The Journal of Emergency Medicine 155

aged 18 years and older receiving IMV. Morbid obesity wasdefined as having a body mass index of 40 kg/m2 or greater.The Nationwide Inpatient Sample database collected datafrom 2004–2008 and measured outcomes in terms of mortality,prolonged IMV > 96 h, length of stay (LOS), tracheostomyrates, and discharge disposition. Morbidly obese patients had1.37-times-increased odds of requiring IMV compared tononobese patients over the 4 years. Adjusted odds showed nosignificant difference in mortality between nonobese and obesepatients receiving IMV (odds ratio [OR] 0.89). Also, the risk formortality was lower for morbidly obese patients who werehospitalized electively. The two groups were similar inrequirements for prolonged IMV (adjusted OR 0.98). However,the rates of tracheostomy were higher in the morbidly obesepatients compared to nonobese patients, 11.3% and 9.7%,respectively. LOS was shorter by 1 day in the morbidly obese,and discharge dispositions to skilled nursing facilities weresignificantly lower among the morbidly obese.

[Shea Cheney, MD

Denver Health Medical Center, Denver, CO]

Comments: This study is limited by its retrospective design,but would seem to indicate some differences in outcomes inmorbidly obese mechanically ventilated patients whencompared to the nonobese. This type of study cannot assessthe reasons for these differences, yet they are really muchmore interesting than the fact that differences may exist in thefirst place. This study merely lays the groundwork for a largerprospective trial that could get at some of these reasons.

, AMBULATORY TREATMENT IN THE MANAGE-MENT OF PNEUMOTHORAX: A SYSTEMATICREVIEW OF THE LITERATURE. Brims FJH, Maskell NA.Thorax 2013;68:664–9.

This systematic review was conducted by searchingacross nine electronic databases of medical literature for articlesdescribing or studying the use of a Heimlich valve (HV) tomanage spontaneous pneumothorax (SP) or iatrogenic pneumo-thorax (IP). The primary measure of interest was use of only anHV for management of pneumothorax with avoidance ofconversion to larger intercostal tube (ICT) or surgery. Addi-tional measures included use of an HV for outpatient-basedtreatment; use of an HV for management of different subtypesof pneumothorax, including primary spontaneous pneumo-thorax (PSP), secondary spontaneous pneumothorax, and IP;need for surgery; recurrence rate more than 1 week afterHV treatment; financial implications; reported complicationsincluding death, life-threatening or serious injury, needfor hospital admission; prolonged admission; or significantdisability or incapacity. The systematic review was conductedbased on the previously validated PRISMA approach, with anextensive literature search over 6 weeks including examinationof texts and grey literature conducted by two independentreviewers. Eighteen studies conducted over four decadeswere ultimately included in the review meeting eligibilitycriteria, including adult patients with SP and IP; conservativemanagement including needle aspiration (NA), ICT, HV withcatheter; and assessment of efficacy of conservative methods.

Studies examining postsurgical and traumatic pneumothoraxwere excluded. Of the 18 studies, two were randomizedcontrolled trials (RCTs) and the rest were a mix of bothprospective and retrospective case series. A total of 1235patients over these studies were reviewed, with 992 cases ofSP (of which 413 were known to be PSP) and 243 IP. Theauthors felt the overall risk of bias was high, as the overallquality of available data was moderate to poor, with only twoRCTs available for review. Pooled data analysis on outcomeswas not possible, as the RCTs used different comparators(HV against NA and HV against ICT). Reported overallsuccess with HV and no further intervention was 85.8%(95% confidence interval [CI] 83.7–87.7). Thirteen of thestudies described use of HV in an outpatient setting with overallsuccess of 77.9% (95% CI 75.2–80.4). Difficulties in dataanalysis were largely due to variability in managementstrategies. Analysis of additional measures revealed an overall10.1% rate of surgical intervention for persistent air leakamongst those treated with HV, though the indications forand timing of surgery varied widely. Five studies examinedlong-term recurrence of pneumothorax after HV treatment,with rates reported in the range of 11% to 24%, with follow-upperiods between 6 months and 31 months. Serious complica-tions were very rare and no deaths were reported in any of theavailable studies. The authors found four studies that reportedon economic utilization, with cost ratio of HV managementalone compared with standard inpatient ICT managementbetween 1:1.5 and 1:3.5. The authors concluded that despitethe mixed methodology and high risk of bias, there are enoughdata to support the use of HV in SP and IP with a conservativeapproach utilizing outpatient management. Advantages forpatients include reduced pain, increased mobility, and lowrate of complications. The authors conclude that it would bereasonable to conduct larger studies examining this approachto validate the findings of this systematic review.

