-fit was poorer when the parameterized model equations were used to predict the variance across the sleep/wake cycles of individual pilots (R² = 0.42, 0.35, 0.31, and 0.28 for the validation flight patterns, respectively), in part because of substantial inter-individual variability in sleep timing and duration.
Conclusions: It is possible to estimate average sleep times during layovers in international patterns with a reasonable degree of accuracy. Models of this type could form the basis of a stand-alone application to estimate the likelihood that a given duty schedule provides pilots, on average, with an adequate opportunity to sleep.
Keywords: Sleep, model, time zones, aviation, pilots

PVT Lapses Differ According To Eyes Open, Closed, or Looking Away

Study Objectives: A lapse during the psychomotor vigilance task (PVT) is usually defined as a response longer than 500 ms; however, it is currently unknown what psychobiological phenomena occur during a lapse. An assessment of what a participant is doing during a lapse may depict varying levels of “disengagement” during these events and provide more insight into the measurement of both a lapse and sleepiness.
Design: Repeated measures
Setting: Participants underwent extended 30-min PVT sessions twice, at 22:00 and 04:00, under: (i) typical non-distractive laboratory conditions, and (ii) an additional distractive condition.
Participants: Twenty-four healthy young adults (mean age: 23.2 y ± 2 y; range 21-25 y [12 m; 12 f]) without any sleep or medical problems and without any prior indication of daytime sleepiness.
Interventions: One night of sleep loss. Distraction comprised a TV located at 90° in the visual periphery showing a popular TV program. For the non-distraction condition, the TV was turned off.
Measurements and Results: Video data (bird’s-eye and frontal view) were used to classify each lapse (≥500 ms) as occurring with eyes open (EO), eyes closed (EC), or due to a head turn (HT). EO lapses were more prevalent, with all lapses (EO, EC, and HT) increasing with sleepiness. There was a significant effect of distraction for HT lapses which was exacerbated when sleepy. For lapse duration there was little effect of sleepiness for EO lapses but a significant effect for EC and HT. The 95% confidence intervals for lapse duration and associated behavior showed those lapses greater than 2669 ms were 95% likely to be EC, whereas those 500-549 ms were 95% likely to be EO. Response times of 1217 ms had a 50:50 probability of being EO:EC.
Conclusions: Discriminating the varying causes of lapses whether due to visual inattention (eyes open), microsleep (eyes closed), or distraction (head turn) may provide further insight into levels of disengagement from the PVT and further insight into developing sleepiness.
Keywords: Lapse, PVT, sleepiness, distraction, behavior

Nocturnal Cerebral Hemodynamics in Snorers and in Patients with Obstructive Sleep Apnea: A Near-Infrared Spectroscopy Study

Study Objectives: Sleep disordered breathing (SDB) of the obstructive type causes hemodynamic consequences, leading to an increased cerebrovascular risk. The severity of SDB at which detrimental circulatory consequences appear is matter of controversy. Aim of the present study is the investigation of cerebral hemodynamics in patients with SDB of variable severity using near-infrared spectroscopy (NIRS).
Design: N/A.
Setting: Sleep laboratory.
Patients or Participants: Nineteen patients with SDB.
Interventions: N/A.
Measurements and Results: Patients underwent nocturnal videopolysomnography (VPSG) coupled with cerebral NIRS. NIRS data were averaged for each patient, and a new method (integral) was applied to quantify cerebral hemodynamic alterations. Nocturnal VPSG disclosed various severities of SDB: snoring (7 patients, apnea-hypopnea index [AHI] = 2 ± 2/h, range: 0.5-4.5); mild SDB (7 patients, AHI = 14 ± 8/h, range: 6.3-28.6); and severe obstructive sleep apnea syndrome (5 patients, AHI = 79 ± 20/h, range: 39.6-92.9). Relative changes of NIRS parameters were significantly larger during obstructive apneas (compared with hypopneas; mean deoxygenated hemoglobin [HHb] change of 0.72 ± 0.23 and 0.13 ± 0.08 μmol/L per sec, p value = 0.048) and in patients with severe SDB (as compared with patients with mild SDB and simple snorers; mean HHb change of 0.84 ± 0.24, 0.02 ± 0.09, and 0.2 ± 0.08 μmol/L per sec, respectively, p value = 0.020). In this group, NIRS and concomitant changes in peripheral oxygen saturation correlated.
Conclusions: The results of this study suggest that acute cerebral hemodynamic consequences of SDB lead to a failure of autoregulatory mechanisms with brain hypoxia only in the presence of frequent apneas (AHI > 30) and obstructive events.
Keywords: Sleep disordered breathing, cerebrovascular circulation, hemodynamics, near-infrared spectroscopy

