Editorials
Time of Hope for the Eventual Elimination of Meningococcal Strains A, C, Y, and W-135 in the United States
In this issue of American Family Physician, Dr. Kimmel expertly reviews meningococcal disease and meningococcal vaccines.1
Meningococcal disease is devastating, causing death in 10 to 14 percent of patients and serious complications in about another 11 to 19 percent despite the use of antibiotics.2 These complications include hearing loss, limb loss, and neurologic disability. One fourth of patients have serious or fatal complications.
Meningococcal disease is uncommon, with an incidence rate of 0.5 to 1.1 cases per 100,000 persons per year, and most cases are sporadic.2 The incidence rate is highest in preschool-age children; a smaller peak occurs in adolescents and young adults.
Until recently, the only vaccine available was a polysaccharide vaccine that has several limitations: it does not provide good immunity in young children, because they do not respond well to polysaccharide antigens; the duration of immunity is moderate; it does not provide an anamnestic response; and it does not lead to sustained reduction in nasopharyngeal carriage.
Recently, tetravalent meningococcal conjugate vaccine was licensed for persons 11 to 55 years of age. Because it is a conjugate vaccine, it has the potential for use in young children. (A supplemental license application has been filed with the U.S. Food and Drug Administration [FDA] for ages two to 10 years, but it is not yet approved for this age group.) The vaccine has a 73 to 97 percent immunogenicity based on a fourfold or greater rise in serum bactericidal activity, and 97 to 100 percent immunogenicity based on achieving a geometric mean titer of 128 or greater.2 As a conjugate vaccine, it may reduce nasopharyngeal carriage and produce some herd immunity once in widespread use in multiple age groups. Local injection site pain occurs in 54 to 59 percent of recipients, but severe pain occurs in only 0.2 to 0.3 percent. Some patients (16 to 17 percent) will develop local induration, but only 3 to 4 percent will develop induration of 1 inch or more.
The vaccine is recommended by the Advisory Committee on Immunization Practices (ACIP) for several groups: (1) persons 11 to 12 years of age, (2) those who need to catch up before entry into high school (about 15 years of age), (3) college freshman, (4) military recruits, and (5) other persons at high risk (e.g., certain international travelers to hyperendemic regions, exposed microbiologists, persons with asplenia or terminal complement deficiencies).2 Unfortunately, at $633,000 per case prevented and $5 million per death prevented, vaccination is not cost-effective for adolescents.3
As of October 2, 2005, five reports of a possible association between the newly licensed tetravalent meningococcal conjugate vaccine and Guillain-Barré syndrome have been filed with the Vaccine Adverse Event Reporting System (VAERS), which is operated by the Centers for Disease Control and Prevention (CDC) and the FDA. All five case reports occurred in adolescents 17 to 18 years of age. Each patient had onset of Guillain-Barré syndrome symptoms 14 to 31 days after vaccination. Of note, the five patients received their respective vaccines from four different lots. The CDC reports that the incidence of Guillain-Barré, based on the number of cases reported within six weeks of receiving the vaccine, is similar to what might have been expected to occur by chance alone, but notes that adverse events temporarily associated with vaccines should be reported to VAERS. As a result, the CDC supports ACIP's recommendations but states that not vaccinating patients who are known to have previously had Guillain-Barré syndrome is prudent. Physicians should be aware of the recent case reports and expect further information from the CDC as the investigation progresses.4
Despite this potential cause for pause, what excites me about meningococcal conjugate vaccine is the potential to eliminate or greatly reduce meningococcal serotypes A, C, Y, and W-135 disease from the United States. The United Kingdom instituted monovalent serogroup C conjugate vaccine in November 1999. Subsequently, disease attack rates dropped in the vaccinated; carriage rates dropped; and then the incidence declined among unvaccinated persons, suggesting herd immunity.5 Widespread vaccination in a number of age groups will be needed for this to occur in the United States, including preschool-age children, for whom the vaccine currently is not licensed. Unfortunately, serotype B is not in the vaccine, so some meningococcal disease still will occur.
