Owusu-Edusei, Kwame Jr PHD; Gift, Thomas L. PHD; Chesson, Harrell W. PHD
From the Division of STD Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia.
The authors thank Charlotte K. Kent, PhD, for her critical review of the final manuscript.
The findings and conclusions in this manuscript are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention (CDC). Mention of company names or products does not imply endorsement by CDC.
Correspondence: Kwame Owusu-Edusei Jr., PhD, 1600 Clifton Road MSE-80, Atlanta, GA 30333. Email: Kowusuedusei@cdc.gov.
Received for publication June 9, 2009, and accepted October 8, 2009.
Gonorrhea is one of the most common reportable sexually transmitted diseases (STD) in the United States,1 with an estimated incidence of 718,000 new cases each year.2 In women, untreated gonorrhea can cause pelvic inflammatory diseases, which can develop into more complicated sequelae such as chronic pelvic pain, ectopic pregnancy, and tubal infertility.3–6 In men, untreated gonorrhea may cause epididymitis and prostatitis.7
In this article we present updated estimates of the direct medical cost per case of care for acute gonorrhea, which has previously been estimated at $93 to $168 per case (adjusted for inflation to 2007 dollars).8 Updates of cost estimates are needed periodically owing to changes in diagnostic tests, treatment recommendations, and delivery services. The cost of acute care is an important component of the estimated lifetime cost per case of gonorrhea, which also includes sequelae costs. These cost estimates are vital in studies of the burden of disease as well as in cost-effectiveness and cost-benefit analyses of STD prevention programs and interventions.
We used outpatient and prescription drug claims data from the MarketScan database (MarketScan Database, Thomson Reuters, Ann Arbor, MI) for 2003 through 2007. MarketScan is a weighted database that contains health care utilization and cost data on persons who have employment-based health insurance and lists claims annually on over 5 million insured persons from more than 100 payers, including large employers, health plans, and government and public organizations.9 In the United States, approximately 60% of the population is enrolled in employer-sponsored private health plans which enables projection of analyses of the data to be representative of all privately insured persons.10
We used International Classification of Diseases 9th revision codes (ICD-9) to identify claims for gonorrhea diagnoses (codes 098.0–098.89) in the database. The codes were used to extract claims for all outpatient visits for which gonorrhea diagnoses were identified as the primary or secondary diagnosis, or both. We assumed that visits that occurred ≤30 days after the initial visit were part of the same episode of infection (our results did not vary substantially when we used a 45- or 60-day follow-up period to define an episode).
We identified all of the recommended drugs11 used to treat gonococcal infections in the database; these were listed by generic and brand names: cefixime, cefotaxime, ceftozoxime, ceftriaxone, ciprofloxacin, levofloxacin, ofloxacin, and spectinomycin. We then used their corresponding National Drug Codes to identify drugs claims for gonorrhea in the MarketScan Database. We linked claims for outpatient visits with gonorrhea diagnoses to prescription drug claims with the assumption that prescription drugs received 7 days before through 30 days after the initial outpatient visit were associated with a given episode of an infection.
Outpatient costs included the costs of diagnosis, testing procedure, and office visits paid by both enrollee and insurance plan. Because we focused on actual payments, we assessed the actual cost of care to the payors. The resulting estimates may therefore be more reflective of the true economic “cost” than a “charge.”
To ensure that costs for other diseases were not included, we used only costs of outpatient claims in which diagnoses were exclusively for gonococcal infections. Thus, we excluded claims for visits at which the primary or secondary diagnosis code was for another disease, but included them when estimating the number of episodes. We calculated average cost per visits that also included nongonorrhea diagnoses for comparison. Drug costs included all prescription drug costs paid by both enrollee and insurance plan. Because not all outpatient visits could be linked to drug claims, total cost per episode was computed as the cost of outpatient care plus prescription drug cost where available. We finally calculated average total costs exclusively for those who had drug claims.
