Introduction
Obstructive sleep apnea (OSA) is characterized by loud snoring interspersed with periods of more than ten seconds of silence during sleep.1, 2 This occurs due to intermittent upper airway collapse or narrowing during sleep leading to hypoxemic and hypercapnic conditions. These may ultimately cause activation of the sympathetic nervous system, excessive daytime sleepiness, and cognitive impairment. Consequently, the patient’s quality of life is drastically affected and the risk of developing cardiovascular or endocrinal disorders may lead to early mortality.3
The disorder can affect patients of all age groups and genders,4 but the prevalence is highest among males aged 40 to 65 years.5 Traditionally, polysomnography (PSG) or an overnight sleep study in an attended setting such as a sleep laboratory has been used as a reference standard for the diagnosis of OSA.6 It determines the apnea-hypopnea index (AHI) which is the number of obstructive airway episodes per hour of sleep. AHI or Respiratory Disturbance Index (RDI)hour is considered 515≥30/hour indicates severe OSA.7
Continuous positive airway pressure (CPAP) is currently considered to be the first-line treatment for OSA in adults. 8 but variable patient compliance is the major drawback of the efficacy of CPAP. Only 30 to 70 % of patients adhere to the CPAP therapy and patients abandon the therapy midway. 9, 10 Owing to the high drop-out rate and intolerance to CPAP, there was a need to seek alternative and more radical treatment modalities.
Surgical treatment of OSA is recommended for patients who have certain anatomical problems (for example, enlarged tonsils) or it may be used as a “salvage” treatment option for patients who are not compliant with CPAP. The various surgical modalities for the management of OSA patients include tracheostomy, Uvulopalatopharyngoplasty (UPPP), Uvulopalatoplasty, laser-assisted Uvulopalatoplasty, Maxilla-Mandibular Advancements, Radiofrequency Ablation, Geniohyoid Muscle Advancement along with Hyoid Suspension.
In the present systematic review, we have looked into the various surgical modalities used for the treatment of OSA and their success on the basis of pre-operative and post-operative AHI.
Materials and Methods
Studies conducted from June 2000 – June 2020 on OSA patients treated by surgery in the age group of 20-65 years and evaluating the impact of surgery on AHI and RDI on Adult OSA Patients were included. Studies were limited to randomized and non-randomized clinical trials, retrospective studies, and review articles. Descriptive studies, case reports, and series were excluded. The systematic review protocol is registered on the PROSPERO database (Reg ID: CRD42020153323).
Search strategy
A systematic search was performed across the databases PubMed via MEDLINE, Google Scholar, and Cochrane Central Register of Controlled Trials till June 2020, using the keywords “Sleep Apneoa” AND “Surgery.” Cross-references from the included articles were scanned for any additional relevant studies. The overall selection process of the articles is depicted in Figure 1.
Data extraction
Two groups of authors (AC, SR, and SS, MW) extracted data independently based on the Data Extraction Template from Cochrane Reviews. Any disagreement was resolved by mutual understanding between the authors. Information related to individual study, including the name of the author, country year, description of the population, sample size, study design, method of randomization, intervention, and details of the eligibility criteria were recorded. AHI was the primary outcome measured. The risk of bias in the included studies was evaluated using the Cochrane collaboration's risk of bias tool. The aspects of included articles that could potentially introduce bias such as randomization, allocation concealment, and blinding were recorded by two independent authors (KW and JL).
Statistical analysis
Heterogeneity was assessed using Cochrane’s Q and I2 statistics. Constant continuity corrections of +1 were performed in case of no events in both test and control groups. Random-effect meta-analysis was performed using the DerSimonian–Laird estimator of variance. As a sensitivity analysis, a fixed-effect meta-analysis was performed using the Mantel–Haenszel method. Risk ratios and 95 % confidence intervals (95 % CI) were calculated as effect estimates. Metanalysis was performed using SPSS v 21.0 (IBM), Epi info v 7.1 (CDC, WHO), Medcalc v 12.5.0.0 (Osteend, Belgium). and GraphPad Prism v. 6.1 and a few online available resources for measuring Heterogeneity and quality checks of individual articles, guidelines like Consort, PRISMA, QUOROM, and MOOSE.