Web sites for current and useful information include http://www.immunizationed.org, a site developed by family physician educators. It offers free Palm OS and Windows handheld applications of the childhood schedule, updates, and pictures of vaccine-preventable diseases. The Web site http://www.aafp.org/x10615.xml provides clinical policies on immunization from the American Academy of Family Physicians. Other useful Web sites are http://www.immunize.org; http://www.cdc.gov/nip; and http://www.immunizationinfo.org.
REFERENCES
1. Kimmel SR. Prevention of meningococcal disease. Am Fam Physician 2005;72:2049-56.
2. Bilukha OO, Rosenstein N, National Center for Infectious Diseases, Centers for Disease Control and Prevention (CDC). Prevention and control of meningococcal disease. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2005;54(RR-7):1-21.
3. Shepard CW, Ortega-Sanchez IR, Scott RD II, Rosenstein NE. Cost-effectiveness of conjugate meningococcal vaccination strategies in the United States. Pediatrics 2005;115:1220-32.
4. Centers for Disease Control and Prevention. Guillain-Barré syndrome among recipients of Menactra meningococcal conjugate vaccine-United States, June-July 2005. MMWR Dispatch 2005;54:1-3.
5. Ramsay ME, Andrews NJ, Trotter CL, Kaczmarski EB, Miller E. Herd immunity from meningococcal serogroup C conjugate vaccination in England: database analysis. BMJ 2003;326:365-6.
The Author
Richard K. Zimmerman, M.D., M.P.H., is associate professor in the Depart-ment of Family Medicine and Clinical Epidemiology at the University of Pittsburgh School of Medicine, with a secondary appointment in the Department of Behavioral and Community Health Sciences. He was a past voting member of the Advisory Committee on Immunization Practices and the AAFP Commission on Clinical Policies and Research.
Address correspondence
to Richard K. Zimmerman, M.D., M.P.H., Department of Family Medicine and
Clinical Epidemiology, University of Pittsburgh School of Medicne, 3518
Fifth Ave., Pittsburgh, PA 15261
(e-mail: zimmer+@pitt.edu). Reprints
are not available from the author.
Trial of Labor After Cesarean Delivery: The Making of a Recommendation
See Practice Guideline
on page 2126.
The recommendations on trial of labor versus elective cesarean delivery for women with a previous cesarean delivery, summarized in this issue of American Family Physician,1 represent the work of a policy team appointed by the American Academy of Family Physicians (AAFP) Commission on Clinical Policies and Research. In formulating these recommendations, the policy team followed the evidence reviewed in an evidence-based report2 from the Agency for Healthcare Research and Quality (AHRQ), which was supplemented by additional literature reviewed by the policy team. The recommendations made by the policy team were based on the best available evidence at the time of the review.
Recommendations based on the best evidence available, however, can fall short when information is not available. For example, the policy team could find no credible evidence that examined the optimal facilities or personnel who should be present when a woman with a previous cesarean delivery attempts a vaginal birth. A recent position statement3 from the American College of Obstetricians and Gynecologists (ACOG) acknowledged this lack of information, yet made strong recommendations that vaginal birth in these circumstances be limited to facilities where immediate cesarean delivery could be performed and where physicians capable of performing the surgical delivery were immediately available. These recommendations have been interpreted to mean that the obstetrician, surgeon, and anesthesiologist must be in the hospital at all times during the patient's labor. This arrangement may be feasible in hospitals replete with surgeons or trainees, but it has not been proven necessary and is not practical in all hospitals that offer maternity care. The result of this recommendation would be to restrict the availability of a trial of labor for many women who might wish to attempt a vaginal birth.
Given this lack of evidence, the AAFP policy team took a different approach. Members thought that
without evidence demonstrating the benefit of an immediately available surgical team, it was inappropriate to limit women's access to vaginal birth services. Moreover, there was some concern that such availability had the potential for harm (i.e., early surgical intervention for women who might otherwise have had successful vaginal births with expectant management). Because uterine rupture is a devastating complication requiring specific and prompt attention, it is clearly prudent that physicians observe patients closely and have a plan available to deal with this situation if the need arises. However, the policy team felt that a recommendation requiring certain services to be available went beyond what could be supported by the evidence. As a result, the AAFP recommendation conflicts with the ACOG recommendation that surgical attendants be immediately available, and it may create some controversy as physicians and institutions debate whether or how to offer services to women with a previous cesarean delivery. Ultimately, we hope that this difference will stimulate better research to demonstrate the optimal conditions for monitoring women with a previous cesarean delivery without denying the availability of this option to many women who reside outside large cities.