Age-Related Reduction in Daytime Sleep Propensity and Nocturnal Slow Wave Sleep

Objective: To investigate whether age-related and experimental reductions in SWS and sleep continuity are associated with increased daytime sleep propensity.
Methods: Assessment of daytime sleep propensity under baseline conditions and following experimental disruption of SWS. Healthy young (20-30 y, n = 44), middle-aged (40-55 y, n = 35) and older (66-83 y, n = 31) men and women, completed a 2-way parallel group study. After an 8-h baseline sleep episode, subjects were randomized to 2 nights with selective SWS disruption by acoustic stimuli, or without disruption, followed by 1 recovery night. Objective and subjective sleep propensity were assessed using the Multiple Sleep Latency Test (MSLT) and the Karolinska Sleepiness Scale (KSS).
Findings: During baseline sleep, SWS decreased (P < 0.001) and the number of awakenings increased (P < 0.001) across the 3 age groups. During the baseline day, MSLT values increased across the three age groups (P < 0.0001) with mean values of 8.7min (SD: 4.5), 11.7 (5.1) and 14.2 (4.1) in the young, middle-aged, and older adults, respectively. KSS values were 3.7 (1.0), 3.2 (0.9), and 3.4 (0.6) (age-group: P = 0.031). Two nights of SWS disruption led to a reduction in MSLT and increase in KSS in all 3 age groups (SWS disruption vs. control: P < 0.05 in all cases).
Conclusions: Healthy aging is associated with a reduction in daytime sleep propensity, sleep continuity, and SWS. In contrast, experimental disruption of SWS leads to an increase in daytime sleep propensity. The age-related decline in SWS and reduction in daytime sleep propensity may reflect a lessening in homeostatic sleep requirement. Healthy older adults without sleep disorders can expect to be less sleepy during the daytime than young adults.
Keywords: Aging, insomnia, slow wave sleep, sleepiness, alertness

A 12-Week, Randomized, Double-Blind, Placebo-Controlled Study Evaluating the Effect of Eszopiclone 2 mg on Sleep/Wake Function in Older Adults with Primary and Comorbid Insomnia

Background: Longer-term pharmacologic studies for insomnia in older individuals are sparse.
Objective: To evaluate the efficacy and safety of 12 weeks of nightly eszopiclone in elderly outpatients with insomnia.
Methods: Participants (65-85 years) met DSM-IV-TR criteria for insomnia with total sleep times (TST) ≤ 6 h, and wake time after sleep onset (WASO) ≥ 45 min. Participants were randomized to 12 weeks of eszopiclone 2 mg (n = 194) or placebo (n = 194), followed by a 2-week single-blind placebo run-out. Subject-reported measures of sleep (sTST, sleep latency [sSL], sWASO) and daytime function (alertness, concentration, well-being, ability to function) were assessed. AEs were monitored.
Results: Subjects treated with 2 mg eszopiclone slept longer at night on average and at every individual time point compared to baseline than placebo subjects, as measured by TST over the 12-week double-blind period (P < 0.0001). Mean sTST over the double-blind period for eszopiclone-treated subjects was 360.08 min compared to 297.86 min at baseline, a mean change of 63.24 min. Over the double-blind period, eszopiclone-treated subjects also experienced a significantly greater improvement in sSL compared to placebo, with a mean decrease of 24.62 min versus a mean decrease of 19.92 min, respectively (P = 0.0014). Eszopiclone subjects also experienced a significantly greater decrease in WASO (mean decrease of 36.4 min) compared to placebo subjects (decrease of 14.8 min) (P < 0.0001). Post-discontinuation, sleep parameters were statistically improved versus baseline for eszopiclone (P-values ≤ 0.01), indicating no rebound. The most common AEs (≥ 5%) were headache (eszopiclone 13.9%, placebo 12.4%), unpleasant taste (12.4%, 1.5%), and nasopharyngitis (5.7%, 6.2%).
Conclusion: In this Phase IV trial of older adults with insomnia, eszopiclone significantly improved patient-reported sleep and daytime function relative to placebo. Improvements occurred within the first week and were maintained for 3 months, with no evidence of rebound insomnia following discontinuation. The 12 weeks of treatment were well tolerated.
Clinical Trial Information: A Long-Term Safety and Efficacy Study of Eszopiclone in Elderly Subjects With Primary Chronic Insomnia; Registration #NCT00386334; URL - http://www.clinicaltrials.gov/ct2/show/NCT00386334?term=eszopiclone&rank=24
Keywords: Eszopiclone, primary insomnia, elderly, sleep, next day function

Reduced Brain Gray Matter Concentration in Patients With Obstructive Sleep Apnea Syndrome

