- Email: [email protected]
Trends in Medical Expulsive Therapy Use for Urinary Stone Disease in U.S. Emergency Departments
Endourology and Stones Trends in Medical Expulsive Therapy Use for Urinary Stone Disease in U.S. Emergency Departments John M. Hollingsworth, Matthew M. Davis, Brady T. West, J. Stuart Wolf Jr, and Brent K. Hollenbeck OBJECTIVES
METHODS
RESULTS
CONCLUSIONS
Between 2000 and 2006, 11 randomized controlled trials were published, demonstrating the efficacy of medical expulsive therapy (MET) for promoting upper tract stone passage. Although its use is gaining traction among urologists, they evaluate a minority of patients who present to the emergency department (ED) for acute renal colic before discharge. As such, measuring the uptake of MET into the broader medical community is important. Data were analyzed (2000-2006) from the National Hospital Ambulatory Medical Care Survey. Sampled ED visits for stones were identified. The use of MET was ascertained by the prescription of a calcium channel or ␣ blocker at the ED visit. National estimates of the prevalence of MET use were computed. Logistic regression was used to examine linear and nonlinear time trends in MET prescription. The use of MET increased throughout the study period. In fact, the odds of being treated with this approach more than doubled with each successive year (OR, 2.15; 95% CI, 1.31-3.5; P ⬍ .001 for the linear trend). However, the overall prevalence of use was exceedingly low at 1.1% (95% CI, 0.6%-1.9%). Given the number needed to treat of 4, this implies a missed opportunity to spare approximately 260 000 individuals annually from stone surgery and its risks. Despite the growing body of evidence to support its safety and efficacy, our analysis reveals the sluggish dissemination of MET into the broader medical community. The observed underuse represents a block in the translation of clinical science into practice and raises a quality of care concern. UROLOGY 74: 1206 –1210, 2009. © 2009 Elsevier Inc.
N
early 1 in 7 Americans suffer from urinary stone disease during their lifetime,1,2 many of whom present acutely to an emergency department (ED), complaining of symptoms consistent with renal colic. In the absence of indications for immediate intervention (eg, pyelonephritis, obstruction of a solitary kidney, intractable symptoms),3 a trial of conservative management is warranted.4 Managed according to the conventional paradigm of hydration and pain control alone, stones will pass spontaneously in only 34% of these patients, with the remainder requiring surgery.5 Although improvements in instrumentation and optics Supported by: PhRMA Foundation Research Starter Grant (to B. K. H.). From the Robert Wood Johnson Clinical Scholars Program, University of Michigan, Michigan; Division of Health Services Research, Department of Urology, University of Michigan, Michigan; Department of Pediatrics and communicable Diseases, Children’s Health Evaluation and Research Unit, University of Michigan, Michigan; Institute for Social Research, Survey Research Center, University of Michigan, Michigan; Department of Urology, Michigan Center for Minimally Invasive Urology, University of Michigan, Michigan; Department of Surgery, Michigan Surgical Collaborative for Outcomes Research and Evaluation, University of Michigan, Michigan Reprint requests: Brent K. Hollenbeck, M.D., M.S., 1500 E Medical Center Dr, TC 3875-0330, Ann Arbor, Michigan 48109-0330. E-mail: [email protected] Submitted: November 15, 2008, accepted (with revisions): March 10, 2009
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© 2009 Elsevier Inc. All Rights Reserved
have allowed for the resolution of stone burden with minimally invasive techniques,6,7 surgery remains expensive, and its risks are nontrivial.8,9 Thus, treatments that safely and reliably reduce the need for surgery are likely to have economic implications, promote health, and improve the quality of care. The use of calcium channel or ␣ blockers, collectively known as medical expulsive therapy (MET), represents one such treatment option. Between 2000 and 2006, 11 randomized controlled trials were published, demonstrating the efficacy of this approach for promoting upper tract stone passage.10 In fact, 1 for every 4 patients treated avoids surgery.11 Evidence suggests that the use of MET is gaining traction in urology, particularly among those with advanced specialty training.12 However, urologists evaluate only 11% of patients seen in the ED for acute renal colic before their discharge.13 Given the diversity of physicians responsible for the initial care of patients with stones, understanding the uptake of MET into the broader medical community is important. It was with this in mind that we measured temporal trends in the prevalence of MET use in EDs in the United States. 0090-4295/09/$34.00 doi:10.1016/j.urology.2009.03.050
