SFSS - Svensk förening för sömnforskning och sömnmedicin

Pia Nerfeldt


Obstructive sleep apnea syndrome (OSAS) has an estimated prevalence of 2 percent in women and 4 percent in men. OSAS is characterized by repeated obstructive events of the pharyngeal upper airway during sleep. OSAS, which often causes excessive daytime sleepiness, is both an individual and a societal problem with large personal suffering and societal costs. The most common cause of OSAS is overweight and obesity, an increasing burden worldwide. In Sweden, 43 percent of the adults are estimated to be overweight. Other causes to OSAS are anatomical narrowness with large tonsils and tongue, alcohol, smoking, and supine sleeping position. The prevalence of alcohol overconsumption is estimated to 10 percent in Swedish adults.

This thesis evaluates two aspects of OSAS; firstly, the prevalence of alcohol over-consumption, secondly the effects of dietary weight reduction in the obese OSAS patient.

In PAPER I we evaluated the overuse of alcohol and benzodiazepines among 98 OSAS patients at our ENT-department, which has not previously been reported. We screened the patients with a local questionnaire, but also objectively with blood and urine tests. A new laboratory marker, Carbohydrate-Deficient-Transferrin (CDT), reflecting the alcohol consumption the last two weeks, was used, in combination with benzodiazepine metabolites in urine. The prevalence of positive CDT was 8.5 percent, which is approximately the same level as estimated in the general population. The prevalence of benzodiazepine use was 3.2 percent. Only 2 persons denied study participation. None of the patients who screened positive for CDT had indicated overuse of alcohol in the questionnaire, and none was willing to accept contact with an abuse-clinic.

In PAPER II we performed a randomized pilot study between weight reduction and expectancy among 20 obese (Body Mass Index > 30) OSAS males. There is a demand for randomized studies on weight reduction and the goal of the study was to evaluate our weight reduction program in obese OSAS patients. The diet consisted of 8 weeks low-calorie-diet (LCD) with a protein drink (Nutrilett®) in combination with weekly group meetings for support. The controls were asked to maintain their weight. Evaluations included changes in weight and Oxygen Desaturation Index (ODI4) measured with polygraphy. The results showed significant differences between the intervention and control group concerning changes in weight and ODI4. However, there was a large drop-out rate (45 %), which makes the results uncertain. On the other hand, this pilot study showed us how difficult it is to motivate obese OSAS patients to change their life-style.

In PAPER III and IV we continued to evaluate the effects of weight reduction with LCD in obese OSAS with a non-randomized prospective intervention study. We improved our selection methods to include better motivated patients compared to in study 2. The LCD was followed by an additional behavioral modifying group therapy for 2 years, which aimed to change dietary and exercise habits. A group of 33 patients (24 males, 9 females) were included, out of who 23 used OSAS-device (19 Continuous Positive Airway Pressure (CPAP), 4 Mandibular Retaining Device (MRD)). The evaluations included weight, bioelectrical impedance, polysomnographic respiratory and sleep parameters, metabolic status, blood pressure, excessive daytime sleepiness and ratings of quality of life. Such extensive information has not been reported previously for this patient group. The weight reduction at 6 months was in mean 18 kilos in 30 patients, a more impressive result than after 2 years, when it was 11 kilos in 23 patients. However, after 2 years nocturnal respiration, arousals, metabolic status (blood insulin levels and dyslipidemia), as well as daytime sleepiness, were still significantly improved compared to baseline values. Quality of life ratings showed significant improvements for the subscales “vitality” and “physical functioning”. Further, there was a significant positive correlation between the reductions in weight and apneas. There were no gender differences, neither between patients with CPAP/MRD-device compared to without. In conclusion, as we found clinically important improvements, we recommend treating well motivated obese OSAS patients with dietary weight reduction in group therapy.

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