Does the physiological success of CPAP titration predict clinical success?

Patients commencing continuous positive airway pressure therapy (CPAP) undergo overnight airway pressure titration in sleep centres to optimize breathing and sleep patterns. We tested the hypothesis that data from formal scoring of the sleep and breathing patterns observed at the best achievable pressure during titration can predict CPAP use and effectiveness, as our clinical experience suggested otherwise. The relationship between CPAP titration scores (apnoea/hypopnoea frequency, arousal frequency and sleep staging) and subsequent CPAP use was examined in 150 sleep apnoea/hypopnoea syndrome patients. One hundred patients were continuing CPAP therapy and 50 were randomly selected patients who had discontinued CPAP. Within the CPAP group, titration scores were compared with CPAP machine use, subjective daytime sleepiness and requirements for airway pressure adjustment. Respiratory irregularities and arousals during titration did not relate to outcome. Sleep-stage analysis revealed a weak relationship between more wakefulness during titration and CPAP discontinuation (P=0.02). There was a correlation between more prolonged Stage 4 sleep during titration and reduced sleepiness on established therapy (P=0.002), but this explained less than 12% of the variance. The absence of rapid eye movement sleep during titration was not associated with poorer outcomes. We conclude that routine scoring of breathing and sleep patterns observed during CPAP titration is of little clinical value, as the results do not predict outcome for individual patients. Satisfactory CPAP therapy may be established even if significant numbers of apnoeas/hypopnoeas or arousals are observed at the optimal pressure during titration.