Vesicoureteral Reflux Imaging in Children

Vesicoureteral Reflux Imaging in Children

Vesicoureteral Reflux Imaging in Children: Comparative Cost Analysis1 L. Santiago Medina, MD, MPH, Elsa Aguirre, RT, Nolan R. Altman, MD Rationale and...

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Vesicoureteral Reflux Imaging in Children: Comparative Cost Analysis1 L. Santiago Medina, MD, MPH, Elsa Aguirre, RT, Nolan R. Altman, MD

Rationale and Objectives. The purpose of this study was to compare the costs of voiding cystourethrography (VCUG) versus radionuclide cystography (RNC) for evaluation of vesicoureteral reflux in children. Materials and Methods. The variable direct costs of performing 25 VCUG and 25 RNC examinations in age- and general health–matched patients suspected of having vesicoureteral reflux was determined by using time and motion analyses. All personnel directly involved in the cases were tracked, and the involvement times were recorded to the nearest minute. All material items used during the procedures were recorded. The cost of labor was determined from personnel reimbursement data, and the cost of materials, from vendor pricing. The fixed direct costs were assessed from hospital accounting records. Mean, standard deviation, and 95% confidence interval (CI) were determined for all direct (fixed and variable) costs. The total costs were determined for each procedure and compared by using the Student t test. Results. There was a significant difference (P ⬍ .0001) between the mean total direct cost of VCUG ($112.17 ⫾ 10.33) and that of RNC ($64.58 ⫾ 1.91). VCUG examination for vesicoureteral reflux in children cost 1.74 times more than RNC examination (95% CI: 1.28, 2.36). Conclusion. When the technique is clinically appropriate, institutions may obtain substantial cost savings by using RNC in place of VCUG for examining children suspected of having vesicoureteral reflux. Key Words. Bladder, radiography; cost-effectiveness; radiography, in infants and children; voiding cystourethrography. ©

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Vesicoureteral reflux is usually found during imaging evaluation of urinary tract infection or prenatally diagnosed hydronephrosis. The prevalence of vesicoureteral reflux in asymptomatic children has been estimated at less than 0.5% (1). According to various published estimates, vesicoureteral reflux is present in 29%–50% of children with urinary tract infection (1,2). The common association of vesicoureteral reflux with urinary tract infection decreases with age and is lower in black children (1,3). There is a high prevalence (8%– 40%) in siblings of chilAcad Radiol 2003; 10:139 –144 1 From the Department of Radiology and Health Outcomes, Policy and Economics (HOPE) Center, Miami Children’s Hospital, 3100 SW 62nd Ave, Miami, FL 33155. Received September 24, 2002; revision requested October 21; revision received and accepted October 30. Address correspondence to L.S.M.

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dren with vesicoureteral reflux (2– 6). Moreover, children of patients with a history of vesicoureteral reflux have an incidence of reflux as high as 66% (2– 6). Either radiographic voiding cystourethrography (VCUG) or radionuclide cystography (RNC) can be used to diagnose vesicoureteral reflux (7). VCUG is usually used to detect vesicoureteral reflux, as it provides highresolution images and anatomic information regarding the bladder and, in male subjects, the urethra. A disadvantage of this modality is the higher radiation doses it delivers (8,9). In addition, since imaging of the bladder with VCUG is intermittent, the sensitivity of the method for detecting reflux is limited. The dynamic process of bladder filling and voiding can be better evaluated with fluoroscopy, but the radiation absorbed dose associated with fluoroscopy is greater, although it can be reduced with grid-controlled pulsed fluoroscopy (8 –10). In addition,

