Cost-effectiveness of split-night polysomnography and home studies in the evaluation of obstructive sleep apnea syndrome.

Study Objectives: Split-night polysomnography (PSG) and unattended home sleep studies have come into use as less-expensive tests for obstructive sleep apnea syndrome, but their impact on cost-effectiveness of the overall evaluation and treatment is unknown. We compared the cost-effectiveness of evaluations that employ these 2 procedures with a conventional approach using full-night PSG.

Methods: We used a decision-tree model that incorporated typical clinical algorithms for each of the 3 strategies to compare their cost-effectiveness from a third-party payer perspective over a 5-year period.

Complex dynamics in a three-level trophic system with intraspecies interaction.

In this paper, we present a three-level trophic food chain, including intraspecies interaction. In contrast with other analyses, we consider the effect on the third trophic level by the first-level parameters. The model shows complex, as well as, chaotic oscillations.