Study Objectives: To investigate differences in brain gray matter concentrations or volumes in patients with obstructive sleep apnea syndrome (OSA) and healthy volunteers.
Designs: Optimized voxel-based morphometry, an automated processing technique for MRI, was used to characterize structural differences in gray matter in newly diagnosed male patients.
Setting: University hospital
Patients and Participants: The study consisted of 36 male OSA and 31 non-apneic male healthy volunteers matched for age (mean age, 44.8 years).
Interventions: Using the t-test, gray matter differences were identified. The statistical significance level was set to a false discovery rate P < 0.05 with an extent threshold of k_E > 200 voxels.
Measurements and Results: The mean apnea-hypopnea index (AHI) of patients was 52.5/ h. On visual inspection of MRI, no structural abnormalities were observed. Compared to healthy volunteers, the gray matter concentrations of OSA patients were significantly decreased in the left gyrus rectus, bilateral superior frontal gyri, left precentral gyrus, bilateral frontomarginal gyri, bilateral anterior cingulate gyri, right insular gyrus, bilateral caudate nuclei, bilateral thalami, bilateral amygdalo-hippocampi, bilateral inferior temporal gyri, and bilateral quadrangular and biventer lobules in the cerebellum (false discovery rate P < 0.05). Gray matter volume was not different between OSA patients and healthy volunteers.
Conclusions: The brain gray matter deficits may suggest that memory impairment, affective and cardiovascular disturbances, executive dysfunctions, and dysregulation of autonomic and respiratory control frequently found in OSA patients might be related to morphological differences in the brain gray matter areas.
Keywords: Obstructive sleep apnea, Brain, Gray matter concentration, MRI, Voxel based morphometry

Dopamine Transporter Regulation during Four Nights of REM Sleep Deprivation Followed by Recovery – An in vivo Molecular Imaging Study in Humans

Objectives: To assess the influence of total or selective REM sleep deprivation on the dopamine transporter (DAT) densities and sleep patterns of healthy volunteers.
Design: Prospective study.
Setting: Evaluation of polysomnography recordings and DAT density after 4 nights of selective REM sleep deprivation followed by 3 nights of sleep recovery compared to a control group and a group that was subjected to 2 nights of total sleep deprivation. Single positron emission computed tomography and [^99mTc]TRODAT-1 were used to assess the cerebral DAT density in the striatum at baseline, after REM sleep deprivation and total sleep deprivation as well as after sleep recovery. Blood was collected daily to examine prolactin and estradiol levels, which were correlated with dopaminergic activity.
Patients or Participants: Thirty healthy male volunteers ranging from 19 to 29 years of age were randomly assigned to one of three experimental groups after giving written informed consent (10 non-sleep deprived, 10 total sleep deprived, and 10 REM sleep deprived).
Measurements and Results: Four nights of REM sleep deprivation and 2 nights of total sleep deprivation induced distinct and heterogeneous patterns of sleep recovery. No significant modulation of DAT availability was observed within groups. In the recovery nights, changes in cortisol, prolactin and estradiol concentrations were significantly correlated with specific sleep stages in the total and REM sleep deprived groups. In addition, DAT density was positively correlated with estradiol concentration and inversely associated with SWS latency only after total sleep deprivation.
Conclusion: Our study demonstrates that although sleep deprivation did not promote significant alterations in DAT density within the striatum, there were significant correlations among transporter availability, hormonal concentrations and sleep parameters.
Keywords: Sleep deprivation, recovery, SPECT, dopamine, prolactin, estradiol, rebound sleep, TRODAT

Sleep Disturbance, Daytime Sleepiness, and Neurocognitive Performance in Children with Juvenile Idiopathic Arthritis

Study Objectives: To compare daytime sleepiness and neurobehavioral performance in children with active and inactive juvenile idiopathic arthritis (JIA), and explore relations among measures of sleep disturbance, daytime sleepiness, and neurobehavioral performance.
Design: Cross-sectional, comparison.
Setting: A university-based research sleep laboratory.
Participants: Seventy (70) children 6-11 years of age with active or inactive JIA.
Measurements and Results: Self-reported daytime sleepiness, multiple sleep latency tests (MSLTs), and computerized neurobehavioral performance test scores were obtained after 2 nights of polysomnography. Children with active disease (mean physician global rating score = 2.9 ± 1.9 SD) showed shorter mean MSLT latency (15 ± 6.0 min) than those with inactive disease (16.5 ± 5.5 min, P < 0.03). Scores on neurobehavioral performance tests showed no group differences. However, number of wake bouts predicted sustained visual attention (rapid visual processing, P < 0.05) and apnea hypopnea index (AHI) predicted reaction time (P < 0.0001), after controlling for age, IQ, medication, and disease status.
Conclusion: Indices of sleep disturbance were associated with validated tests of neurobehavioral performance in JIA, regardless of disease activity. Additional research is needed about the extent of sleep disturbances in relation to neurocognitive performance in JIA and compared to healthy children.
Keywords: Juvenile idiopathic arthritis, polysomnography, neurobehavioral performance, daytime sleepiness