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because repeated examinations are necessary, often over several years, the cumulative radiation exposure is of clinical concern (8 –10). For this reason, RNC has been gaining acceptance for the follow-up of patients with vesicoureteral reflux. In some instances—for example, in the evaluation of asymptomatic siblings or offspring of patients with known reflux (5)—it is also used as a screening procedure. Although VCUG allows the detection of more instances of low-grade reflux than does RNC, RNC has been found more sensitive for the detection of high-grade reflux (8,9). It has been suggested not only that RNC provides useful information in selected cases at a lower radiation dose than does VCUG but also that RNC may be less expensive. However, to our knowledge, the total direct costs of performing VCUG and RNC have not been well quantified. Our goal in this study was to determine the total direct cost (including fixed and variable costs) of using VCUG versus RNC for the evaluation of vesicoureteral reflux. MATERIALS AND METHODS In February 2001, 50 patients scheduled to undergo VCUG or RNC for the evaluation of vesicoureteral reflux were prospectively studied at Miami Children’s Hospital (Fla), a pediatric institution. Age- and general health– matched patients were recruited prospectively and sequentially. The referring physician selected the type of imaging to be used in the examination of each patient. This selection occurred independently of the patients’ involvement in our study. All patients had a comparable general health status. The parent or guardian was able to accurately answer questions about the child’s medical history and any substantial coexistent morbidity. Imaging Procedures VCUG.—All VCUG examinations were performed by an experienced, board-certified pediatric radiologist. No sedation was used. A flowchart of the temporal progression of a VCUG procedure is shown in Figure 1. For each patient, the procedure began when the patient arrived in the digital fluoroscopic suite (Legacy digital fluoroscopy suite; General Electric Medical Systems, Milwaukee, Wis). Initially, the procedure was explained to the patient and guardian. The patient then was positioned on the fluoroscopic table. Standard sterile technique was used dur-

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Figure 1. Flowchart of VCUG.

ing the entire study. The bladder was catheterized. With gravity drip administration, the bladder was filled with the cystourethrographic iodinated contrast medium iothalamate meglumine (Cysto-Conray II; Mallinckrodt, St Louis, Mo). Multiple fluoroscopic images were obtained by the radiologist during the filling, voiding, and postvoiding period. The patient was discharged with postprocedure instructions. Finally, the images were developed and the study was interpreted by the radiologist. The radiologist’s interpretation time included notification or discussion with the referring physician if applicable. Teaching time spent by the radiologist was not included in the analysis. RNC.—A flowchart of the temporal progression of an RNC procedure is shown in Figure 2. No sedative was used. For each patient, the procedure began when the patient arrived in the nuclear medicine suite (model ZLC 370; Siemens, Chicago, Ill). Initially, the procedure was explained to the patient and guardian. Standard sterile technique was used during the entire study. The bladder was catheterized. The catheter was connected to a bag of normal saline that dripped into the urinary bladder by gravity. The radiopharmaceutical, diethylenetriaminepentaacetic acid, or DTPA, with 1 mCi technetium-99m

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VESICOURETERAL IMAGING: COMPARATIVE COST

Indirect costs are those incurred independently of the procedure and include expenses for the grounds (eg, walkways, parking areas, and landscaping) and general administration, human resources, utilities, housekeeping, and general maintenance (13). However, because indirect costs are incurred regardless of the procedure performed, they usually do not reflect the cost of choosing one procedure over the other (13). For this reason, indirect costs were excluded from the final statistical cost analysis. For this study, fixed direct costs included expenses for equipment, depreciation, maintenance, and service. The variable direct costs included those for all labor and materials (supplies) directly attributable to the performance of the procedures. Cost analysis was performed from a medical center perspective.

Figure 2.

Flowchart of RNC.

(Mallinckrodt, St Louis, Mo), was injected into the saline drip. Multiple continuous posterior planar images were obtained by the technologist during the filling, voiding, and postvoiding period. The patient was discharged with postprocedure instructions. Finally, the images were developed and interpreted by the radiologist. The radiologist’s interpretation time included notification or discussion with the referring physician if applicable. Teaching time was not included in the analysis. Definition of Costs Costs were categorized as direct or indirect. Direct costs included both fixed and variable costs, following the system of classification used by the U.S. Panel on CostEffectiveness in Health and Medicine (11) and our medical center’s cost accounting department. Fixed costs are those that do not change with the procedure, such as the equipment cost and depreciation (12). Variable costs are those that vary with the procedure—for example, the costs of labor (of the radiologist, nurse, and technologist) and supplies (contrast media used, catheter, and tray) (12). Direct costs are all costs associated with the performance of the examination and include the fixed and variable costs discussed above (12).

