Biopsy Procedures and Molecular Testing Utilization and Related Costs in Patients with Metastatic Lung Cancer

BACKGROUND: Epidermal growth factor receptor (EGFR) gene mutations and anaplastic lymphoma kinase (ALK) gene rearrangements are key therapeutic targets for biomarker-driven treatment with an EGFR or ALK tyrosine kinase inhibitor (TKI) in patients with metastatic non-small cell lung cancer (NSCLC). To appropriately guide treatment decisions, since 2011, the National Comprehensive Cancer Network and the American Society of Clinical Oncology therefore recommend EGFR and ALK analysis in tumor samples obtained at the time of diagnosis in patients with non-squamous NSCLC. Currently, there are limited data on utilization patterns and cost of biopsy procedures and biomarker tests in patients with metastatic NSCLC who receive an EGFR or ALK TKI. OBJECTIVES: To (a) describe utilization patterns and costs associated with biopsy procedures and biomarker testing in patients with NSCLC who received erlotinib or crizotinib between 2009 and 2012 and (b) investigate the timing of these procedures relative to the erlotinib or crizotinib index date. METHODS: Adult patients with metastatic lung cancer were identified by ICD-9-CM diagnostic codes within the Truven Health Analytic MarketScan database. Patients were included in the analysis if they had an index erlotinib or crizotinib claim between January 1, 2009, and September 30, 2012 (index period) and were continuously enrolled for ≥ 12 months before the index claim. Because there is no specific ICD-9-CM diagnostic code for NSCLC, patients with metastatic lung cancer who received erlotinib or crizotinib were considered to have metastatic NSCLC. Using CPT and ICD-9-CM codes, lung biopsy procedures performed during the 24 months before or 12 months after the index claim date were identified. For every patient, biomarker testing claims for EGFR and ALK were identified using the molecular pathology stacked CPT code during the 2 months before or 1 month after the index date. The frequency of claims for biopsy procedures and biomarker testing was analyzed descriptively. The overall summary measures for biomarker testing, especially frequency of EGFR testing in patients receiving erlotinib, was also described as before and after 2011, the year when biomarker testing became part of the guidelines. Per patient and overall costs for biopsy procedures and biomarker testing were calculated from payer and patient perspectives. RESULTS: Of the 4,926 identified patients, 4,801 (97.5%) received erlotinib, and 125 (2.5%) received crizotinib. Biopsy procedure claims were identified for 3,579 (72.7%) patients, including 3,503 (73.0%) erlotinib recipients and 76 (60.8%) crizotinib recipients. Biomarker testing claims were identified for 675 (13.7%) patients, including 634 (13.2%) erlotinib recipients and 41 (32.8%) crizotinib recipients. Overall, most biomarker testing procedures (476 of 741) were identified in 435 (of 675) patients after year 2011. Also, among erlotinib recipients, percentage of patients receiving EGFR testing was increased over the index period. Per patient mean (SD) numbers of biopsy procedures and biomarker tests were 1.2 (1.1) and 0.2 (0.4), respectively. In the outpatient setting, per patient mean (SD) cost per biopsy procedure was $1,223 ($1,899) from the payer perspective and $60 ($147) from the patient perspective, whereas in the inpatient setting, it was $8,163 ($18,712) and $180 ($691), respectively. Among patients receiving at least 1 biomarker test, the per patient mean (SD) cost for the overall population was $891 ($1,062) and $43 ($229); for erlotinib recipients, it was $906 ($1,084) and $42 ($228); and for crizotinib recipients, it was $664 ($576) and $55 ($243) in payer and patient perspectives, respectively. CONCLUSIONS: This study provides insight into the use and cost of biopsy and biomarker testing procedures in patients with metastatic NSCLC. The low frequency of biomarker testing highlights the need for more awareness of testing to guide treatment decisions in these patients. Costs associated with biopsy procedures and biomarker testing provide insight into the economic impact on metastatic NSCLC patients treated with targeted therapy.

