Economic and operational burden associated with malnutrition in chronic obstructive pulmonary disease

Background - Malnutrition is common in patients with chronic obstructive pulmonary disease (COPD). This study aimed to explore its association with all-cause mortality, emergency hospitalisation and subsequently healthcare costs. Methods - A prospective cohort observational pilot study was carried out in outpatients with COPD that attended routine respiratory clinics at a large tertiary Australian hospital during 2011. Electronic hospital records and hospital coding was used to determine nutritional status and whether a patient was coded as nourished or malnourished and information on healthcare use and 1-year mortality was recorded. Results - Eight hundred and thirty four patients with COPD attended clinics during 2011, of those 286 went on to be hospitalised during the 12 month follow-up period. Malnourished patients had a significantly higher 1-year mortality (27.7% vs. 12.1%; p = 0.001) and were hospitalised more frequently (1.11 SD 1.24 vs. 1.51 SD 1.43; p = 0.051). Only malnutrition (OR 0.36 95% CI 0.14–0.91; p = 0.032) and emergency hospitalisation rate (OR 1.58 95% CI 1.2–2.1; p = 0.001) were independently associated with 1-year mortality. Length of hospital stay was almost twice the duration in those coded for malnutrition (11.57 SD 10.93 days vs. 6.67 SD 10.2 days; p = 0.003) and at almost double the cost (AUD $23,652 SD$26,472 vs. $12,362 SD$21,865; p = 0.002) than those who were well-nourished. Conclusion - Malnutrition is an independent predictor of 1-year mortality and healthcare use in patients with COPD. Malnourished patients with COPD present both an economic and operational burden

The 2012 AASM respiratory event criteria increase the incidence of hypopneas in an adult Sleep center population

Study Objectives To investigate the effect of the 2012 American Academy of Sleep Medicine (AASM) respiratory event criteria on severity and prevalence of obstructive sleep apnea (OSA) relative to previous respiratory event criteria. Methods A retrospective, randomized comparison was conducted in an Australian clinical sleep laboratory in a tertiary hospital. The polysomnograms (PSG) of 112 consecutive patients undertaking polysomnography (PSG) for suspected OSA were re-scored for respiratory events using either 2007 AASM recommended (AASM2007Rec), 2007 AASM alternate (AASM2007Alt), Chicago criteria (AASM1999), or 2012 AASM recommended (AASM2012) respiratory event criteria. Results The median AHI using AASM2012 was approximately 90% greater than the AASM2007Rec AHI, approximately 25% greater than the AASM2007Alt AHI, and approximately 15% lower than the AASM1999 AHI. These changes increased OSA diagnoses by approximately 20% and 5% for AASM2007Rec and AASM2007Alt, respectively. Minimal changes in OSA diagnoses were observed between AASM1999 and AASM2012 criteria. To achieve the same OSA prevalence as AASM2012, the threshold for previous criteria would have to shift to 2.6/h, 3.6/h, and 7.3/h for AASM2007Rec, AASM2007Alt, and AASM1999, respectively. Differences between the AASM2007Rec and AASM2012 hypopnea indices (HI) were predominantly due to the change in desaturation levels required. Alterations to respiratory event duration rules had no effect on the HI. Conclusions This study demonstrates that implementation of the 2012 AASM respiratory event criteria will increase the AHI in patients undergoing PSG, and more patients are likely to be diagnosed with OSA

Objective measure of sleepiness and sleep latency via bispectrum analysis of EEG

Chronic sleepiness is a common symptom in the sleep disorders, such as, Obstructive Sleep Apnea, Periodic leg movement disorder, narcolepsy, etc. It affects 8% of the adult population and is associated with significant morbidity and increased risk to individual and society. MSLT and MWT are the existing tests for measuring sleepiness. Sleep Latency (SL) is the main measures of sleepiness computed in these tests. These are the laboratory- based tests and require services of an expert sleep technician. There are no tests available to detect inadvertent sleep onset in real time and which can be performed in any professional work environment to measure sleepiness level. In this article, we propose a fully automated, objective sleepiness analysis technique based on the single channel of EEG. The method uses a one-dimensional slice of the EEG Bispectrum representing a nonlinear transformation of the underlying EEG generator to compute a novel index called Sleepiness Index. The SL is then computed from the SI. Working on the patient's database of 42 subjects we computed SI and estimated SL. A strong significant correlation (r ≥ 0.70, < 0.001) was found between technician scored SL and that computed via SI. The proposed technology holds promise in the automation of the MSLT and MWT tests. It can also be developed into a sleep management system, wherein the SI is incorporated into a sleepiness index alert unit to alarm the user when sleepiness level crosses the predetermined threshold

Automatic estimation of macro-sleep-architecture using a aingle channel of EEG

Scoring of Macro Sleep Architecture (MSA) is a critical process in assessing several sleep disorders. MSA is defined as classification of sleep into three major states of sleep, State Wake, State REM and State NREM. Existing methods of MSA analysis require the recording of six channels of electrophysiological signals such as the EEG, EOG and EMG. They depend on the manual scoring of overnight data records using the R&K Criteria (1968), developed for visual analysis of signals based on morphological features. Manual analysis of MSA is tedious, subjective and suffers from both inter and intra scorer variability. In addition to this due to dependency of MSA on several biological signals, makes it impossible to incorporate in portable apnea screening devices. Non-availability of MSA hampers these devices accuracy making them non-acceptable among medical community. In this paper we propose a novel method for MSA analysis, which requires just one channel of only EEG data. We also develop a fully automated, objective MSA analysis technique, which uses a single one-dimensional slice of the Bisprectrum of EEG, representing a nonlinear transformation of a system function that can be considered as the EEG generator. The method was evaluated on an overnight clinical database of 23 patients. The results were compared with those obtained by an experienced human scorer. The method proposed in this paper led to agreements in the range of 70%-87%, comparable to that possible between two expert human scorers