Factors influencing adherence to oral appliance therapy in adults with obstructive sleep apnea: a systematic review and meta-analysis

Abstract

Study objectives: The review aimed to identify the factors influencing adherence to oral appliance therapy in adults with obstructive sleep apnea.

Methods: The protocol was initially registered with the International Register of Systematic Reviews (Prospero: CRD42019122615) prior to undertaking a comprehensive electronic search of databases and references without language and date restrictions. Quality assessment was undertaken using the Cochrane Collaboration's risk of bias tool and Quality in Prognosis Studies (QUIPS) tool.

Results: Studies exhibited low or unclear risk of bias for the domains assessed by the respective quality assessment tools. The influence of independent variables such as disease characteristics, patient characteristics, appliance features, and psychological and social factors on adherence levels was also assessed. There was a total of 31 included studies, which consisted of 8 randomized controlled trials, 2 controlled clinical trial, 7 prospective cohorts, 11 retrospective cohorts, and the remaining 3 studies were a case-series, case-control, and a mixed-methods. All 31 included studies were subject to qualitative analysis, with only 4 studies included in the quantitative analysis. Results of the meta-analysis demonstrated increased adherence with custom-made appliances, with a pooled mean difference of -1.34 (-2.02 to -0.66) and low levels of heterogeneity (I² = 0%).

Conclusions: A weak relationship was observed between objective adherence and patient and disease characteristics, such as age, sex, obesity, apnea-hypopnea index, and daytime sleepiness, to oral appliance therapy. Nonadherent patients reported more side effects with oral appliance therapy than users and tended to discontinue the treatment within the first 3 months. Custom-made oral appliances were preferred and increased adherence reported in comparison to ready-made appliances. Further research is imperative to examine the relationship between psychosocial factors and adherence to oral appliance therapy.

Keywords: dental sleep medicine; obstructive sleep apnea; oral appliance therapy; patient adherence.

Figure 1. A PRISMA flow diagram shows the number of articles identified at each stage of the search.

Figure 2. Risk of bias summary: review authors’ judgements about each risk of bias item for each included study.

Figure 3. Forest plot of patient-reported adherence for custom-made oral appliance and ready-made oral appliance.

The forest plot demonstrates 4 studies that indicate increased patient adherence with custom-made appliances in comparison to ready-made appliances. The squares represent the point estimate of the corresponding studies. The area of each square is proportional to the study’s weight in the meta-analysis, and the lateral points (horizontal line) indicate the confidence intervals of the respective study. The overall effect or the summary estimate is plotted as a diamond, and the lateral points demonstrate the confidence intervals of the estimate. A mean difference of zero (vertical line) indicates no effect; studies with confidence intervals crossing the vertical line are inconclusive. Powerful studies have narrower confidence intervals. In the graph, the Quinnell study and the overall effect estimate have narrow confidence intervals that do not cross zero, indicating that the meta-analysis could be considered as statistically significant.