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How Safe Is Safe? Risk in Radiotherapy
Int. J. Radiation Oncology Biol. Phys., Vol. 78, No. 2, pp. 321–322, 2010 Copyright Ó 2010 Elsevier Inc. Printed in the USA. All rights reserved 0360-3016/$–see front matter
doi:10.1016/j.ijrobp.2010.04.047
EDITORIAL
HOW SAFE IS SAFE? RISK IN RADIOTHERAPY ERIC C. FORD, PH.D., AND STEPHANIE TEREZAKIS, M.D. Departments of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, Baltimore, MD
2002 to 2008, there were an average of 19 serious injuries or fatalities each year on U.S. commercial carriers (2). In this same period, there were 712 million enplaned passengers per year (3). If the average passenger flies 3.8 times per year (4), then there are approximately 183 million people flying each year in United States. The chance of dying or being injured on a U.S. domestic flight each year is therefore approximately 1 in 10 million: some 16,000 times lower than the risk of a mistake during radiotherapy. A major limitation in this comparison is the severity of the incidents. The airline accidents rate quoted here is for serious injury or death, whereas the overwhelming majority of radiation delivery errors often have much less severe consequences. This can be seen qualitatively by comparing the accidents reported in the NTSB database (www.ntsb.gov) with those cited by the New York Times articles. Errors of the severity highlighted in the New York Times are very rare. Incidents in radiotherapy more often result in modest underdosing of all or part of an intended target or modest overdosing of a normal tissue structure, often with unclear clinical consequences. In a study of 555 reported errors over 5 years at the Princess Margaret Hospital, 94% of errors were judged to be of ‘‘little or no clinical significance’’ by a radiation oncologist (5). Taking into account, then, that perhaps only 6% of incidents are serious, the risk of serious injury from radiotherapy is perhaps 1,000 times higher than in the airline industry instead of 16,000 times higher. This is still a disturbing statistic, and there is some indication that it may actually be an underestimate. Previous studies in radiation oncology that focus on specific aspects of the delivery process have reported rates of 1%–5% per treatment course (6) (see also references therein), higher than the 0.2% estimate cited earlier. Further, as noted, the number of accidents that the New York Times quoted is likely an underrepresentation of what actually occurs. Perhaps the most important fact is that no one knows what the actual rate of injury is in our field. One can argue that it is not fair to compare the statistics from the airline industry to radiotherapy, a treatment that is often vital for a patient’s continued survival. A more
Receiving radiotherapy could be compared to taking an airplane flight. It can be an uncomfortable and scary process for some people, but it is often necessary to get from point A to point B. In the vast majority of cases, everything goes well. The recent front-page article in the New York Times (‘‘Radiation Offers New Cures, and Ways to Do Harm,’’ Sunday, January 24, 2010) highlights what can happen when the technologically advanced processes do not go well and leads us to ask the question: How safe are our patients? Although radiation oncology does not have the equivalent of the National Transportation Safety Board to provide data on the frequency of accidents, a back-of-the-envelope estimate can be made. The investigation by the New York Times suggests that there were 621 misadministrations in New York State over an 8-year period from 2001 to 2009. This is likely a substantial underestimation of the problem, as noted by the reporters, because it is based largely on incidents serious enough to be reported to the New York State Department of Health. Nevertheless, if this error rate is representative of the nation as a whole, then, scaling to the U.S. population (308.6 million in the United States vs. 19.5 million in New York State), we calculate that there may be some 1,225 mistreatments per year. Although 1,225 is a large number, considering the large number of radiation treatments that are delivered each year, it is a small fraction of the total number of patients treated. To quantify how small, we estimate that there are currently approximately 740,000 patients in the United States receiving radiation each year. This is based on the fact that approximately 1.5 million people were diagnosed with cancer in 2009 (1), and approximately 50% of cancer patients receive radiation at some point according to statistics from the National Cancer Institute. The estimated rate of misadministrations for each patient is then approximately 0.2% (1 in 600). The question then is, how bad is 0.2%, given that the goal is zero? As a comparison, we consider the airline industry, which is often invoked as the gold standard for risk analysis. From
Conflict of interest: none.
