Owusu-Edusei, Kwame PhD, PMP; Nguyen, Hang T. BS; Gift, Thomas L. PhD
Sexually transmitted infections (STIs) continue to pose a public health problem in the United States, particularly among adolescents and youth.1 In 2008, approximately 9 million cases of selected STIs occurred in persons aged 15 to 24 years,2 suggesting a total lifetime medical cost of approximately $7.8 billion3 (2010 US dollars).
Most STIs are asymptomatic and are diagnosed through opportunistic screening.4 The Centers for Disease Control and Prevention and other organizations have guidelines for screening for many STIs and for screening in populations at increased risk;1 additional studies have explored the potential for additional guidelines for screening for infections, which currently lack guidelines.5,6
The objective of this study was to examine the utilization and cost of the diagnostic methods used for STI screening among the privately insured adolescent and young adult population in the United States. Information on diagnostic method utilization is important for identifying and monitoring private sector testing practices. On the other hand, cost information for STI diagnostic methods is important for several reasons. The cost of tests is relevant for cost projections for future screening programs. They are important for estimating the overall cost of prevention and control activities. They are also important for economic evaluation (such as cost-effectiveness and cost-benefit analysis) of screening/prevention programs. Comparison of private versus public testing costs provides a measure of price differences and could aid in determining the true economic cost of testing. It is also relevant when conducting limited-perspective cost-effectiveness analyses. Finally, this study will provide test utilization and cost benchmarks that can be useful for assessing trends.
MATERIALS AND METHODS
Given the disproportionately high number of reported STI cases among persons aged 15 to 24 years (approximately 50%2), we focused on STI testing in that age range. We analyzed testing claims for 8 major STIs; human immunodeficiency virus (HIV), human papillomavirus (HPV), genital herpes simplex virus type 2 (HSV-2), hepatitis B virus (HBV), chlamydia (Chlamydia trachomatis [CT]), gonorrhea (Neisseria gonorrhoeae [NG]), trichomoniasis (Trichomonas vaginalis [TV]), and syphilis (Treponema pallidum [TP]). Data on outpatient claims for testing from the MarketScan database (MarketScan Database; Truven Health Analytics, Ann Arbor, MI) for 2008 were used in this study. The MarketScan database contains data on persons who have employment-based health insurance. In 2008, the database listed claims on more than 34 million insured persons from more than 100 payers, including large employers, health plans, and government and public organizations.7
We compiled a list of current procedural terminology (CPT) codes for the 8 STIs from various sources, including previously published studies.8–15 The CPT codes were used to identify the claims for tests performed on enrollees aged 15 to 24 years (in 2008) for all 8 STIs. Current procedural terminology code utilization for each sex and for the combined total of both sexes was measured using the claims rate, which was computed as the number of claims for each sex and for the total (for that particular CPT code) per 100,000 enrollees (for each sex and for the total) using enrollee data from the enrollment table as the denominator. The average cost for each CPT code was determined based on the total payments (which included costs paid by both the enrollee and insurance plan) associated with each claim. We analyzed costs of nonspecific CPT codes, as well. These were combination assay codes that could be used for chlamydia and gonorrhea (direct probe technique  and amplified probe technique ), dark-field examination codes used for syphilis (87164 and 87166), culture codes that could be used for gonorrhea (87077 and 87081), and wet mount (87210) and culture (87070) codes, which are sometimes used for trichomoniasis diagnosis. However, although they are listed in the table, we did not include them in the overall final utilization and cost estimates for each STI because these CPT codes are not uniquely used for STIs and could potentially represent testing for non-STI conditions.
To assess differences between cost and utilization in men and women, we used a 2-sided t test to test for differences in average costs and a 2-sided z test to test for differences in claims rates. The average cost per claim for each CPT was compared with the Centers for Medicare and Medicaid Services (CMS) fee schedule (national limit) for 2008 using a 2-sided t test.16 Finally, we extrapolated the claims rates and costs from the database to the entire population of persons aged 15 to 24 years with employer-based health insurance in the United States for 2008.