Data were analyzed from the National Hospital Ambulatory Medical Care Survey (NHAMCS). Designed by the National Center for Health Statistics and administered by the US Census Bureau, the NHAMCS is an annual 4-stage probability sample of outpatient or ED visits to randomly selected, nonfederal short-stay hospitals in the U.S. All aspects of each visit are weighted, and the weights are adjusted to account for nonresponse and nonparticipation, allowing for extrapolation to the universe of ambulatory visits.14 Sampled ED visits for stones between 2000 and 2006 were identified through International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9) diagnosis codes, using a previously described algorithm (Appendix).15 Up to 8 medications (6 in 2000-2002) administered during the encounter or prescribed at discharge were recorded for each ED visit. As evidenced by the prescription of a calcium channel or ␣ blocker at that visit, MET use was characterized by the unique five-digit codes (Appendix) of Ambulatory Care Drug Database.16 Because MET agents are also prescribed for the treatment of hypertension and benign prostatic hyperplasia, indicator variables were constructed to identify these concurrent diagnoses using those ICD-9 codes in the Appendix. Although the test-retest reliability of the NHAMCS instrument for the collection of concurrent diagnosis data has not been formally evaluated, a similar methodology used by the National Center for Health Statistics to collect other ambulatory care information has been validated with a direct observation reference standard.17 Estimates of the prevalence of MET use were computed using these data. Logistic regression was used to examine linear and nonlinear time trends in the prescription of MET. Adjustments were made for the number of randomized controlled trials supporting use of MET published each year. Because no patients with a concurrent diagnosis of hypertension or benign prostatic hyperplasia were prescribed MET at their visit, inclusion of these covariates predicted a negative outcome perfectly; thus, they were excluded. To account for the complex sampling methodology of NHAMCS, all analyses used the svy commands provided in Stata (Version 10.1), with appropriate options for subpopulation estimation. Significance testing was two-sided, and a type-1 error rate was set at 0.05. This study was approved by the institutional review board.
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MATERIAL AND METHODS
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Figure 1. Prevalence of medical expulsive therapy use among emergency department visits for urinary stones by Survey Year (NHAMCS 2000-2006)—a missed opportunity. Sum of the light-blue hatched bars and the orange bars ⫽ estimated number of eligible ED visits for stone disease (in thousands) at which MET was not prescribed; orange bars ⫽ estimated number of persons seen in the ED for stones that potentially would have been spared from surgery by a trial of MET (in thousands); dark blue bars ⫽ estimated number of ED visits for stones (in thousands) at which MET was prescribed. The table below the figure displays the number of randomized controlled trials of MET published by year, as well as the cumulative total over the study period.
.001 for the linear trend). However, the estimated percentage of patients treated with MET peaked at only 3.9% in 2006, and the overall observed prevalence of use during the study period was exceedingly low at 1.1% (95% CI, 0.6%-1.9%). Moreover, the frequency of MET prescription did not differ significantly between ED visits for ureteral calculus disease (ICD-9 code 592.1) and those for all other stone diagnoses (1.2% vs 1.0%, respectively; P ⫽ .730). Given the number needed to treat of 4, the observed trend implies a missed opportunity to spare approximately 260 000 individuals annually (or 1.6 million during the 7-year study period) from stone surgery and its risks (Fig. 1).
RESULTS The frequency of ED visits for urinary stone disease was stable over the study period, ranging from 3.2 visits (95% confidence interval (CI), 2.5-3.8) per 1000 US population in 2006 to 4.2 visits (95% CI, 3.3-5.1) per 1000 US population in 2004. Mean age was comparable between patients who were treated with MET and those who were not (41.0 vs 41.4 years, respectively). Although 39.6% of eligible visits were made by women, they accounted for only 21% of the encounters at which MET was prescribed. Non-whites comprised ⬍10% of all stone cases. A similar proportion of nonwhites (8.5%) received MET. As illustrated in the Fig. 1, the use of MET increased throughout the study period. In fact, the odds of being treated with this approach more than doubled with each successive year (odds ratio, 2.15; 95% CI, 1.31-3.5; P ⬍ UROLOGY 74 (6), 2009
COMMENT Despite the growing body of evidence to support its safety and efficacy for promoting upper tract stone passage,10,11 our analysis reveals the sluggish dissemination of MET into the broader medical community. The exceedingly low prevalence of use (prescribed at only 1.1% of eligible ED visits during the 7-year study period) implies a missed opportunity to spare approximately 260 000 individuals annually from surgery and its risks. Taken together, the observed underuse of MET represents a block in the translation of clinical science into practice and raises a concern for the quality of care. There are several plausible explanations for our results. The first relates to the mode in which research findings 1207