OBJECTIVES: To (a) describe utilization patterns and costs associated with biopsy procedures and biomarker testing in patients with NSCLC who received erlotinib or crizotinib between 2009 and 2012 and (b) investigate the timing of these procedures relative to the erlotinib or crizotinib index date.
METHODS: Adult patients with metastatic lung cancer were identified by ICD-9-CM diagnostic codes within the Truven Health Analytic MarketScan database. Patients were included in the analysis if they had an index erlotinib or crizotinib claim between January 1, 2009, and September 30, 2012 (index period) and were continuously enrolled for ≥ 12 months before the index claim. Because there is no specific ICD-9-CM diagnostic code for NSCLC, patients with metastatic lung cancer who received erlotinib or crizotinib were considered to have metastatic NSCLC. Using CPT and ICD-9-CM codes, lung biopsy procedures performed during the 24 months before or 12 months after the index claim date were identified. For every patient, biomarker testing claims for EGFR and ALK were identified using the molecular pathology stacked CPT code during the 2 months before or 1 month after the index date. The frequency of claims for biopsy procedures and biomarker testing was analyzed descriptively. The overall summary measures for biomarker testing, especially frequency of EGFR testing in patients receiving erlotinib, was also described as before and after 2011, the year when biomarker testing became part of the guidelines. Per patient and overall costs for biopsy procedures and biomarker testing were calculated from payer and patient perspectives.
RESULTS: Of the 4,926 identified patients, 4,801 (97.5%) received erlotinib, and 125 (2.5%) received crizotinib. Biopsy procedure claims were identified for 3,579 (72.7%) patients, including 3,503 (73.0%) erlotinib recipients and 76 (60.8%) crizotinib recipients. Biomarker testing claims were identified for 675 (13.7%) patients, including 634 (13.2%) erlotinib recipients and 41 (32.8%) crizotinib recipients. Overall, most biomarker testing procedures (476 of 741) were identified in 435 (of 675) patients after year 2011. Also, among erlotinib recipients, percentage of patients receiving EGFR testing was increased over the index period. Per patient mean (SD) numbers of biopsy procedures and biomarker tests were 1.2 (1.1) and 0.2 (0.4), respectively. In the outpatient setting, per patient mean (SD) cost per biopsy procedure was $1,223 ($1,899) from the payer perspective and $60 ($147) from the patient perspective, whereas in the inpatient setting, it was $8,163 ($18,712) and $180 ($691), respectively. Among patients receiving at least 1 biomarker test, the per patient mean (SD) cost for the overall population was $891 ($1,062) and T remendous advances in lung cancer biology over the past decade have paved the way for targeted therapy in patients with advanced non-small cell lung cancer (NSCLC). 1 Mutations in the epidermal growth factor receptor (EGFR) gene and rearrangements of the anaplastic lymphoma kinase (ALK) gene have become key therapeutic targets for biomarker-driven treatment in patients with non-squamous NSCLC. 2 • Epidermal growth factor receptor (EGFR) gene mutations and anaplastic lymphoma kinase (ALK) gene rearrangements have become key therapeutic targets for biomarker-driven treatment in patients with advanced/metastatic non-small cell lung cancer (NSCLC) of non-squamous etiology. • Guidelines recommend EGFR and ALK biomarker testing to identify patients eligible for erlotinib and crizotinib therapy. • There is a lack of information on the use and cost of biopsy procedures and biomarker testing.

What is already known about this subject
• This retrospective claims database analysis study provided information on the utilization patterns of and costs associated with biopsy procedures and biomarker testing in patients with advanced lung cancer who received erlotinib or crizotinib. • Despite guideline recommendations, the frequency of biomarker testing after year 2011 is low. • The costs for biopsy sample collection and biomarker testing varied considerably, providing insight into the economic impact of these procedures in the management of patients with metastatic NSCLC who receive biomarker-driven therapies.