Measurement of Costs Fixed direct costs.—All fixed direct costs were determined from our medical center’s accounting system. The fixed direct costs of each examination were based on equipment utilization and on total costs incurred during the measurement period, as reported by our management departments (12). Fixed costs of equipment were based on a 5-year linear depreciation according to the American Hospital Association Health Data and Coding Standards Group (14). Variable direct costs.—All variable direct costs were tracked by the same investigator (E.A.) for all patient studies. All materials used during the procedures were recorded, and their costs were assigned based on the actual prices paid by the medical center’s purchasing department. Labor was tracked by using time and motion analysis. The amount of time spent by the individuals laboring on the examination was recorded to the nearest minute. Laborers included all physicians, technologists, nurses, and assistants involved in the examination. The costs of the work performed by salaried workers were based on their total annual compensation, including benefits and salary, divided by the estimated number of their billable work hours per year (13). The time for interpretation of the imaging studies by the radiologist also was measured. All images were interpreted and the results dictated by the attending radiologist. Teaching time was not included as part of the analysis. Statistical Analysis Total direct costs (both fixed and variable) were tabulated for all the examinations. Variable direct components

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were further subdivided into labor (total labor and physician labor) and supplies (total supplies and contrast material). The mean and standard deviation (SD) and the 95% confidence interval (CI) for each cost category (15–17) were calculated. Student t test statistical analysis was performed with Instat software (GraphPad Software, San Diego, Calif). RESULTS Twenty-five patients underwent VCUG, and another 25 patients underwent RNC. The mean age (⫾ SD) of these patients was 4 years ⫾ 2.35 and 4 years ⫾ 2.41, respectively. Of the patients who underwent RNC, eight (32%) were girls and 17 (68%) were boys; of those who underwent VCUG, 10 (40%) were girls and 15 (60%) were boys. Four VCUG patients (16%) and two RNC patients (8%) were hospital inpatients at the time of the examination. Indications for VCUG included urinary tract infection (n ⫽ 16), follow-up for vesicoureteral reflux (n ⫽ 3), urinary incontinence (n ⫽ 2), family members with vesicoureteral reflux (n ⫽ 2), and others (n ⫽ 2). Indications for RNC included urinary tract infection (n ⫽ 13), follow-up for vesicoureteral reflux (n ⫽ 5), family members with vesicoureteral reflux (n ⫽ 4), urinary incontinence (n ⫽ 1), and others (n ⫽ 2). The direct fixed and variable costs for the VCUG and RNC examinations are shown in the Table. The mean total direct cost (⫾ SD) of performing VCUG was $112.17 ⫾ 10.33 (95% CI: $108.12, $116.22), and the mean total direct cost of performing RNC was $64.58 ⫾ 1.91 (95% CI: $63.83, $65.33). The mean total direct costs differed significantly statistically between the VCUG and RNC groups (P ⬍ .0001). The mean total cost of VCUG relative to RNC for assessment of vesicoureteral reflux was 1.74 (95% CI: 1.28, 2.36). The mean direct fixed cost (⫾ SD) of performing VCUG was $43.46 ⫾ 1.05 (95% CI: $43.05, $43.87), and the mean direct fixed cost of performing RNC was $28.85 ⫾ 1.03 (95% CI: $28.45, $29.25). The mean fixed cost of VCUG relative to RNC was 1.51 (95% CI: 0.94, 2.4). The higher fixed cost of VCUG over RNC is explained by the higher cost of the digital fluoroscopic unit in comparison with the single-head planar nuclear medicine unit. The mean direct variable cost (⫾ SD) of performing VCUG was $68.71 ⫾ 10.33 (95% CI: $64.66, $72.76), and the mean direct variable cost of performing RNC was $35.73 ⫾ 1.91 (95% CI: $34.98, $36.48). The mean vari-

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Direct Costs of VCUG and RNC Examinations of Children

Cost Category

VCUG* (U.S.$)