[Alex Badulak, MD

Denver Health Medical Center, Denver, CO]

Comments: It is difficult to reconcile the authors’ findingswith their conclusions. Given the very small body of veryheterogeneous studies and case series, it seems that no solidconclusions could be made from this review. I suspect that theauthors may have their own bias that is expressed in theirconclusions. That being said, this does seem to be a conceptthat would be amenable to a prospective study.

, CHOOSING WISELY: HIGHEST-COST TESTS INOUTPATIENT NEUROLOGY. Burke JF, Skolarus LE,Callaghan BC, et al. Ann Neurol 2013;73:679–83.

The Choosing Wisely initiative launched by the AmericanBoard of Internal Medicine in response to unsustainablegrowth in health care expenditures has encouraged specialtiesto identify the five ‘‘non-value added’’ tests and procedures ineach field to assess when they may be wasteful. This articleidentified the tests/procedures ordered by neurologists from2007–2010 with the highest expenditures. The NationalAmbulatory Medical Care Survey database was used toanalyze all neurologists’ visits from 2007–2010, which included

156 Abstracts

125,029 visits across 195 unique neurologists throughInternational Classification of Diseases-9th revision codes. Totalpayments were determined from Medicare physician feeschedule and Medicare Clinical Laboratory Fee Schedule.A total of 58 million (95% confidence interval [CI] = 44–72million) visits to neurologists were identified. A total of $13.3billion (95% CI $10.1–16.5 billion) was spent on diagnostictests ordered at neurologist visits. Magnetic resonance imaging(MRI) accounted for 57% of all diagnostic expenditures($7.5 billion; 95% CI $5.7–$9.4 billion). Electromyography(EMG) and electroencephalography (EEG) accounted for 67%of non-MRI-related expenditures (EMG 20% of expenditureswith $2.6 billion and EEG 8% of expenditures with $1.1billion). Laboratory testing accounted for < 1.6% of overallexpenditures in 2010. The three most common diagnosticcategories were disorders of the peripheral nervous system,migraine, and back pain. The diagnostic category with thehighest single test expenditures was disorders of the peripheralnervous system due to associated EMG costs of $820 million(95% CI $520 million–$1.1 billion). The second diagnosticcategory with the highest expenditure was migraine dueto associated MRI costs of $690 million (95% CI $350million–$1 billion). Next steps include identifying specificclinical situations when EMG, EEG, or MRI are consideredunnecessary or wasteful.

[Java Tunson, MD

Denver Health Medical Center, Denver, CO]

Comments: The ever-increasing costs of health care in theUnited States are an issue for both patients and providers.Although this study may suggest that EEG, EMG, and MRIaccount for the highest expenditures of tests ordered byneurologists, this does not, in turn, lead to a conclusion thatthese tests should not be done. There first needs to be anunderstanding of whether or not the performance of these testswas clinically useful or not, because the hidden costs of notcorrectly making a diagnosis are not included in this study.Furthermore, consideration needs to be given to whether or

not less costly alternatives even exist. If they do not, this maymake the question even more difficult to answer.

, STATIN TOXICITY FROM MACROLIDE ANTIBIO-TIC COPRESCRIPTION: A POPULATION BASEDCOHORT STUDY. Patel A, Shariff S, Bailey D, et al.Ann Intern Med 2013;158:869–76.

Clarithromycin and erythromycin both inhibit cytochromeP450 isoenzyme 3A4 (CYP3A4), whereas azithromycin doesnot. Statins, such as atorvastatin, lovastatin, and simvastatin,are metabolized by CYP34A. Inhibition of CYP34A can causeaccumulation of these statins and increase the incidence of theirtoxic effects. This retrospective cohort study compared therates of statin toxicity among users of clarithromycin anderythromycin to users of azithromycin in Canada. Data werecollected from June 2003 to December 2010 from four differentCanadian databases. The study’s population included all adultsaged 65 years and older who filled a prescription at least twicefor a statin metabolized by CYP3A4, such as atorvastatin,lovastatin, and simvastatin, and continued to use said statin inconjunction with a macrolide. The investigators characterizedadverse outcomes as hospitalizations for hyperkalemia, acutekidney injury (AKI), rhabdomyolysis, and all-cause mortalitywith associated statin and macrolide use. The authors found arelative risk of 2.17 for rhabdomyolysis, 1.78 for AKI, and1.75 for all-cause mortality when clarithromycin or erythro-mycin were taken by statin users, compared to azithromycin.There was no significant difference in the risk of hospitalizationfor hyperkalemia between the two groups.

[Shea Cheney, MD

Denver Health Medical Center, Denver, CO]

Comments: Because it is retrospective, this study could notattest to the causality between the use of the investigated drugsand the outcomes that were measured. Nonetheless, the resultswere compelling, and given the biologic plausibility of thefindings, emergency physicians should take heed of this possiblecommon drug interaction.