Table 2.
Baseline characteristics of the final full-text articles
| First author/year [Ref.] | Study design | Study population | Study groups | Intervention | Outcomes/associations | Follow-up period | Results |
|---|---|---|---|---|---|---|---|
| Papandreou et al. [31] | RCT | 40 OSA patients M/F: 34/6 | 20 assigned to the MD vs 20 assigned to a PD | MD vs PD | The primary outcome measures were the change in OSA severity measured by AHI and oxygen saturation indices and the AHI during REM sleep | 6 months |
Change in MD vs PD in: (1) AHI: − 15.6 ± 11.4 vs – 14 ± 22.6 (p = 0.791) (2) AHI/REM decrease 18.4 ± 17.6 in MD and 2.6 ± 23.7 in PD (p = 0.025) (3) Mean SaO2% in MD vs 1.5 ± 1.7 PD 1 ± 1.5 (p = 0.379) (4) Lowest SaO2% MD 4.9 ± 3.8 PD 1 ± 1.5 (p = 0.163) (5) Change in MedDietScore: MD 12.7 ± 4.9 PD 0.95 ± 4.5 (p < 0.001) |
| Fiori et al. [33] | RCT | 56 M/F: 56/0 54 patients with severe OSA | 18 assigned to placebo vs 18 assigned to sodium-restricted diet vs 18 assigned to diuretic | Placebo pill vs combination of placebo pill and sodium-restricted diet vs spironolactone plus furosemide | The primary outcome was the change in OSA severity. Secondary outcomes were lowest oxygen saturation and excessive daytime sleepiness, assessed by the Epworth Sleepiness Scale | 1 week |
(1) Change in AHI from baseline to follow-up was 14.4% (delta value − 7.3 events per hour, 95% confidence interval, − 13.8 to − 0.9) in the diuretic group, 22.3% (− 10.7; 95% CI, − 15.6 to − 5.7) in the diet group, and 0.8% (0.4; 95% CI, − 2.5 to 3.2) in the placebo group (p = 0.001 for time × group interaction) (2) Lowest oxygen saturation: placebo 77.5 ± 7.1, diet 77.9 ± 7.8, diuretic 76 ± 11.3 (3) ESS placebo 10.7 ± 5.4, diet 11.6 ± 4.8, diuretic 13.2 ± 5.3 (p = 0.6 for time × group interaction) (4) AHI reduction at follow-up: − 14.4% (− 13.8 to − 0.9) in the diuretic group, − 22.3% (− 10.7; 95% CI, − 15.6 to − 5.7) in the diet group, and − 0.8% (0.4; 95% CI, − 2.5 to 3.2) in the placebo group (p = 0.001) |
| Georgoulis et al. [25••] | RCT |
187 OSA patients M/F: 141/46 |
65 assigned to SCG vs 62 assigned to MDG vs 60 assigned to MLG | Hypocaloric diet vs MD diet vs MD lifestyle | The primary outcome was participants’ AHI derived from PSG. The secondary outcomes were the proportion of patients classified as having severe OSA, the apnea index (AI), the hypopnea index (HI), and the oxygen desaturation index (ODI) as well as average and minimum SaO2 and parameters of sleep architecture, i.e., percent time spent in non-REM and REM sleep, sleep latency, and sleep efficiency, as well as OSA symptomatology, i.e., the degree of insomnia and sleepiness, and the proportion of patients classified as having insomnia (AIS > 6) and severe daytime sleepiness (ESS > 10) | 12 months |
