Cost-effectiveness of Imaging Protocolsfor Suspected AppendicitisRebecca Jennings, MD,a,d He Guo, MSc, MPP,b Adam Goldin, MD, MPH,c Davene R. Wright, PhDa,d,e

abstractBACKGROUND: Inaccurate diagnosis of appendicitis leads to increased costs and morbidity.Ultrasound costs less than computed tomography (CT) or MRI but has lower sensitivity andmay not visualize the appendix.

METHODS: We conducted a cost-effectiveness analysis using a decision-analytic model of 10imaging strategies for suspected appendicitis in a hypothetical cohort of patients: no imagingwith discharge or surgery; CT only; MRI only; or staged approach with CT or MRI after 1)negative ultrasound result or ultrasound without appendix visualization, 2) ultrasoundwithout appendix visualization, or 3) ultrasound without appendix visualization but withsecondary signs of inflammation. Inputs were derived from published literature andsecondary data (quality-of-life and cost data). Sensitivity analyses varied risk of appendicitisand proportion of visualized ultrasound. Outcomes were effectiveness (quality-adjusted life-years [QALYs]), total direct medical costs, and cost-effectiveness (cost per QALY gained).

RESULTS: The most cost-effective strategy for patients at moderate risk for appendicitis is initialultrasound, followed by CT if the appendix is not visualized but secondary signs are present(cost of $4815.03; effectiveness of 0.99694 QALYs). Other strategies were well above standardwillingness-to-pay thresholds or were more costly and less effective. Cost-effectiveness wassensitive to patients’ risk of appendicitis but not the proportion of visualized appendices.

CONCLUSIONS:Tailored approaches to imaging based on patients’ risk of appendicitis are the mostcost-effective. Imaging is not cost-effective in patients with a probability ,16% or .95%. Formoderate-risk patients, ultrasound without secondary signs of inflammation is sufficient evenwithout appendix visualization.

WHAT’S KNOWN ON THIS SUBJECT: Ultrasound-firstimaging protocols are used to evaluate suspectedappendicitis to decrease cost and radiation exposurefrom computed tomography use, but there is a paucityof data on the optimal ultrasound approach to achievecost-effectiveness.

WHAT THIS STUDY ADDS: For patients with low tomedium risk of appendicitis, it is most cost-effective toperform an ultrasound first. If the appendix is notvisualized, providers can forego a follow-up computedtomography if the ultrasound has no secondary signsof inflammation.

To cite: Jennings R, Guo H, Goldin A, et al. Cost-effectiveness of Imaging Protocols for Suspected Appendicitis.Pediatrics. 2020;145(2):e20191352

aDepartments of Pediatrics and cPediatric General and Thoracic Surgery, Unviersity of Washington, SeattleChildren’s Hospital, Seattle, Washington; bSchool of Pharmacy, The Comparative Health Outcomes, Policy, andEconomics (CHOICE) Institute, University of Washington, Seattle, Washington; dSeattle Children’s Research Institute,Seattle, Washington; and eDepartment of Population Medicine, Harvard Medical School and Harvard Pilgrim HealthCare Institute, Harvard University, Boston, Massachusetts

Drs Jennings and Wright conceptualized and designed the study, drafted the initial manuscript, andreviewed and revised the manuscript; Ms Guo helped design the model, conducted the initialanalyses, and reviewed and revised the manuscript; Dr Goldin provided critical review of theconceptualization and design of the study, helped interpret the data, and critically reviewed themanuscript for important intellectual content; and all authors approved the final manuscript assubmitted and agree to be accountable for all aspects of the work.

DOI: https://doi.org/10.1542/peds.2019-1352

Accepted for publication Nov 18, 2019

Address correspondence to Rebecca Jennings, MD, Department of Pediatrics, Seattle Children’sHospital, 4800 Sand Point Way NE, M/S FA.2.115, Seattle, WA 98105. E-mail: rebecca.jennings@seattlechildrens.org

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Appendicitis is the most commonindication for pediatric emergencysurgery.1 Appendicitis with andwithout peritonitis are the fifth and12th most costly pediatric conditionsat general hospitals and cost $278million and $156 million annually,respectively.2 It is important todiagnose pediatric patients withappendicitis accurately because bothfalse-negative and false-positivediagnoses are associated withincreased morbidity and costs.3,4

Diagnosing appendicitis relies heavilyon imaging and a provider’sassessment of the risk of appendicitisfor a given patient.5 Ultrasound andcomputed tomography (CT) are themost common imaging modalities.6

