Clinical characteristics of the subgroup of patients who underwent polysomnography*
| WHO group I | WHO group II | WHO group III | WHO group IV | P† | |
| Number of patients (N=83) | 37 | 30 | 11 | 5 | |
| Demographics | |||||
| Age, years | 57 (46–69) | 65 (54–74) | 68 (54–73) | 55 (49–56) | 0.03 |
| Male gender | 8 (22%) | 8 (27%) | 6 (55%) | 3 (60%) | 0.08 |
| Body mass index, kg/m2 | 30 (26–33) | 35 (29–40) | 26 (25–33) | 30 (29–31) | 0.06 |
| Chronic medical conditions | |||||
| Connective tissue disease | 22 (59%) | 4 (13%) | 3 (27%) | 0 (0%) | <0.01 |
| Chronic obstructive pulmonary disease | 5 (14%) | 1 (3%) | 5 (45%) | 0 (0%) | <0.01 |
| Interstitial lung disease | 9 (24%) | 2 (7%) | 6 (55%) | 0 (0%) | <0.01 |
| Right heart catheterisation | |||||
| MPAP, mm Hg | 34 (27–44) | 43 (33–54) | 31 (28–40) | 37 (37–42) | 0.14 |
| PAOP, mm Hg | 11 (9–13) | 19 (17–26) | 12 (9–14) | 14 (11–14) | <0.01 |
| PVR, wood units | 3.3 (2.4–7.4) | 3.5 (2.5–7.4) | 4.8 (3.2–5.8) | 4.3 (4.0–6.1) | 0.84 |
| Sleep study | |||||
| Total sleep time, minutes | 317.3 (251.8–348.4) | 327.3 (242.0–377.4) | 302.9 (238.2–350.5) | 363.0 (274.0–382.3) | 0.90 |
| Time with SpO2<90%, % | 8.6 (0.1–41.0) | 14.0 (3.1–39.4) | 4.6 (0.4–39.3) | 98.8 (90.7–99.6) | <0.01 |
| AHI≥5 | 13 (35%) | 27 (90%) | 4 (36%) | 5 (100%) | <0.01 |
| 5≤AHI < 15 | 8 (22%) | 10 (33%) | 4 (36%) | 3 (60%) | 0.29 |
| 15≤AHI < 30 | 1 (3%) | 8 (27%) | 0 (0%) | 0 (0%) | <0.01 |
| AHI≥30 | 4 (11%) | 9 (30%) | 0 (0%) | 2 (40%) | 0.04 |
| AHI, events per hour | 2.5 (0.9–8.6) | 22.5 (6.2–32.1) | 3.7 (2.1–8.2) | 10.6 (10.0–31.7) | <0.01 |
| Obstructive apnoeas | 0 (0–5) | 6 (0–33) | 2 (0–8) | 5 (0–13) | 0.13 |
| Central apnoeas | 0 (0–1) | 0 (0–3) | 1 (0–9) | 4 (0–5) | 0.18 |
| Mixed apnoeas | 0 (0–1) | 0 (0–2) | 0 (0–0) | 0 (0–1) | 0.77 |
| Hypopnoeas | 7 (3–26) | 63 (36–100) | 3 (1–34) | 64 (51–162) | <0.01 |
*Data are summarised as median (IQR) for continuous variables and N (%) for categorical variables.
†P values are caclulated using the Kruskal-Wallis test for continuous variables and the Χ2 test for categorical variables. P<0.05 was considered statistically significant. P-values <0.05 are indicated in boldface.
AHI, apnoea-hypopnea index; MPAP, mean pulmonary artery pressure; PAOP, pulmonary artery occlusion pressure; PVR, pulmonary vascular resistance.