Gift, Thomas L. PhD; Irwin, Kathleen L. MD, MPH
From the Centers for Disease Control and Prevention, Atlanta, Georgia
Correspondence: Thomas L. Gift, PhD, Centers for Disease Control and Prevention, 1600 Clifton Rd., NE Mail Stop E-80, Atlanta, GA 30333. E-mail: firstname.lastname@example.org.
SEXUALLY TRANSMITTED DISEASE (STD) prevalence among low-income emergency department (ED) patients is higher than that in many other health care settings.1 Routine STD screening may offer clinical benefits to ED patients and may complement other STD control strategies in communities with high STD incidence. While gonorrhea prevalence among ED patients is typically lower than chlamydia prevalence, a greater proportion of patients with gonorrhea than chlamydial infection receive treatment in the ED.2
In this issue, Aledort et al.3 model various ED gonorrhea screening strategies for young, asymptomatic women with high prevalence. They found that screening would be a cost-effective alternative to not screening and that an investigational rapid immunochromotographic strip test (RIS) using self-collected vaginal swabs would offer advantages over endocervical Gram stains and nonrapid, nucleic acid amplification tests (NAAT) using urine or endocervical specimens. Although the sensitivity of RIS (<80%3) is lower than the sensitivity of NAAT, RIS use would result in treating a higher proportion of test-positive patients than NAAT. RIS use would also prevent more cases of pelvic inflammatory disease (PID), and yield more quality-adjusted life years (QALYs). The RIS would not be cost saving compared to urine-based NAAT, but the incremental cost per QALY gained over NAAT would be less than many interventions considered cost effective. Also, the cost of RIS using clinician-collected specimens would be more than the urine-based NAAT, but the difference was minor (11% or less, depending on the age groups screened). Both NAAT and RIS would be superior in terms of cost and outcomes to the other rapid test considered, the Gram stain. This analysis is consistent with another study showing that gonorrhea and chlamydia screening of women with urine-based NAAT in a Baltimore ED with high gonorrhea and chlamydia prevalence was cost saving compared to no screening.4
This intriguing analysis of an investigational rapid test should prompt decision makers to address the clinical, operational, and economic barriers that have stalled routine STD screening in most ED.1 First, STDs are not a priority for most EDs patients. Only 3.4% of ED visits in 2002 were primarily motivated by genitourinary symptoms.5 Most gonorrhea infections in women are asymptomatic,6,7 and no evidence suggests that women will request screening in the absence of symptoms. Most ED clinicians are urged to manage symptomatic conditions during their brief encounters and to refer patients elsewhere for preventive services such as screening.
Second, logistic barriers have precluded routine STD screening using endocervical specimens. Most EDs lack enough gynecologic examination facilities or skilled examiners to routinely collect endocervical specimens, and patients without genitourinary complaints may decline speculum examinations. Here, self-collected vaginal specimens provide logistic advantages and would reduce demand on clinician time. Given the typical length of ED visits (about 55% exceed 2 hours5), “standing” rapid screening programs could conceivably offer patients swabs for self-collection, process the test, and post results before patients see their clinicians.
Third, ensuring adequate treatment and follow-up of patients testing positive is difficult, especially when symptoms that might prompt treatment are absent, and many communities have closed low-cost public clinics and other “safety net” providers. Concerns about poor follow-up deter ED screening, and the increased scrutiny of “medical errors” due to poor continuity of care has only heightened this concern.8 Human immunodeficiency virus (HIV) screening is poorly implemented in EDs, even for patients with suspected STD,9,10 despite national guidelines recommending screening.11 A survey of ED clinicians noted poor follow-up as the leading concern.9 Rapid tests that permit on-site treatment of laboratory-confirmed infection would eliminate this barrier. Aledort et al.3 showed that treatment rate would substantially influence the cost effectiveness of RIS: if the probability of treatment following a positive NAAT fell from a baseline value of 80% to 40%, RIS would be the best of 6 different strategies in terms of both cost and effectiveness. Retrospective studies showing that only 26%–43% of ED patients not presumptively treated at initial visits were eventually treated caution that actual treatment rates may be near or less than the lower bound of this sensitivity analysis.12,13 This analysis of treatment rate also highlights the potential value of rapid tests in other episodic care settings such as jails. Without rapid tests, treatment before release is difficult, and increasing the treatment rate can increase cost effectiveness of screening.14
Fourth, routine STD screening may not be reimbursed. Several ED STD screening programs have been financed and staffed by health departments, often in response to local outbreaks.15 If health departments do not support screening, public or private insurers must pay. However, they may decline to pay for the many uninsured or underinsured ED5 patients or those who have non-STD–related complaints. Obviously, low cost tests would favor reimbursement.
Aledort et al.3 noted 1 important limitation of their analysis that should be considered by others evaluating the cost effectiveness of STD screening. In women, gonorrhea screening is not generally warranted or recommended unless chlamydia screening is already offered16 because chlamydia prevalence is higher than gonorrhea prevalence in nearly all settings.1,17 Thus, ED gonorrhea screening programs would likely supplement existing chlamydia screening programs. Evaluating the effectiveness and costs of gonorrhea screening (with rapid or nonrapid tests) against alternatives of chlamydia screening is an important area for further modeling.
Three other potential limitations of this study merit consideration. First, the analysis relied on gonorrhea prevalence estimates from an ED in Baltimore, a city that has long reported among the highest gonorrhea rates in the United States.17 Aledort et al.3 found that screening for gonorrhea in general and with a rapid test in particular was prohibitively costly in terms of cost per case of PID averted or QALY gained as prevalence in all age groups declined. Also, the relatively low specificity of RIS (< 95%3) would yield very low positive predictive value in low-prevalence populations. False-positive test results could lead to additional costs not incorporated in the analysis. These include additional testing to rule out false-positive results, counseling test-positive patients about a stigmatized condition that raises issues about partner fidelity, and examining and treating sex partners. Screening yield and cost effectiveness could be improved by targeting screening to high-prevalence subgroups. However, unless targeted populations were identified solely by age—a less predictive risk factor than sexual behaviors—targeting would involve individual sexual risk assessment. This would increase clinician labor costs and may reduce patient acceptability. Second, the total costs and cases of PID using urine-based NAAT and clinician-collected RIS specimens were only slightly less than those using patient-collected RIS specimens. This suggests that patient-collected specimens, which would reduce clinician burden, might be more practical, especially if results were available before the clinician encounter. Finally, the analysis included costs of averted long-term sequelae as benefits of screening, a standard in public health applications. However, ED decision makers may find analyses of short-term costs and benefits more relevant to their bottom line. Costly and serious sequelae of STD often occur months to years after initial infection, so a shorter time horizon that includes only short-term outcomes can substantially reduce cost effectiveness.
If sensitive and specific rapid gonorrhea tests become commercially available, they would increase the options for the ED. The decision to initiate STD screening in the ED should weigh clinical benefits and risks, acceptability to patients and clinicians, and operational factors such as ability to systematically identify persons eligible for screening, collect specimens, treat persons with positive tests, and obtain reimbursement. Up-front program resources and short- and long-term economic benefits are also important parts of the equation for decision makers managing large health systems, as well as busy clinicians who want to use their limited time with patients in the most meaningful way.
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