Ultrasound costs less than CT anddoes not use radiation, but it is lessaccurate than CT for visualizing theappendix and detectingappendicitis.6,7 When providers fail tovisualize the appendix usingultrasound, they employ additionalimaging (eg, CT) to clarify thediagnosis, increasing imaging costs. Inpediatric emergency departments(EDs), the appendix is only identifiedin 25% to 73% of right-lowerquadrant (RLQ) ultrasounds.8 Theaccuracy of ultrasounds that do notvisualize the appendix can beincreased by incorporating secondarysigns of inflammation.9 Somehospitals use MRI for the evaluationof suspected appendicitis as primaryor follow-up imaging as a way toreduce patient exposure toradiation.10,11 MRI is more sensitiveand specific than CT for suspectedappendicitis,12,13 but it is more costly.

A staged ultrasound approach, inwhich ultrasound is an initial imagingmodality, can improve diagnosticaccuracy and decrease CT use.14–17 Itis unclear if a staged ultrasoundapproach is cost-effective in settingswhere the appendix is infrequentlyvisualized. Many imaging strategiescall for tailoring evaluation bystratifying patient risk,18,19 such asonly performing imaging on medium-

risk patients, and not performing a CTif there are no secondary signs ofinflammation in the RLQ seen onultrasound. The precise pretestprobability of (ie, likelihood ofhaving) appendicitis, for whichdifferent approaches to the evaluationof appendicitis are cost-effective, isunknown.

The cost-effectiveness of variousimaging approaches can be evaluatedby using decision-analytic models,which conduct virtual clinical trials,simulating costs and health effects ofdifferent screening approaches on thesame population of theoreticalpatients. This method can comparemultiple diagnostic approaches,particularly when inaccuratediagnosis is rare but burdensome.Previous decision-analytic modelsassessed the cost-effectiveness ofvarious imaging protocols fordiagnosing pediatric appendicitis butdid not address ultrasounds that donot visualize the appendix, did notevaluate MRI, or did not stratifypatients by risk.7,20–22 We aimed toidentify the most cost-effectiveimaging strategy for suspectedappendicitis using more robustmodeling assumptions than havebeen previously employed. Oursecondary aims were to identifyhealth and facility characteristics thatimpact cost-effectiveness.

METHODS

Decision-Analytic Model

We simulated a hypothetical cohort ofchildren presenting to an ED withsuspected appendicitis usinga decision-analytic Markov cohortmodel created in TreeAge (TreeAgePro Healthcare; TreeAge Software Inc,Williamstown, MA). We compared thefollowing imaging strategies (Fig 1):CT only (strategy A); MRI only(strategy B); or a staged approachusing ultrasound followed by CT orMRI (1) after all ultrasounds that areeither negative or do not visualize theappendix (strategies C and F), (2)

after all ultrasounds that do notvisualize the appendix (strategies Dand G), or (3) only after ultrasoundsthat do not visualize the appendix ifthe ultrasound has secondary signs ofinflammation in the RLQ (strategies Eand H). Lastly, we modeled dischargeand surgery for all patients withoutany imaging (strategies I and J,respectively) to evaluate the test andtest-treatment threshold of imaging.Strategies represented existingdescribed protocols and the existingliterature.7,20,22

We estimated the costs of imagingand surgical procedures, and thecosts and health effects attributableto false-negative and positivediagnoses, including increased risk ofperforation and negativeappendectomy, respectively. Weassumed patients who had imagingtests that were falsely interpreted asnegative returned to the ED, at whichpoint they would be diagnosed withappendicitis and have an increasedperforation risk. A simplified versionof 1 arm of the decision tree (strategyE) is shown in Fig 2. The full decisiontree is provided (Supplemental Figs 4and 5). The study was deemedexempt by the Seattle Children’sHospital Institutional Review Board.

Model Input Data

We estimated input parametersincluding imaging test characteristicsand health outcomes of children withsuspected acute appendicitis frompublished studies (Table 1). We usedmeta-analyses describing imaging testcharacteristics when available.12,23

For ultrasound test characteristics,we included published studies thatcompared positive or negativeultrasound results for pediatricpatients with suspected appendicitisto positive or negative rates ofappendicitis at surgery or follow-up.Test characteristics of ultrasoundsthat visualize the appendix wereestimated from published studies thatexcluded nonvisualizedappendices.8,9,16–18,24–27,30–33 Test

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characteristics of the presence ofsecondary signs of inflammationin ultrasounds that do not visualizethe appendix were estimatedfrom studies that separately reportedthe test characteristics whenthe appendix is not visualized,with and without secondarysigns,9,16,24,27,30-32 assuming thatpatients with secondary signshad appendicitis and thosewithout secondary signs didnot have appendicitis. Weused a weighted averagefrom these studies for

sensitivity and specificity pointestimates.

