RESUMEN
INTRODUCTION: Obstructive sleep apnea (OSA) is a chronic disease with a high populational prevalence that is characterized as airway closure during sleep. Treatment is multidisciplinary and varies according to each case. Continuous positive airway pressure (CPAP), oral appliances, and surgery are the primary therapeutic options. Non-invasive conservative treatments such as sleep hygiene, positional therapy, physical exercises, and weight loss aim to reduce the worsening of the disease while being complementary to the invasive primary treatment. OBJECTIVE: To analyze the impact of non-invasive conservative therapies on the clinical manifestations of OSA syndrome (OSA), compared with other interventions. METHOD: This was a systematic review with meta-analysis. The searches were performed without filters for the time period, type of publication, or language. Randomized clinical trials on subjects over 18 years of age diagnosed with untreated OSA were included. Responses to non-invasive conservative treatment were compared with responses to the primary intervention. Primary outcomes were assessed using the Epworth Sleepiness Scale and/or Functional Outcomes of Sleep Questionnaire (FOSQ). RESULTS: A total of eight studies were included in the review. The heterogeneity of the effect was estimated at 89.77%. Six studies compared conservative treatment with CPAP, one with oral appliances, and one with oropharyngeal exercises. Using the Epworth Sleepiness Scale measurements, the standardized difference in the estimated means, based on the random-effects model, was 0.457 (95% CI (1.082 to 0.169)) and the mean result did not differ significantly from zero (z = 1.43; p = 0.153). The conservative therapies assessed in this study improved the subjective quality of sleep, although the post-treatment ESE scores did not show significant results. The reduction in AHI and better outcomes in the evaluated domains, as well as in cognition and mood, were superior in the groups that received CPAP and IOD. CONCLUSION: The most commonly used treatments of choice for OSA are invasive, including the use of CPAP, oral appliances, and surgeries, being the most utilized options. This study demonstrated that non-invasive conservative treatments, such as sleep hygiene, yield results as effective as invasive treatments. Further studies are needed to confirm this result and to predict whether invasive treatment can be used as the primary treatment or only as a supplement.