Prevalence and correlates of nocturnal desaturations in a sample of elderly people.

We designed an epidemiological study to estimate the prevalence and correlates of nocturnal desaturations in a sample of elderly subjects from the general population. Sleep-related respiratory disturbances were assessed by questionnaire and MESAM IV (MADAUS electronic sleep apnoea monitor) ambulatory monitoring. An oxygen desaturation index (ODI), oxygen desaturation being defined as a decrease in SaO2 of or exceeding 4%, was then computed from these data. An oxygen desaturation index > or = 10 was observed in 27.0% of the 293 subjects studied (mean age 76.6+/-5.7 y, median=75 y, min.=69, max.=99), an oxygen desaturation index > or = 30in 4.4%. Multivariate analysis identified as correlates to an oxygen desaturation index > or = 10: male gender (OR=1.80; P=0.04), a high body mass index (BMI) in men (OR=1.20 per kg m2; P=0.0009), and advanced age in women (OR=1.09 per y; P=0.02). A positive association was found between loud snoring (OR=1.75; P=0.06) and an oxygen desaturation index > or = 10. However, there was no statistically significant relationship between an oxygen desaturation index > or = 10 and either daytime somnolence (OR=1.50; P=0.19) or trouble getting to sleep (OR=0.59; P=0.09). We found no significant relationship in our sample between oxygen desaturation index and arterial hypertension or cardiac dysrhythmia. Previous studies on younger populations have reported different results. It may well be the advanced age of our sample that explains these inconsistencies. For the elderly persons we studied our results underline the relatively high prevalence of sleep-related respiratory disturbances. However, these may be of less consequence than in younger populations.