Clinical and Polysomnographic Characteristics of Patients with Extreme Obstructive Sleep Apnea, AHI > 100: A Case-Control Study

Background: Severe obstructive sleep apnea (OSA), defined by apnea-hypopnea index (AHI) as more than 30 events per hour, was previously related to more comorbidity. However, limited studies separated the patients with AHI > 100 from those with a less severe manifestation of the disease. Objectives: The current study aimed at describing the characteristics of this subgroup and comparing them with less severe conditions. Methods: A retrospective analysis was conducted on 114 patients with OSA. Nocturnal polysomnography was used to diagnose severe OSA. Patients were categorized into two groups: (1) 60 < AHI < 100 (very severe OSA), (2) AHI ≥ 100 (extreme OSA). Demographic, medical history, and polysomnographic variables were evaluated and compared between the two groups. Results: Extreme OSA was diagnosed in 19 patients, the mean body mass index (BMI) was significantly higher in this group (39.26 ± 5.93 vs. 35.68 ± 6.45 kg/m2, P = 0.025). They also had lower minimal O2 saturation (65.68 ± 10.16 vs. 74.10 ± 8.74, P = 0.003) and more time with < 90% O2 saturation (T < 90%) (81.78 ± 22.57 vs. 58.87 ± 33.14, P = 0.01). OHS prevalence was significantly higher in the group with extreme OSA (P = 0.04). The most frequent comorbidity was hypertension, with an incidence of 60.5%, for the extreme group, although there was no significant difference between the two groups in terms of clinical associations. Conclusions: The current study results suggested that greater BMI and lower minimal O2 saturation, as well as increased T < 90%, were associated with extreme OSA, although no differences were observed in the associated diseases between the compared groups.