An unrelated issue, but one germane to any evidence-based review, is that the recommendations are limited to the information available at the time that the report was prepared. The current guideline reflects a comprehensive review of the literature through March 2004. A recently published and widely advertised large study4 examined the outcomes of women undergoing a trial of labor compared with planned repeat cesarean delivery in a collaborative group of 19 large U.S. teaching institutions. This cohort study showed that the symptomatic rupture rate during a trial of labor was 0.7 percent, which was consistent with the literature reviewed in the AHRQ evidence-based report. The only other maternal outcome that differed between groups was the rate of endometritis, which was higher in the trial-of-labor group (odds ratio [OR], 1.62). In examining neonatal outcomes, researchers found that infants born after a trial of labor were more likely to have hypoxic-ischemic encephalopathy (OR, 0.08) than those born after an elective cesarean delivery (OR, zero).
The results of this trial are important, but the study has several limitations that should be noted. Nearly all low birth weight deliveries occurred in the trial-of-labor group. Similarly, women in the trial-of-labor group were nearly three times as likely to deliver prematurely (i.e., before 37 weeks' gestation). This raises questions about the comparability of this group with the elective repeat cesarean delivery group. Another limitation is that hypoxic-ischemic encephalopathy is more common in premature infants and therefore may account for many of the observed neonatal differences. Also, during the time that this cohort was studied, prostaglandin was still used for labor induction in women with a prior cesarean delivery. The rate of uterine rupture when prostaglandins were used was twice the rate when no prostaglandins were used, which limits the applicability of the information because of the current recommendation that prostaglandins be avoided. The results of this study were not included in the evidence reviewed by the AAFP policy team. However, this study does show that the landscape of information is constantly changing. Any evidence-based conclusion is only as good as the evidence that was available when the recommendations were made. Consequently, we urge readers interested in this topic to closely monitor the literature for new developments that may help clarify the many areas of this issue that remain unclear.
REFERENCES
1. Wall E, Roberts R, Deutchman M, Hueston W, Atwood LA, Ireland B. AAFP releases guidelines on trial of labor after cesarean delivery. Am Fam Physician 2005;72:2126-31.
2. Guise JM. Vaginal birth after cesarean (VBAC). Evidence report/technology assessment no. 71 (prepared by the Oregon Health & Science University Evidence-based Practice Center under contract no. 290-97-0018). AHRQ publication no. 03-E018. Rockville, Md.: U.S. Department of Health and Human Services, 2003.
3. ACOG practice bulletin number 54: vaginal birth after previous cesarean. Obstet Gynecol 2004;104:203-12.
4. Landon MB, Hauth JC, Leveno KJ, Spong CY, Leindecker
S, Varner MW, et al. Maternal and perinatal outcomes associated with a trial
of labor after prior cesarean delivery. N Engl J Med 2004;351:
2581-9.
The Authors
Eric Wall, M.D., M.P.H., is medical director of LifeWise Health Plan of Oregon in Portland.
Richard Roberts, M.D., J.D., is professor of family medicine at the University of Wisconsin Medical School in Madison.
Mark Deutchman, M.D., is professor of family medicine at the University of Colorado at Denver and Health Sciences Center.
William Hueston, M.D., is chairman of the Department of Family Medicine at the Medical University of South Carolina in Charleston.
Lesley A. Atwood, M.D., is a family physician at Allina Medical Clinic in Hastings, Minn.
Belinda Ireland, M.D., M.S., is clinical sciences analyst at the American Academy of Family Physicians, Leawood, Kan.
Address correspondence to Belinda Ireland, M.D., M.S., American Academy of Family Physicians, 11400 Tomahawk Creek Pkwy., Leawood, KS 66211 (e-mail: bireland@aafp.org). Reprints are not available from the authors.
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Copyright © 2005 by the American Academy of Family Physicians. |
