Patient compliance and satisfaction with a new forehead device for positional obstructive sleep apnoea treatment: a post hoc analysis of a randomised controlled trial

Introduction

Obstructive sleep apnoea (OSA) is defined as a chronic multifactorial disease.1 It is characterised by recurrent complete or partial collapse of the upper airway during sleep2 and is a recognised risk factor for complications (cardio- and cerebrovascular diseases), poor quality of life or workplace and road accidents.3 4

Concerns have increased about an effective treatment, since the effects of untreated OSA are well described.4 Hygiene and dietary measures should be implemented in all patients with OSA, regardless of whether continuous positive airway pressure (CPAP) therapy is indicated. CPAP is an effective treatment to reduce OSA severity and remains the treatment of choice in OSA patients.5

However, the American Academy of Sleep Medicine also assumes that a significant proportion of patients are unable to tolerate CPAP therapy.6 In addition, the efficacy is limited by poor adherence or compliance and by side effects such as discomfort, airway dryness, skin irritation, claustrophobia, etc.4 Generally, the prevalence of non-compliant CPAP users is approximately 40%–50% in the long term.3 6 7

Despite these shortcomings, CPAP continues to stand as the first-line treatment for OSA.6 However, there is a growing interest in non-CPAP alternatives for patients diagnosed with mild or moderate OSA or for those who refuse conventional treatment.8 The influence of body position in OSA is well recognised, with the symptom severity being increased when patients are in the supine position.9–12 This effect is due to a posterior displacement of the tongue, favoured by gravity, which increases upper airway collapsibility,9 Moreover, decreased lung volume occurs in the supine position due to diaphragm displacement.9

The prevalence of positional OSA (POSA) varies approximately 50%–60%.9 13 POSA is defined as an Apnoea-Hypopnoea Index (AHI)≥5 events/hour and at least twice as high in the supine position as in other positions.1 10 Recently, interest in POSA has increased since a large percentage of patients may show significant improvements by simply changing their position during sleep.1 An increasing amount of literature is being published on the role of positional therapy (PT), including suggestions of strategies to prevent sleeping in the supine position.1 14

Some of these strategies are based on passive physical means, such as a bulky mass strapped to the patient’s back,12 special pillows12 or the tennis ball technique,12 15 which have been reported to be effective in reducing AHI.12 15 However, due to backache, shoulder pain, discomfort or no improvement in sleep quality or daytime sleepiness, there is poor compliance, and subsequently, disappointing long-term results for passive PT, with compliance rates between 10% and 40%.16 17

For this reason, new active devices (AD) for PT, whose action mechanism is based on vibratory stimuli,7 have been introduced into the therapeutic options for POSA management.15 18 The studies suggest that this therapy successfully prevents POSA patients from adopting the supine position and consequently reduces the AHI without negatively influencing sleep architecture and with better acceptance in the short and long term.19 20 In line with this trend, we developed a new forehead vibration-based device that has proven effective in the management of POSA patients.3 21

The main aim of this study was to evaluate the use and compliance of this forehead PT device in the short term and mid-term. The secondary aims were to analyse the effectiveness of the device in reducing time spent with the head in the supine position, to evaluate patient satisfaction and to identify possible side effects.

Methods

Results

The flow chart of the study is described in Hidalgo Armas et al,21 showing a total of 87 patients included in the two arms evaluated in this study: 44 in the ID group and 43 in the AD group. Nine patients were lost to follow-up in these groups (6 patients in the ID group: 3 lost to follow-up, and 3 withdrew consent; and 3 patients in the AD group: 2 lost to follow-up and 1 withdrew consent), resulting in 78 patients completing the 12-week follow-up. The anthropometric characteristics and baseline PSG data are shown in table 1. Patients were middle-aged (52.2±11.6 years), mostly men (79.3%), without somnolence (ESS of 6.6±3.3) and overweight (BMI 28.6±4.0 kg/m²). Both groups were comparable in all the evaluated parameters.

The median (IQR) global use of the device was 6.9 hours (5.8–7.6 hours) in the ID group and 6.7 hours (5.8–7.2) in the AD group (p=0.309) and similar in both groups throughout the 12 weeks (p>0.05, except in week 11 (p=0.048)) (figure 1A).

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When analysing these compliance data daily, during the first fourteen days of therapy, the median use of the device was similar in both groups (p>0.05), with values higher than 6.5 hours (figure 1B).