Among enrollees aged 15 to 24 years in 2008, the claims rate for HPV (18,085/100,000) was significantly (P < 0.001) higher than any of the other STIs, whereas the estimated claims rate for trichomoniasis (517/100,000) was significantly (P < 0.001) lower than any of the other STIs (Fig. 1; nonspecific CPTs were excluded). When considering the nonviral STIs, chlamydia (8955/100,000) and gonorrhea (8262/100,000) had significantly (P < 0.001) higher claims rates than did trichomoniasis (517/100,000) and syphilis (3781/100,000), excluding nonspecific CPTs. The estimated claims rate for females was significantly (P < 0.001) higher than for males for all the 8 STIs examined (Fig. 1).
Average cost estimates by STI excluding nonspecific CPTs are presented in Figure 2. The estimated average costs by STI were as follows: $24 (HIV), $34 (HPV), $29 (HBV), $25 (HSV-2), $43 (chlamydia), $42 (gonorrhea), $28 (trichomoniasis), and $24 (syphilis). Except for trichomoniasis, the average cost per STI for males and females was significantly different (P < 0.01), but for many STIs, the magnitude of the cost difference was small (<5%). The average cost of diagnostic tests for syphilis was significantly (P < 0.001) lower for males than for females ($10 vs. $27) because of claims for an obstetrics panel CPT code, which includes a syphilis test (80055). Excluding 80055, the average cost per syphilis test in females was $9.24, which was significantly lower than the cost for males (P < 0.001).
Chlamydia (CT) and Gonorrhea (NG)
The overall claims rate for chlamydia was 8955/100,000 (Fig. 1). Our results showed that CPT code 87491 (amplified probe technique, 7893/100,000) was the most commonly used, making up almost 90% of the overall total number of chlamydia testing claims (Table 1). This would be true even if we considered the multiple-antigen testing codes (87800 [direct probe] and 87801 [amplified probe]), which accounted for a combined claims rate of 1237/100,000. The 2 most costly chlamydia testing methods were for the amplified probe technique (87491 [$44.37]) and CT quantification (87492 [$64.82]), which were each significantly more costly than all other chlamydia testing methods (P < 0.001). Few claims were found for the quantification assay (87492; n = 88 for both sexes).
The overall claims rate for gonorrhea was 8262/100,000 (Fig. 1). As with chlamydia, our results showed that the amplified probe (87591) was the most commonly used test (7558/100,000), accounting for more than 90% of the overall total number of claims—this percentage excludes the nonspecific CPT codes of culture (87081) and smear, Gram stain (87205), but even if those numbers were included, amplified probe testing would account for 57% of the total. However, similar to chlamydia, the estimated average cost for the amplified probe technique (87591) was $43.29 and that for NG quantification (87592) was $64.02 and were each significantly more costly than all other gonorrhea testing methods (P < 0.001). As with chlamydia, few claims were found for the quantification assay (87592; n = 159). The estimated average cost for the nonspecific CPT codes sometimes used for chlamydia and gonorrhea combination tests was $46.25 for the direct probe technique (87800) and $168.91 for the amplified probe technique (87801).
Hepatitis B Virus (HBV)
The overall claims rate for HBV was 2814/100,000 (Fig. 1), and the most commonly used diagnostic method was hepatitis B surface antigen (HBsAg; 87340 [1291/100,000]), followed by acute hepatitis panel (80074 [572/100,000]) and hepatitis B surface antibody (86706 [550/100,000]). Together, these 3 CPTs made up more than 85% of the overall total number of diagnostic method claims (Table 1). These rates are for overall numbers of claims versus numbers of enrollees only; depending on how HBV testing is coded, multiple tests can be used to diagnose HBV in 1 patient, resulting in multiple claims for a single diagnosis.17 The estimated average costs for the acute hepatitis panel (80074 [$74.32]), HBV-amplified probe technique (87516 [$70.44]), and HBV quantification (87517 [$73.76]) were each significantly higher (P < 0.001) than the estimated average costs for all the other diagnostic methods combined. The acute hepatitis panel (80074) includes hepatitis A IgM antibody (86709), hepatitis B core IgM antibody (86705), HBsAg (87340), and hepatitis C antibody (86803).8
Human Immunodeficiency Virus (HIV)
The overall claims rate for HIV diagnostic methods was 3779/100,000 (Fig. 1). We found that the most commonly used diagnostic method (>83% of the claims) for HIV was single-assay HIV-1 and HIV-2 (86703), which had a claims rate of 3155/100,000 (significantly higher [P < 0.001] than all the other diagnostic methods) for both males and females (Table 1). The cost for claims for nucleic acid (DNA or RNA) genotype/phenotype analyses (87901 [$289.81], 87903 [$484.86], and 87904 [$119.97]) and HIV quantification (87536 [$129.5]) was significantly higher (P < 0.001) than the estimated average cost for the other diagnostic methods (both individually and combined; Table 1).