Based on our definition of an episode, we determined the number of episodes per patient. We used a 2-sided t test to test for differences in average costs. We used the medical care component of the Consumer Price Index for All Urban Consumers12 to adjust all costs to 2007 US dollars. To calculate average costs per case, we used the weights available in the database that were designed to make the database representative of the national employer-sponsored privately insured population under the age of 65 years.9
The estimated total number of enrollees with gonorrhea diagnoses, number of outpatient visits, number of episodes and the average cost estimates are presented in Table 1. When we used 30-, 45-, and 60-day windows to define an episode, the total number of episodes decreased by less than 2% (18,653–18,287) and there was no significant difference in estimated costs. The number of episodes ranged from 1 to 6 and 1 to 8 for males and females, respectively. However, repeat episodes were uncommon; less than 9% had 2 or more episodes. There were a total of 5515 male patients with 6376 visits, and 11,366 female patients with 13,307 visits (Table 1). The proportion of visits, which also included nongonorrhea diagnoses, was significantly higher (P < 0.01) for the females than the males (27% vs. 18%). Although over 80% of patients had prescription drug coverage, we found drug claims for less than 18% of them. There were no significant differences in the proportion of patients with prescription drug coverage and drug claims between males and females.
Average total cost per episode for males (all ages) was significantly higher (P < 0.01) than for females ($153 vs. $101) for visits that were exclusively for gonococcal infections. However, this result is likely attributable to our exclusion of visits that were not exclusively coded for gonococcal infection. When including visits that also included nongonorrhea diagnoses, the average cost per visit was significantly higher (P < 0.01) for females than males ($244 vs. $188). Thus, females had proportionately more visits and higher average cost for visits that included nongonorrhea diagnoses, consistent with previous reports of the sex-specific frequency of visits.13
The estimated overall average costs per episode (males and females combined) exclusively for visits with gonorrhea diagnoses were $119 and $85 for outpatient and drug claims, respectively (Table 1). Fluoroquinolones made up over 95% of the drug claims—86% were for levofloxacin and ciprofloxacin, and they were the most costly. We found that the average number of days supplied were higher than the recommended treatment courses for chlamydia (dual treatment is recommended if chlamydial infection is not ruled out, and it is reasonable to presume that clinicians might routinely prescribe such treatment in all cases).11 The overall average total cost (males and females) was $109 per episode, which included episodes for which we did not find drug claims. When we estimated total cost per episode exclusively for those who had drug claims, the overall average total cost was $210 (male, $227; female, $205). When considering estimates for those who had drug claims, our estimates are higher than the cost of treatment of acute gonorrhea used in previous estimates of the economic burden of gonorrhea after adjusting for inflation.8 This difference is likely due primarily to differences in treatment settings. The higher estimate in this study was calculated for privately insured populations, whereas the previous estimate reflected a midpoint between lower-cost treatment settings (such as STD clinics) and higher-cost treatment settings (such as among private providers).
There are limitations in this study associated with the use of medical claims data to estimate incidence and average cost per episode. First, care for gonorrhea may not be identified with one of the gonorrhea-specific codes we examined (098.0–098.89). Other less-specific ICD-9 codes could be used. Second, there is no definition of an episode based on visits that will correctly capture all cases. Consequently, it is almost impossible to differentiate between follow-up visits for a particular episodes and visits for a subsequent one, which eventually affects the cost and number of episodes estimated. However, most cases involved only one visit, and we confirmed the robustness of our results by using 3 definitions for an episode based on the interval after the initial visit and found no significant difference in the results. The third and most important limitation, which was partly a consequence of the first, was the difficulty in finding the associated treatment costs (drug claims) for each episode. Drug treatment costs were not found for a majority of episodes, possibly due to treatment with free samples, with a regimen not covered by the insurance plan or not paid via insurance claim, or with a regimen not recommended by CDC. However, we believe that most of the cases diagnosed were treated, given that the population in our study was insured. Thus, our estimates for those who were treated (i.e., exclusively for those who had drug claims) are likely more realistic. A fourth limitation is that the estimates are representative of the employer-sponsored privately insured population and may not be representative of the entire US population. Finally, we note that it is difficult to determine the impact of these limitations on the cost-per-case estimates, as we have no way to assess whether the cases of gonorrhea included in our analysis truly reflect the “average” case of gonorrhea. Thus, our results could over- or underestimate the cost per case of gonorrhea, and we would have no knowledge of the direction of this bias, if any.
