" first responders are not at greater risk than the general population for HCV infection "
The Center for Disease Control and Prevention (CDC) is a highly respected and world-renowned organization. When it speaks, physicians worldwide listen. It has world-class resources in biostatistics, epidemiology, infectious disease and an entire division dedicated to the various forms of Hepatitis. But, it is still staffed by human beings, capable of error or lacking in information or experience. It is also held to strict scientific principles and regulations. It is my intention to examine their report in the light of my Fire and EMS experience and my medical and scientific training and expertise.
In the Morbidity Mortality Weekly Report (MMWR) July 28, 2000 / 49 (29);660-5 Hepatitis C Virus Infection Among Firefighters, Emergency Medical Technicians, and Paramedics --- Selected Locations, United States, 19912000 opening paragraph is the statement " this report indicates (emphasis added) that first responders are not at greater risk than the general population for HCV infection; therefore, routine HCV testing is not warranted.". Their report was issued because of "inquiries from state and local health departments and occupational health services for routine (emphasis added) HCV testing among " first responders (firefighters, EMTs and paramedics). Their report is a summary of five studies of HCV infection among first responders. They start right off with the Philadelphia study.
The Philly Firefighters were screened Nov-Dec 1999 using Hepatitis C Check an enzyme immunoassay (EIA) test. Under the FDA approved conditions for reporting a positive anti-HCV result (from the Hepatitis C Check) is that the sample must test positive twice to the EIA and a positive supplemental test (such as a recombinant immunoblot assay [RIBA ]).
In June 2000, the CDC reviewed the results of those tests and reports (they did not seek additional information or perform any retesting). In so doing, they found that 3%, not 4.5% tested anti-HCV positive. Somewhere in their comparison, 10 participants "fell out" also (2146 to 2136). The problem here is two fold. First, a screening test is not for diagnosis. Rather, it is to identify those individuals in a population that require additional testing. Second, RIBA is a diagnostic test, one that is used to confirm disease in those who have screened positive. The accepted standard for a positive screen by EIA method is two positive results from the same specimen. Using this standard for screening, gives 4.1% screen test positive. Regardless of which you choose, 3%, 4.1% or 4.5%, they are all higher than the national prevalence of 1.8% by a factor of 1.7 to 2.5 times. Another question for those 31 that the CDC says do not count, is have they had additional follow-up testing? Do we know if they have had a RIBA or the reverse transcriptase polymerase chain reaction (RT-PCR) test since the initial screening? If so, what are those results? Neither this CDC report nor I have that information.
In the Atlanta survey performed in 1991 for Hepatitis B (same risk factors, same modes of transmission but 10 times greater transmission rate than Hepatitis C), serum samples were obtained from 437 firefighters. These frozen samples were tested in May of 2000 using EIA 3.0 and confirmed by RIBA 3.0. They found a prevalence of 2.1%, 1.2 times greater than the national average (1.8%). This is still a statistically significant difference (t test CI = 95%)!
In the Connecticut survey performed in 1992 for immune response to hepatitis B vaccine, serum samples were obtained from 382 first responders statewide. These frozen samples were similarly tested in June of 2000 and a prevalence of 1.3% was found. Is there a geographic difference in prevalence rates? Is there a rural-urban difference? Is there an exposure intensity difference?
In the Miami-Dade study in Mar-Apr 2000 serum samples were obtained from 1314 firefighters. 2.7% screened positive by EIA alone, and 1.5% were confirmed positive for HCV RNA by transcription mediated amplification (TMA ). It is important to note that HCV RNA can be detected intermittently, therefore a single negative RNA test can be a false negative. Again we must ask, have the other 1.2% who screened positive, and initially were TMA negative, been re-checked by TMA ?
In the Pittsburgh study in Jan-Mar 2000 serum samples were obtained from 154 Paramedics. 3.2% were screened positive but no supplemental testing was performed. Have they since that time been further tested and what are those results?
The CDC report uses the Third National Health and Nutrition Examination Survey 1988-1994 (NHANES III) to establish a national prevalence of 1.8%. This is an unpublished study. Why is it unpublished? In the scientific community, use of unpublished data is cause to raise an eyebrow, even from the CDC. What screening method was used? A "risk factor profile"? That does not negate serum testing data.
There are several other issues in this report of concern to me.
First is the implied assumption of single needle stick exposure as a risk factor, or more specifically, as a "non-risk" factor. The CDC in Vol. 47/No RR-19 MMWR Oct 16, 1998 states "HCV is transmitted primarily through large or repeated direct percutaneous exposures to blood.". If anything, this reinforces that HCV is an occupational disease, due to the repetition of exposure of first responders to blood.
Next is the glossing over of the higher prevalence rates found in age specific groups. In Philly, 4.9% in the 40-49 year olds; Atlanta 4.0% in the 35-39 (now 45-49) year olds; Connecticut 2.6% in 40-49 (now 50-59) year olds; Miami-Dade 3.7% in the >50 year olds; NHANES III 4.9% in 30-49 (now 40-59) year olds. This begs the questions: "Why a consistent age difference?"; "What is different in the past 20 years that those under 40 do not have the prevalence rate that those over 40 have?". Lets go back 20 years, to the late 1970s and early 1980s. That is right about the time HIV was discovered and universal precautions were implemented by hospitals and most Fire Departments, most but not all. What was the time frame of implementation in some of these departments? Is there a difference in the prevalence between departments? Even in Connecticut, a statewide study with a prevalence lower than the national average, this age difference is present.