(1) Mean AHI change − 4.2 (-7.4, -1.0) (p = 0.006) for the SCG, − 24.7 (− 30.4, − 19.1) (p < 0.001) for the MDG and − 27.3 (− 33.9, − 20.6) (p < 0.001) for the MLG (2) Mean ESS change − 2.34 (− 3.51, − 1.16) (p = 0.002) for the SCG, − 5.66 (− 7.11, − 4.22) (p < 0.001) for the MDG, and − 7.02 (− 8.55, − 5.49) (p < 0.001) for the MLG (3) Mean AIS change − 2.68 (− 3.87, − 1.49) (p < 0.001) for the SCG, − 5.01 (− 6.21, − 3.81) (p < 0.001) for the MDG, and − 4.74 (− 5.83, − 3.66) (p < 0.001) for the MLG (4) Mean percent body weight change: − 7.4 ± 4.1% for the MDG, − 10.6 ± 5.8% for the MLG, − 0.3 ± 3.6% for the SCG (5) Proportion of patients with excessive daytime sleepiness (SCG: 53% vs 32%, p = 0.002, MDG: 54% vs 5%, p < 0.001, MLG: 47% vs 2%, p < 0.001) (6) Proportion of patients with insomnia (SCG: 79% vs 60%, p = 0.002, MDG: 75% vs 12%, p < 0.001, MLG: 71% vs 14%, p < 0.001) (7) ODI: MDG vs SCG − 10.9 (− 20.5, − 1.35), p = 0.014, MLG VS SCG 12.8 (− 23.7, − 1.87) p = 0.001 |
| de Melo et al. [32••] | RCT |
45 OSA patients M/F: 45/0 |
19 assigned to low-protein group vs 18 assigned to the high-protein group | 1 month | The study outcomes were the effects of a low-energy, high-protein diet on obese men’s OSA severity and metabolic parameters | 1 month |
(1) BMI (from 34.9 ± 4.1 to 33.7 ± 4.3 kg/m2 in the LP group; from 34.3 ± 3.0 to 33.1 ± 3.1 kg/m2 in the HP group; p < 0.001) (2) Fat mass (from 38.1 ± 6.1% to 37.2 ± 7.1% in the LP group; from 39.5 ± 5.5% to 38.6 ± 5.9% in the HP group; p = 0.009) (3) Fat-free mass (from 66.3 ± 6.5 to 63.9 ± 4.7 kg in the LP group; from 63.4 ± 6.9 to 62.4 ± 6.8 kg the in HP group; p < 0.001) (4) AHI (from 54.0 ± 25.0 to 33.7 ± 31.7 n/h in the LP group; from 39.7 ± 24.3 n/h to 21.4 ± 25.9 in the HP group; p = 0.006) (5) Arousal index (AI) (from 39.0 ± 16.4 to 24.2 ± 22.0 n/h in the LP group; from 32.2 ± 21.8 to 16.5 ± 18.5 n/h in the HP group; p = 0.006) (6) AI REM (from 57.0 ± 27.2 to 35.6 ± 32.6 n/h in the LP group; from 41.9 ± 23.2 to 23.9 ± 22.5 n/h in the HP group; p = 0.011) (7) AI NREM (from 53.8 ± 27.2 to 30.9 ± 28.9 n/h in the LP group; from 34.22 ± 22.7 to 16.7 ± 21.8 n/h in the HP group; p < 0.001) (8) Glucose (from 87.4 ± 40.6 to 89.5 ± 33.0 mg/dL in the LP group; from 104.3 ± 28.5 to 74.1 ± 47.7 mg/dL in the HP group; p < 0.05) (9) Insulin (16.9 ± 7.9 to 12.4 ± 5.7 uUI/mL in the LP group; from 16.3 ± 10.3 to 7.9 ± 6.6 uUI/mL the in HP group; p < 0.001) (10) Total cholesterol levels (174.0 ± 67.8 to 168.7 ± 49.1 mg/dL in the LP group; from 169.7 ± 52.0 to 134.0 ± 83.3 mg/dL in the HP group; p = 0.004) |
AHI apnea hypopnea index, AI arousal index, BMI body mass index, ESS Epworth Sleepiness Scale, HP high protein, ILI intensive lifestyle intervention, LP low protein, MD Mediterranean diet, MDG Mediterranean diet group, MLG Mediterranean lifestyle group, NREM non-rapid eye movement (sleep), OSA obstructive sleep apnea, PD prudent diet, RCT randomized controlled trial, REM rapid eye movement, SaO2 oxygen saturation, SCG standard care group