We estimated visualization rates forpatients with and withoutappendicitis separately usingweighted averages from publisheddata.8,9,16,18,24–27,30–33 Noneof the appendix visualizationstudies differentiated betweenruptured and nonrupturedappendices.

Mortality from a negativeappendectomy was assumed to beequal to mortality for pediatric

patients with uncomplicatedappendicitis.

Health-Related Quality of Life

Health-related quality of lifeassociated with perforated anduncomplicated appendicitis wasestimated by using the PediatricQuality of Life Inventory (PedsQL),which was administered to patientshospitalized at our freestandingchildren’s hospital from June 2009 toApril 2018. The PedsQL, a validatedstandardized questionnaire, producesscores on 4 subscales: physical,emotional, social, and schoolfunctioning. We used publishedregression equations to estimateutility values from the PedsQLsubscales.44 We identified patientsusing International Classification ofDiseases, Ninth Revision, ClinicalModification and InternationalClassification of Diseases, 10thRevision, Clinical Modification codes of540.9 and K35.80 or K35.89 for acuteappendicitis and 540.0 and K35.2 or540.1 and K35.3 for perforatedappendicitis.21 We assumed theutility value for negativeappendectomy would be the same asfor uncomplicated acute appendicitis.We used published PedsQL data forED patients with minor injuries toestimate the utility values for EDpatients presenting with abdominalpain but no appendicitis, defined asthe “well state.”42,43

Costs

Inpatient costs for uncomplicated andperforated appendicitis wereestimated by using the 2016 Kids’Inpatient Database (KID), a nationaldatabase of hospital charge data. Wedefined patients with uncomplicatedand perforated appendicitis usingInternational Classification ofDiseases, 10th Revision, ClinicalModification codes of K35.80 orK35.89 and K35.2 or K35.3,respectively. We assumed that thecost of negative appendectomies wasthe same as that of uncomplicatedappendicitis. We also included

FIGURE 1Schematic of imaging strategies included in model.

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professional fees in total costs (notincluded in KID cost data) byincluding professional charges basedon assumed Current ProceduralTerminology (CPT) codes charged byproviders21 and average length ofstay in the KID for uncomplicated andperforated appendicitis. Weestimated imaging and ED visits costsusing 2017 Medicare hospital fees40

and professional fees by CPT code.41

Total cost estimates are included inTable 1, and the components areshown in Supplemental Table 3. All

costs were adjusted to 2017 USdollars by using the Personal HealthCare Expenditure deflator.45

Cost-effectiveness Analysis

A cost-effectiveness analysis wasconducted from the payer perspectiveover a 1-year time horizon.46 Ourprimary effectiveness measure wasthe quality-adjusted life-year (QALY),a composite measure of morbidityand mortality.46 QALYs for eachstrategy were calculated as thenumber of years spent living a health

state (ie, appendicitis or appendicitiswith perforation) multiplied by theutility value for that health state(Table 1). Because appendicitis andED visits are temporary health states,the patient was assumed toexperience decreased utility for1 month then return to a state ofperfect health for the remaining11 months of the year. We rankedeach of the 10 alternative screeningapproaches according to increasingcost. Approaches that were morecostly but less effective than an

FIGURE 2Simplified version of strategy E.

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alternative approach were considereddominated and excluded from furthercalculations.46 The remainingapproaches were reranked accordingto increasing costs. The leastexpensive and least effectivescreening approach was the baselinefor comparison. We then calculatedthe net costs, the cost of the strategyminus the cost of the next-lowest–ranking strategy, and netQALYs (the effectiveness of thestrategy minus the effectivenessof the next-lowest–ranking strategy)for each screening alternative.Our cost-effectiveness outcomewas the incremental cost-effectiveness ratio (ICER) for eachalternative, or net costs divided bynet QALYs.47

Sensitivity Analyses

We conducted 1- and 2-waysensitivity analyses to assess howrobust our results were to inputs.Ranges are reported in Table 1. In our2-way sensitivity analysis, we variedthe pretest probability of appendicitisand proportion of ultrasounds thatvisualize the appendix from 0% to100%. The latter was varied at a fixedratio for patients with and withoutappendicitis. We assessed thresholdsat which the most cost-effectiveapproach changes. This allowed us tocreate a tailored imaging approachbased on a patient’s pretestprobability of appendicitis anda hospital’s appendixvisualization rate.