on MET were communicated to its potential end users. Before the release of the 2007 practice guidelines for ureteral calculi management, in which MET became a recommended part of the treatment algorithm,4 its dissemination relied almost exclusively on passive communication. Though supportive data were reported in prominent subspecialty journals, such a single-channel form of communication is generally ineffective at affecting provider behavior.18 A related explanation for the slow uptake of MET pertains to the diversity of clinicians who care for patients with symptomatic stones. Primary trial data on MET appear almost exclusively in the urologic literature.10,11 Given the limited readership of these journals, the awareness of MET among nonurologists may be low. However, these are the same physicians who provide initial entry for most stone patients into the health care system.13 The omission of MET from a recent narrative review on stone disease published in a high-profile, multispecialty journal provides support that such a knowledge gap might exist.3 Additional research is necessary to explore these proposed impediments, as well as alternative explanations for the observed trend. After the impediments constraining the uptake of this efficacious process of care have been identified, an intervention targeted at overcoming its translational block can be devised. If variation in the use of MET is primarily attributable to patient-level factors, then informing recurrent stone formers, who arguably stand to benefit the most from MET, about its role in their management through educational pamphlets might increase patient acceptance. Conversely, if the physician is the most responsible party, then maintenance-of-certification vignettes involving MET may broaden the awareness of this clinical practice. Similarly, if physician extenders or ancillary service providers (eg, pharmacists) are found to contribute substantially to the variation in MET use, then continuing medical educational coursework may lead to a swifter dissemination. Although the NHAMCS provides us with the unique opportunity to measure the prevalence of MET use in the US EDs, we must recognize several limitations of the NHAMCS dataset. First, the NHAMCS uses a crosssectional design, with its unit of analysis being the patient encounter. Because an individual cannot be followed across visits, the potential exists for frequent users of medical care to bias our estimates of MET use. Nonetheless, given the sampling method that the NHAMCS uses, the likelihood of capturing repeated visits from the same patient is small.14 Second, gathered visit information on diagnoses and medications prescribed are coded centrally by NHAMCS personnel. Although this process is subject to rigorous quality control procedures,14 coding inaccuracies may exist. Third, the diagnosis codes that we used to identify eligible ED visits are somewhat heterogeneous and may include individuals for whom a trial of MET is unwar1208
ranted (eg, patients with nephrocalcinosis). As such, the annual number of individuals that we estimated, who could be spared from surgical intervention through increased MET uptake, is best interpreted as a ceiling, and the actual number may be lower. Fourth, the goal of the survey is to help define broad medical practice and management, and not the care of stone disease specifically. Therefore, the collected data lack some pertinent clinical information (eg, stone size) that may influence a provider’s stone treatment. For example, contemporary practice guidelines on ureteral calculi recommend MET as an initial treatment option only for individuals with stones of sizes ⱕ10-mm.4 If most ED visits during the study interval were for larger stones, then the low prevalence of MET use that we observed may be appropriate. Finally, we must reconcile our results with the findings of other authors. Pearle et al19 previously measured the annual number of visits made to US EDs for a primary diagnosis of urinary stone disease using the same data source. They demonstrated relative stability in this number between 1994 and 1998, although there was a 50% increase in 2000. The stable trend that we observed would suggest that this sharp increase represented simply year-to-year variability. However, in comparing the 2 studies, it is important to note that the duration examined and the algorithms used to ascertain eligible visits differed.
CONCLUSIONS Despite the growing body of evidence to support its safety and efficacy, our analysis reveals the sluggish dissemination of MET into the broader medical community. Given the low cost of MET ($28) and the expense of stone procedures ($4773 for ureteroscopy),20 these observed trends likely have significant economic implications for the US health care system. Further, this underuse represents a block in the translation of clinical science into practice and raises a quality of care concern. Additional research is necessary to explore possible explanations for the observed trend so that an intervention to increase uptake of MET can be appropriately targeted. Meanwhile, these data raise the question as to whether all patients with acute stone disease seen should be referred for optimal management to urologists with an interest in stone disease.
References 1. Sierakowski R, Finlayson B, Landes RR, et al. The frequency of urolithiasis in hospital discharge diagnoses in the United States. Invest Urol. 1978;15:438-441. 2. Johnson CM, Wilson DM, O’Fallon WM, et al. Renal stone epidemiology: a 25-year study in Rochester, Minnesota. Kidney Int. 1979;16:624-631. 3. Teichman JM. Clinical practice. Acute renal colic from ureteral calculus. N Engl J Med. 2004;350:684-693.
