Kathryn Myers

Does This Patient Have Obstructive Sleep Apnea?: The Rational Clinical Examination Systematic Review

IMPORTANCE Obstructive sleep apnea is a common disease, responsible for daytime sleepiness. Prior to referring patients for definitive testing, the likelihood of obstructive sleep apnea should be established in the clinical examination. OBJECTIVE To systematically review the clinical examination accuracy in diagnosing obstructive sleep apnea. DATA SOURCES MEDLINE and reference lists from articles were searched from 1966 to June 2013. Titles and abstracts (n = 4449) were reviewed for eligibility and appraised for evidence levels. STUDY SELECTION For inclusion, studies must have used full, attended nocturnal polysomnography for the reference standard (n = 42). MAIN OUTCOMES AND MEASURES Community and referral-based prevalence of obstructive sleep apnea; accuracy of symptoms and signs for the diagnosis of obstructive sleep apnea. RESULTS The prevalence of sleep apnea in community-screened patients is 2% to 14% (sample sizes 360-1741) and 21% to 90% (sample sizes 42-2677) for patients referred for sleep evaluation. The prevalence varies based on the apnea-hypopnea index (AHI) threshold used for the evaluation (≥5 events/h, prevalence 14%; ≥15/h, prevalence 6%) and whether the disease definition requires symptoms in addition to an abnormal AHI (≥5/h with symptoms, prevalence 2%-4%). Among patients referred for sleep evaluation, those with sleep apnea weighed more (summary body mass index, 31.4; 95% CI, 30.5-32.2) than those without sleep apnea (summary BMI, 28.3; 95% CI, 27.6-29.0; P < .001 for the comparison). The most useful observation for identifying patients with obstructive sleep apnea was nocturnal choking or gasping (summary likelihood ratio [LR], 3.3; 95% CI, 2.1-4.6) when the diagnosis was established by AHI ≥10/h). Snoring is common in sleep apnea patients but is not useful for establishing the diagnosis (summary LR, 1.1; 95% CI, 1.0-1.1). Patients with mild snoring and body mass index lower than 26 are unlikely to have moderate or severe obstructive sleep apnea (LR, 0.07; 95% CI, 0.03-0.19 at threshold of AHI ≥15/h). CONCLUSIONS AND RELEVANCE Nocturnal gasping or choking is the most reliable indicator of obstructive sleep apnea, whereas snoring is not very specific. The clinical examination of patients with suspected obstructive sleep apnea is useful for selecting patients for more definitive testing.

Clinical and Pharmacogenetic Predictors of Circulating Atorvastatin and Rosuvastatin Concentrations in Routine Clinical Care

Background—A barrier to statin therapy is myopathy associated with elevated systemic drug exposure. Our objective was to examine the association between clinical and pharmacogenetic variables and statin concentrations in patients. Methods and Results—In total, 299 patients taking atorvastatin or rosuvastatin were prospectively recruited at an outpatient referral center. The contribution of clinical variables and transporter gene polymorphisms to statin concentration was assessed using multiple linear regression. We observed 45-fold variation in statin concentration among patients taking the same dose. After adjustment for sex, age, body mass index, ethnicity, dose, and time from last dose, SLCO1B1 c.521T>C (P<0.001) and ABCG2 c.421C>A (P<0.01) were important to rosuvastatin concentration (adjusted R2=0.56 for the final model). Atorvastatin concentration was associated with SLCO1B1 c.388A>G (P<0.01) and c.521T>C (P<0.05) and 4&bgr;-hydroxycholesterol, a CYP3A activity marker (adjusted R2=0.47). A second cohort of 579 patients from primary and specialty care databases were retrospectively genotyped. In this cohort, genotypes associated with statin concentration were not differently distributed among dosing groups, implying providers had not yet optimized each patient’s risk–benefit ratio. Nearly 50% of patients in routine practice taking the highest doses were predicted to have statin concentrations greater than the 90th percentile. Conclusions—Interindividual variability in statin exposure in patients is associated with uptake and efflux transporter polymorphisms. An algorithm incorporating genomic and clinical variables to avoid high atorvastatin and rosuvastatin levels is described; further study will determine whether this approach reduces incidence of statin myopathy.

Two models of raters in a structured oral examination: does it make a difference?

Oral examinations have become more standardized over recent years. Traditionally a small number of raters were used for this type of examination. Past studies suggested that more raters should improve reliability. We compared the results of a multi-station structured oral examination using two different rater models, those based in a station, (station-specific raters), and those who follow a candidate throughout the entire examination, (candidate-specific raters).Two station-specific and two candidate-specific raters simultaneously evaluated internal medicine residents’ performance at each station. No significant differences were found in examination scores. Reliability was higher for the candidate-specific raters. Inter-rater reliability, internal consistency and a study of station inter-correlations suggested that a halo effect may be present for candidates examined by candidate-specific raters. This study suggests that although the model of candidate-specific raters was more reliable than the model of station-specific raters for the overall examination, the presence of a halo effect may influence individual examination outcomes.

