We’ve done several columns on the need to reduce potential harm from radiation involved in diagnostic imaging studies (see our November 23, 2010 Patient Safety Tip of the Week “Focus on Cumulative Radiation Exposure”, which also links to our other columns). Then, in February, Bob Wachter in his healthcare blog “Wachter’s World” discussed an amazing statistic revealed by his colleague Rebecca Smith-Bindman: a 20-year old woman who gets an abdominal/pelvic CT scan has a 1 in 250 chance of developing cancer related to that single scan!
But a number of initiatives have been ongoing to help reduce that potential exposure to radiation. Some are clinical interventions designed to avoid imaging studies that utilize ionizing radiation. Others are technical interventions to reduce radiation dose and still others are interventions to help better track radiation exposure.
A study on a large population under the age of 18 (Dorfman 2011) showed that 7.9% of children received at least one CT scan. But another study (Nigrovic 2011) found that clinically observing children with blunt head trauma in the emergency department has the potential to significantly reduce the number needing CT scans. In their study of over 40,000 children with blunt head trauma, they found that use of observation was associated with almost 50% reduction in the number of CT scans done. They do note that further research is needed to determine the optimal period of observation needed.
Another study (Vaiman 2011) looked at the common practice in ENT for performing CT angiography to localize the vertebral arteries prior to surgery on the neck (so that anomalous vertebral arteries are avoided during the surgery). They performed ultrasound on 500 such patients who also had CT angriography and found a high correlation between the two modalities. They suggest that substantial amounts of radiation might be avoided by using ultrasound rather than CT angiography in such cases.
Technical interventions may also help reduce the dose of radiation. One study (Alibek 2011) looked at the impact of dose reduction software on both image quality and radiation exposure in children undergoing CT scanning of chest, abdomen or pelvis. They found that image quality remained acceptable and radiation dose was diminished approximately 30% on average.
And there is also activity at the national level. The American College of Radiology (ACR) and the American College of Emergency Physicians (ACEP) jointly sponsored a workshop on use of CT scanning in emergency departments. That group (Linton 2011) developed several recommendations:
· Educate health care providers and others of the status and appropriate applications of CT scanning in emergency medicine and acute care.
· Promote processes and skills to reduce the need for CT imaging when possible, such as the use of traditional radiography, ultrasound and emergency point-of-care ultrasound.
· Communicate concerns on the overutilization of CT to hospitals, together with recommended collaborative protocols to reduce variability in CT scanning utilization in emergency medicine.
· Develop mechanisms for reliable recording for emergency medicine patients of the number and doses received in CT scans and other imaging procedures.
· Develop evidence-based guidelines that address the benefits of CT imaging in emergency medicine, including improvements in patient treatments and outcomes.
But the impact of “education” on understanding of radiation exposure related to CT scanning remains unclear. A study by Horowitz (Yee 2011) found that a short lecture to clinical housestaff on the issue had no significant impact on ordering patterns for CT scans. That highlights the need for more real-time interventions such as use of clinical decision support tools during computerized order entry.
The American College of Radiology (ACR) has also launched a dose index registry that allows imaging facilities to compare their dose indices to those at comparable facilities.
But still lacking is a good system in which you carry with you (not literally but probably in your electronic personal health record) a tally of your cumulative radiation dose over a lifetime. Some day that will happen and hopefully that will be taken into account when decisions about the need for imaging studies are made.
Wachter R. A Game-Changing Statistic: 1 in 250. Wachter’s World 2011; February 11, 2011
Dorfman AL, Fazel R, Einstein AJ, et al. Use of Medical Imaging Procedures With Ionizing Radiation in Children. Population-Based Study. Arch Pediatr Adolesc Med. 2011; 165(5): 458-464
Nigrovic LE, Schunk JE, Foerster A, et al. The Effect of Observation on Cranial Computed Tomography Utilization for Children After Blunt Head Trauma. Pediatrics 2011; peds.2010-3373; published ahead of print May 9, 2011
Vaiman M, Beckerman I, Eviatar E. Detection of anomalous vertebral arteries by ultrasound as an alternative to radiological methods. European Archives of Oto-Rhino-Laryngology 2011; Online First, 12 March 2011
Alibek S, Brand M, Suess C. Dose Reduction in Pediatric Computed Tomography with Automated Exposure Control. Academic Radiology 2011; 18(6): 690-693
American College of Radiology. Dose Index Registry.
Linton O, Tenforde TS, Amis ES, et al. Summary of Workshop on CT in Emergency Medicine: Ensuring Appropriate Use
Journal of the American College of Radiology 2011; 8(5): 325-329
Yee KM. Does radiation dose education affect CT ordering practices?
