Clinical and polysomnographic data of positional sleep apnea and its predictors.

INTRODUCTION: In Asian population, facial structure may contribute to the primary pathophysiology of obstructive sleep apnea (OSA). We hypothesized that sleep position may have more effect on OSA in Asians compared to the Western population. If this hypothesis is accurate, positional therapy will have a major impact on treatment of OSA among Asians. PATIENTS/METHODS: We reviewed 263 polysomnographic studies from our laboratory from January 1, 2010 to June 30, 2010. Criteria for positional and non-positional OSA were (1) supine respiratory disturbance index (RDI)/non-supine RDI ≥2 and total RDI ≥5 and (2) supine RDI/non-supine RDI <2 and total RDI ≥5, respectively. We aimed to determine the difference in baseline characteristics, polysomnographic findings, and predictors for positional OSA. RESULTS: We found 144 patients diagnosed with OSA (RDI ≥5), and 96 patients met the criteria for positional OSA (67%), in which in almost half of these patients (47%), RDI was normalized (RDI < 5) in non-supine position. Snoring frequency were significantly lower among positional OSA and OSA was less severe indicated by lower RDI and arousal index, higher mean and nadir oxygen saturation, and higher %NREM3. We also found that low snoring frequency (less than 20% of total sleep time) was a significant predictor for positional OSA (odd ratio of 3.27; p = 0.011), contrarily to low mean oxygen saturation (<95%) which was found to be a negative predictor (odd ratio of 0.31; p = 0.009). Among OSA patients, low RDI (<15) was a significant predictor for normalization of RDI in non-supine position (odd ratio of 8.77; p = < 0.001), contrarily to low mean oxygen saturation (<95%) which was also found to be a negative predictor (odd ratio of 0.13; p = 0.001). CONCLUSION: Positional OSA is very prevalent and noted in almost 70% of our patients. Low snoring frequency was noted to be a positive predictor for positional OSA, contrarily to low mean oxygen saturation which was found to be a negative predictor. These findings are encouraging that positional therapy can be very beneficial as the treatment modality for OSA among Asians.

Severity of obstructive sleep apnea in patients with and without cardiovascular-related diseases.

BACKGROUND: Previous studies have often investigated the association of obstructive sleep apnea (OSA) with cardiovascular morbidity and mortality, but the possibility of reverse causation has not been clearly defined. OBJECTIVE: To examine if the presence of any of the cardiovascular-related diseases, including hypertension, diabetes mellitus, coronary artery disease, and/or cerebrovascular disease, correlates with more severe OSA. METHODS: This was a retrospective study where all patients age ≥ 18 years referred to our sleep laboratory for suspected OSA were included. The data from the full-night baseline and split-night polysomnographic reports were reviewed. Data were then evaluated by logistic regression analysis to compare between 2 groups, the severity of OSA (respiratory disturbance index [RDI] < 15 vs RDI ≥ 15, and RDI < 5 vs RDI ≥ 5), other polysomnographic variables and daytime sleepiness score (Epworth Sleepiness Scale [ESS] score < 10 and ≥ 10). RESULTS: 190 patients were analyzed. The patients with any of the cardiovascular-related diseases were noted to have more severe sleep apnea (RDI ≥ 15), with an adjusted odds ratio of 3.24. Sleep efficiency ≥ 90% and mean oxygen saturation ≥ 95% were observed less commonly in the patients with any of the cardiovascular-related diseases (adjusted odds ratios of 0.45 and 0.36, respectively). There was no statistically significant difference in ESS score. CONCLUSIONS: Patients with any of the cardiovascular-related diseases are at a higher risk of having moderate to severe OSA without significant increase in daytime sleepiness. Therefore, we suggest that patients with any of the cardiovascular-related diseases should be screened for OSA, even if they are asymptomatic.

Exploring the knowledge of nasopharyngeal carcinoma among medical doctors at primary health care level in Perak state, Malaysia.

Nasopharyngeal carcinoma (NPC) is among the commonest cancers in Malaysia. The prognosis for NPC like most other head and neck cancer is dependent on its staging. Majority of patients in Malaysia at the time of diagnosis are either at stage III or IV (27 and 47%, respectively). The lack of knowledge among primary care medical doctors regarding NPC may contribute to this delay in diagnosis. The aim of this study was to assess the knowledge of the primary care doctors in the state of Perak on the various aspects of NPC. The doctors at the primary care level in the state of Perak were recruited to take part in this study on a voluntary basis. A total number of 154 out of 198 doctors participated in this survey. They were given a questionnaire to fill in to test their knowledge on different aspects of NPC and its treatment. The overall respondents' score was poor with a score of 67.5% on all sections. The doctors appear to be able to identify common presenting features of NPC with a mean score of 85.3% but for the uncommon presentations of NPC, the scores were poorer with 61.8%. In addition, 54.1% of the participants answered that they would refer a patient with symptoms suspicious of NPC after a period of 1 month from the onset of symptom. However, only 34% would refer within 2 weeks. Based on the results of this study, the authors feel that it is clear that the doctors posted in the primary care hospitals and clinics appear to have inadequate knowledge to diagnose and refer patients with suspected NPC. As early diagnosis can often lead to a better prognostic outcome, steps must be taken to raise the awareness among these doctors.

Comparison of polysomnographic and clinical presentations and predictors for cardiovascular-related diseases between non-obese and obese obstructive sleep apnea among Asians.

INTRODUCTION: Unlike Caucasians, many Asians with obstructive sleep apnea (OSA) are non-obese but are affected by the disease due to predisposing craniofacial structure. Therefore, non-obese and obese OSA may represent different disease entities. The associated risk factors for developing cardiovascular-related diseases, consequently, may be considered separately for the two types of OSA. METHOD: We reviewed polysomnographic studies performed in adults (aged ≥ 18 years) diagnosed with OSA (respiratory disturbance index [RDI] ≥ 5). We divided the patients into obese (body mass index [BMI] ≥ 25) and non-obese (BMI < 25) groups. We aimed to determine the differences between these two groups in terms of clinical presentations, polysomno-graphic findings, and association with cardiovascular-related diseases including hypertension, diabetes mellitus, coronary artery disease, and/or cerebrovascular disease. RESULTS: Among 194 patients with OSA (RDI ≥ 5), 63.4% were non-obese and 36.6% were obese. Compared with obese OSA patients, non-obese OSA patients were noted to have smaller neck size, less prevalence of hypertension, and less history of frequent nocturia (> 3-4/week), with equal prevalence of excessive daytime sleepiness. Overall, non-obese OSA patients were noted to have milder disease indicated by lower total, supine, and non-supine, NREM RDI and higher mean and nadir oxygen saturations. In the non-obese group, only total obstructive apnea index (OAI) was noted to be a predictor for developing any of the cardiovascular-related diseases after controlling for age, sex, and RDI (odds ratio = 9.7). However, in the obese OSA group, frequent snoring (> 50% of total sleep time), low sleep efficiency (≤ 90%), and low mean oxygen saturation (< 95%) were noted to be significant predictors of cardiovascular-related diseases (odds ratios = 12.3, 4.2, and 5.2, respectively). CONCLUSION: Among Asians, most OSA patients were not obese. Compared to obese OSA patients, non-obese OSA patients were noted to have less prevalence of hypertension and less history of nocturia. They were also noted to have overall milder OSA. Only OAI was noted to be a significant predictor for cardiovascular-related disease in the non-obese OSA group.