The relation between OSA and mood disorders has been clearly described [4, 25], highlighting an association between depression and OSA [26]. Several proposed mechanisms link OSA and depression, including a disrupted sleep architecture and intermittent episodes of hypoxemia, which can cause an imbalance in neurotransmitters that impair various neuropsychological and affective domains such as mood [27,28,29]. Previous studies have evaluated the impact of treatment of OSA on mood symptoms, but results indicated a high level of bias in the studies used [30]. Therefore, there is a gap in knowledge about the influence of treatments for OSA on mood symptoms. Previous systematic reviews have tried to address the role of CPAP in depressive symptoms in patients with OSA [31, 32], but their results were limited [26]. We synthesized data from approximately 3488 participants, and we explored the effect of OSA treatments on depression. Our SR-MA concluded that improvement in PROMs depression score is seen in the CPAP and the surgery groups as well as compared its impact to CPAP therapy on depression in adults.

Our focus was on the effect of treatments on depression. Our study also examined how these treatments helped improve polysomnographic metrics in OSA patients. Previous studies have used a reduction of AHI as one of the metrics for treatment efficacy [33, 34]. Our meta-analysis showed a significant reduction in AHI in both treatment groups. When we investigated the percent reduction in our study, a bigger reduction was seen in the CPAP group, but it was not significantly different. CPAP remains the gold standard in managing symptoms in OSA, demonstrating a more pronounced improvement in AHI than with surgical interventions. This reduction in AHI supports previous findings from SR-MA about the efficacy of CPAP over other treatments in OSA patients, yet tolerance is a big pitfall [35]. However, other non-randomized studies that compared the efficacy of surgical intervention versus CPAP have found that surgical interventions might result in a bigger reduction in AHI [36, 37]. In a randomized clinical trial by MacKay et al., reported that patients who underwent combined palatal and tongue surgery had reduced number of apnea and hypopnea events and ESS scores at 6 months when compared to patient with medical management [36]. We have also shown the superiority of surgery in health care utilization; [10] including inpatient, outpatient services and pharmaceuticals. Similarly, while CPAP and surgery groups improved clinically relevant outcomes, surgery was shown to have a superior benefit in the long term, which could be attributed to compliance [9]. It is crucial to acknowledge the variability in surgical interventions encompassed in our study, ranging from UPPP to HNS and MMA. The heterogeneity in surgical techniques likely contributes to the observed differences in AHI outcomes. It is crucial to identify different OSA phenotypes when considering various surgical options. Surgical interventions significantly reduce AHI and result in a significant percent reduction, similar to CPAP, suggesting their role in addressing OSA in non-CPAP adherent patients alongside improving subjective outcomes. Another important point is that AHI as an outcome might not be the best metric to evaluate OSA severity [38]. The comparable reduction in AHI and depression PROMs highlights this fact.

The ESS is a subjective marker for daytime sleepiness and overall sleep quality. While both CPAP and surgical interventions improved ESS scores, both reductions were similar reporting no difference in this subjective outcome between treatments. Our study’s findings are similar to other systematic reviews, which stated that treatment of OSA leads to a reduction in ESS [32, 39, 40], as a marker of daytime sleepiness that subsequently improves patients’ quality of life [41, 42].

In this study, our primary goal was to evaluate the impact of sleep surgery on depression that significantly affects patients’ mental health and overall well-being [25]. Intriguingly, both CPAP and surgical interventions demonstrated comparable reductions in depression scores. The comparable improvement in depression scores in both groups prompts a reevaluation of the relationship between physiological improvements and mental health outcomes in OSA management. It suggests that while CPAP might help physiological parameters, surgical interventions can exert a comparable impact on the mental health of individuals with OSA. This could be explained by the longevity of surgery results and CPAP intolerance leading to sleep disruption.

Our study demonstrates that surgical interventions for OSA are not inferior to continuous CPAP therapy, particularly in improving depressive symptoms. Non-inferiority analysis was conducted to compare the effectiveness of both treatments [43]. Notably, the BDI-II scores also improved significantly in both groups, highlighting that the higher mean difference in depression score reduction with surgery did not reach statistical significance (p = 0.55). These findings advocate for considering surgical interventions as a viable alternative to CPAP, particularly for patients who experience difficulties with CPAP adherence with or without mood disorders. The comparable effectiveness in both objective and subjective outcomes underscores the potential of surgical interventions to address both physiological and psychological aspects of OSA, supporting a more individualized and patient-centered approach in clinical practice.