Identification of Patients Receiving Erlotinib or Crizotinib
The study period spanned from January 1, 2007, to September 30, 2013. The index period was January 1, 2009, through September 30, 2012. Patients were included in the study if they were aged ≥ 18 years; had ≥ 1 International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis code at the primary and/or secondary position for metastatic lung cancer (162. 2-162.5, 162.8-162.9) during the study period; had an index pharmacy claim for erlotinib or crizotinib identified by National Drug Code numbers (54868-5290, 54868-5447, 54868-5474, 50242-062, 50242-063, or 50242-064 for erlotinib; 0069-8140 or 0069-8141 for crizotinib) during the index period with no other erlotinib or crizotinib pharmacy claim in the previous 180 days; and had a continuous enrollment for ≥ 12 months before the index date (i.e., the date of the first pharmacy claim for erlotinib or crizotinib identified during the index period). Since the ICD-9-CM classification system does not provide separate diagnosis codes for NSCLC, in this study, patients with metastatic lung cancer who received erlotinib or crizotinib were assumed to have NSCLC, since these therapies are indicated exclusively for treatment of NSCLC. Patients were further categorized as newly diagnosed or previously diagnosed. Patients were defined as Nearly 90% of EGFR mutations manifest as either deletions in exon 19 or substitutions in exon 21 (L858R); both of these EGFR mutations confer increased sensitivity to tyrosine kinase inhibitors (TKIs) that target the intracellular tyrosine kinase domain. 3 Fusion of the echinoderm microtubule-associated protein-like-4 (EML4) and ALK genes is associated with lung adenocarcinomas lacking EGFR mutations and is correlated with ALK expression. 4 In the United States, prevalence of EGFR mutations is 10%-15%, and ALK rearrangements are 2%-7%, depending on the population studied and the detection method used. [5][6][7][8][9] Randomized controlled trials comparing EGFR TKIs to chemotherapy in first-line EGFR mutation-positive NSCLC patients have demonstrated a significant progression-free survival (PFS; range = 9.2-13.1 months; hazard ratio range = 0.16-0.48) and response rates ranging from 61%-83%. [10][11][12] Based on these results, where sensitizing EGFR mutations predicted better response and PFS in patients with NSCLC, 10,[12][13][14][15][16] in 2011, the National Comprehensive Cancer Network (NCCN) and American Society of Clinical Oncology (ASCO) recommended EGFR analysis in tumor samples collected at the time of non-squamous NSCLC diagnosis before administration of erlotinib. 17,18 After further approval of crizotinib in August 2011, NCCN recommended ALK analysis as well. 19 In 2013, the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology also recommended EGFR and ALK testing for selection of lung cancer patients for EGFR and ALK TKIs. 20 Compared with chemotherapy, these therapies have shown better quality of life and improvement in symptoms in the clinical trial setting 21,22 and in clinical practice. 23 A recent analysis also suggested that biomarker testing for EGFR mutations and ALK overexpression and biomarker conditional treatment is a cost-effective strategy compared with treatment with chemotherapy and no testing in metastatic NSCLC. 24 Currently, there is a lack of information on utilization patterns of biopsy procedures and biomarker testing in NSCLC. This information is necessary to gain insight into the treatment patterns of targeted therapies as more and more similar therapies are becoming available. Since NSCLC treatment decisions are now based on a complex algorithm in which histology and biomarkers are important factors, a multidisciplinary approach to NSCLC management is imperative. 25,26 Such a multidisciplinary approach means that it is important to understand the type of provider associated with these procedures, the settings of care (inpatient and outpatient), and the types of visits.
It is also crucial to explore costs associated with biopsy and biomarker testing procedures, as expanding use of targeted therapies necessitates increased use of these procedures, which may affect health care costs. 27 An analysis conducted using integrated medical and pharmaceutical data from 4 Blue Cross Blue Shield plans showed a wide variation observed in per patient cost for EGFR testing. From a payer perspective, newly diagnosed if they had no identifiable ICD-9-CM code for lung cancer in 1 year before the first ICD-9-CM lung cancer code identified in the index period; others were defined as previously diagnosed.

Biopsy Procedures and Biomarker Testing Identification
Lung biopsy procedures performed at least up to 12 months and until 24 months before and 12 months after the index date were identified by Current Procedural Terminology (CPT) and/or ICD-9-CM procedure codes (Appendix A, available in online article). All CPT codes of the same biopsy type on the same day were considered to be related to the same biopsy procedure. Nonbiopsy-specific CPT codes for guided needle placement were considered to be associated with biopsy procedure only when they were identified on the same day as the biopsyrelated CPT code. For inpatient admission claims, all claims with the biopsy procedure code as the primary procedure under the same diagnosis-related group code were considered to be associated with the same biopsy procedure. CPT codes for ancillary biopsy procedures were also identified. For all lung biopsy procedures, information on the type of biopsy, provider, facility where the biopsy was performed, and the type of visit (i.e., inpatient, outpatient, or emergency room) was identified.
During a period of 2 months before and 1 month after the index date, biomarker testing for EGFR and ALK was identified by using CPT codes classified as molecular pathology stacking codes (83890-83914) or array codes (88384-88386; Appendices B and C, available in online article). These CPT codes are a series of codes representing individual steps or techniques used in performing a test. Although these codes were discontinued as of January 2013, they were considered to be appropriate for this study, since the biomarker testing identification period ranged from November 1, 2008, to October 30, 2012. During the biomarker testing identification period, there was no specific identification code for EGFR and ALK; therefore, it was assumed that testing conducted in patients receiving erlotinib was for EGFR, and testing conducted in patients receiving crizotinib was for ALK. All biomarker testing-related CPT codes with the same date were identified as related to the same test and were considered to be part of the same pathology code stack. For all biomarker testing, information on the location of testing was also identified.

