The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts

PREDICTORS OF OBSTRUCTIVE SLEEP APNEA - RESULTS FROM A RETROSPECTIVE COHORT STUDY

Luqi Chi1,3, Timothy J. Albright2, Pamela Polashenski3, Walter Polashenski3, Ruth Kouides3, Kenneth Plotkin4



Background: Hallmarks of obstructive Sleep Apnea (OSA) are sleep-related collapse of the upper airway, yielding apnea/hypopnea and multiple arousals from sleep to reestablish airway patency. OSA is a serious public health disorder that affects at least 4% of middle-aged men and 2% of middle-aged women in its symptomatic form. It is associated with significant cardiovascular and neuro-physiologic morbidity. It is important to detect the presence of OSA, as it is highly treatable with CPAP. Alternative options include upper airway surgery and oral appliances. The aim of this study is to identify predictors of OSA in the referred population.

Methods: A retrospective cohort study. Inclusion: All patients referred to the sleep clinic to evaluate for OSA between 9/04-3/06; Exclusion: OSA on treatments; referred for reasons other than sleep-disordered breathing. Statistics: T test or Kruskal-Wallis test; Chi-square test; Predictors of OSA in univariate analysis entered logistic regression models to determine independent predictors of OSA.

Results: (OR: Odds Ratio, CI: confidence interval)

  1. n=270, 95% Caucasians, 59% men, 41% women, Age 49.8�14.3(year), 59% moderate to severe OSA (Apnea Hypopnea Index,AHI>=15), 20% mild OSA (AHI>=5 but <15), 21% no OSA (AHI<5), 4% CHF and stroke;
  2. BMI(OR 1.11, 95%CI 1.06-1.16) and crowded upper airway (OR 3.39, 95%CI 1.09-10.50) were risk factors for OSA;
  3. Female gender was a protective factor (OR 0.39, 95%CI 0.21-0.75);
  4. Women with moderate/severe OSA were older compared to mild/no OSA (p<0.001), but this difference was not seen in men(p=0.385). Age was a risk factor for women (OR 1.06 95 % CI 1.0-1.1);
  5. Snoring was a predictors of OSA(linear trend, p<0.001; OR 3.0, 95%CI 1.4-6.6 for men and OR 5.6, 95%CI 2.1-15 for women);
  6. Witnessed apnea was a good predictor for OSA for men (linear trend p<0.001; OR 3.54, 95%CI 1.6-8.0), but not for women (no linear trend).
Conclusion:
  1. Men and women share common predictors - BMI, neck circumference, crowded airway, snoring;
  2. Female gender associated with a lower risk for OSA;
  3. Men may develop OSA earlier than women. It may be caused by higher collapsibility of the upper airway. Women develop OSA as they age, probably due to decrease of protective hormones;
  4. Witnessed apnea is a good predictor of OSA for men, not for women.
  5. Patients with mild OSA, CHF and stroke as well as elderly patients may be under-recognized and/or under-referred.