Table 2.
Operating characteristics of NF RDI for diagnosing OSA and severe OSA
| Cut Off | Sensitivity (95% confidence interval) | Specificity (95% confidence interval) | LR+ | LR− | Post-test probability |
|
|---|---|---|---|---|---|---|
| Of OSA if test positive | Of no OSA if test negative | |||||
| For diagnosing OSA (PSG AHI ≥ 5)i | ||||||
| 10 | 0.94 (0.92-0.98) | 0.62 (0.47-0.77) | 2.5 | 0.10 | 0.90 | 0.74 |
| 20 | 0.79 (0.72-0.85) | 0.79 (0.66-0.91) | 3.8 | 0.27 | 0.93 | 0.51 |
| 30 | 0.47 (0.41-0.53) | 0.94 (0.88-1.00) | 7.8 | 0.56 | 0.97 | 0.33 |
| For diagnosing OSA (PSG AHI ≥ 30)ii | ||||||
| 20 | 0.98 (0.91-1.00) | 0.60 (0.49-0.74) | 2.5 | 0.03 | 0.46 | 0.99 |
| 30 | 0.98 (0.92-1.00) | 0.81 (0.76-0.88) | 5.2 | 0.02 | 0.64 | 0.99 |
PSG AHI, polysomnography derived apnea-hypopnea index; LR+, positive likelihood ratio; LR−, negative likelihood ratio; NF RDI, nasal flow respiratory disturbance index;
i
Prevalence (Pre test probability) = 0.78;
ii
Prevalence (Pre test probability) = 0.26.