Additionally, the percentage of patients fulfilling the criteria for good compliance was greater than 60% during the entire follow-up period in both groups (figure 2A), with a mean value of 72.0 (±45.4%) for the ID group and 85.0 (±36.6%) for the AD group (p=0.194). During the first 6 weeks, the percentage of compliant patients was higher in the AD group than in the ID group, although these differences were only significant in the second and third weeks. During the second part of the follow-up period, both groups had a similar percentage of compliant patients. When analysing the percentage of patients with ‘optimal’ compliance, we obtained values above 57% in the AD group throughout the whole follow-up period (figure 2B).

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The median percentage of days per week using the device was similar between groups (p>0.05), with a median use of 91.4% (53.7%–99.7%) with ID and 89.4% (77.1%–96.8%) with AD (figure 3).

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The median global percentage of time in the supine position recorded by the forehead device was 12.4% (8.2%–21.3%) in the ID group and 2.9% (1.3%–4.9%) in the AD group (p<0.001) and was significantly lower (p<0.001) in the AD group since the first week (figure 4A).

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In addition, the median percentage of time in the supine position during the first 14 days was significantly lower in the AD group (p<0.001) than in the ID group, with values lower than 4% for the AD group and higher than 8% for the ID group. There were no remarkable changes during the first fourteen days of the study (figure 4B).

The results of the patient satisfaction survey at week 12 show mean values above 8.5 over 10 in all items evaluated, with low variability between patients and with no significant differences between the ID and AD groups (figure 5).

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Questionnaires about side effects showed no significant differences between groups in terms of discomfort, difficulty sleeping, morning headache and sweating, with incidence rates of 35.9%, 10.4%, 12.5% and 10.0%, respectively, in the AD group. The percentage of patients reporting awakenings during the night in the AD group (60.6%) was higher than that in the ID group (29.7%) (p=0.006). Conversely, 27% of patients reported skin irritation in the ID group with no cases in the AD group (p=0.002) (table 2). No additional side effects were reported.

Discussion

This study provides additional clinically relevant information to the previous validation study of a forehead PT device.21 The results show that the use hours, the percentage of nights used per week and the percentage of patients with good compliance were similar in both groups during the follow-up period. As expected, the percentage of time in the supine position was significantly lower in the AD group than in the ID group. No relevant side effects were reported, and patient satisfaction was high in both groups.

The median daily use of the device was higher than 6.5 hours/day in both groups, which is equivalent to other published studies with similar AD,8 17 19 22–27 where the mean/median daily use ranged from 7.6 hours/night at a month26 to 5.2 hours/night at 12 months.20 The fact that daily use was almost equivalent between the ID and AD patient groups provides confirmation that the device vibration was well tolerated and did not hamper the routine use of the device. These results are in line with our previous publication in which no differences in arousal index or sleep efficiency were observed between both groups during PSG at the end of the follow-up period.21

As expected, our forehead device was able to significantly reduce the time patients spent with their heads in the supine position in the AD group. This is in agreement with our previous publication,21 in which the AD group had a greater and significant reduction in the AHI and time in the supine position measured at the chest compared with the ID group, thus suggesting that applying the vibration at the forehead could be effective in changing both head and body position. Our results are not directly comparable to those of other studies, since all of them provide data on body position measured at the chest by PSG and not at the forehead. However, they reported similar reductions in the percentage of time in the supine position measured at the chest,13 17 24 28–30 although many of them had values higher than our results.1 9 19 20 23 25–27 31

The time spent in the supine position measured by the device at the forehead in the ID group (median 12.4%) was low compared with the value measured at the chest by PSG in our previous publication (mean 43.7%).21 Although not directly comparable, our findings are in line with the results of van Kesteren et al,32 who reported an overall 23% reduction in mean time spent with their heads in the supine position compared with their trunks in the supine position, but their heads turned sideways. Additionally, this reduction increased to approximately 55% in those patients in whom head placement in the supine position aggravated the severity of OSA.32 The reduction in time spent with patients' heads in the supine position compared with their trunks could be explained by a placebo effect, since the simple fact of placing the device on the forehead could induce the patients to modify their head position.