Peripheral arterial disease: Application of the Chronic Care Model

Management of chronic diseases is one of the greatest challenges facing health care professionals globally. With the aging population increasing worldwide, the number of patients afflicted with chronic diseases will increase. Peripheral Arterial Disease (PAD) is a common, chronic atherosclerotic vascular disease that is associated with a high risk of stroke, myocardial infarction and cardiovascular death. The objective of this study was to determine if a multidisciplinary Vascular Risk Management Clinic (VRMC) would improve risk factor management and health outcomes for patients with PAD with poorly-controlled risk factors. A multidisciplinary VRMC was established utilizing a novel application of the Chronic Care Model to meet the needs of PAD patients. Interventions included optimization of medical therapy, investigations for undiagnosed atherosclerosis in other vascular distributions, smoking cessation therapy, dietary assessment and counseling, and active involvement of patients in evaluating progress towards their risk factor target goals. Assessment of risk factor control was done at each clinic visit and included measures of symptom severity, blood pressure, fasting blood sugar (FBS), lipid profile, body mass index (BMI), and smoking status. Analysis of risk factors was performed for the first 103 patients followed in the clinic. Average follow-up time was 528 days, and statistically significant improvements were seen in blood pressure, LDL, HDL, total cholesterol (TC), and TC/HDL ratio, while BMI, FBS, and triglycerides remained stable. Participation in a specialized vascular risk management clinic resulted in significant improvement in risk factors for disease progression compared to baseline status.

Intravascular Hemolysis Secondary to Aorto-atrial Fistula Presenting as Red Urine

Intravascular hemolysis is a rare but potentially life threatening cause of red urine characterized by brisk hemolysis and release of large amounts of hemoglobin into the urine. We present an unusual case of red urine in a 20-year-old male who was subsequently diagnosed with intravascular hemolysis due to an aorto-atrial fistula. Fistula formation was likely secondary to a recently implanted atrial septal occluder, which is a reported but exceedingly rare complication of the device. We discuss the diagnostic approach to hemolytic anemia and conclude with a literature review of other cases of device associated fistula formation and hemolysis.

Point of care ultrasound training for internal medicine: a Canadian multi-centre learner needs assessment study

BackgroundSignificant gaps currently exist in the Canadian internal medicine point-of-care ultrasound (POCUS) curriculum. From a learner’s perspective, it remains unknown what key POCUS skills should be prioritized. This needs assessment study seeks to establish educational priorities for POCUS for internal medicine residents at five Canadian residency training programs.MethodsAll internal medicine trainees [postgraduate year (PGY) 1–5] from five internal medicine residency training programs in Canada (n = 598) were invited to complete an online survey on 15 diagnostic POCUS applications, 9 bedside procedures, and 18 POCUS knowledge items. For POCUS applications and procedures, participants were asked how applicable they are to patient care in internal medicine and the participants’ reported skills in those domains. Self-reported knowledge and skills were rated on a 5-point Likert scale, where 1 = very poor and 5 = very good. Applicability was rated, where 1 = not at all applicable and 5 = very applicable.ResultsA total of 253 of 598 residents (42%) participated in our study. Data from one centre (n = 15) was removed because of low response rate (15%) and significant baseline differences between those trainees and the remaining participants. Of the remaining analyzable data from four training programs (n = 238), participants reported highest applicability to internal medicine for the following applications and procedures: identifying ascites/free fluid [mean applicability score of 4.9 ± standard deviation (SD) 0.4]; gross left ventricular function (mean 4.8 ± SD 0.5) and pericardial effusion (mean 4.7 ± SD 0.5); thoracentesis (mean score 4.9 ± SD 0.3), central line insertion (mean 4.9 ± SD 0.3), and paracentesis (mean 4.9 ± SD 0.3), respectively. Overall reported knowledge/skills was low, with skill gaps being the highest for identifying deep vein thrombosis (mean gap 2.7 ± SD 1.1), right ventricular strain (mean 2.7 ± SD 1.1), and gross left ventricular function (mean 2.7 ± SD 1.0).ConclusionsMany POCUS applications and procedures were felt to be applicable to the practice of internal medicine. Significant skill gaps exist in the four Canadian training programs included in the study. POCUS curriculum development efforts should target training based on these perceived skill gaps.