Evaluation of Sham-CPAP as a Placebo in CPAP Intervention Studies

Study Objectives: To evaluate the use of sham-continuous positive airway pressure (CPAP) treatment as a placebo intervention.
Design and Setting: Analysis of polysomnograms performed in fixed order without sham-CPAP and on the first night of the sham-CPAP intervention in participants in the CPAP Apnea Trial North American Program (CATNAP), a randomized, placebo controlled trial evaluating the effects of CPAP treatment on daytime function in adults with newly diagnosed mild to moderate obstructive sleep apnea (apnea hypopnea index (AHI) 5 - 30).
Participants: The first 104 CATNAP participants randomized to the sham-CPAP intervention arm.
Measurements and Results: Compared to the polysomnographic measures without sham-CPAP, the study on the first night with sham-CPAP had statistically significant differences that suggested a decrease in sleep quality: decreased sleep efficiency, increased arousal index, increased time in stage 1 NREM sleep, and prolonged latency to REM sleep. However, all of these differences had a relatively small effect size. Compared to the polysomnogram without sham-CPAP, the number of hypopneas on the sham-CPAP polysomnogram was significantly increased and the number of apneas significantly decreased. Relatively minor differences in AHI with and without sham-CPAP were present and were dependent on the criteria used to score hypopneas.
Conclusion: Comparison of polysomnograms with and without sham-CPAP revealed differences that, although statistically significant, were small in magnitude and had relatively low effect sizes suggesting minimal clinical significance. The results support the use of sham-CPAP as a placebo intervention in trials evaluating the effects of CPAP treatment in patients with obstructive sleep apnea.
Clinical Trial Information: This paper was a secondary analysis of clinical trial data. CATNAP: CPAP Apnea Trial North American Program, the trial from which the data were obtained, is registered with clinicaltrial.gov. Registration #NCT00089752.
Keywords: CPAP, randomized controlled trial, placebo, sham-CPAP, polysomnogram

Randomized Controlled Trial of Variable-Pressure Versus Fixed-Pressure Continuous Positive Airway Pressure (CPAP) Treatment for Patients with Obstructive Sleep Apnea/Hypopnea Syndrome (OSAHS)

Study Objective: To determine whether fixed-pressure or variable-pressure CPAP was preferred by patients and gave better outcomes in patients with the obstructive sleep apnea/hypopnea syndrome (OSAHS).
Design: Randomized blinded cross-over trial with 6 weeks of fixed and 6 weeks of variable-pressure CPAP
Setting: Sleep center
Patients: 200 consecutive consenting CPAP naïve patients with daytime sleepiness and >15 apneas + hypopneas/h after an attended auto-CPAP titration night.
Interventions: CPAP therapy using the same device (Autoset Spirit) set for 6 weeks in fixed pressure mode and for 6 weeks in variable pressure mode, the order of therapies being randomized.
Measurements and Results: All measurements were recorded at the end of each limb by a researcher blind to treatment. These included symptoms, Epworth Score, CPAP usage, objective sleepiness by modified Osler test, vigilance and health related quality of life. A total of 181 of 200 patients completed the study. At the end of the study, patients expressed no significant difference in the primary outcome, patient preference, 72 patients preferring fixed and 69 preferring variable-pressure CPAP. Epworth score was lower on variable (9.5, SEM 0.4) than fixed-pressure CPAP (10.0, SEM 0.3; p = 0.031). Mean CPAP use was higher on variable (4.2, SEM 0.2 h/night) than fixed-pressure CPAP (4.0, SEM 0.2 h/night; p = 0.047). There were no other significant differences between treatments.
Conclusions This study shows no difference in patient preference and only a marginal benefit of variable over fixed-pressure CPAP in OSAHS in terms of subjective sleepiness and CPAP use. The clinical value of this difference remains to be determined.
Clinical Trial Information: Variable-pressure versus fixed-pressure continuous positive airway pressure (CPAP) treatment for patients with obstructive sleep apnoea/hypopnoea syndrome (OSAHS); Registration # ISRCTN43085025; http://www.controlled-trials.com/ISRCTN43085025
Keywords: Variable pressure, fixed pressure, obstructive sleep apnea/hypopnea syndrome