Results
Figure 1 shows the PRISMA flow diagram for studies selection. A total of nine retrospective observational studies and one prospective observational study were included. There were nine studies from North America and one study from Southeast Asia. Results of the methodological quality as assessed with Murad’s tool are shown in Table 2.
The studies included a total of 1836 patients, with 1369 (74.6%) males and 467 (25.4%) females. One study (6) did not provide information on the method of diagnosis of OSA. All the other studies used polysomnography to confirm a diagnosis of OSA. Table 3 shows the individual study characteristics and main outcomes.
Most patients in the included studies fell under the category of moderate to severe OSA as indicated by the reported mean or average Apnoea-Hypopnoea Index (AHI) or Respiratory Disturbance Index (RDI). Two studies did not assess the severity of OSA among their participants (6, 7).
The majority of studies that reported participants’ average Body Mass Index (BMI) were either in the overweight or obese category apart from Pang et al (8) which reported a mean BMI of 24.6. However, it is worth noting that this study was conducted in Singapore and the World Health Organisation (WHO) has recognised that a BMI ≥ 23kg/m2among the Asian population indicates an increased health risk similar to that of BMI ≥ 25kg/m2 in other populations (9). Two studies did not have information on BMI (6, 10).
We evaluated the procedures reported; One study did not specify the exact number of each surgery performed and was excluded from this calculation (7). Of the 1741 surgeries performed, there were 268 (15.4%) nasal surgeries, 738 (42.4%) palatopharyngeal surgeries and 735 (42.2%) combined nasal and palatopharyngeal surgeries (including concurrent tongue surgery). Nasal surgeries were either a septoplasty or procedures to turbinates such as submucous diathermy/turbinoplasty or both a septoplasty and turbinate surgery. All palatopharyngeal surgeries included at least uvulopalatopharyngoplasty with various additional procedures such as expansion sphincteroplasty, anterior palatoplasty or tongue surgery however most studies did not provide the numbers of the additional procedures.