J Huazhong Univ Sci Technol [Med Sci] 33(5):623-627,2013 10.1007/s11596-013-1169-9 J DOI Huazhong Univ Sci Technol [Med Sci] 33(5):2013
623
Electrical Stimulation Therapy Improves Sleep Respiratory Parameters in Obstructive Sleep Apnea Syndrome: A Meta-analysis Jie-wen TAN (谭杰文)1#, Wei-wei QI (齐炜炜)2, Rui-xin YE (叶瑞心)1, Yuan-yuan WU (吴媛媛)1 1
Department of Rehabilitation, The Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China Faculty of Rehabilitation, Zhongshan Medical College, Sun Yat-sen University, Guangzhou 510089, China
2
© Huazhong University of Science and Technology and Springer-Verlag Berlin Heidelberg 2013
Summary: Recent clinical trials have shown that electrical stimulation has beneficial effects in obstructive sleep apnea syndrome (OSAS). The purpose of this study was to evaluate the efficacy of electrical stimulation therapy for OSAS with a meta-analysis. The meta-analysis of all relative studies was performed through searching international literature, including PUBMED, CNKI, and EMBASE databases. This literature analysis compared all patients undergoing electrical stimulation therapy with respect to the respiratory disturbance index (RDI) and changes in sleep structure. Six studies were selected involving a total of 91 patients. The meta-analysis indicated that electrical stimulation therapy reduced RDI, longest apnea time, and improved the minimum SaO2. Based on the evidence found, electrical stimulation may be a potential therapy for OSAS, warranting further clinical trials. Key words: obstructive sleep apnea syndrome; electrical stimulation; meta-analysis
Obstructive sleep apnea syndrome (OSAS) is a common disease that is characterized by respiration disturbances during sleep. The incidence of OSAS is higher in males than in females (4%–6% vs. 2%)[1]. The primary clinical manifestation is intermittent and repetitive obstruction of the upper respiratory tract leading to hypopnea or apnea. These chronic changes in sleep structure are associated with central nervous system and cardiovascular comorbidities[2]. Clinical evidence indicates that OSAS is associated with essential and resistant hypertension, cardiac rhythm perturbations (e.g., atrial fibrillation, bradyarrhythmias, supraventricular and ventricular arrhythmias), coronary artery disease, acute myocardial infarction, and heart failure[3]. Current therapeutic interventions for the management of OSAS include continuous positive airway pressure (CPAP), pharmacologic intervention, and surgery; however, few provide adequate patient satisfaction. Recent clinical trials using electrical stimulation in these patients have shown significant improvement and satisfaction[1, 2]. Theories for its mechanism of action are believed to be the result of activation of the genioglossus muscle. Contraction of this muscle moves the tongue forward, opening the pharyngeal cavity. Therefore, to evaluate the validity of this treatment we performed a meta-analysis to study the efficacy of electrical stimulation therapy for OSAS.
1 MATERIALS AND METHODS 1.1 Retrieve Strategy The literature search was limited to the databases PUBMED, EMBASE and CKNI beginning in 1980 and ending in June 2013. Key terms used in the search in#
Corresponding author, E-mail: [email protected]
cluded: “obstructive sleep apnea syndrome”, “electrical stimulation,” and “clinical research”. The language of the literature was not limited. Using these parameters, the search yielded 132 literature documents. 1.2 Inclusion and Exclusion Criteria The inclusion criteria included: (1) study design, public prospective observational studies or retrospective observational control studies investigating electrical stimulation as therapy for OSAS; (2) study population, patients who meet the diagnostic criteria for OSAS; and (3) results including the respiratory disturbance index (RDI) and changes in sleep structure (including frequency of apnea and oxygen saturation) before and after electrical stimulation therapy. According to the International Classification of Sleep Disorders, OSAS is defined as apnea-hypopnea index (AHI) >15/h in an asymptomatic patient or AHI >5/h in a patient with excessive daytime sleepiness or combining symptoms and an RDI ≥ 5 or an RDI ≥ 15 without symptoms[4]. Exclusion criteria included: (1) literature with no effective statistical data; (2) review articles. 1.3 Screening and Quality Evaluation Two independent evaluators performed data collection, extraction and quality evaluation. If controversy developed in the two evaluators, a third evaluator would participate in the process. Based on the Manuals of Cochrane System Evaluation[5] and the inclusion/exclusion criteria for this study, we implemented a quality evaluation rating scale[6] (table 1). We assessed all literature based on the following indexes: the study population (sample size and general conditions), study design, diagnostic and therapeutic effect criteria, interventions, statistical analysis, and follow-up. Each core item was graded according the following standard: 0 (did not meet the standard), 0.5 (partially met the standard)
624 and 1 (met the standard). 1.4 Statistical Analysis This study evaluated the efficacy of electrical stimulation as a therapy for OSAS using the indexes of RDI, longest apnea time and minimum oxyhemoglobin saturation (SaO2). Heterogeneity analysis of continuous variables was performed by Q-test. All data were analyzed using Meta Analysis Software Review Manager 4.2 and STATA version 12.0 statistical software. For statistical analysis, continuous data were calculated as the weight mean difference (WMD) with 95% confidence interval (CI). The results were analyzed in heterogeneity. Since the extracted data were successive type measurement data, heterogeneity was expressed by the Q test. We used the fixed effect model to summarize the accuracy index when P>0.1. When heterogeneity existed, the random effects model was utilized. Size of the test is α=0.1. Meta-analysis was used to obtain the accurate index and the 95% CI. 1.5 Biased Estimate Publication bias is a selection bias due to the direction and nature of the finding. Since researchers, evaluators and editors have preferences in submitting, accepting and publishing literature, a bias may result as a function of these parameters, potentially leading to adverse effects[7]. Therefore, potential publication bias was also assessed by both the Begg’s rank correlation test[8] and Egger linear regression test at P
