W. Ward Flemons

Automated analysis of digital oximetry in the diagnosis of obstructive sleep apnoea

BACKGROUND The gold standard diagnostic test for obstructive sleep apnoea (OSA) is overnight polysomnography (PSG) which is costly in terms of time and money. Consequently, a number of alternatives to PSG have been proposed. Oximetry is appealing because of its widespread availability and ease of application. The diagnostic performance of an automated analysis algorithm based on falls and recovery of digitally recorded oxygen saturation was compared with PSG. METHODS Two hundred and forty six patients with suspected OSA were randomly selected for PSG and automated off line analysis of the digitally recorded oximeter signal. RESULTS The PSG derived apnoea hypopnoea index (AHI) and oximeter derived respiratory disturbance index (RDI) were highly correlated (R = 0.97). The mean (2SD) of the differences between AHI and RDI was 2.18 (12.34)/h. The sensitivity and specificity of the algorithm depended on the AHI and RDI criteria selected for OSA case designation. Using case designation criteria of 15/h for AHI and RDI, the sensitivity and specificity were 98% and 88%, respectively. If the PSG derived AHI included EEG based arousals as part of the hypopnoea definition, the mean (2SD) of the differences between RDI and AHI was –0.12 (15.62)/h and the sensitivity and specificity profile did not change significantly. CONCLUSIONS In a population of patients suspected of having OSA, off line automated analysis of the oximetry signal provides a close estimate of AHI as well as excellent diagnostic sensitivity and specificity for OSA.

Quality of life consequences of sleep-disordered breathing

Sleep-disordered breathing occurs in approximately 2% to 4% of the adult population and includes conditions in which patients stop breathing completely (apnea) or have marked reductions in airflow (hypopnea) during sleep. Typical symptoms of sleep apnea include snoring, restless sleep, excessive daytime somnolence, nocturnal enuresis, irritability, depression, memory deficits, inability to concentrate, and decreased alertness. The clinically relevant outcomes of these symptoms include impairment in work efficiency, increased automobile accident rates, and decrements in quality of life. Treatment of sleep apnea, primarily with continuous positive airway pressure, reduces sleepiness and improves mood disturbances, neurocognition, and performance. Traditional measurements of sleep apnea severity do not correlate well with current tests and scales that are used to quantify alterations in alertness, performance, quality of life, or sleepiness. A disease-specific quality of life scale has been developed following patient and physician interviews and literature reviews. The Calgary Sleep Apnea Quality of Life Index is expected to capture aspects of quality of life important to sleep apnea patients, such as cognitive function, performance, and mood, that could be improved with appropriate treatment of sleep-disordered breathing.

Clinical prediction of the sleep apnea syndrome

Polysomnography, the standard diagnostic test for people suspected of having sleep apnea, is a limited resource due to its expense. Decisions about which patients to refer to a sleep center and which require polysomnography can be made based on an estimate of the probability that they have sleep apnea. Clinical features that are associated with the severity of sleep apnea, as judged by the apnea-hypopnea index, can be combined together using statistical modeling into a clinical prediction rule, whose diagnostic performance can be summarized by its sensitivity and specificity or by likelihood ratios. To date, at least seven different sleep apnea clinical prediction rules have been developed, most incorporate anthropomorphic variables such as the body mass index, waist circumference, and/or neck circumference, and some type of abnormal respiration during sleep (snoring, apneas, choking and/or gasping) witnessed by a bed partner. In general these rules have reasonably high sensitivities but only intermediate specificities, thus they can be useful in excluding the diagnosis but do not usually raise the probability of sleep apnea high enough to warrant initiating therapy without at least some type of additional testing to confirm the diagnosis. In isolation the apnea-hypopnea index is not an optimal indicator of disease severity, thus ultimately clinical decisions about the need for polysomnography and/or the need for treatment must take into account other important clinical information such as symptom severity, quality of life, and the presence or absence of comorbid illness.

