Table 6

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)

VariablesCluster membership, CPAP use and Framingham risk scoreAHI severity, CPAP use and Framingham risk score
Cluster labelHR95% CIp ValueHR95% CIp Value
PLMS2.021.32 to 3.08
NREM and poor sleep1.280.85 to 1.94
REM and hypoxia1.370.89 to 2.11
Hypopnoea and hypoxia1.741.02 to 2.99
Arousal and poor sleep1.790.97 to 3.29
Combined severe1.691.09 to 2.62
AHI severity 0.5403
Mild/none (AHI <15)Ref
Moderate (15≤AHI<30)1.210.85 to 1.73
Severe (AHI ≥30)1.110.82 to 1.50
CPAP use 0.00210.0068
Not regularRefRef
Regular0.620.46 to 0.840.660.49 to 0.89
Framingham risk score
(change per 10 points)
1.281.19 to 1.37<0.00011.301.22 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.