AuntMinnie.com May 3, 2011
We’ve highlighted many of the dangers that can occur in the radiology suite and noted that many of them have nothing to do with the radiological procedures themselves (see our Patient Safety Tips of the Week for October 16, 2007 “Radiology as a Site at High-Risk for Medication Errors”, February 19, 2008 “ , September 16, 2008 “More on Radiology as a High Risk Area” and August 11, 2009 “ ”).
However, there clearly are risks inherent to the radiology procedures themselves. We noted the risks associated with radiation in one of this month’s other columns (see What’s New in the Patient Safety World for June 2011 “Progress in Reducing Radiation from CT Scans”). Both CT scanning and MRI scanning can also cause serious harm related to the contrast agents used.
For MRI, it is the gadolinium-based contrast agents that can cause nephrogenic systemic fibrosis (NSF) (Miller 2007), a potentially debilitating condition that may evolve rapidly over several weeks. It is commonly seen when gadolinium-based contrast agents are used in patients with renal dysfunction. The Massachusetts General Hospital (MGH) implemented a program in 2008 to reduce the risk of NSF in patients undergoing MRI, using the estimated glomerular filtration rate to identify patients at risk for NSF (Wang 2011). For patients with Stage 3 kidney disease (eGFR less than 60) they used a reduced dose of gadolinium-based contrast and no contrast for patients with Stage 4 or 5 kidney disease (eGFR less than 30 and 15, respectively). Whereas they had seen 34 cases of NSF from 2002 to 2007 (Abujudeh 2009), they have seen no cases since they implemented the risk reduction protocol.
Contrast-induced nephropathy (CIN) occurs after intravascular injection of contrast in CT scans or angiography (Rudnick 2006). Risk factors include diabetes, old age, dehydration, hypotension, hemodynamic instability, reduced cardiac output, contrast volume, and pre-existing renal disease. A new risk stratification nomogram (Kim 2011) has been used to predict the risk of CIN after contrast-enhanced abdominal CT scans in emergency departments.
In patients identified as at-risk for CIN, contrast can be avoided or used in reduced concentration. Use of newer contrast agents has often been recommended in the past but recent studies (Shin 2011) have shown no difference in the incidence of CIN in patients with impaired renal function undergoing coronary angiography with low-osmolar non-ionic contrast agents compared to iso-osmolar ones. Hydration is important and measures such as use of N-acetyl cysteine or bicarbonate may be considered but have mixed results in clinical trials. A recent study (Patti 2011) also demonstrated that high-dose atorvastatin may prevent CIN after percutaneous coronary interventions.
One is always balancing the risks vs. the potential gains from imaging studies. But it is clear that careful attention to risk profiles for these serious complications may help prevent adverse outcomes.
Miller JC. Nephrogenic Systemic Fibrosis. MGH Radiology Rounds 2007; 5(6) June 2007
Wang Y, Alkasab TK, Narin O, et al. Incidence of Nephrogenic Systemic Fibrosis after Adoption of Restrictive Gadolinium-based Contrast Agent Guidelines. Radiology 2011; published online May 17, 2011
Abujudeh HH, Kaewlai R, Kagan A, et al. Nephrogenic Systemic Fibrosis after Gadopentetate Dimeglumine Exposure: Case Series of 36 Patients. Radiology 2009; August 25, 2009
Rudnick MR, Kesselheim A, Goldfarb S. Contrast-induced nephropathy: How it develops, how to prevent it. Cleveland Clinic Journal of Medicine 2006; 73(1): 75-80
Kim KS, Kim K, Hwang SK, et al. Risk stratification nomogram for nephropathy after abdominal contrast-enhanced computed tomography. The American Journal of Emergency Medicine 2011; 29: 412-417
Patti G, Ricottini E, Nusca A, et al. Short-Term, High-Dose Atorvastatin Pretreatment to Prevent Contrast-Induced Nephropathy in Patients With Acute Coronary Syndromes Undergoing Percutaneous Coronary Intervention (from the ARMYDA-CIN [Atorvastatin for Reduction of MYocardial Damage during Angioplasty–Contrast-Induced Nephropathy] Trial. American Journal of Cardiology 2011; published online 29 April 2011
Shin D-H, Choi D-J, Youn T-J, et al. Comparison of Contrast-Induced Nephrotoxicity of Iodixanol and Iopromide in Patients With Renal Insufficiency Undergoing Coronary Angiography. American Journal of Cardiology 2011; published online May 5, 2011
We adopt many interventions after they are shown to be “effective” in studies using “before/after” designs. Even though we rank such studies on the “evidence scale” much lower than randomized controlled trials (RCT’s), there are some studies that are not amenable to RCT’s. But all too often we don’t want to wait for RCT’s to be done and we adopt the intervention as “evidence based”.