UROLOGY 74 (6), 2009
4. Preminger GM, Tiselius HG, Assimos DG, et al. Guideline for the management of ureteral calculi. J Urol. 2007;178:2418-2434. 5. Parekattil SJ, Kumar U, Hegarty NJ, et al. External validation of outcome prediction model for ureteral/renal calculi. J Urol. 2006; 175:575-579. 6. Bierkens AF, Hendrikx AJ, De La Rosette JJ, et al. Treatment of mid- and lower ureteric calculi: extracorporeal shock-wave lithotripsy vs laser ureteroscopy. A comparison of costs, morbidity, and effectiveness. Br J Urol. 1998;81:31-35. 7. Hochreiter WW, Danuser H, Perrig M, et al. Extracorporeal shock wave lithotripsy for distal ureteral calculi: what a powerful machine can achieve. J Urol. 2003;169:878-880. 8. Daniels GF Jr, Garnett JE, Carter MF. Ureteroscopic results and complications: experience with 130 cases. J Urol. 1988;139:710-713. 9. Krambeck AE, Gettman MT, Rohlinger AL, et al. Diabetes mellitus and hypertension associated with shock wave lithotripsy of renal and proximal ureteral stones at 19 years of follow up. J Urol. 2006;175:1742-1747. 10. Singh A, Alter HJ, Littlepage A. A systematic review of medical therapy to facilitate passage of ureteral calculi. Ann Emerg Med. 2007;50:552-563. 11. Hollingsworth JM, Rogers MA, Kaufman SR, et al. Medical therapy to facilitate urinary stone passage: a meta-analysis. Lancet. 2006;368:1171-1179.
12. Bandi G, Best SL, Nakada SY. Current practice patterns in the management of upper urinary tract calculi in the north central United States. J Endourol. 2008;22:631-636. 13. Sterrett SP, Moore NW, Nakada SY. Emergency room follow-up trends in urolithiasis: single-center report. Urology. 2009;73:1195-1197. 14. McCaig LF, McLemore T. Plan and operation of the National Hospital Ambulatory Medical Survey. Series 1: programs and collection procedures. Vital Health Stat. Series 1. Programs Collect Proced. 1994;1-78. 15. Brown J. Diagnostic and treatment patterns for renal colic in US emergency departments. Int Urol Nephrol. 2006;38:87-92. 16. Ambulatory Care Drug Database System. U.S. Centers for Disease Control and Prevention Web site. Available at: http://www.cdc. gov/drugs. Accessed July 1, 2008. 17. Gilchrist VJ, Stange KC, Flocke SA, et al. A comparison of the national ambulatory medical care survey (NAMCS) measurement approach with direct observation of outpatient visits. Med Care. 2004;42:276-280. 18. Lomas J. Words without action? The production, dissemination, and impact of consensus recommendations. Annu Rev Public Health. 1991;12:41-65. 19. Pearle MS, Calhoun EA, Curhan GC, et al. Urologic diseases in America project: urolithiasis. J Urol. 2005;173:848-857. 20. Bensalah K, Pearle M, Lotan Y. Cost-effectiveness of medical expulsive therapy using alpha-blockers for the treatment of distal ureteral stones. Eur Urol. 2008;53:411-418.
APPENDIX ICD-9 Diagnosis/NCHS 5-Digit Drug Codes Include emergency department visits for— Upper tract urinary stone 270.0, 274.11, 592.0, 592.1, 592.9, 788.0 Exclude stone visits with an indication for immediate urinary diversion— Renal insufficiency 440.1, 580, 580.0, 580.4, 580.8, 580.81, 580.89, 580.9, 581, 581.0, 581.2, 581.3, 581.8, 581.81, 581.89, 581.9, 582, 582.0, 582.1, 582.2, 582.4, 582.8, 582.1, 582.89, 582.9, 583, 583.0, 583.1, 583.2, 583.4, 583.6, 583.7, 583.8, 583.81, 583.89, 583.9, 584, 584.5, 584.6, 584.7, 584.8, 584.9, 585, 585.1, 585.2, 585.3, 585.4, 585.5, 585.6, 585.9, 586, 587, 589, 589.0, 589.1, 589.9, 593.9 or Pyelonephritis 590.0, 590.1, 590.8, 590.80, 590.81 Other conditions commonly treated with calcium channel or alpha blockers— Hypertension 401, 401.0, 401.1, 401.9, 402, 402.0, 402.00, 402.01, 402.10, 402.11, 402.9, 402.90, 402.91, 403, 403.0, 403.2, 403.9, 404, 404.0, 404.1, 404.9, 405, 405.0, 405.01, 405.09, 405.1, 405.11, 405.19, 405.9, 405.91, 405.99, 642.4, 642.3, 997.91 and Benign prostatic hyperplasia 599.6, 599.60, 599.69, 600, 600.0, 600.01, 600.1, 600.10, 600.11, 600.2, 600.20, 600.21, 600.3, 600.9, 600.90, 600.91, 788.2, 788.20, 788.21, 788.29, 788.4, 788.41, 788.42, 788.43, 788.6, 788.61, 788.62, 788.63, 788.64, 788.65, 788.69 Medical expulsive therapy agents— Tamsulosin 00053, 59731, 97126 Alfuzosin 04138, 70814 Terazosin 15307, 56290, 94133 Doxazosin 51953, 92012, 92120 Prazosin 19455, 24805, 54765, 70346, 89062 Nifedipine 01019, 02231, 03142, 04122, 25213, 53922, 60040, 89067, 91039 ICD-9 indicates International Classification of Diseases, Ninth Revision, Clinical Modification; NCHS, National Center for Health Statistic.
