Table 4.
Baseline demographic, anthropometric, sleep and comorbidity characteristics for clusters grouped by conventional OSA severity designations (based on median cluster AHI: none/mild (Clusters A and B), moderate (Clusters C and D) and severe (Clusters E, F and G))
| Variable/cluster | (A) Mild |
(B) PLMS |
(C) NREM and sleep |
(D) poor REM and hypoxia |
(E) Hypopnoea and hypoxia |
(F) Arousal and poor sleep |
(G) Combined severe |
X2 or F-stat. p value § |
|---|---|---|---|---|---|---|---|---|
| N | 533 | 119 | 186 | 168 | 75 | 42 | 124 | |
| Mean±SD, Median (IQR) or N (%) | ||||||||
| Age (years) | 55.3±11.8 | 63.7±10.5 | 62.0±10.8 | 57.8±10.9 | 59.2±11.8 | 65.7±10.9 | 58.0±10.9 | <0.0001 |
| Men | 489 (91.7) | 115 (96.6) | 184 (98.9) | 162 (96.4) | 70 (93.3) | 40 (95.2) | 123 (99.2) | 0.0006 |
| White | 421 (81.1) | 103 (89.6) | 151 (83.4) | 115 (83.9) | 66 (88.0) | 29 (70.7) | 93 (75.0) | <0.0001 |
| Employed | 193 (37.2) | 29 (25.2) | 64 (35.4) | 62 (37.1) | 20 (26.7) | 14 (34.1) | 43 (34.7) | <0.0001 |
| BMI (kg/m2) | 32.4 (6.4) | 33.7 (6.5) | 34.7 (7.7) | 36.8 (7.0) | 40.0 (8.5) | 38.8 (7.9) | 37.2 (6.9) | <0.0001 |
| ESS* | 10.5±5.7 | 9.1 ±5.6 | 11.0±5.7 | 11.1±5.8 | 12.4±5.7 | 10.5±6.6 | 12.1±6.0 | 0.0610 |
| AHI (#/hour) | 3.6 (9.0) | 9.9 (18.6) | 19.3(30.6) | 18.9 (24.5) | 44.2 (39.0) | 67.8 (30.4) | 83.9 (28.0) | <0.0001 |
| None/mild OSA | 446 (83.7) | 75 (63.0) | 76 (40.9) | 68 (40.5) | 10 (13.3) | 0 (0) | 1 (0.8) | <0.0001 |
| Moderate OSA | 64 (12.0) | 29 (24.4) | 47 (25.3) | 46 (27.4) | 12 (16.0) | 0 (0) | 0 (0) | <0.0001 |
| Severe OSA | 23 (4.3) | 15 (12.6) | 63 (33.9) | 54 (32.1) | 53 (70.7) | 42 (100) | 123 (99.2) | <0.0001 |
| CPAP use† | 128 (24.6) | 38 (33.0) | 64 (35.4) | 72 (43.1) | 37 (49.3) | 12 (29.3) | 51 (41.1) | <0.0001 |
| Smoking | 185 (36.8) | 36 (31.9) | 69 (39.2) | 50 (30.5) | 17 (23.6) | 12 (31.6) | 58 (48.3) | 0.0094 |
| Alcohol use | 244 (48.9) | 49 (45.4) | 93 (55.0) | 78 (48.7) | 30 (41.7) | 20 (50.0) | 67 (56.8) | 0.3086 |
| Drug use | 29 (5.9) | 5 (4.7) | 7 (4.3) | 11 (7.1) | 3 (4.3) | 1 (2.6) | 11 (9.4) | 0.5269 |
| Home oxygen | 22 (4.3) | 11 (9.7) | 21 (11.7) | 16 (9.9) | 6 (8.2) | 2 (4.9) | 9 (7.4) | 0.0181 |
| CCI score 0 | 192 (37) | 25 (22) | 51 (28) | 57 (35) | 21 (28) | 8 (20) | 41 (34) | <0.0001 |
| CCI score 1–2 | 217 (42) | 51 (45) | 72 (40) | 65 (40) | 35 (47) | 22 (54) | 43 (42) | <0.0001 |
| CCI score >2 | 109 (21) | 38 (33) | 56 (31) | 42 (26) | 18 (24) | 8 (27) | 38 (31) | <0.0001 |
| FRS‡ | 23.2 (15.5) | 30.9 (15.9) | 32.1 (17.8) | 27.8 (18.1) | 29.5 (17.3) | 36.4 (19.0) | 30.3 (17.3) | <0.0001 |
OSA severity definition: none/mild (AHI <15), moderate (AHI 15 to <30) and severe (AHI ≥30).
Data available for 43%, 49%, 44%, 49%, 49%, 52% and 49% of cluster A, B, C, D, E, F and G members, respectively.
Per cent of those with OSA and regular CPAP use (> 4 hours per night) of those for whom CPAP was indicated.
Data available for 81.4%, 84%, 84%, 85%, 87%, 86% and 87% of cluster A, B, C, D, E, F and G members, respectively.
Bonferroni corrected for multiple comparisons.
AHI, apnoea–hypopnoea index (events per hour); BMI, body mass index; CCI, Charlson comorbidity index; CPAP, continuous positive airway pressure; ESS, Epworth sleepiness scale; FRS, Framingham risk score; OSA, obstructive sleep apnoea; PLMS, periodic limb movements of sleep; NREM, non-rapid eye movement; REM, rapid eye movement.