623
Electrical Stimulation Therapy Improves Sleep Respiratory Parameters in Obstructive Sleep Apnea Syndrome: A Meta-analysis Jie-wen TAN (谭杰文)1#, Wei-wei QI (齐炜炜)2, Rui-xin YE (叶瑞心)1, Yuan-yuan WU (吴媛媛)1 1
Department of Rehabilitation, The Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China Faculty of Rehabilitation, Zhongshan Medical College, Sun Yat-sen University, Guangzhou 510089, China
2
© Huazhong University of Science and Technology and Springer-Verlag Berlin Heidelberg 2013
Summary: Recent clinical trials have shown that electrical stimulation has beneficial effects in obstructive sleep apnea syndrome (OSAS). The purpose of this study was to evaluate the efficacy of electrical stimulation therapy for OSAS with a meta-analysis. The meta-analysis of all relative studies was performed through searching international literature, including PUBMED, CNKI, and EMBASE databases. This literature analysis compared all patients undergoing electrical stimulation therapy with respect to the respiratory disturbance index (RDI) and changes in sleep structure. Six studies were selected involving a total of 91 patients. The meta-analysis indicated that electrical stimulation therapy reduced RDI, longest apnea time, and improved the minimum SaO2. Based on the evidence found, electrical stimulation may be a potential therapy for OSAS, warranting further clinical trials. Key words: obstructive sleep apnea syndrome; electrical stimulation; meta-analysis
Obstructive sleep apnea syndrome (OSAS) is a common disease that is characterized by respiration disturbances during sleep. The incidence of OSAS is higher in males than in females (4%–6% vs. 2%)[1]. The primary clinical manifestation is intermittent and repetitive obstruction of the upper respiratory tract leading to hypopnea or apnea. These chronic changes in sleep structure are associated with central nervous system and cardiovascular comorbidities[2]. Clinical evidence indicates that OSAS is associated with essential and resistant hypertension, cardiac rhythm perturbations (e.g., atrial fibrillation, bradyarrhythmias, supraventricular and ventricular arrhythmias), coronary artery disease, acute myocardial infarction, and heart failure[3]. Current therapeutic interventions for the management of OSAS include continuous positive airway pressure (CPAP), pharmacologic intervention, and surgery; however, few provide adequate patient satisfaction. Recent clinical trials using electrical stimulation in these patients have shown significant improvement and satisfaction[1, 2]. Theories for its mechanism of action are believed to be the result of activation of the genioglossus muscle. Contraction of this muscle moves the tongue forward, opening the pharyngeal cavity. Therefore, to evaluate the validity of this treatment we performed a meta-analysis to study the efficacy of electrical stimulation therapy for OSAS.
1 MATERIALS AND METHODS 1.1 Retrieve Strategy The literature search was limited to the databases PUBMED, EMBASE and CKNI beginning in 1980 and ending in June 2013. Key terms used in the search in#
Corresponding author, E-mail: [email protected]
cluded: “obstructive sleep apnea syndrome”, “electrical stimulation,” and “clinical research”. The language of the literature was not limited. Using these parameters, the search yielded 132 literature documents. 1.2 Inclusion and Exclusion Criteria The inclusion criteria included: (1) study design, public prospective observational studies or retrospective observational control studies investigating electrical stimulation as therapy for OSAS; (2) study population, patients who meet the diagnostic criteria for OSAS; and (3) results including the respiratory disturbance index (RDI) and changes in sleep structure (including frequency of apnea and oxygen saturation) before and after electrical stimulation therapy. According to the International Classification of Sleep Disorders, OSAS is defined as apnea-hypopnea index (AHI) >15/h in an asymptomatic patient or AHI >5/h in a patient with excessive daytime sleepiness or combining symptoms and an RDI ≥ 5 or an RDI ≥ 15 without symptoms[4]. Exclusion criteria included: (1) literature with no effective statistical data; (2) review articles. 1.3 Screening and Quality Evaluation Two independent evaluators performed data collection, extraction and quality evaluation. If controversy developed in the two evaluators, a third evaluator would participate in the process. Based on the Manuals of Cochrane System Evaluation[5] and the inclusion/exclusion criteria for this study, we implemented a quality evaluation rating scale[6] (table 1). We assessed all literature based on the following indexes: the study population (sample size and general conditions), study design, diagnostic and therapeutic effect criteria, interventions, statistical analysis, and follow-up. Each core item was graded according the following standard: 0 (did not meet the standard), 0.5 (partially met the standard)
624 and 1 (met the standard). 1.4 Statistical Analysis This study evaluated the efficacy of electrical stimulation as a therapy for OSAS using the indexes of RDI, longest apnea time and minimum oxyhemoglobin saturation (SaO2). Heterogeneity analysis of continuous variables was performed by Q-test. All data were analyzed using Meta Analysis Software Review Manager 4.2 and STATA version 12.0 statistical software. For statistical analysis, continuous data were calculated as the weight mean difference (WMD) with 95% confidence interval (CI). The results were analyzed in heterogeneity. Since the extracted data were successive type measurement data, heterogeneity was expressed by the Q test. We used the fixed effect model to summarize the accuracy index when P>0.1. When heterogeneity existed, the random effects model was utilized. Size of the test is α=0.1. Meta-analysis was used to obtain the accurate index and the 95% CI. 1.5 Biased Estimate Publication bias is a selection bias due to the direction and nature of the finding. Since researchers, evaluators and editors have preferences in submitting, accepting and publishing literature, a bias may result as a function of these parameters, potentially leading to adverse effects[7]. Therefore, potential publication bias was also assessed by both the Begg’s rank correlation test[8] and Egger linear regression test at P