Despite limitations, our study provides a more recent estimate of the direct medical cost of acute gonococcal infections, using recent claims data that reflect the actual cost of providing care for gonorrhea to the employer-sponsored privately insured US population. This updated estimate of the cost of acute care can help to inform economic studies of gonorrhea prevention activities. The cost of acute care is an important component of the lifetime direct medical cost per case of gonorrhea, which also includes the cost of sequelae such as epididymitis in men and chronic pelvic pain, ectopic pregnancy, and tubal infertility in women.3–7 Our estimate does not include the cost of gonorrhea-associated sequelae such as pelvic inflammatory disease and epididymitis. Other costs that we did not assess in this analysis include: intangible costs (such as pain and suffering), indirect costs (such as lost productivity costs, which have previously been estimated to be as much as 50% of the estimated direct cost for bacterial STDs14,15), and potential HIV costs attributable to the facilitative effects of gonorrhea on HIV transmission and acquisition.16,17
1. Centers for Disease Control and Prevention. Sexually Transmitted Disease Surveillance, 2007. Atlanta, GA: US Department of Health and Human Services, 2008.
2. Weinstock H, Berman S, Cates W. Sexually transmitted diseases among American youth: Incidence and prevalence estimates, 2000. Perspect Sex Reprod Health 2004; 36:6–10.
3. Buchan H, Vessey M, Goldacre M, et al. Morbidity following pelvic inflammatory disease. Br J Obstet Gynaecol 1993; 100:558–562.
4. Hillis SD, Joesoef R, Marchbanks PA, et al. Delayed care of pelvic inflammatory disease as risk factor for impaired fertility. Am J Obstet Gynecol 1993; 168:1503–1509.
5. Westrom L. Effect of pelvic inflammatory disease on fertility. Venereology 1995; 8:219–222.
6. Westrom L, Joesoef R, Reynolds G, et al. Pelvic inflammatory disease and fertility-a cohort study of 1844 women with laparoscopically verified disease and 657 control women with normal laparoscopic results. Sex Transm Dis 1992; 19:185–192.
7. Hook EW, Handsfield H. Gonnococcal infections in the adult. In: Holmes KK, Sparling PF, Stamm WE, et al, eds. Sexually Transmitted Diseases 4th ed. New York: McGraw Hill, 2008; 627–645.
8. Chesson HW, Blandford JM, Gift TL, et al. The estimated direct medical cost of sexually transmitted diseases among American youth, 2000. Perspect Sex Reprod Health 2004; 36:11–19.
9. The MEDSTAT Group's Training. Presented to the Centers for Disease Control and Prevention. In, The MEDSTAT Group's “MarketScan Database Training.” Atlanta, GA: Thompson Medstat, 2002.
10. US Census Bureau. Statistical Abstract of the United States: 2009. 128th ed. Washington, DC: U.S. Census Bureau; 2008; 124–210.
11. Centers for Disease Control and Prevention. Sexually transmitted disease treatment guidelines, 2006. MMWR Recomm Rep 2006; 55:1–94.
12. United States Department of Labor. Consumer Price Indexes-all urban consumers [Internet]. Washington, DC: United States Department of Labor. Accessed June 15, 2009. Available at: http://www.bls.gov/cpi/home.htm
13. Buve A, Gourbin C, Laga M. Gender and sexually transmitted diseases. In: Holmes KK, Sparling PF, Stamm WE, et al, eds. Sexually Transmitted Diseases 4th ed. New York: McGraw Hill, 2008; 151–164.
14. Blandford JM, Gift TL. Productivity losses attributable to untreated chlamydial infection and associated pelvic inflammatory disease in reproductive-aged women. Sex Transm Dis 2006; 33:S117–S121.
15. Chesson HW, Collins D, Koski K. Formulas for estimating the costs averted by sexually transmitted infection (STI) prevention programs in the United States. Cost Eff Resour Alloc 2008; 6:10.
16. Sexton J, Garnett G, Rottingen JA. Metaanalysis and metaregression in interpreting study variability in the impact of sexually transmitted diseases on susceptibility to HIV infection. Sex Transm Dis 2005; 32:351–357.
17. Fleming DT, Wasserheit JN. From epidemiological synergy to public health policy and practice: The contribution of other sexually transmitted diseases to sexual transmission of HIV infection. Sex Transm Infect 1999; 75:3–17.