Reply to letter: "RE: Association of obstructive sleep apnea with non-alcoholic fatty liver disease in patients with obesity: an observational study"

Effects of obstructive sleep apnea on non-alcoholic fatty liver disease in patients with obesity: a systematic review

INTRODUCTION

Obesity has been linked to non-alcoholic fatty liver disease (NAFLD), a widespread chronic liver ailment, as well as obstructive sleep apnea (OSA). The development of NAFLD is influenced by repeated intermittent hypoxia, a feature of OSA.

METHODS

This systematic review (SR) investigated CENTRAL, PubMed, and EMBASE databases. The endpoint of this SR was to assess which OSA-related indicators could predict the presence of NAFLD and the effect of bariatric metabolic surgery (BMS) on improving OSA and NAFLD over time.

RESULTS

Compared to previous SRs published in 2013, 14 new publications were added to our SR, alongside studies conducted prior to 2013. The SR ultimately included 28 studies (18 cross-sectional and 10 cohort trials). In the majority of studies, significant correlations were observed between OSA, OSA-related outcomes, and NAFLD. However, the apnea-hypopnea index (AHI) alone proved to be an inadequate predictor of NAFLD. Instead, respiratory and metabolic changes were found to alleviate oxidative stress induced by hypoxemia. Six studies involved patients who underwent BMS, with one evaluating patients before and after BMS, revealing associations between increased OSA and NAFLD improvement following BMS. Six months after surgery, 100% of patients in the mild-to-moderate OSA group were free from fatty liver, and an 89% reduction was observed in the severe OSA group.

CONCLUSION

For the first time, BMS has been tested in treating both OSA and NAFLD pre and postoperative with positive results. Further research, ideally with histological and functional data, is needed to confirm these findings. The SR identified 14 distinct liver outcome tests; however, high heterogeneity and incomplete data precluded a meta-analysis. It is imperative to pay greater attention to the influence of OSA-related factors and uniformity in liver outcomes testing concerning NAFLD. To accomplish this, study designs should be enhanced by incorporating more comprehensive pre- and postoperative evaluations, extending follow-up periods, and employing a more consistent methodology for liver diagnosis in patients with obesity.

Updating obesity management strategies: an audit of Italian specialists

Obesity negatively affects physical and psychological health and increases health care costs. Although there is increasing interest in early diagnosis and timely intervention, there are several principles of care included in the current guidelines for clinical management of obesity that can potentially be updated and improved to address the "clinical inertia" and, consequently, to optimize the management of adult obesity. Using an online Delphi-based process, an Italian board of experts involved in the management of obesity discussed the usefulness of a pro-active approach to the care of patients with obesity, providing a consensus document with practical indications to identify risk factors for morbidity and death and raise awareness throughout the treatment continuum, including the early stages of the disease. In clinical practice, it seems inappropriate to delay an intervention that could avoid progression to a more severe level of obesity and/or prevent the onset of obesity-related comorbidities.Level of evidence Level V, report of expert committee.