Biopsy Procedure and Biomarker Testing Cost Identification
Costs associated with lung biopsy procedures and biomarker testing were estimated from payer and patient perspectives. Payer costs included the net payment made by the payer toward the biopsy procedure or biomarker test; patient costs included the amount paid by the patient, which collectively included the amount paid as copayment, coinsurance, and/or deductible. Costs were described by the type of facility (inpatient or outpatient). Costs of biopsy procedures and biomarker testing were calculated based on the associated CPT codes previously described. For biopsy procedures, costs associated with accompanying ancillary procedures were also taken into account and contributed to the final cost. For biomarker testing, costs for interpretation and reporting were also taken into account. All costs were adjusted to April 2016, based on the Consumer Price Index.

Statistical Analyses
All study variables, including baseline characteristics and frequency of biopsy procedures and biomarker testing, were analyzed using descriptive statistics. The overall summary measures for biomarker testing and for patients receiving erlotinib, especially frequency of EGFR testing, was described before and after 2011, the year when biomarker testing became part of the guidelines. Costs of biopsy procedures were calculated separately for the inpatient and outpatient settings, with summary statistics of net payment by payer and copayment by patients, including coinsurance and/deductibles, presented for the overall cohort. Costs of biomarker testing were calculated similarly without differentiating the setting of the test.
Statistical analyses were conducted using SAS software, version 9.2 (SAS Institute, Cary, NC).

■■ Results
After applying the eligibility criteria, 4,926 patients with metastatic lung cancer who received erlotinib or crizotinib during the index period were identified. Of these, 4,801 (97.5%) received erlotinib, and 125 (2.5%) received crizotinib ( Figure 1). Among erlotinib and crizotinib recipients, biopsy procedure claims were identified in 3,503 (73.0%) and 76 (60.8%) patients, respectively. Mean (standard deviation [SD]) number of biopsy procedures was 1.2 (1.1) for the total population. Biomarker testing claims were identified in 634 (13.2%) erlotinib and 41 (32.8%) crizotinib recipients. Overall mean (SD) number of testing procedures was 0.2 (0.4), and it was 0.1 (0.3) after 2011 in the total population. Patient baseline characteristics are summarized in Table 1 for the total population and for erlotinib and crizotinib recipients. Overall, 2,600 (52.8%) patients were female, and mean (SD) age at index date was 67 (11.6) years. Study population was evenly distributed throughout the study period except in 2012 because of the early cut-off date. Preferred provider organization plans covered almost half of the study population (n = 2,251, 45.7%). The majority of patients (n = 3,740, 76%) were newly diagnosed. Crizotinib recipients, of whom 121 (96.8%) were newly diagnosed, were more likely to start therapy in 2012. Table 2 describes the characteristics and frequency of biopsy procedures. A total of 5,730 biopsy procedures were identified in 3,579 (72.7%) patients. Of all procedures, 4,393 (76.7%) were performed in newly diagnosed patients. Among those patients who received ≥ 1 biopsy procedure, 2,143 (59.9%) had only 1 procedure. Samples were most commonly collected by bronchial biopsy (n = 3,183, 55.6%) followed by percutaneous biopsy (n = 1,750, 30.5%). Most biopsy procedures were performed at outpatient visits (n = 4,200, 73.3%). The facility where the biopsy was performed was unknown for 57.7% of biopsy procedures because of incomplete data. Of the 2,426 biopsies for which the type of facility was known, the majority

