Telephone follow-up as a substitute for standard out-clinic follow-up in CPAP therapy for obstructive sleep apnea patients: a randomized controlled trial

Obstructive sleep apnea (OSA) is a common and underdiagnosed sleep disorder, characterized by intermitted breathing pauses during sleep due to partially or complete collapse of the upper airway tissue [1‐3]. This condition results in a fragmented sleep pattern, exerting a profound impact on the physical and mental health of the individual with OSA. OSA is associated with the risk of cardiovascular disease, stroke, type 2 diabetes, depression, cognitive impairment, and the risk of car accidents during driving. Left untreated, OSA escalates the risk of mortality [1, 2]. Risk factors contributing to the development of OSA are male sex, increasing age, obesity, craniofacial differences, ethnicity, and genetic predisposition [3, 4]. The estimated prevalence of symptomatic OSA consisting of daytime sleepiness and snoring are 4% for men and 2% for women in Denmark [5]. The diagnostic criterion for OSA is the apnea–hypopnea-index (AHI), which measures the average apnea and hypopnea periods per hour of sleep. OSA is classified in mild (5–14 AHI), moderate (15–29 AHI) and severe (≥ 30 AHI) categories [6].

Continuous positive airway pressure (CPAP) therapy during sleep is the gold standard treatment for OSA [7]. The essence of CPAP therapy comprises delivering a consistent airflow through a mask, ensuring the upper airway remains unobstructed [8]. However, the efficacy of CPAP therapy materializes only when individuals consistently use the device, emphasizing the necessity for long-term treatment commitment [7]. Despite the proven clinical benefits of CPAP in OSA treatment, a significant challenge arises in adherence. Research indicates that 30% to 86% of individuals with OSA underutilize or entirely disregard their CPAP therapy. This nonadherence is attributed to discomfort during device use or a perceived lack of effectiveness [9, 10]. In the Danish context, almost half of individuals initiating CPAP therapy discontinue within the first year [11]. Addressing these adherence barriers is crucial in ensuring its effectiveness in the long-term management of OSA.

The demographic challenges looming over Denmark forecast a surge in activity within specialty out-clinics. Though, resources are not proportionally increasing, leaving the hospitals under pressure [12]. In response to this imbalance, telemedicine emerges as a necessary solution for innovating the healthcare system [7, 9]. In recent years multiple international studies has investigated telemedicine´s potential to enhance CPAP adherence for individuals with OSA. These studies explore various interventions, from automated feedback messages and continuous telemonitoring to telephone consultations and online education programs [1, 7, 13‐15]. The present study aims to:

This prospective, assessor blinded, (1:1) randomized controlled trial was initiated and conducted at the pulmonary clinic, Vejle Hospital, Denmark.

In this randomized study, allocation to telephone follow-up consultations indicated a slight non-significant decrease in CPAP adherence compared with the standard out-clinic follow-up consultation. When measuring adherence as average minutes of CPAP use, no significant difference emerged between the groups.

While this study aligns with other studies demonstrating no minute-based differences [7, 13, 19], a meta-analysis suggested telemonitoring devices with active features could impact positively on adherence to CPAP therapy [20]. Another study only showed a significant increase in adherence within the first months, whereafter adherence became non-significant in the evaluation after 12 months [21]. Unlike the present study, previous studies incorporate more active telemonitoring devices, utilizing automated messages or continuous personnel contact to address non-adherence effectively [1, 7, 13, 14]. In contrast, our study relied solely on telephone consultations as substitute for in-person visits, supplemented by the Airview™ function for data collection during consultations. This makes direct comparison challenging. However, the meta-analysis highlight the potential efficacy of other, more actively involved telemedicine interventions to increase CPAP adherence [20].

In relation to the present study, it is relevant to contemplate the role of telephone consultations in fostering increased adherence. Notably, our study did not incorporate ‘active’ interventions aimed at influencing participants towards enhanced adherence, such as automated messages or outpatient clinic phone calls for nonadherent individuals. The primary outcome revealed no significant difference in adherence to CPAP therapy between the TC and SC group. However, a higher proportion of participants in the TC group demonstrated compliance with consultations compared to the SC group. It is likely that non-adherent participants in the SC group may have been more inclined to withdraw from the study to avoid follow-up consultations. In contrast, the TC group encountered a considerably less intrusive action on their everyday life through telephone calls. This circumstance likely contributed to the higher completion rate in the TC group although resulting in a diminished utilization of CPAP devices. This observation is supported by a study [22], which indicated that participants viewed video consultations favorably as a substitute for face-to-face consultations, due to convenience and time efficiency. Nevertheless, as highlighted in the previously mentioned study [22], it is important to note that some participants express a preference for face-to-face consultations, and others encounter technical difficulties with video consultations. These factors could potentially influence our study outcomes, particularly considering that the SC group had a median of fewer additional consultations than the TC group, though not statistically significant. This underpins that telemedicine cannot completely replace face-to-face consultations [22], emphasizing the dependency on individual patient preferences and treatment-related issues.

The varying results across our study and others using telemedicine interventions may originate from various determinants influencing adherence and non-adherence. Notably, participants who completed the study exhibited a significantly higher baseline AHI compared to those who dropped out, suggesting that a high AHI may increase the likelihood of patient adherence to treatment. A sub-analysis was conducted to examine adherence among patients categorized into mild, moderate, and severe obstructive sleep apnea (OSA) groups. It was observed that adherence rates measured in percentage improved progressively from the mild to the moderate and then to the severe OSA groups, in the unadjusted analysis. However, this trend reached statistical significance (p = 0.016) only when considering the entire cohort of participants. When the analysis was confined to either TC or SC groups individually, significance was not achieved, possibly due to the smaller size of these subgroups. This finding aligns with a Danish longitudinal study [11], which identified a positive association between severe AHI and increased adherence to CPAP use. While the literature recognizes the impact of perceived effectiveness and treatment side effects on adherence [9], our study did not specifically address these determinants in the interventions comparing adherence between TC and SC. Our findings showed that using TC as a substitute for SC might retain patients in the out-clinics. This observation is supported by Woehrle et al. 2017 who found that a telemedicine-based proactive strategy using the Airview™ device for the management of patients receiving PAP therapy, had a decreasing effect on the therapy termination rate over time, regardless of gender, device used and insurance type [23]. Having the ability to retain patients in treatment, might after all provide a foundation for offering patients other interventions that contribute to increased adherence to CPAP therapy.

The study found that TC did not affect adherence to CPAP therapy compared to SC significantly, and thereby might be considered as an alternative to in-person consultations to some extent. We found a higher compliance rate for follow-up consultations among participants in the TC group. This suggest that substituting TC for SC might retain patients in the outpatient clinics, which could serve as a basis for providing additional interventions to patients that support better adherence to CPAP therapy. Furthermore, the only influencing factor found was a higher baseline AHI among participants who completed the study compared to dropouts, indicating that a high AHI may increase the likelihood of patient adherence to therapy.