UROLOGY 74 (6), 2009
1209
METHODS
RESULTS
CONCLUSIONS
Between 2000 and 2006, 11 randomized controlled trials were published, demonstrating the efficacy of medical expulsive therapy (MET) for promoting upper tract stone passage. Although its use is gaining traction among urologists, they evaluate a minority of patients who present to the emergency department (ED) for acute renal colic before discharge. As such, measuring the uptake of MET into the broader medical community is important. Data were analyzed (2000-2006) from the National Hospital Ambulatory Medical Care Survey. Sampled ED visits for stones were identified. The use of MET was ascertained by the prescription of a calcium channel or ␣ blocker at the ED visit. National estimates of the prevalence of MET use were computed. Logistic regression was used to examine linear and nonlinear time trends in MET prescription. The use of MET increased throughout the study period. In fact, the odds of being treated with this approach more than doubled with each successive year (OR, 2.15; 95% CI, 1.31-3.5; P ⬍ .001 for the linear trend). However, the overall prevalence of use was exceedingly low at 1.1% (95% CI, 0.6%-1.9%). Given the number needed to treat of 4, this implies a missed opportunity to spare approximately 260 000 individuals annually from stone surgery and its risks. Despite the growing body of evidence to support its safety and efficacy, our analysis reveals the sluggish dissemination of MET into the broader medical community. The observed underuse represents a block in the translation of clinical science into practice and raises a quality of care concern. UROLOGY 74: 1206 –1210, 2009. © 2009 Elsevier Inc.
N
early 1 in 7 Americans suffer from urinary stone disease during their lifetime,1,2 many of whom present acutely to an emergency department (ED), complaining of symptoms consistent with renal colic. In the absence of indications for immediate intervention (eg, pyelonephritis, obstruction of a solitary kidney, intractable symptoms),3 a trial of conservative management is warranted.4 Managed according to the conventional paradigm of hydration and pain control alone, stones will pass spontaneously in only 34% of these patients, with the remainder requiring surgery.5 Although improvements in instrumentation and optics Supported by: PhRMA Foundation Research Starter Grant (to B. K. H.). From the Robert Wood Johnson Clinical Scholars Program, University of Michigan, Michigan; Division of Health Services Research, Department of Urology, University of Michigan, Michigan; Department of Pediatrics and communicable Diseases, Children’s Health Evaluation and Research Unit, University of Michigan, Michigan; Institute for Social Research, Survey Research Center, University of Michigan, Michigan; Department of Urology, Michigan Center for Minimally Invasive Urology, University of Michigan, Michigan; Department of Surgery, Michigan Surgical Collaborative for Outcomes Research and Evaluation, University of Michigan, Michigan Reprint requests: Brent K. Hollenbeck, M.D., M.S., 1500 E Medical Center Dr, TC 3875-0330, Ann Arbor, Michigan 48109-0330. E-mail: [email protected] Submitted: November 15, 2008, accepted (with revisions): March 10, 2009
1206
© 2009 Elsevier Inc. All Rights Reserved
have allowed for the resolution of stone burden with minimally invasive techniques,6,7 surgery remains expensive, and its risks are nontrivial.8,9 Thus, treatments that safely and reliably reduce the need for surgery are likely to have economic implications, promote health, and improve the quality of care. The use of calcium channel or ␣ blockers, collectively known as medical expulsive therapy (MET), represents one such treatment option. Between 2000 and 2006, 11 randomized controlled trials were published, demonstrating the efficacy of this approach for promoting upper tract stone passage.10 In fact, 1 for every 4 patients treated avoids surgery.11 Evidence suggests that the use of MET is gaining traction in urology, particularly among those with advanced specialty training.12 However, urologists evaluate only 11% of patients seen in the ED for acute renal colic before their discharge.13 Given the diversity of physicians responsible for the initial care of patients with stones, understanding the uptake of MET into the broader medical community is important. It was with this in mind that we measured temporal trends in the prevalence of MET use in EDs in the United States. 0090-4295/09/$34.00 doi:10.1016/j.urology.2009.03.050
Data were analyzed from the National Hospital Ambulatory Medical Care Survey (NHAMCS). Designed by the National Center for Health Statistics and administered by the US Census Bureau, the NHAMCS is an annual 4-stage probability sample of outpatient or ED visits to randomly selected, nonfederal short-stay hospitals in the U.S. All aspects of each visit are weighted, and the weights are adjusted to account for nonresponse and nonparticipation, allowing for extrapolation to the universe of ambulatory visits.14 Sampled ED visits for stones between 2000 and 2006 were identified through International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9) diagnosis codes, using a previously described algorithm (Appendix).15 Up to 8 medications (6 in 2000-2002) administered during the encounter or prescribed at discharge were recorded for each ED visit. As evidenced by the prescription of a calcium channel or ␣ blocker at that visit, MET use was characterized by the unique five-digit codes (Appendix) of Ambulatory Care Drug Database.16 Because MET agents are also prescribed for the treatment of hypertension and benign prostatic hyperplasia, indicator variables were constructed