Patient Baseline Characteristics
(n = 2,189, 90.2%) were performed in an acute care hospital. Among the personnel performing the biopsy procedures, radiologists (n = 2,120, 36.8%) were the most common, followed by pulmonologists (n = 1,076, 18.8%), physicians (n = 923, 16.1 %), and pathologists (n = 372, 6.5%). Table 3 describes the summary of biomarker testing procedures. A total of 741 biomarker testing procedures were identified in 675 (13.7%) patients, with 654 and 87 performed in newly and previously diagnosed patients, respectively. Among those patients who received biomarker testing, 614 (91%) had ≥ 1 test. Overall, most biomarker testing procedures (476 of 741) were identified in 435 (of 675) patients after 2011. Frequency of patients receiving EGFR testing increased over the index period with more than 60% of the procedures occurring after 2011 (except for 2012 because of limits on the study period). Most biomarker tests were performed at either

Summary of Biomarker Testing Procedures
setting (inpatient vs. outpatient) and by perspective (payer vs. patient). Overall mean (SD) biopsy procedure cost was $1,223 ($1,899) from the payer and $60 ($147) from the patient perspective in the outpatient setting. Incremental increases in per an independent laboratory (n = 275, 37.1%) or an outpatient hospital (n = 266, 36%). Table 4 describes the cost of biopsy procedures among patients receiving at least 1 biopsy procedure, categorized by  patient cost were observed with an increasing number of biopsy procedures. Mean (SD) cost for a biopsy procedure in erlotinib recipients was $60 ($147) and $1,220 ($1,896) from the patient and payer perspectives, respectively. In crizotinib recipients, mean (SD) costs were $70 ($145) and $1,340 ($2,035), respectively. Costs of the biopsy procedures in the outpatient setting were higher in newly diagnosed patients compared with previously diagnosed patients regardless of whether they received erlotinib or crizotinib. In the inpatient setting, mean (SD) biopsy procedure cost was $8,163 ($18,712) from the payer and $179 ($693) from the patient perspective. Similar to the outpatient setting, per patient costs incrementally increased with the increase in the number of biopsy procedures. Table 5 shows the costs of biomarker testing in patients who received at least 1 test. Overall per patient mean (SD) cost was $43 ($229) and $891 ($1,062) from the patient and payer perspectives, respectively. For erlotinib recipients, per patient mean (SD) cost was $42 ($228) from the patient and $906 ($1,084) from the payer perspective, whereas it was $55 ($243) and $664 ($576) in crizotinib recipients from patient and payer perspectives, respectively. For patients receiving 1 biomarker test, per patient mean (SD) cost was $43 ($236) from patient and $819 ($932) payer perspectives. For patients receiving 2 tests, per patient mean (SD) cost was $38 ($159) from patient and $1,640 ($1,854) payer perspectives.