Received Feb 13, 2010, and in revised form March 29, 2010. Accepted for publication April 3, 2010. 321
322
I. J. Radiation Oncology d Biology d Physics
favorable comparison could be drawn if one considers emergency cardiac surgery in which the risk of death from preventable accidents is approximately 1,000 times higher than commercial aviation (7). There are, however, other areas of medicine that are able to operate much more safely. Modern anesthesiology and blood transfusion are examples that have risk profiles similar to commercial aviation (7, 8). Anesthesiology has been able to reduce mortality rates by a factor of 20 in the past 25 years (9). These examples reveal that it is possible to operate extremely safely in a high-risk setting. The key to this success is the use of systematic safety measures that reduce the likelihood of an error occurring over many steps in a complex process such as radiation therapy treatment. An analysis has been performed and found that a routine course of radiation therapy has some 270 separate nodes of potential error (10). The systematic safety solutions that the airline industry has adopted may serve as a model for improving safety in a complex environment like this. One tool is the Aviation Safety Action Program (ASAP), an airline-–government partnership adopted in 2000 that includes a national anonymous near-miss reporting system that serves as a learning re-
Volume 78, Number 2, 2010
source (11). Another simple, standard tool from the airlines is the preflight safety checklist. Such systematic safety tools can have a significant impact. The checklist, for example, has been employed in other areas of health care for remarkable, measurable benefit (12). These and other tools need to be employed to promote the culture of safety in the field. There has been a growing awareness in radiation oncology as to the value of systematic approaches to safety improvement, and both American Society for Therapeutic Radiology and Oncology and the American Association of Physicists in Medicine have working groups dedicated to the issue. In 2007, the two organizations hosted a major symposium on quality assurance, and many of these points were discussed (13) (see also references therein). Finally, specific funding mechanisms should be developed that will allow for more indepth study of these safety issues, along with the development of tools that could be implemented in any clinic to minimize treatment errors. Most people feel safe getting on an airplane. They are safe. In most cases, when our patients come in to receive radiation therapy, they are also safe. The question is how safe, and can they be made safer?
REFERENCES 1. National Cancer Institute. Surveillance, Epidemiology, and End Results (SEER) stat fact sheet. 2010. Available at: http://seer. cancer.gov/statfacts/html/all.html. 2. National Transportation Safety Board. Aviation accident statistics. Available at: www.ntsb.gov/aviation/Stats.htm. 3. Bureau of Transportation Statistics. Transportation statistics. 2010. Available at: www.transtats.bts.gov. 4. Travel Industry of America/Bureau Of Transportation Safety a air travel survey results. Washington, DC: Travel Industry of America; 2002. 5. Huang G, Medlam G, Lee J, Billingsley S, Bissonnette JP, Ringash J, et al. Error in the delivery of radiation therapy: Results of a quality assurance review. Int J Radiat Oncol Biol Phys 2005;61:1590–1595. 6. Marks LB, Light KL, Hubbs JL, Georgas DL, Jones EL, Wright MC, et al. The impact of advanced technologies on treatment deviations in radiation treatment delivery. Int J Radiat Oncol Biol Phys 2007;69:1579–1586. 7. Amalberti R, Auroy Y, Berwick D, Barach P. Five system barriers to achieving ultrasafe health care. Ann Intern Med 2005; 142:756–764.
8. Botney R. Improving patient safety in anesthesia: A success story? Int J Radiat Oncol Biol Phys 2008;71(Suppl. 1):S182– S186. 9. Gaba DM. Anaesthesiology as a model for patient safety in health care. BMJ 2000;320:785–788. 10. Ford EC, Gaudette R, Myers L, Vanderver B, Engineer L, Zellars R, et al. Evaluation of safety in a radiation oncology setting using failure mode and effects analysis. Int J Radiat Oncol Biol Phys 2009;74:852–858. 11. Logan TJ. Error prevention as developed in airlines. Int J Radiat Oncol Biol Phys 2008;71(Suppl. 1):S178–S181. 12. Pronovost PJ, Vohr E. Safe patients, smart hospitals: How one doctor’s checklist can help us change health care from the inside out. Hudson Street Press; 2010. 13. Williamson JF, Dunscombe PB, Sharpe MB, Thomadsen BR, Purdy JA, Deye JA. Quality assurance needs for modern image-based radiotherapy: Recommendations from 2007 interorganizational symposium on ‘‘quality assurance of radiation therapy: Challenges of advanced technology.’’ Int J Radiat Oncol Biol Phys 2008;71(Suppl. 1): 2–12.