There is mention of no "duration of employment" relationship with HCV in the Miami-Dade study. But, did they determine how many of the Firefighters were or are Volunteer Firefighters prior to or concurrent with being a Career Firefighter? This is a common situation in many parts of the country, and would add a considerable length of "duration" to the exposure equation. Even more so when the "repeated exposures to blood" etiology is factored in.
There is repeated reference to identifying first responders who are anti-HCV positive with risk factors other than occupational exposure. We must remember that the presence (or absence) of a risk factor does not guarantee that that is the method of contraction of a disease. It only means that it is a possible source. National medical journals cite up to 60% of current HCV cases have no identifiable risk factors.
The MMWR 47/No RR-19 mentions that seroconversion among health-care workers after unintentional needle sticks or sharps exposures is 1.8%, but with a range of 0 7%. That is a pretty wide range, which indicates there may be other variables involved. It also mentions that most county and state health departments do not have the personnel to conduct adequate surveillance of many diseases, including Hepatitis B. With the high rate of chronic HCV (80% +/- 5%) and over half of all liver transplants today due to HCV, it behooves us as a nation to thoroughly identify the risk factors and institute a surveillance program. That means routine screening of subgroups.
The use of laboratory testing to establish a baseline in occupational screening is common practice. OSHA mandates certain testing in given occupations, pre-employment and continuous while within an occupation. Without the knowledge that an employee was "negative" (or positive)for a disease or condition prior to employment, there is no way for the employer to prove (or disprove) that they contracted the disease from an occupational exposure.
In summation, this CDC report opens more questions than it answers. The data analysis performed by the CDC is appropriate. What I must call into question is the interpretation of that analysis. Is there a geographic difference in incidence and prevalence? Why is there an age difference? Did all first responder organizations institute "universal precautions" at the same time? If not, is there a difference between those departments prevalence of HCV? How "large" and how "repeated" is the " large or repeated direct exposure to blood." have to be? There are some bad assumptions made regarding risk factors as the etiology of a disease. The use of unpublished data as a basis of reference is questionable. Until these and other questions have been answered, First Responders should remain in the "high risk factor" for HCV group, along with other health care workers.
Finally, and most importantly, what about those Philadelphia Firefighters that the CDC excludes from use as a "positive" screen? Have these Firefighters had the further evaluation and testing they require? If not, why not?
About the Author
Charles E. Truthan, DO, FACOFP, Diplomate of the American Osteopathic Board of Family Physicians, Fellow in the American College of Osteopathic Family Physicians. Since 1973, Dr. Truthan has been an active participant in Fire and Emergency Medical Services. Dr. Truthan 's interest in medicine first began after he joined the Willoughby Hills (Ohio) Fire Department as a volunteer in 1973. Since that time, he has completed training in: Fire Fighter level 1 and 2, EMT-Ambulance, EMT-Intermediate, EMT-Paramedic, EMT Instructor, State of Ohio Fire Safety Inspector, Heavy Rescue, EVOC, Water Rescue, ACLS, BCLS, ATLS, ACLS Instructor, BCLS Instructor, BTLS Instructor, Member- Board of Directors for Wisconsin BTLS. He has also served with the Ottawa Hills (Ohio) FD, Springfield Twp. (Ohio) FD, The Plains (Ohio) EMS, The City of Cleveland (Ohio) EMS, Lake Delton (Wisconsin) FD. Currently, he is the Medical Director for the Cascade Charter Township (Michigan) Fire Department. He has also served as consultant to the Detroit City (Michigan) Fire Department. Due to an injury that halted his active clinical practice in 1996, Dr. Truthan has returned full-time to his Fire Service roots by assisting Fire Departments in complying with the regulations of 29 CFR 1910.134
During his Family Practice Residency, Dr. Truthan served as the Medical-Safety Director of the first Quad City (Iowa) Air Show. The manual he wrote, encompassed all fire, safety and disaster planning for the show, and is still in use today. Upon completion of his residency training, he served one year with the U.S. Public Health Service detailed to the U.S. Coast Guard. After that, he worked for two years in several Emergency rooms in central Wisconsin. He then served for two years as the Chief of Medical Services, Troop Medical Clinic #1, at Fort McCoy, Wisconsin. During that time, he dealt with Occupational Medicine, Family Medicine and Urgent Care. Dr. Truthan continues his commission in the U.S. Public Health Service and has served several short tours for the U.S. Coast Guard. He moved to Grand Rapids in December of 1993. There, he has practiced in Urgent Care, Occupational Medicine, Family Medicine, Emergency Medicine and was a flight physician with the local helicopter unit, until an injury in 1996 halted his full time clinical practice.
In addition to his Fire EMS experience, Dr. Truthan also holds a Certificate in Medical Management from Tulane University and the American College of Physician Executives. He is past president of the Wisconsin Association of Osteopathic Physicians and Surgeons, and of the Wisconsin Society of the American College of Osteopathic Family Physicians. Dr. Truthan currently serves on several committees at the state and national levels for Osteopathic Medicine. He also serves on the advisory board for the American Firefighter Magazine.
Dr. Truthan is the founder of F.D. Doc, P.C. and F.D. Doc Services, Inc.. Both companies provide occupational health services for Firefighters. In addition, Dr. Truthan has written a generic Respiratory Protection Program that is being co-marketed with the National Volunteer Fire Council. Dr. Truthan contributes articles regularly to Vinelines on-line Magazine, TOES, and Los Angeles Firefighter.
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