Table 2. Patient demographics in CPAP group.

*This study had patients do different duration of treatment as well.

**Study calculated the average BMI, AHI, LOS, and ESS of all participants rather than just one type of treatment.

***The patients in this study participated in both treatments. BMI and AHI are the mean of all participants.

AHI: apnea-hypopnea index; LOS: lowest oxygen saturation; ESS: Epworth score scale; RCT: randomized controlled trial; CPAP: continuous positive airway pressure

Study	Year	Type of study	No. of patients	Duration of treatment (weeks)	BMI (mean ± SD)	Pre-treatment AHI (mean ± SD)	Pre-treatment LOS (mean ± SD)	Pre-treatment ESS (mean ± SD)
Phillips et al. [5]	2013	RCT crossover	108	4	29.5 ± 5.5	25.6 ± 12.3	82.7 ± 7.6	9.1 ± 4.2
Venema et al. [7]	2020	RCT	17	520	33.2 ± 3.6	49.6 ± 26.1	76.7 ± 10.1	15.3 ± 3.5
Schutz et al. [9]	2013	RCT	9	8	25.90 ± 5.31	25.1 ± 10.5	-	9.88 ± 5.7
Barnes et al. [10]	2004	RCT	89	12	31.1 ± 0.5**	14.0 ±1.1 **	87.8 ± 0.4**	9.2 ± 0.4**
Silva et al. [11]	2021	RCT	31	26, 52*	28.7 ± 6.5	10.0 ± 4.6	85 ± 7	-
Randerath et al. [12]	2002	RCT crossover	20	6	31.2 ± 6.4	17.5 ± 7.7	83.6 ± 4.6	-
Ferguson et al. [13]	1996	RCT crossover	20	8	30.4 ± 4.8***	24.5 ± 8.8***	82.6 ± 6.0	-
Lam et al. [14]	2007	RCT	34	10	27.6 ± 0.6	23.8 ± 1.9	75.0 ± 1.4	12 ± 1