to identify these concurrent diagnoses using those ICD-9 codes in the Appendix. Although the test-retest reliability of the NHAMCS instrument for the collection of concurrent diagnosis data has not been formally evaluated, a similar methodology used by the National Center for Health Statistics to collect other ambulatory care information has been validated with a direct observation reference standard.17 Estimates of the prevalence of MET use were computed using these data. Logistic regression was used to examine linear and nonlinear time trends in the prescription of MET. Adjustments were made for the number of randomized controlled trials supporting use of MET published each year. Because no patients with a concurrent diagnosis of hypertension or benign prostatic hyperplasia were prescribed MET at their visit, inclusion of these covariates predicted a negative outcome perfectly; thus, they were excluded. To account for the complex sampling methodology of NHAMCS, all analyses used the svy commands provided in Stata (Version 10.1), with appropriate options for subpopulation estimation. Significance testing was two-sided, and a type-1 error rate was set at 0.05. This study was approved by the institutional review board.
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Figure 1. Prevalence of medical expulsive therapy use among emergency department visits for urinary stones by Survey Year (NHAMCS 2000-2006)—a missed opportunity. Sum of the light-blue hatched bars and the orange bars ⫽ estimated number of eligible ED visits for stone disease (in thousands) at which MET was not prescribed; orange bars ⫽ estimated number of persons seen in the ED for stones that potentially would have been spared from surgery by a trial of MET (in thousands); dark blue bars ⫽ estimated number of ED visits for stones (in thousands) at which MET was prescribed. The table below the figure displays the number of randomized controlled trials of MET published by year, as well as the cumulative total over the study period.
.001 for the linear trend). However, the estimated percentage of patients treated with MET peaked at only 3.9% in 2006, and the overall observed prevalence of use during the study period was exceedingly low at 1.1% (95% CI, 0.6%-1.9%). Moreover, the frequency of MET prescription did not differ significantly between ED visits for ureteral calculus disease (ICD-9 code 592.1) and those for all other stone diagnoses (1.2% vs 1.0%, respectively; P ⫽ .730). Given the number needed to treat of 4, the observed trend implies a missed opportunity to spare approximately 260 000 individuals annually (or 1.6 million during the 7-year study period) from stone surgery and its risks (Fig. 1).
RESULTS The frequency of ED visits for urinary stone disease was stable over the study period, ranging from 3.2 visits (95% confidence interval (CI), 2.5-3.8) per 1000 US population in 2006 to 4.2 visits (95% CI, 3.3-5.1) per 1000 US population in 2004. Mean age was comparable between patients who were treated with MET and those who were not (41.0 vs 41.4 years, respectively). Although 39.6% of eligible visits were made by women, they accounted for only 21% of the encounters at which MET was prescribed. Non-whites comprised ⬍10% of all stone cases. A similar proportion of nonwhites (8.5%) received MET. As illustrated in the Fig. 1, the use of MET increased throughout the study period. In fact, the odds of being treated with this approach more than doubled with each successive year (odds ratio, 2.15; 95% CI, 1.31-3.5; P ⬍ UROLOGY 74 (6), 2009
COMMENT Despite the growing body of evidence to support its safety and efficacy for promoting upper tract stone passage,10,11 our analysis reveals the sluggish dissemination of MET into the broader medical community. The exceedingly low prevalence of use (prescribed at only 1.1% of eligible ED visits during the 7-year study period) implies a missed opportunity to spare approximately 260 000 individuals annually from surgery and its risks. Taken together, the observed underuse of MET represents a block in the translation of clinical science into practice and raises a concern for the quality of care. There are several plausible explanations for our results. The first relates to the mode in which research findings 1207
on MET were communicated to its potential end users. Before the release of the 2007 practice guidelines for ureteral calculi management, in which MET became a recommended part of the treatment algorithm,4 its dissemination relied almost exclusively on passive communication. Though supportive data were reported in prominent subspecialty journals, such a single-channel form of communication is generally ineffective at affecting provider behavior.18 A related explanation for the slow uptake of MET pertains to the diversity of clinicians who care for patients with symptomatic stones. Primary trial data on MET appear almost exclusively in the urologic literature.10,11 Given the limited readership of these journals, the awareness of MET among nonurologists may be low. However, these are the same physicians who provide initial entry for most stone patients into the health care system.13 The omission of MET from a recent narrative review on stone disease published in a high-profile, multispecialty journal provides support that such a knowledge gap might exist.3 Additional research is necessary to explore these proposed impediments, as well as alternative explanations for the observed trend. After the impediments constraining the uptake of this efficacious process of care have been identified, an intervention targeted at overcoming its translational block can be devised. If variation in the use of MET