Human Papillomavirus (HPV)
The estimated overall claims rate for HPV (18,085/100,000) was the highest among all STIs (Fig. 1). We found a small number of claims for cytology (<0.3% of the total) for men. These could be coding errors, although anal cytology can be used to screen men for anal cancer.18 The cytology-related CPTs were a greater proportion of overall HPV testing in men than in women, and many cytology CPTs were more costly than other HPV testing. Therefore, male HPV test cost more on average than female tests. Excluding the male cytology CPTs did not significantly change the overall average cost of HPV testing for both sexes combined. The most commonly used HPV diagnostic method was an automated thin-layer process (88175 [6925/100,000]), followed by a manual thin-layer process (88142 [4988/100,000]), cytology requiring physician interpretation (88141 [2426/100,000]), and HPV-amplified probe technique (87621 [1919/100,000]) (Table 1). Together, they made up more than 90% of the overall total number of claims for HPV diagnostic methods. The estimated average costs for HPV quantification (87622 [$91.01]), cytopathology, smears, and other sources (88162 [$96.68], 88172, and 88173 [cytopathology, evaluation of fine needle aspirate procedures; $87.31 and $131.93], respectively) were significantly higher (P < 0.001) than the estimated average cost for all the other codes (Table 1).
Herpes Simplex Virus Type 2 (HSV-2)
The overall claims rate for HSV-2 was 1062/100,000 (Fig. 1). The estimated claims rate was significantly higher for HSV-2 (86696 [767/100,000]) than the 86694 (nonspecific HSV type, 296/100,000) (Table 1). The estimated average cost of CPT code 86694 ($24.30) was significantly lower than the average cost of 86696 ($25.02; P < 0.01).
The overall claims rate for syphilis was 3781/100,000 (Fig. 1). We found that the most common diagnostic method used was qualitative nontreponemal (86592 [2577/100,000]) obstetric panel including syphilis test (80055 [1023/100,000]; Table 1). These 2 testing CPT codes made up more than 95% of the overall total number of claims for the diagnostic methods for syphilis that we examined. However, the estimated average cost for the obstetric panel including syphilis test ($63.33) was significantly (P < 0.001) higher than the other diagnostic methods (Table 1). The CPT code 80055 includes codes 86592 and 87340 (HBsAg).8 We found a small number of claims (2/100,000) for the obstetric panel including syphilis test in male enrollees. These could be coding errors, but removing them had no significant impact on the overall claims rate or average cost per claim. Our analysis also indicated that the overall average cost of nontreponemal tests (86592 [$8.04] and 86593 [$9.68]) were significantly (P < 0.001) lower than the estimated costs for treponemal tests (86781 [$33.97] and 87285 [$23.02]) (Table 1).
Among the 8 STIs examined, the estimated overall claims rate for trichomoniasis was the lowest (517/100,000; (TP) Fig. 1). Excluding nonspecific CPT codes (culture, bacteria, other ; smear, wet mount, saline ; and detect agent not otherwise specified, DNA direct probe ), we found that more than 95% of claims for diagnostic methods for trichomoniasis were for TV, direct probe technique (87660 [499/100,000]; Table 1). The nonspecific CPT codes (87070, 87210, and 87797) could have accounted for most actual trichomoniasis diagnoses. The cost of CPT code 87660 ($28.35) was significantly higher (P < 0.05) than the cost for TV with optical verification (87808 [$24.04]). The estimated average costs for the nonspecific diagnostic methods sometimes used for trichomoniasis diagnosis were $20.77 (87070, culture), $10.60 (87210, wet mount), and $32.11 (87797, direct probe).