Results
The initial search in June 2020 of electronic databases yielded 196 unduplicated articles, which were assessed independently. Based on the abstracts and titles, these were reduced to 17 relevant articles. The main reasons for the exclusion of these articles were lack of clarity of the procedure, study design and outcome, quality issues, and completeness of data.
All the 17 manuscripts identified as relevant to our question were searched for full-text and analyzed for inclusion independently by review authors. Table 1, Table 2 show a summary of the findings of our review. Two manuscripts were relevant for meta-analysis (Figure 2). According to our meta-analysis, the SMD was 0.207, which indicates that the treatment group had a more beneficial outcome as compared to the control group.
Discussion
Due to its poor compliance, CPAP is no longer used after a one-year post-prescription. Hence, different surgical modalities for the management of OSA have gained a large footprint with data to support its use. Surgeons also need to consider individual variations in anatomy and also the financial capability of each patient while tailoring their treatment plan. Varying degree be easily performed by surgeons in their routine practice. While each procedure has its own advantages and shortcomings, selecting the most appropriate one is a matter of personal judgment and expertise.11 There is no standard protocol for reconstruction of upper airways accepted by all surgeons globally. Plentiful research has been done in evaluating and comparing different surgical treatment modalities in OSA patients.
Table 1
Summary of included studies with baseline characteristics
Table 2
Methods and results of the included studies
Our meta-analysis compared the pre-operative baseline parameters of various studies and the difference in the post-surgical outcomes. Overall, AHI is significantly improved by surgical treatment of OSA. Kuhlo et al. first described the surgical method for the successful treatment of OSA while Fujita et al. advocated UPPP.12, 13 The success rate of UPPP was, however, 50% at most. The airway collapsibility resulting in failure of UPPP iobstruction of the tongue base, palate, and hypopharynx.14 soft palate and base of the tongue a UPPP and Anterior Mandibular Osteotomy with Genioglossus Muscle Advancement and Hyoid Suspension,has yielded successful results in almost all the cases.15 authors. 16, 17 less than 10.35.18
OSA is a cumulative result of a complex interaction between multiple factors and thus, the treatment modalities continue to evolve along with an increased understanding of the subject. Aggressive procedures are not preferred by patients or even surgeons, owing to the associated risk of additional morbidity. Various site-specific procedures have been developed as adjuncts to surgery in order to improve the success rate. 19 Multiple sites of obstruction such as nose, palate, lingual tonsils, supraglottic, and tongue base may be present in the patients and can be treated satisfactorily. 20, 21 The ultimate goal is to achieve a large and patent upper airway. There is yet, a paucity of comparative studies assessing the effectiveness of these approaches in correcting the upper airway.
The results of our meta-analysis provided some insight into the superiority of results produced based on the differences achieved in the AHI. However, since the data in all the included studies is quite heterogenous, as indicated by statistical tests, the reliability of this comparison should only be considered with caution. This would imply that even the studies using the same surgical techniques would yield heterogeneous data in terms of measured outcomes. Thus, a potential limitation of our systematic review is the relatively less amount of homogeneous data from included studies.
Although surgical interventions for OSA were introduced more than three decades ago, there are still only a few randomized control trials with long-term clinical follow-up available pertaining to the subject. Without adequate evidence, it may not be possible to determine the mortality rate associated with the different surgical procedures. A mortality rate of 0.2% following Uvulopalatopharyngoplasty was reported by Kezirian et al. in 2004 along with serious postoperative complications in 1.5% of the patients. 22, 23
A Funnel plot has been included to examine the risks of publication bias across all studies comprising the assessment of AHI using different surgical techniques for the treatment of OSA patients (Figure 3). Overall, there appears to be some bias in the large studies that reported poor treatment outcomes. It may be of use to include data from sources than randomized trials, such as observational studies, when seeking to predict the probability of adverse effects.
Conclusion
In conclusion, the heterogenous and limited nature of studies regarding surgical treatment of OSA renders it difficult to compare their superiority in different aspects such as patient acceptability, success rate, efficiency, and mortality rate. Our meta-analysis indicated that the treatment group had more beneficial outcomes as compared to the control groups across all the different surgical modalities for the treatment of OSA. The surgical procedures would definitely improve the sleep schedule and overall quality of life for OSA patients.
