Comparison of adjusted Cox proportional hazards models for primary outcome using cluster membership versus OSA severity as measured by AHI (n=1036*, see legend for analyses by none vs mild, moderate and severe groups)
| Variables | Cluster membership, CPAP use and Framingham risk score | AHI severity, CPAP use and Framingham risk score | ||||
| Cluster label | HR | 95% CI | p Value | HR | 95% CI | p Value |
| Mild | Ref | – | 0.0265 | – | – | |
| PLMS | 2.02 | 1.32 to 3.08 | – | – | ||
| NREM and poor sleep | 1.28 | 0.85 to 1.94 | – | – | ||
| REM and hypoxia | 1.37 | 0.89 to 2.11 | – | – | ||
| Hypopnoea and hypoxia | 1.74 | 1.02 to 2.99 | – | – | ||
| Arousal and poor sleep | 1.79 | 0.97 to 3.29 | – | – | ||
| Combined severe | 1.69 | 1.09 to 2.62 | – | – | ||
| AHI severity | 0.5403 | |||||
| Mild/none (AHI <15) | – | – | Ref | – | ||
| Moderate (15≤AHI<30) | – | – | 1.21 | 0.85 to 1.73 | ||
| Severe (AHI ≥30) | – | – | 1.11 | 0.82 to 1.50 | ||
| CPAP use | 0.0021 | 0.0068 | ||||
| Not regular | Ref | – | Ref | – | ||
| Regular | 0.62 | 0.46 to 0.84 | 0.66 | 0.49 to 0.89 | ||
|
Framingham risk score (change per 10 points) | 1.28 | 1.19 to 1.37 | <0.0001 | 1.30 | 1.22 to 1.39 | <0.0001 |
Addition of ethnicity and alcohol use did not meaningfully change the cluster model results (data not shown). Significant associations with primary outcome were also not found when continuous AHI (p>value 0.2276) or three severity categories (none (AHI<5, reference) versus mild (5≤AHI<15,p value of 0.4192), moderate (15≤AHI<30, p value of 0.1775) or severe (AHI≥30, p value of 0.2218)) were evaluated (data not shown).
*Subjects without any component of the Framingham risk score excluded.
AHI, apnoea–hypopnoea index (events/hour of total sleep time); CPAP, continuous positive airway pressure; NREM, non-rapid eye movement; OSA, obstructive sleep apnoea; PLMS, periodic limb movements of sleep; REM, rapid eye movement.