A great paper (Joffe 2011) just came out that basically took a non-intervention and applied a before/after design, demonstrating the non-intervention was successful! Many pediatric hospitals had reported significant improvements in a variety of outcome parameters (eg. out-of-ICU cardiopulmonary arrests, hospital mortality, etc.) after implementing medical emergency teams (MET’s). This hospital did not implement a MET. But it compared its hospital mortality over time to that reported in hospitals purporting to have demonstrated a positive impact of MET’s. Indeed, during the time periods of 2 published MET studies, their hospital showed a similar improvement in hospital mortality!
They go on to discuss the many potential reasons for their improvement and they do discuss the pros and cons of MET’s. However, the major thrust of the article is that before/after studies like those published on MET’s (i.e. studies using historical controls without consideration of temporal trends, case mix or severity adjustment) may come to erroneous conclusions about the efficacy of an intervention.
How many things have you implemented based upon published results of such before/after studies? We bet it’s more than you are aware of. This is a very enlightening article!
Joffe AR, Anton NR, Burkholder SC. Reduction in Hospital Mortality Over Time in a Hospital Without a Pediatric Medical Emergency Team: Limitations of Before-and-After Study Designs. Arch Pediatr Adolesc Med. 2011;165(5):419-423
In early 2010 we did several columns on radiation safety issues after the NY Times publication of its eye-opening 2-part series (Bogdanich 2010a and 2010b) on the hazards of radiation (see our February 2, 2010 Patient Safety Tip of the Week “The Hazards of Radiation” and our March 2010 What’s New in the Patient Safety World column “More on Radiation Safety”). And earlier this year we highlighted some studies in a new journal, Practical Radiation Oncology, on activities related to reducing risks of radiation overdose during radiation oncology treatments (see our February 2011 What’s New in the Patient Safety World column “New Journal Highlights Safety in Radiation Oncology”).
One of the papers (Marks 2011) discussed a FMEA (failure mode and effects analysis) to identify potential sources for error and mitigate them. The Radiation Medicine Department at North Shore-Long Island Jewish Health System also did a FMEA (North Shore-Long Island Jewish Health System 2011). They mapped out all the processes involved in planning for and providing radiation treatments and broke the process down into key components. They then implemented a “no-fly” policy in which no treatment may be started until each of those key components has been signed off on. If one or more steps had not been satisfactorily completed, the treatment would be rescheduled. They educated their patients about the importance of stopping and rescheduling and most patients felt comfortable and confident with the concept. The department also found that the number of cases that had to be stopped and rescheduled dropped considerably within a month of implementation.
Do you have a “no-fly” policy?
Bogdanich W. The Radiation Boom. Radiation Offers New Cures, and Ways to Do Harm. New York Times. January 24, 2010
Bogdanich W. The Radiation Boom. As Technology Surges, Radiation Safeguards Lag.
The New York Times. January 26, 2010
Marks LB, Jackson M, Xie L, et al. The challenge of maximizing safety in radiation oncology. Practical Radiation Oncology 2011; 1(1): 2-14
North Shore-Long Island Jewish Health System. Ensuring The Safety Of Radiation Therapy. Medical News Today. May 20, 2011
We’ve done several columns on the fact that there are dangers on weekends in most hospitals that go above and beyond those present on weekdays or even weekday nights.
Yet another study (Ricciardi 2011) has come to similar conclusions about mortality for a variety of conditions. The authors studied nonelective hospital admissions in a large all-payor database and analyzed data by day of the week admitted. They found that mortality rates were higher for 15 of 26 major diagnostic categories when patients were admitted on weekends. Even after adjustment for comorbidities and a variety of other clinical and demographic characteristics there remained a significant increase in mortality, on the order of 10% higher for those admitted on weekends.
They discuss some of the potential underlying root causes. Some services that do not show the “weekend effect”, such as trauma and burn services, tend to have processes and staffing that are more geared for a 24x7 week. They go on to discuss staffing issues, both the quantity of weekend staffing and the experience level as well.
We’ve discussed the numerous factors that may contribute to the “weekend effect” in our previous columns:
Ricciardi R, Roberts PL, Read TE, et al. Mortality Rate After Nonelective Hospital Admission. Arch Surg. 2011; 146(5): 545-551