Advancing Measurement of Patient Safety Culture

OBJECTIVE To examine the psychometric and unit of analysis/strength of culture issues in patient safety culture (PSC) measurement. DATA SOURCE Two cross-sectional surveys of health care staff in 10 Canadian health care organizations totaling 11,586 respondents. STUDY DESIGN A cross-validation study of a measure of PSC using survey data gathered using the Modified Stanford PSC survey (MSI-2005 and MSI-2006); a within-group agreement analysis of MSI-2006 data. Extraction Methods. Exploratory factor analyses (EFA) of the MSI-05 survey data and confirmatory factor analysis (CFA) of the MSI-06 survey data; Rwg coefficients of homogeneity were calculated for 37 units and six organizations in the MSI-06 data set to examine within-group agreement. PRINCIPAL FINDINGS The CFA did not yield acceptable levels of fit. EFA and reliability analysis of MSI-06 data suggest two reliable dimensions of PSC: Organization leadership for safety (alpha=0.88) and Unit leadership for safety (alpha=0.81). Within-group agreement analysis shows stronger within-unit agreement than within-organization agreement on assessed PSC dimensions. CONCLUSIONS The field of PSC measurement has not been able to meet strict requirements for sound measurement using conventional approaches of CFA. Additional work is needed to identify and soundly measure key dimensions of PSC. The field would also benefit from further attention to strength of culture/unit of analysis issues.

Validity of AHRQ patient safety indicators derived from ICD-10 hospital discharge abstract data (chart review study)

Objective To assess if the Agency for Healthcare Research and Quality patient safety indictors (PSIs) could be used for case findings in the International Classification of Disease 10th revision (ICD-10) hospital discharge abstract data. Design We identified and randomly selected 490 patients with a foreign body left during a procedure (PSI 5—foreign body), selected infections (IV site) due to medical care (PSI 7—infection), postoperative pulmonary embolism (PE) or deep vein thrombosis (DVT; PSI 12—PE/DVT), postoperative sepsis (PSI 13—sepsis)and accidental puncture or laceration (PSI 15—laceration) among patients discharged from three adult acute care hospitals in Calgary, Canada in 2007 and 2008. Their charts were reviewed for determining the presence of PSIs and used as the reference standard, positive predictive value (PPV) statistics were calculated to determine the proportion of positives in the administrative data representing ‘true positives’. Results The PPV for PSI 5—foreign body was 62.5% (95% CI 35.4% to 84.8%), PSI 7—infection was 79.1% (67.4% to 88.1%), PSI 12—PE/DVT was 89.5% (66.9% to 98.7%), PSI 13—sepsis was 12.5% (1.6% to 38.4%) and PSI 15—laceration was 86.4% (75.0% to 94.0%) after excluding those who presented to the hospital with the condition. Conclusions Several PSIs had high PPV in the ICD administrative data and are thus powerful tools for true positive case finding. The tools could be used to identify potential cases from the large volume of admissions for verification through chart reviews. In contrast, their sensitivity has not been well characterised and users of PSIs should be cautious if using them for ‘quality of care reporting’ presenting the rate of PSIs because under-coded data would generate falsely low PSI rates.

Randomized Double-Blind Trial of the Effects of Humidified Compared with Nonhumidified Low Flow Oxygen Therapy on the Symptoms of Patients

OBJECTIVE: To determine the effects of humidified versus nonhumidified low flow oxygen therapy on the subjective symptoms of patients.

What is the value and impact of quality and safety teams? A scoping review

BackgroundThe purpose of this study was to conduct a scoping review of the literature about the establishment and impact of quality and safety team initiatives in acute care.MethodsStudies were identified through electronic searches of Medline, Embase, CINAHL, PsycINFO, ABI Inform, Cochrane databases. Grey literature and bibliographies were also searched. Qualitative or quantitative studies that occurred in acute care, describing how quality and safety teams were established or implemented, the impact of teams, or the barriers and/or facilitators of teams were included. Two reviewers independently extracted data on study design, sample, interventions, and outcomes. Quality assessment of full text articles was done independently by two reviewers. Studies were categorized according to dimensions of quality.ResultsOf 6,674 articles identified, 99 were included in the study. The heterogeneity of studies and results reported precluded quantitative data analyses. Findings revealed limited information about attributes of successful and unsuccessful team initiatives, barriers and facilitators to team initiatives, unique or combined contribution of selected interventions, or how to effectively establish these teams.ConclusionsNot unlike systematic reviews of quality improvement collaboratives, this broad review revealed that while teams reported a number of positive results, there are many methodological issues. This study is unique in utilizing traditional quality assessment and more novel methods of quality assessment and reporting of results (SQUIRE) to appraise studies. Rigorous design, evaluation, and reporting of quality and safety team initiatives are required.