is primarily attributable to patient-level factors, then informing recurrent stone formers, who arguably stand to benefit the most from MET, about its role in their management through educational pamphlets might increase patient acceptance. Conversely, if the physician is the most responsible party, then maintenance-of-certification vignettes involving MET may broaden the awareness of this clinical practice. Similarly, if physician extenders or ancillary service providers (eg, pharmacists) are found to contribute substantially to the variation in MET use, then continuing medical educational coursework may lead to a swifter dissemination. Although the NHAMCS provides us with the unique opportunity to measure the prevalence of MET use in the US EDs, we must recognize several limitations of the NHAMCS dataset. First, the NHAMCS uses a crosssectional design, with its unit of analysis being the patient encounter. Because an individual cannot be followed across visits, the potential exists for frequent users of medical care to bias our estimates of MET use. Nonetheless, given the sampling method that the NHAMCS uses, the likelihood of capturing repeated visits from the same patient is small.14 Second, gathered visit information on diagnoses and medications prescribed are coded centrally by NHAMCS personnel. Although this process is subject to rigorous quality control procedures,14 coding inaccuracies may exist. Third, the diagnosis codes that we used to identify eligible ED visits are somewhat heterogeneous and may include individuals for whom a trial of MET is unwar1208
ranted (eg, patients with nephrocalcinosis). As such, the annual number of individuals that we estimated, who could be spared from surgical intervention through increased MET uptake, is best interpreted as a ceiling, and the actual number may be lower. Fourth, the goal of the survey is to help define broad medical practice and management, and not the care of stone disease specifically. Therefore, the collected data lack some pertinent clinical information (eg, stone size) that may influence a provider’s stone treatment. For example, contemporary practice guidelines on ureteral calculi recommend MET as an initial treatment option only for individuals with stones of sizes ⱕ10-mm.4 If most ED visits during the study interval were for larger stones, then the low prevalence of MET use that we observed may be appropriate. Finally, we must reconcile our results with the findings of other authors. Pearle et al19 previously measured the annual number of visits made to US EDs for a primary diagnosis of urinary stone disease using the same data source. They demonstrated relative stability in this number between 1994 and 1998, although there was a 50% increase in 2000. The stable trend that we observed would suggest that this sharp increase represented simply year-to-year variability. However, in comparing the 2 studies, it is important to note that the duration examined and the algorithms used to ascertain eligible visits differed.
CONCLUSIONS Despite the growing body of evidence to support its safety and efficacy, our analysis reveals the sluggish dissemination of MET into the broader medical community. Given the low cost of MET ($28) and the expense of stone procedures ($4773 for ureteroscopy),20 these observed trends likely have significant economic implications for the US health care system. Further, this underuse represents a block in the translation of clinical science into practice and raises a quality of care concern. Additional research is necessary to explore possible explanations for the observed trend so that an intervention to increase uptake of MET can be appropriately targeted. Meanwhile, these data raise the question as to whether all patients with acute stone disease seen should be referred for optimal management to urologists with an interest in stone disease.
References 1. Sierakowski R, Finlayson B, Landes RR, et al. The frequency of urolithiasis in hospital discharge diagnoses in the United States. Invest Urol. 1978;15:438-441. 2. Johnson CM, Wilson DM, O’Fallon WM, et al. Renal stone epidemiology: a 25-year study in Rochester, Minnesota. Kidney Int. 1979;16:624-631. 3. Teichman JM. Clinical practice. Acute renal colic from ureteral calculus. N Engl J Med. 2004;350:684-693.
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4. Preminger GM, Tiselius HG, Assimos DG, et al. Guideline for the management of ureteral calculi. J Urol. 2007;178:2418-2434. 5. Parekattil SJ, Kumar U, Hegarty NJ, et al. External validation of outcome prediction model for ureteral/renal calculi. J Urol. 2006; 175:575-579. 6. Bierkens AF, Hendrikx AJ, De La Rosette JJ, et al. Treatment of mid- and lower ureteric calculi: extracorporeal shock-wave lithotripsy vs laser ureteroscopy. A comparison of costs, morbidity, and effectiveness. Br J Urol. 1998;81:31-35. 7. Hochreiter WW, Danuser H, Perrig M, et al. Extracorporeal shock wave lithotripsy for distal ureteral calculi: what a powerful machine can achieve. J Urol. 2003;169:878-880. 8. Daniels GF Jr, Garnett JE, Carter MF. Ureteroscopic results and complications: experience with 130 cases. J Urol. 1988;139:710-713. 9. Krambeck AE, Gettman MT, Rohlinger AL, et al. Diabetes mellitus and hypertension associated with shock wave lithotripsy of renal and proximal ureteral stones at 19 years of follow up. J Urol. 2006;175:1742-1747. 10. Singh A, Alter HJ, Littlepage A. A systematic review of medical therapy to facilitate passage of ureteral calculi. Ann Emerg Med. 2007;50:552-563. 11. Hollingsworth JM, Rogers MA, Kaufman SR, et al. Medical therapy to facilitate urinary stone passage: a meta-analysis. Lancet. 2006;368:1171-1179.