Comparison With CMS Fees
Commercial costs averaged 40% higher than CMS fees (range, 29% lower to 269% higher). Overall, the costs for commercial claims were lower than the CMS fees for 11 CPTs by an average of 11% (range, 1%–29%). Most of the CPTs for which commercial costs were lower than CMS were relatively little-used assays, with claims rates less than 50/100,000. The costs for commercial claims were higher than CMS fees for 67 CPTs by an average of 49% (range, 1%–269%). The difference between the average commercial claims costs and CMS fees was significant (P < 0.05 or lower) in 63 of 78 CPTs for which there were both claims and established CMS fees.
Total Cost of STI Testing in the Privately Insured Population
The 5.2 million enrolled persons aged 15 to 24 years in the insurance claims database may not be fully representative of the estimated 24.3 million persons aged 15 to 24 years in the US population in 2008 who had employer-based health insurance.19 However, extrapolating the claims rates and costs from the database to the entire population of persons aged 15 to 24 years with employer-based health insurance would indicate that the population-level cost of STI testing was $403.1 million in 2008. The most costly was HPV ($149.7 million), followed by chlamydia ($94.2 million), gonorrhea ($85.4 million), syphilis ($22.1 million), HIV ($21.7 million), HBV ($20.0 million), HSV-2 ($6.4 million), and trichomoniasis ($3.6 million), excluding costs for nonspecific tests. The 2 multiantigen CPT codes (87800 and 87801) would potentially add another $27.4 million to chlamydia and gonorrhea testing costs.
To present the private sector perspective of diagnostic method utilization and costs, we analyzed CPT codes used for screening 8 major STIs for over 5 million insured persons in the United States aged 15 to 24 years in 2008. Our results indicated that utilization of all the STI diagnostic methods was substantially higher (at least 2-fold) for females than for males, which is consistent with previously published reports on sex-specific frequency of outpatient visits.20 The utilization was highest for HPV and lowest for trichomoniasis—a reflection of the existing screening guidelines. The relatively low utilization rate for trichomoniasis is suggestive of the proportionately low public health attention it continues to receive.21
For most individual CPTs, we did not find any significant difference in the estimated costs between males and females. When considering all diagnostic methods (males and females combined) for a given disease, we did find significant cost differences, but in most cases, the magnitudes of the differences were small (Fig. 2). The 2 exceptions were syphilis and HPV. The cost difference between males and females for syphilis was driven by the inclusion of the obstetric panel (80055), which was more costly because it includes additional tests beyond the one for syphilis. The cost difference in HPV was attributable to a larger proportion of claims for males being for relatively costly CPTs: 30% of male claims for HPV testing were for cytopathology, evaluation of fine needle aspirate, and interpretation and report (88173). However, CPT code 88173 accounted for only 0.3% of female claims. The average cost per claim for CPT code 88173 was $131.93 and did not differ significantly by sex, which was primarily performed for pregnant women. Overall testing for HPV was very low in men, which limits the practical significance of higher testing costs in men compared with women. The database contains claims from different regions of the country and different insurers, and some insurers may vary what they will pay for given CPT codes based on the patient’s diagnosis—we did not explore these potential differences.
The estimated average cost for diagnostic methods ranged from $24 (HIV and syphilis) to $43 (chlamydia). When considering the nonviral STIs, chlamydia and gonorrhea had significantly (P < 0.01) higher utilization and average costs than did trichomoniasis and syphilis. We estimated that the total cost of all diagnostic methods for the 8 STIs we examined was $403.1 million for the insured population aged 15 to 24 years in the United States. To our knowledge, this is the first and most comprehensive analysis of CPT code utilization and costs; thus, comparison of our results to others is not possible.