■■ Discussion
This study analyzed the utilization patterns of and costs associated with biopsy procedures and biomarker testing in patients with metastatic lung cancer receiving erlotinib or crizotinib using a U.S. claims database. A steady increase in the number of erlotinib or crizotinib recipients over the course of the index period was observed. Results in crizotinib recipients should be interpreted with caution because of the small sample size, which was a result of the limited time between crizotinib approval in August 2011 and the end of the index period in September 2012.
Biopsy procedures were identified for only 73.0% of patients. It is possible that an archival tissue sample may have been used in patients without an identifiable biopsy CPT code. Approximately one third of patients (29.1%) received more than 1 biopsy procedure over the course of their disease, especially around the index date. Inadequate tissue sample may have prompted another biopsy procedure in these patients. Some studies have highlighted this issue and reported that only about 50% of tissue samples are adequate for biomarker testing. 13,29,30 Moreover, a study conducted by Ellis et al. (2013) that investigated challenges in implementing EGFR testing in Canada identified inadequate diagnostic tissue for molecular testing as one of the major challenges. 31 An international survey conducted among oncologists showed that in addition to inadequate tissue, poor performance status and long turnaround time were the main reasons for not testing. 32 Although guidelines recommend that EGFR and ALK testing be done before starting treatment, we found that only 13.2% of  Cost of Biomarker Testing in Patients with ≥1 Biomarker Testing Procedure erlotinib and 32.8% of crizotinib recipients received biomarker testing at any time. In erlotinib recipients, most patients received biomarker testing after 2011 (n = 395, 62.3%) but still the mean (SD) number of biomarker testing/patient was low (0.09 [0.3]). EGFR assay has been commercially available since 2005, but it became part of the guidelines only in early 2011, which shows delayed uptake of EGFR testing. 33,34 A study examining hospital use of the EGFR assay showed that in 2010 only 12% of U.S. acute care hospitals ordered the EGFR assay, suggesting most lung cancer patients did not have access to this test. 35 We did observe an increase in the number of patients receiving EGFR testing from 2009 onward, indicating a steady adoption of the guideline recommendations. Erlotinib recipients without any identifiable biomarker testing claim may have been treated based on clinical characteristics associated with EGFR mutation (e.g., nonsmoker, female, and Asian) in the absence of biomarker testing, since guidelines were still evolving during the index period of this study. As anticipated, we found more newly diagnosed patients receiving biomarker testing than previously diagnosed patients (16% vs. 6.7%) as these drugs are approved for first-line treatment. Our results are consistent with another analysis conducted using integrated medical and pharmaceutical data from 4 Blue Cross and Blue Shield plans, where only 36 of 125 (28.8.%) erlotinib recipients received a biomarker test in 2011. 28 A multidisciplinary approach may be warranted to overcome the challenges in implementing recommended biomarker tests. 36 The cost of biopsy and biomarker testing procedures varied by the setting. The mean biopsy procedure cost in the inpatient setting ($8,163) was consistent with that observed in a retrospective cohort study using the 5% Medicare random national sample data during 2009-2011 ($8,869 without adverse events). 37 Unlike our study, this study did not look at the cost exclusively in patients receiving targeted therapies. The variability in the cost for biomarker testing might be explained by the lack of uniformity in the use of CPT codes while submitting claims for reimbursement during the index period.

Limitations
The results of this study should be considered in the context of several limitations. Because there is no specific ICD-9-CM code for NSCLC, patients with metastatic lung cancer receiving erlotinib or crizotinib were assumed to have non-small cell histology. Since biomarker test results (positive or negative) were not available in the claims database, we were unable to evaluate if the treatment was related to the test outcome. It is also difficult to accurately identify the biomarker testing procedures, since they are not consistently captured in the claims database. Different CPT codes are used for billing purposes of relatively similar biomarker tests. Of note, the CPT code for EGFR testing has been available since 2013, although a code for ALK testing is still lacking. Considering the scope of the current database, the link between the timing of the biomarker testing and the corresponding biopsy procedure performed to obtain the tissue sample cannot be established. A biopsy may have been performed for relapses or treatment change or as a part of a diagnostic work-up, but these reasons cannot be assessed from the database. Also, the reimbursed procedures and tests that were not part of this database are not included in the analysis. Because our study was restricted to patients receiving erlotinib or crizotinib, the results of this study cannot be generalized to all patients with metastatic lung cancer because these patients have different clinical presentation. Finally, because the MarketScan database does not capture information on smoking status or histology, we were not able to clearly identify factors associated with EGFR testing.

■■ Conclusions
This study provides insight into utilization patterns and the cost of biopsy procedures and biomarker testing in patients with metastatic lung cancer. Despite inclusion in the treatment guidelines, the low frequency of biomarker testing after 2011 suggests a need for increased awareness of the importance of biomarker testing for guiding treatment decisions in these patients. Biopsy procedures and biomarker testing incurred significant costs in patients with metastatic lung cancer receiving targeted therapies, which suggests that they have a tangible economic impact.

CPT Code
Molecular diagnostics; molecular isolation or extraction, each nucleic acid type (i.e., DNA or RNA) 83890 Isolation or extraction of highly purified nucleic acid, each nucleic acid type (i.e., DNA or RNA) 83891 Enzymatic digestion, each enzyme treatment 83892 Dot/slot blot production, each nucleic acid preparation 83893 Separation by gel electrophoresis (e.g., agarose, polyacrylamide), each nucleic acid preparation 83894 Nucleic acid probe, each 20 83896 Nucleic acid transfer (e.g., Southern, Northern), each nucleic acid preparation 83897 Amplification, target, each nucleic acid sequence 83898 Amplification, target, multiplex, first 2 nucleic acid sequences 83900 Amplification, target, multiplex, each additional nucleic acid sequence beyond 2 (list separately in addition to code for primary procedure)