doi:10.1016/j.ijrobp.2010.04.047
EDITORIAL
HOW SAFE IS SAFE? RISK IN RADIOTHERAPY ERIC C. FORD, PH.D., AND STEPHANIE TEREZAKIS, M.D. Departments of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, Baltimore, MD
2002 to 2008, there were an average of 19 serious injuries or fatalities each year on U.S. commercial carriers (2). In this same period, there were 712 million enplaned passengers per year (3). If the average passenger flies 3.8 times per year (4), then there are approximately 183 million people flying each year in United States. The chance of dying or being injured on a U.S. domestic flight each year is therefore approximately 1 in 10 million: some 16,000 times lower than the risk of a mistake during radiotherapy. A major limitation in this comparison is the severity of the incidents. The airline accidents rate quoted here is for serious injury or death, whereas the overwhelming majority of radiation delivery errors often have much less severe consequences. This can be seen qualitatively by comparing the accidents reported in the NTSB database (www.ntsb.gov) with those cited by the New York Times articles. Errors of the severity highlighted in the New York Times are very rare. Incidents in radiotherapy more often result in modest underdosing of all or part of an intended target or modest overdosing of a normal tissue structure, often with unclear clinical consequences. In a study of 555 reported errors over 5 years at the Princess Margaret Hospital, 94% of errors were judged to be of ‘‘little or no clinical significance’’ by a radiation oncologist (5). Taking into account, then, that perhaps only 6% of incidents are serious, the risk of serious injury from radiotherapy is perhaps 1,000 times higher than in the airline industry instead of 16,000 times higher. This is still a disturbing statistic, and there is some indication that it may actually be an underestimate. Previous studies in radiation oncology that focus on specific aspects of the delivery process have reported rates of 1%–5% per treatment course (6) (see also references therein), higher than the 0.2% estimate cited earlier. Further, as noted, the number of accidents that the New York Times quoted is likely an underrepresentation of what actually occurs. Perhaps the most important fact is that no one knows what the actual rate of injury is in our field. One can argue that it is not fair to compare the statistics from the airline industry to radiotherapy, a treatment that is often vital for a patient’s continued survival. A more
Receiving radiotherapy could be compared to taking an airplane flight. It can be an uncomfortable and scary process for some people, but it is often necessary to get from point A to point B. In the vast majority of cases, everything goes well. The recent front-page article in the New York Times (‘‘Radiation Offers New Cures, and Ways to Do Harm,’’ Sunday, January 24, 2010) highlights what can happen when the technologically advanced processes do not go well and leads us to ask the question: How safe are our patients? Although radiation oncology does not have the equivalent of the National Transportation Safety Board to provide data on the frequency of accidents, a back-of-the-envelope estimate can be made. The investigation by the New York Times suggests that there were 621 misadministrations in New York State over an 8-year period from 2001 to 2009. This is likely a substantial underestimation of the problem, as noted by the reporters, because it is based largely on incidents serious enough to be reported to the New York State Department of Health. Nevertheless, if this error rate is representative of the nation as a whole, then, scaling to the U.S. population (308.6 million in the United States vs. 19.5 million in New York State), we calculate that there may be some 1,225 mistreatments per year. Although 1,225 is a large number, considering the large number of radiation treatments that are delivered each year, it is a small fraction of the total number of patients treated. To quantify how small, we estimate that there are currently approximately 740,000 patients in the United States receiving radiation each year. This is based on the fact that approximately 1.5 million people were diagnosed with cancer in 2009 (1), and approximately 50% of cancer patients receive radiation at some point according to statistics from the National Cancer Institute. The estimated rate of misadministrations for each patient is then approximately 0.2% (1 in 600). The question then is, how bad is 0.2%, given that the goal is zero? As a comparison, we consider the airline industry, which is often invoked as the gold standard for risk analysis. From
Conflict of interest: none.
