Figure 3.

Bland Altman plots showing the mean difference (thin lines) and the limits of agreement ([2SD] thick lines) for polysomnography apnea-hypopnea index (PSG AHI) and nasal flow respiratory disturbance index (NF RDI) for all subjects (A), for males (B) and for females (C)

Overall NF RDI slightly overestimated AHI severity. The limits of agreement were large but were generally lower at low AHI. There was no difference between genders in the degree of AHI overestimation. The limits of agreement were also comparable for both genders.