RNC* (U.S.$)

Ratio of VCUG Costs and RNC Costs

Fixed costs Variable costs Total Labor Total Physician labor Supplies Total Contrast media Total direct cost

43.46 ⫾ 1.05

28.85 ⫾ 1.03

1.51

68.71 ⫾ 10.33

35.73 ⫾ 1.91

1.92

44.42 ⫾ 10.33 32.20 ⫾ 9.37

17.88 ⫾ 1.79 4.42 ⫾ 1.33

2.48 7.29

24.29 ⫾ 0.15 8.79 112.17 ⫾ 10.33

17.85 ⫾ 0.25 3.00 64.58 ⫾ 1.91

1.36 2.93 1.74

Note.—Mean age of patients examined was 4 years ⫾ 2.35 for VCUG and 4 years ⫾ 2.41 for RNC. *Data are given as mean ⫾ standard deviation.

able cost of VCUG relative to RNC was 1.92 (95% CI: 1.28, 2.88). The cost of personnel (variable labor) for VCUG was 2.48 (95% CI: 2.70, 19.69) times greater than for RNC, mainly because of the requirement for radiologist involvement during VCUG fluoroscopy. Supplies accounted for 21.7% and 27.6% of the total direct costs for VCUG and RNC, respectively. However, the mean supplies cost for VCUG relative to that for RNC was 1.36 (95% CI: 0.74, 2.51). As part of the supplies, the mean cost of contrast media for VCUG relative to that for RNC was 2.93 (95% CI: 0.79, 10.87) because of the higher cost of the VCUG ionic contrast agent in comparison to the RNC radiopharmaceutical. Overall, contrast material accounted for only 7.8% and 4.6% of the total direct cost of the VCUG and RNC examinations, respectively. DISCUSSION The results of this study indicate that, from the perspective of the medical center, RNC costs substantially less than does VCUG for imaging vesicoureteral reflux. VCUG has higher total direct costs than RNC because of higher fixed and variable costs. The higher fixed and variable costs of VCUG resulted from the higher costs of the digital fluoroscopic unit, of physician labor, and of ionic contrast media. The mean physician labor cost of VCUG relative to RNC for vesicoureteral reflux assessment was 7.29 (95% CI: 2.70, 19.69). This difference is due mainly to the phy-

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sician’s involvement in the fluoroscopic evaluation during VCUG examinations. The physician is not directly involved in RNC examinations, which are performed by technologists and nurses. Therefore, medical centers should consider the use of physician extenders (ie, physician assistants, nurses, or technologists) to cut the costs of physician time and labor for VCUG. Cost-effectiveness and cost-benefit analyses are being published more frequently in the medical literature, but the investigative methods on which such analyses are based are not always rigorous (18). We performed a costidentification analysis in which equivalent outcome of the diagnostic strategies was assumed for the evaluation of vesicoureteral reflux in children (19). We chose to define costs from the perspective of the medical center (20) because managed care and discounted fee-for-service have become the predominant economic models for reimbursing health care expenses in the United States. These studies are important because health care providers must understand their costs of performing procedures to maintain appropriate net revenue (13). This is especially important under capitation, in which health care providers must bear the full burden of expenses without a possibility of recovering additional revenues over the prepaid premiums when the costs are not met (13). In addition, our time and motion analyses of direct fixed and variable costs provide a level of rigor that eliminates the assumptions inherent in analyses based on estimated cost measurement (21-24), charge-based (25–29), ratio of costs to charges (21,30 – 35), and relative value units (30,36,37). Our results may not be generalizable to all medical institutions and centers. The data were collected from only one institution rather than from multiple medical centers with different physician and patient mixes. In addition, because our service is attending radiologist– driven and residents did not participate in any of the study procedures, we do not know the magnitude of the effect of junior staff involvement on procedure time, labor, and supplies costs. Furthermore, because absolute costs—particularly those for labor—are affected by volume discounts and regional standards, the absolute costs reported in this study may not be generalizable to other institutions and other geographic regions. However, the relative costs should not be affected by these variables and thus should be relevant to most institutions in the United States (13). Indirect costs—the expenses of running a medical center, that cannot be specifically attributed to an examination—are apportioned somewhat arbitrarily and hence were not included in our final statistical analysis (13).