Received Feb 13, 2010, and in revised form March 29, 2010. Accepted for publication April 3, 2010. 321
322
I. J. Radiation Oncology d Biology d Physics
favorable comparison could be drawn if one considers emergency cardiac surgery in which the risk of death from preventable accidents is approximately 1,000 times higher than commercial aviation (7). There are, however, other areas of medicine that are able to operate much more safely. Modern anesthesiology and blood transfusion are examples that have risk profiles similar to commercial aviation (7, 8). Anesthesiology has been able to reduce mortality rates by a factor of 20 in the past 25 years (9). These examples reveal that it is possible to operate extremely safely in a high-risk setting. The key to this success is the use of systematic safety measures that reduce the likelihood of an error occurring over many steps in a complex process such as radiation therapy treatment. An analysis has been performed and found that a routine course of radiation therapy has some 270 separate nodes of potential error (10). The systematic safety solutions that the airline industry has adopted may serve as a model for improving safety in a complex environment like this. One tool is the Aviation Safety Action Program (ASAP), an airline-–government partnership adopted in 2000 that includes a national anonymous near-miss reporting system that serves as a learning re-
Volume 78, Number 2, 2010
source (11). Another simple, standard tool from the airlines is the preflight safety checklist. Such systematic safety tools can have a significant impact. The checklist, for example, has been employed in other areas of health care for remarkable, measurable benefit (12). These and other tools need to be employed to promote the culture of safety in the field. There has been a growing awareness in radiation oncology as to the value of systematic approaches to safety improvement, and both American Society for Therapeutic Radiology and Oncology and the American Association of Physicists in Medicine have working groups dedicated to the issue. In 2007, the two organizations hosted a major symposium on quality assurance, and many of these points were discussed (13) (see also references therein). Finally, specific funding mechanisms should be developed that will allow for more indepth study of these safety issues, along with the development of tools that could be implemented in any clinic to minimize treatment errors. Most people feel safe getting on an airplane. They are safe. In most cases, when our patients come in to receive radiation therapy, they are also safe. The question is how safe, and can they be made safer?
REFERENCES 1. National Cancer Institute. Surveillance, Epidemiology, and End Results (SEER) stat fact sheet. 2010. Available at: http://seer. cancer.gov/statfacts/html/all.html. 2. National Transportation Safety Board. Aviation accident statistics. Available at: www.ntsb.gov/aviation/Stats.htm. 3. Bureau of Transportation Statistics. Transportation statistics. 2010. Available at: www.transtats.bts.gov. 4. Travel Industry of America/Bureau Of Transportation Safety a air travel survey results. Washington, DC: Travel Industry of America; 2002. 5. Huang G, Medlam G, Lee J, Billingsley S, Bissonnette JP, Ringash J, et al. Error in the delivery of radiation therapy: Results of a quality assurance review. Int J Radiat Oncol Biol Phys 2005;61:1590–1595. 6. Marks LB, Light KL, Hubbs JL, Georgas DL, Jones EL, Wright MC, et al. The impact of advanced technologies on treatment deviations in radiation treatment delivery. Int J Radiat Oncol Biol Phys 2007;69:1579–1586. 7. Amalberti R, Auroy Y, Berwick D, Barach P. Five system barriers to achieving ultrasafe health care. Ann Intern Med 2005; 142:756–764.
8. Botney R. Improving patient safety in anesthesia: A success story? Int J Radiat Oncol Biol Phys 2008;71(Suppl. 1):S182– S186. 9. Gaba DM. Anaesthesiology as a model for patient safety in health care. BMJ 2000;320:785–788. 10. Ford EC, Gaudette R, Myers L, Vanderver B, Engineer L, Zellars R, et al. Evaluation of safety in a radiation oncology setting using failure mode and effects analysis. Int J Radiat Oncol Biol Phys 2009;74:852–858. 11. Logan TJ. Error prevention as developed in airlines. Int J Radiat Oncol Biol Phys 2008;71(Suppl. 1):S178–S181. 12. Pronovost PJ, Vohr E. Safe patients, smart hospitals: How one doctor’s checklist can help us change health care from the inside out. Hudson Street Press; 2010. 13. Williamson JF, Dunscombe PB, Sharpe MB, Thomadsen BR, Purdy JA, Deye JA. Quality assurance needs for modern image-based radiotherapy: Recommendations from 2007 interorganizational symposium on ‘‘quality assurance of radiation therapy: Challenges of advanced technology.’’ Int J Radiat Oncol Biol Phys 2008;71(Suppl. 1): 2–12.