Our CPT code-specific average cost estimates are correlated with the CMS online fee schedule.16 In most cases, the commercial costs were higher, but it is interesting to note that the commercial costs were significantly lower than the CMS fees for the 2 most commonly used tests in women, amplified probe tests for chlamydia (87491) and gonorrhea (87591). The commercial costs were 10% to 12% lower than the CMS fees for these tests, suggesting that the CMS fees may be higher than necessary. The multiple-antigen CPT codes for direct probe (87800) and amplified probe (87801) testing can be used for combination chlamydia/gonorrhea assays. In the CMS fee schedule, the combination test fees are twice the fees for the single-antigen equivalents, but the same is not true in these claims data. The combination direct probe test cost is only approximately 31%–36% higher than the single-antigen costs. For the amplified probe, the combination cost is nearly 4 times the price of one of the single-antigen amplified test costs, or almost double the cost of the 2 single-antigen tests combined. Because many processing steps are consolidated in combination testing, the cost of performing a combination test may be lower than the cost of performing 2 single-antigen tests.22,23 Using either the multiple-antigen fees or billing separately for chlamydia and gonorrhea tests when a combination test is used may lead to a total testing payment that does not reflect the true cost of testing—which could lead to distortions when considering the cost-effectiveness of chlamydia and gonorrhea testing from the payer’s perspective. One limitation associated with the multiple-antigen codes is that they can be used for non–chlamydia/gonorrhea testing—for example, a multiplex nonamplified assay for organisms associated with vaginitis can be coded 87800, and there are Food and Drud Administration–approved multiplex nucleic acid amplification tests for influenza that can be coded 87801.24
The major limitation of this analysis is the shortcoming associated with the use of claims data in general. The data may be inaccurate for one or a combination of several reasons, including clinician diagnostic and data entry errors.25,26 For instance, as presented in this study, some of the diagnostic methods that were described to be specifically for females appeared in claims for males. Although some may represent anal cytologies in men, others could be coding errors. The small number of claims for the chlamydia and gonorrhea quantification assays is probably also coding errors because there are no current quantification tests for these organisms (C. Gaydos, personal communication). A database of this size likely contains other coding errors that are not easy or even possible to identify. However, very small numbers of claims were involved in questionable claims such as these (the chlamydia and gonorrhea testing claims for the quantification assays represented <0.003% of the total claims for their respective STIs). Another limitation is that we could not differentiate between diagnostic testing and routine screening.
Despite our comprehensive search, we may have missed some CPT codes used for STI screening specific to some jurisdictions, providers, or insurers. We also omitted from the per-disease average costs and claims rates of nonspecific codes such as 87800 (direct probe technique) and 87801 (amplified probe technique), which can be used for chlamydia and gonorrhea diagnosis via combination assay. The relatively low number of combination assay coded claims compared with the single-antigen codes for chlamydia and gonorrhea indicates that the single-antigen codes seem to be the predominant way these tests were coded in 2008, although the similar testing volume for the 2 infections suggests that a large amount of combination testing took place. Given that CPT code 80055 includes code 873408 (HBsAg), we may have overestimated the rate for syphilis and underestimated the rate for HBV.
The difficulty associated with nonspecific CPT codes is most acute for trichomoniasis. Wet mount may be the most commonly used test to diagnose trichomoniasis, but the nonspecificity of the CPT code prevents us from including it in our estimate of the overall claims rate.27,28 Trichomoniasis claims could also potentially be coded as 87800 if a combination probe test was used for diagnosis.29 This probably partially explains the substantially low claims rates found for trichomoniasis in both males and females. These omissions imply that the overall STI diagnostic method utilization and the overall cost may have been underestimated in this analysis. Finally, our utilization and cost estimates for the privately insured population aged 15 to 24 years cannot necessarily be extrapolated to the entire US population aged 15 to 24 years or to persons of other ages. However, given that this is an insured population, we believe that the estimated overall utilization rates may be higher than would be found in the overall US population for the same age group.
Despite the limitations mentioned earlier, there are strengths worth mentioning. This is the first such analysis based on data from the largest administrative database in the United States, which gives the private sector perspective of the utilization and costs of STI diagnostic methods. The information provided in this study can spur further studies into understanding the pattern of utilization of these diagnostic methods, as well as analyzing the factors (such as cost, performance, health plan, and geography) that determine the choice of diagnostic method.
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