Likewise, it is necessary to highlight the role that head position plays in the reduction in the AHI, as has been shown in other studies2 32 33 in which an overall reduction between −5 and −10 events/hour in the AHI is observed when only the head is in lateral position. This reduction can be of a greater magnitude in less obese patients,2 such as POSA patients.3 Consequently, applying the stimulus at the head can provide beneficial effects, allowing a greater freedom of movement for patients to adopt different positions during sleep (especially for women who sleep more in the supine position).32 34 This could be very useful in the management of POSA patients who also suffer from musculoskeletal problems, especially shoulder and back pain, which has been reported as an adverse effect in other studies.17 28

Other devices that apply a vibration stimulus on the chest are designed to allow a training phase of 10 nights, in which the vibration activity increases progressively to gradually train the patient in avoiding the supine sleep position19 26 28; however, no data on the effect during the first nights have been previously reported. Our day-by-day analysis of the use time during the first 2 weeks of treatment revealed that patients in both the ID and AD groups used the device during the same time from the first day and that the use time was maintained relatively constant during the first 2 weeks and throughout the follow-up period. A similar behaviour was observed when analysing the percentage of time in the supine position on a daily basis; a reduced percentage of supine sleep in the AD group was also achieved from the beginning and with small variations during the follow-up period. These findings suggest that the therapeutic effect is obtained from the first night and that no training period is necessary. The earlier effect of the device avoids having patients undertreated during some days and is important for achieving a prompt reduction of symptoms.

Patients in both groups used the device the same percentage of days per week during the whole follow-up period (85.7%), which is in agreement with other studies ranging between 100% at a month13 17 and 69% at a year8 and suggests that the treatment is well tolerated at mid-term.

In this study, we analysed two different criteria for compliance. First, good compliance was defined as ≥4 hours/night and ≥70% of nights as CPAP criteria.5 We obtained high compliance rates in both groups, similar to other studies evaluated between 1 and 12 months of follow-up.8 17 19 25 31 Considering that when this criterion is applied to PT, it provides compliance rates higher than usual values for CPAP,6 it can be speculated that a more restrictive criterion could be more suitable in positional treatment for encouraging patients to adhere to therapy. Additionally, it has been reported that the effectiveness of treatment is directly related to the amount of therapy used.35 36 When considering ‘optimal’ compliance, we obtained compliance rates at 3 months with AD higher than values reported for CPAP at the same follow-up period.36 37 Other studies on PT have also used this criterion, although with lower compliance rates.24 This ‘optimal’ compliance criterion is in line with other studies that suggest that CPAP use of 5 hours/night is necessary to restore sleepiness to normal levels.35 36

Patients were satisfied with the device, rating all the studied items with values of 8.5 or higher over 10 in both groups. This positive evaluation is supported by the high daily use and the percentage of compliant patients compared with CPAP treatment.8 9 Other studies have shown similar positive patient satisfaction.25

No major side effects that required interruption of treatment were recorded. Minor side effects were described, being the most reported in both groups; frequent awakenings were significantly higher in the AD group (60%), although half of them reported this side effect less than once per week. This value is in line with other studies on similar devices reporting awakening rates between 61% and 78%,1 9 although higher than others.20 This could be explained by the intended effect of the vibratory stimulus for inducing a body position change that might be subjectively perceived, as reported in other studies.1 22 23 25 However, these awakenings did not translate into a worsening in subjective evaluation of device by patients (figure 5), in patient compliance (figure 4), or in objective measurements in macro and microstructure of sleep by PSG.21

Although a few patients reported skin irritation in the ID group, none of them required medical intervention, and all completed the study protocol. The differences between the two groups were attributed to chance.

Other side effects were reported occasionally. In other studies, side effects were also reported, such as discomfort, with rates between 17% and 29%,1 20 difficulty initiating sleep in 67%,1 or back or shoulder pain, with incidences ranging from 4% to 33%.1 13 23 25 Since our device allows patients to turn only their heads without turning their bodies, it could be useful for those patients with musculoskeletal problems.

Our study had the limitation of not having a simultaneous recording of the postural device with the sleep study by PSG, which supposes the difficulty of comparing the changes in head position with respect to body. In addition, the lack of consensus regarding the criteria for measuring position changes and their influence on treatment results for PT assumes an additional difficulty when comparing different treatment modalities.

Conclusion

This RCT showed that high compliance rates could be achieved with the use of the Somnibel device in patients with POSA, both in terms of use time and percentage of days used, with values above the usual compliance rates of CPAP treatment. The effect of the device is immediate from the first day and sustained over time, avoiding the need for an adaptation period. Patients were highly satisfied with the device use, and minor side effects were reported. These results reinforce the clinical utility of the device when considering the previously published data from this RCT in which a significant reduction in AHI, desaturation index and TST in the supine position was reported.21 In addition, the device increased TST and the percentages of time spent in the N3 and N3+REM phases without disturbing the patients’ sleep. This therapy could be very useful in the management of POSA regardless of its severity. Future studies are needed to evaluate its value when used in combination with other therapies or in other subgroups of POSA patients.