These findings have substantial implications for clinical practice, advocating for a more holistic approach to OSA management that considers all aspects of the condition. Physicians shouldn’t just prioritize improvement in physiologic metrics like AHI and recognize that patient-reported outcomes and mental health affect patients’ symptoms. A higher percent reduction in reduction in depression scores in surgical groups prompts a reevaluation of the hierarchy of treatment modalities, emphasizing the need to tailor interventions to individual patient phenotypes, needs, and preferences. When adherence to CPAP is a challenge, it should be recognized that surgical interventions are potential treatments that can address both subjective and objective aspects of the condition [44,45,46,47]. The concept of mean disease alleviation which integrates both efficacy and adherence as a true measure of therapeutic effect, becomes more meaningful here. Of note, while both groups reached a significant reduction in their BDI-II scores, they also achieved more than the minimum clinically important difference known to be more than 17.5% reduction. However, the difference between both groups barely reached that difference (M = 10%) [48].

Despite the comprehensive nature of our study, several limitations should be acknowledged. The heterogeneity in surgical interventions, varying follow-up periods after both CPAP and surgery, and differences in depression measurement tools pose challenges in synthesizing results. One limitation of this study is the disproportionate contribution of a single large trial to the analysis of depression scores in the CPAP group. Of the 3488 patients included in the meta-analysis for depression outcomes, 3100 were derived from one study. This concentration of data from a single source introduces potential bias and limits the generalizability of the CPAP findings. The large sample size from this study could disproportionately influence the overall effect size, making the results more reflective of that specific population rather than a diverse representation across multiple studies. To mitigate this, we applied appropriate weighting in the meta-analysis, but we acknowledge that this remains a notable limitation. Future studies should aim to include a broader range of trials with more balanced sample sizes to provide a more comprehensive evaluation of depression outcomes in patients with OSA. In addition, non-specific sleep symptoms might falsely elevate patient scores on depression PROMs. Popular scales, such as the BDI, have questions related to sleep symptoms such as insomnia and fatigue that are common among both OSA and psychiatric conditions. However, BDI has demonstrated high internal consistency and reliability in various medical settings, indicating that it can reliably measure depressive symptoms across different clinical populations [49, 50]. A study by Aloia et al. suggests that the BDI-II scale effectively captures depressive symptoms despite the overlap with somatic symptoms of OSA [50]. Another limitation of our study is the lack of consistent data on CPAP adherence across the included studies. While adherence to CPAP is a critical factor influencing treatment efficacy, especially in improving both AHI and depressive symptoms, it was not uniformly reported, limiting our ability to fully assess its impact on the results. Additionally, baseline variables such as body mass index (BMI), which is known to affect both OSA severity and treatment outcomes, were inconsistently reported across studies. This prevents a more detailed sub-analysis of how BMI or other baseline characteristics may influence the efficacy of CPAP or surgical interventions in reducing depressive symptoms. Future studies should aim to collect and report data on adherence and baseline variables more consistently to better understand their role in treatment outcomes. Other limitations include lack of data on co-morbid conditions, medication use, and hypoxic burden (like oxygen-desaturation index), as these factors can also have an impact on depression. In addition, the CPAP group had more severe OSA at baseline as compared to the surgical group, which could potentially have an impact on the degree of improvement that can be produced in subjective symptoms with long-standing severe OSA. Thus, we added the AHI percent reduction to account for this limitation.

It is important to note that culture significantly influence depression, affecting symptom presentation and the acceptance of mental health diagnoses. Our study included data from various cultural contexts, encompassing Eastern and Western populations. For instance, in Western cultures, depression is commonly characterized by psychological symptoms, whereas in many Eastern cultures, it tends to manifest more through somatic symptoms [51]. Including both cultural perspectives in our study is crucial to enhance its generalizability and applicability across diverse populations.

Future research should explore the impact of specific surgical procedures, stratify by severity of OSA, and evaluate long-term mental health outcomes. This can provide insights into which treatment is more appropriate for certain patients. Furthermore, investigating the role of individual patient characteristics and preferences in treatment outcomes can contribute to developing personalized treatment algorithms and provide more precision medicine in OSA.