RESUMO
Limited and controversial data exist on the natural evolution of sleep disordered breathing (SDB) in untreated individuals. This study examines the evolution of SDB over a 3-yr period in a community-based sample of elderly subjects. From the initial cohort of 854 healthy subjects aged mean ± SD 68.4 ± 0.8 yrs, 519 untreated subjects accepted clinical and instrumental follow-up 3.6 ± 1.6 yrs later. SDB was defined as a respiratory disturbance index (RDI) >15 events · h(-1). At baseline, 202 (39%) subjects had an RDI ≤ 15 events · h(-1) and 317 (61%) had an RDI >15 events · h(-1). 3 yrs later, 280 (54%) subjects were non-SDB and 239 (46%) had SDB. Between evaluations, the RDI decreased from 22.3 ± 16.2 to 16.4 ± 13.0 events · h(-1), with a greater decrease in the number of cases with an RDI >30 events · h(-1) that in those with RDI ≥ 30 events · h(-1). In the non-SDB group, 81% had a stable RDI and 19% increased their RDI by a mean of 13.7 events · h(-1). In the SDB group, the RDI decreased to values ≤ 15 events · h(-1) in 36.6% of cases, 63.4% still having SDB. The RDI changes did not depend on weight changes. In healthy elderly subjects, the prevalence and severity of SDB did not show a tendency toward natural worsening, some cases having improvement or a remission independent of weight changes. These findings also suggest that in the elderly, natural SDB progression is still hypothetical.