VESICOURETERAL IMAGING: COMPARATIVE COST

Nevertheless, variations in the indirect costs of a major medical center versus those of a freestanding imaging center can be substantial and affect the overall but not relative costs of performing the procedures (13). Additional professional costs, such as those for technologist, nurse, and physician training and for imaging protocol development, also were not included in our analysis. As a result, the absolute values measured were useful only in calculating the relative direct costs and did not represent the total examination costs (13). In summary, our study demonstrated that the direct costs of performing VCUG for the assessment of vesicoureteral reflux were 1.74 times higher than those of performing RNC. Given the likelihood that RNC has lower radiation dose and higher sensitivity for the detection of high-grade reflux (8,9), the substantial cost reduction achieved by performing RNC should provide further justification for its replacement of VCUG in the follow-up of children with vesicoureteral reflux and in the evaluation of asymptomatic siblings or offspring of patients with known reflux. ACKNOWLEDGMENTS

We are indebted to the radiologists, radiologic and nuclear medicine technologists, nurses, assistants, and personnel at the Department of Radiology and the Fiscal Department of Miami Children’s Hospital for their help in collecting the important data. REFERENCES 1. Medical versus surgical treatment of primary vesicoureteral reflux: report of the International Reflux Study Committee. Pediatrics 1981; 67: 392– 400. 2. Bissett GS III, Strife JL, Dunbar JS. Urography and voiding cystourethrography: findings in girls with urinary tract infection. AJR Am J Roentgenol 1987; 148:479 – 482. 3. Askari A, Belman AB. Vesicoureteral reflux in black girls. J Urol 1982; 127:747–748. 4. Jerkins GR, Noe HN. Familial vesicoureteral reflux: a prospective study. J Urol 1982; 128:774 –778. 5. Van den Abbeele AD, Treves ST, Lebowitz RL, et al. Vesico-ureteral reflux in asymptomatic siblings of patients with known reflux: radionuclide cystography. Pediatrics 1987; 79:147–153. 6. Noe HN, Wyatt RJ, Peeden JN Jr, Rivas ML. The transmission of vesicoureteral reflux from parent to child. J Urol 1992; 148:1869 –1871. 7. Strife JL, Bisset GS III, Kirks DR, et al. Nuclear cystography and renal sonography: findings in girls with urinary tract infection. AJR Am J Roentgenol 1989; 153:115–119. 8. Blaufox MD, Gruskin A, Sandler P, et al. Radionuclide scintigraphy for detection of vesicoureteral reflux in children. J Pediatr 1971; 79:239 – 246. 9. Conway JJ, King LR, Belman AB, et al. Detection of vesicoureteral reflux with radionuclide cystography: a comparison study with roentgenographic cystography. Am J Roentgenol Radium Ther Nucl Med 1972; 115:720 –727.