12. Bandi G, Best SL, Nakada SY. Current practice patterns in the management of upper urinary tract calculi in the north central United States. J Endourol. 2008;22:631-636. 13. Sterrett SP, Moore NW, Nakada SY. Emergency room follow-up trends in urolithiasis: single-center report. Urology. 2009;73:1195-1197. 14. McCaig LF, McLemore T. Plan and operation of the National Hospital Ambulatory Medical Survey. Series 1: programs and collection procedures. Vital Health Stat. Series 1. Programs Collect Proced. 1994;1-78. 15. Brown J. Diagnostic and treatment patterns for renal colic in US emergency departments. Int Urol Nephrol. 2006;38:87-92. 16. Ambulatory Care Drug Database System. U.S. Centers for Disease Control and Prevention Web site. Available at: http://www.cdc. gov/drugs. Accessed July 1, 2008. 17. Gilchrist VJ, Stange KC, Flocke SA, et al. A comparison of the national ambulatory medical care survey (NAMCS) measurement approach with direct observation of outpatient visits. Med Care. 2004;42:276-280. 18. Lomas J. Words without action? The production, dissemination, and impact of consensus recommendations. Annu Rev Public Health. 1991;12:41-65. 19. Pearle MS, Calhoun EA, Curhan GC, et al. Urologic diseases in America project: urolithiasis. J Urol. 2005;173:848-857. 20. Bensalah K, Pearle M, Lotan Y. Cost-effectiveness of medical expulsive therapy using alpha-blockers for the treatment of distal ureteral stones. Eur Urol. 2008;53:411-418.
APPENDIX ICD-9 Diagnosis/NCHS 5-Digit Drug Codes Include emergency department visits for— Upper tract urinary stone 270.0, 274.11, 592.0, 592.1, 592.9, 788.0 Exclude stone visits with an indication for immediate urinary diversion— Renal insufficiency 440.1, 580, 580.0, 580.4, 580.8, 580.81, 580.89, 580.9, 581, 581.0, 581.2, 581.3, 581.8, 581.81, 581.89, 581.9, 582, 582.0, 582.1, 582.2, 582.4, 582.8, 582.1, 582.89, 582.9, 583, 583.0, 583.1, 583.2, 583.4, 583.6, 583.7, 583.8, 583.81, 583.89, 583.9, 584, 584.5, 584.6, 584.7, 584.8, 584.9, 585, 585.1, 585.2, 585.3, 585.4, 585.5, 585.6, 585.9, 586, 587, 589, 589.0, 589.1, 589.9, 593.9 or Pyelonephritis 590.0, 590.1, 590.8, 590.80, 590.81 Other conditions commonly treated with calcium channel or alpha blockers— Hypertension 401, 401.0, 401.1, 401.9, 402, 402.0, 402.00, 402.01, 402.10, 402.11, 402.9, 402.90, 402.91, 403, 403.0, 403.2, 403.9, 404, 404.0, 404.1, 404.9, 405, 405.0, 405.01, 405.09, 405.1, 405.11, 405.19, 405.9, 405.91, 405.99, 642.4, 642.3, 997.91 and Benign prostatic hyperplasia 599.6, 599.60, 599.69, 600, 600.0, 600.01, 600.1, 600.10, 600.11, 600.2, 600.20, 600.21, 600.3, 600.9, 600.90, 600.91, 788.2, 788.20, 788.21, 788.29, 788.4, 788.41, 788.42, 788.43, 788.6, 788.61, 788.62, 788.63, 788.64, 788.65, 788.69 Medical expulsive therapy agents— Tamsulosin 00053, 59731, 97126 Alfuzosin 04138, 70814 Terazosin 15307, 56290, 94133 Doxazosin 51953, 92012, 92120 Prazosin 19455, 24805, 54765, 70346, 89062 Nifedipine 01019, 02231, 03142, 04122, 25213, 53922, 60040, 89067, 91039 ICD-9 indicates International Classification of Diseases, Ninth Revision, Clinical Modification; NCHS, National Center for Health Statistic.
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