Deriving ICD-10 Codes for Patient Safety Indicators for Large-scale Surveillance Using Administrative Hospital Data

Background: Existing administrative data patient safety indicators (PSIs) have been limited by uncertainty around the timing of onset of included diagnoses. Objective: We undertook de novo PSI development through a data-driven approach that drew upon “diagnosis timing” information available in some countries’ administrative hospital data. Research Design: Administrative database analysis and modified Delphi rating process. Subjects: All hospitalized adults in Canada in 2009. Measures: We queried all hospitalizations for ICD-10-CA diagnosis codes arising during hospital stay. We then undertook a modified Delphi panel process to rate the extent to which each of the identified diagnoses has a potential link to suboptimal quality of care. We grouped the identified quality/safety-related diagnoses into relevant clinical categories. Lastly, we queried Alberta hospital discharge data to assess the frequency of the newly defined PSI events. Results: Among 2,416,413 national hospitalizations, we found 2590 unique ICD-10-CA codes flagged as having arisen after admission. Seven panelists evaluated these in a 2-round review process, and identified a listing of 640 ICD-10-CA diagnosis codes judged to be linked to suboptimal quality of care and thus appropriate for inclusion in PSIs. These were then grouped by patient safety experts into 18 clinically relevant PSI categories. We then analyzed data on 2,381,652 Alberta hospital discharges from 2005 through 2012, and found that 134,299 (5.2%) hospitalizations had at least 1 PSI diagnosis. Conclusion: The resulting work creates a foundation for a new set of PSIs for routine large-scale surveillance of hospital and health system performance.

The Seamless Transfer-of-Care Protocol: a randomized controlled trial assessing the efficacy of an electronic transfer-of-care communication tool

BackgroundThe transition between acute care and community care represents a vulnerable period in health care delivery. The vulnerability of this period has been attributed to changes to patients’ medication regimens during hospitalization, failure to reconcile discrepancies between admission and discharge and the burdening of patients/families to take over care responsibilities at discharge and to relay important information to the primary care physician. Electronic communication platforms can provide an immediate link between acute care and community care physicians (and other community providers), designed to ensure consistent information transfer. This study examines whether a transfer-of-care (TOC) communication tool is efficacious and cost-effective for reducing hospital readmission, adverse events and adverse drug events as well as reducing death.MethodsA randomized controlled trial conducted on the Medical Teaching Unit of a Canadian tertiary care centre will evaluate the efficacy and cost-effectiveness of a TOC communication tool. Medical in-patients admitted to the unit will be considered for this study. Data will be collected upon admission, and a total of 1400 patients will be randomized. The control group’s acute care stay will be summarized using a traditional dictated summary, while the intervention group will have a summary generated using the TOC communication tool. The primary outcome will be a composite, at 3 months, of death or readmission to any Alberta acute-care hospital. Secondary outcomes will be the occurrence of post-discharge adverse events and adverse drug events at 1 month post discharge. Patients with adverse outcomes will have their cases reviewed by two Royal College certified internists or College-certified family physicians, blinded to patients’ group assignments, to determine the type, severity, preventability and ameliorability of all detected adverse outcomes. An accompanying economic evaluation will assess the cost per life saved, cost per readmission avoided and cost per QALY gained with the TOC communication tool compared to traditional dictation summaries.DiscussionThis paper outlines the study protocol for a randomized controlled trial evaluating an electronic transfer-of-care communication tool, with sufficient statistical power to assess the impact of the tool on the significant outcomes of post-discharge death or readmission. The study findings will inform health systems around the world on the potential benefits of such tools, and the value for money associated with their widespread implementation.Trial registrationClinicalTrials.gov NCT01402609.

Using patient flow simulation to improve access at a multidisciplinary sleep centre

The lack of timely access to diagnosis and treatment for sleep disorders is well described, but little attention has been paid to understanding how multiple system constraints contribute to long waiting times. The objectives of this study were to identify system constraints leading to long waiting times at a multidisciplinary sleep centre, and to use patient flow simulation modelling to test solutions that could improve access. Discrete‐event simulation models of patient flow were constructed using historical data from 150 patients referred to the sleep centre, and used to both examine reasons for access delays and to test alternative system configurations that were predicted by administrators to reduce waiting times. Four possible solutions were modelled and compared with baseline, including addition of capacity to different areas at the sleep centre and elimination of prioritization by urgency. Within the model, adding physician capacity improved time from patient referral to initial physician appointment, but worsened time from polysomnography requisition to test completion, and had no effect on time from patient referral to treatment initiation. Adding respiratory therapist did not improve model performance compared with baseline. Eliminating triage prioritization worsened time to physician assessment and treatment initiation for urgent patients without improving waiting times overall. This study demonstrates that discrete‐event simulation can identify multiple constraints in access‐limited healthcare systems and allow suggested solutions to be tested before implementation. The model of this sleep centre predicted that investments in capacity expansion proposed by administrators would not reduce the time to a clinically meaningful patient outcome.