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10. Boland GW, Murphy B, Arellano R, Niklason L, Mueller PR. Dose reduction in gastrointestinal and genitourinary fluoroscopy: use of gridcontrolled pulsed fluoroscopy. AJR Am J Roentgenol 2000; 175:1453– 1457. 11. Gold MR, Siegel SE, Russell LB, Weinstein MC, eds. Cost-effectiveness in health and medicine. New York, NY: Oxford University Press, 1996; 193–194. 12. Baumol WJ, Blinder AS. Production, inputs, and costs: building blocks for supply analysis. In: Baumol WJ, Blinder AS, eds. Microeconomics: principles and policy. 7th ed. Fort Worth, Tex: Dryden, 1997; 147–179. 13. Rubin GD, Armerding MD, Dake MD, Napel SN. Cost identification of abdominal aortic aneurysm imaging by using time and motion analyses. Radiology 2000; 215:63–70. 14. American Hospital Association. Estimated useful lives of depreciable hospital assets. Chicago, Ill: American Hospital Publishing, 1998. 15. Hennekens CH, Buring JE. Epidemiology in medicine. Boston, Mass: Little, Brown, 1987; 252–258. 16. Rosner B. Fundamentals of biostatistics. 4th ed. Belmont, Calif: Duxbury, 1995; 141–190. 17. Glantz SA. Primer of biostatistics. 2nd ed. New York, NY: McGrawHill, 1987; 163–190. 18. Blackmore CC, Magid DJ. Methodologic evaluation of the radiology cost-effectiveness literature. Radiology 1997; 203:87–91. 19. Eisenberg JM. Clinical economics: a guide to the economic analysis of clinical practices. JAMA 1989; 262:2879 –2886. 20. Weinstein MC, Statson WB. Foundations of cost-effectiveness analysis for health and medical practices. N Engl J Med 1977; 296:716 – 721. 21. Silverman SG, Dueson TE, Kane N, et al. Percutaneous abdominal biopsy: cost-identification analysis. Radiology 1998; 206:429 – 435. 22. Remar EM, Herts BR, Streem SB, et al. Spiral noncontrast CT versus combined plain radiography and renal US after extra-corporeal shock wave lithotripsy: cost-identification analysis. Radiology 1997; 204:33– 37. 23. Van Erkel AR, van Rossum AB, Bloem JL, Kievet J, Pattynama PM. Spiral CT angiography for suspected pulmonary embolism: a costeffectiveness analysis. Radiology 1996; 201:29 –36.

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24. Vanninen R, Manninen H, Soimakallio S. Imaging of carotid artery stenosis: clinical efficacy and cost-effectiveness. AJNR Am J Neuroradiol 1995; 16:1875–1883. 25. Picus D. Comparing competing medical procedures: cost or charges— what should it matter? Radiology 1996; 199:623– 625; discussion, 624 – 625. 26. Finkler SA. The distinction between cost and charges. Ann Intern Med 1982; 96:102–109. 27. Russi TJ, Libby DM, Henschke CI. Clinical utility of computed tomography in the diagnosis of pulmonary embolism. Clin Imaging 1997; 21: 175–182. 28. Rubens DJ, Strang JG, Fultz PJ, Gottlieb RH. Sonographic guidance of mediastinal biopsy: an effective alternative to CT guidance. AJR Am J Roentgenol 1997; 169:1605–1610. 29. Dwamena BA, Kloos RT, Fendrick AM, et al. Diagnostic evaluation of the adrenal incidentaloma: a decision and cost-effectiveness analyses. J Nucl Med 1998; 39:707–712. 30. Yin D, Forman HP. Health care cost-benefit and cost-effectiveness: an overview. J Vasc Interv Radiol 1995; 6:311–320. 31. Shwartz M, Young DW, Siegrist R. The ratio of costs to charges: how good a basis for estimating costs? Inquiry 1995; 32:476 – 481. 32. Topol EJ, Leya F, Pinkerton CA, et al. A comparison of directional atherectomy with coronary angioplasty in patients with coronary artery disease: the CAVEAT Study Group. N Engl J Med 1993; 329:221–227. 33. Guzman LA, Simpfendorfer C, Fix J, Franco I, Whitlow PL. Comparison of costs of new atherectomy devices and balloon angioplasty for coronary artery disease. Am J Cardiol 1994; 74:22–25. 34. Hunink MG, Cullen KA, Donaldson MC. Hospital costs of revascularization procedures for femoropopliteal arterial disease. J Vasc Surg 1994; 19:632– 641. 35. Brasel KJ, Weigelt JA. Blunt thoracic aortic trauma: a cost-utility approach for injury detection. Arch Surg 1996; 131:619 – 626. 36. Yin D, Baum RA, Carpenter JP, Langlotz CP, Pentecost MJ. Cost-effectiveness of MR angiography in cases of limb-threatening peripheral vascular disease. Radiology 1995; 104:757–764. 37. Hunink MG, Bos JJ. Triage of patients to angiography for detection of aortic rupture after blunt chest trauma: cost-effectiveness analysis of using CT. AJR Am J Roentgenol 1995; 165:27–36.