RESULTS

Cost-effectiveness

Results are summarized in Table 2.Strategy E is the least costly strategy,with a cost of $4815 and 0.9969QALYs. In this strategy, all patientswith suspected appendicitis undergoan initial ultrasound. If the ultrasounddoes not visualize the appendix buthas secondary signs of inflammation,then the patient undergoes a CT. Ifthere are no secondary signs ofinflammation on ultrasound, then thepatient is discharged. All but 3strategies were dominated, withlower effectiveness and higher costthan their next least expensivecomparators being observed (Table 2,Supplemental Table 4). Strategies B

TABLE 1 Model Inputs

Probability Factor Point Estimate Range

Proportion of patients with appendicitis8–10,14–16,24–29 0.326 0.145–0.614Ultrasound with visualized appendix, sensitivity8,9,16–18,24–26,30–33 0.986 0.957–1.0Ultrasound with visualized appendix, specificity8,9,16–18,24–26,30–33 0.936 0.654–1.0Proportion ultrasound that do not visualize appendix among patients with appendicitis8,9,16,18,24–27,30–33 0.158 0.0172–0.394Proportion ultrasound that do not visualize appendix among patients without appendicitis8,9,16,18,24–27,30–33 0.466 0.104–0.910Secondary signs of inflammation on ultrasound without visualized appendix, sensitivity9,16,24,27,30–32,34 0.534 0.29–1.0Secondary signs of inflammation ultrasound without visualized appendix, specificity9,16,24,27,30–32 0.9439 0.6–0.99CT, sensitivity23 0.95 0.92–0.97CT, specificity23 0.92 0.90–0.94MRI, sensitivity12 0.965 0.943–0.978MRI, specificity12 0.961 0.935–0.977Proportion of patients with perforation at presentation358,15,29,30,33,36 0.286 0.174–0.405Proportion of patients with perforation after delayed diagnosis3,37 0.774 0.774–0.81Mortality, uncomplicated appendicitis36,38 0.0001 0.0001–0.0001Mortality, perforated appendicitis36,38,39 0.000347 0.0002–0.0004Cost of limited abdominal ultrasound, $40,41 228.61 171.46–285.77a

Cost of abdominal and pelvic CT with contrast, $40,41 805.55 604.44–1007.40a

Cost of abdominal and pelvic MRI without contrast, $40,41 1160.80 1284.41–2140.69a

Cost of hospitalization for appendicitis without rupture, $ 9460.90 4559.69–16 010.45Cost of hospitalization for appendicitis with rupture, $ 15387.10 5792.20–32 310.18Cost of ED visit without imaging, $ 665.83 499.37–832.38a

Disutility for appendicitis without ruptureb 0.0624 0.0146–0.1509Disutility for appendicitis with ruptureb 0.0837 0.0149–0.2275Disutility for ED visit42,43,b 0.017 0.009–0.026

a 75% to 125% of 2017 Medicare reimbursement.b Disutility is defined as 1-utility.

TABLE 2 Cost-effective Analysis

Strategy Cost, $ IncrementalCost, $

Effectiveness,QALYs

IncrementalEffectiveness

ICER, $ perQALY

Strategy E: staged ultrasound, CT if US does not visualize appendix but hassecondary signs of inflammation

4815.03 0 0.99694 0 0

Strategy H: staged ultrasound, MRI if ultrasound does not visualize appendix buthas secondary signs of inflammation

5070.69 255.66 0.996986 4.37 3 1025 5 846 752

Strategy B: MRI 5521.28 450.59 0.997015 2.90 3 1025 1.563107

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(MRI only) and H (staged ultrasoundwith MRI only if ultrasound does notvisualize the appendix but hassecondary signs of inflammation)provide small QALY gains overstrategy E, but the ICER for each issignificantly higher than standardwillingness-to-pay thresholds of$100 000 to $150000 per QALYgained.46

Sensitivity Analysis

The 1-way sensitivity analysisdemonstrated that ICERs were mostsensitive to the prevalence ofappendicitis, the cost of appendicitistreatment, and the specificity ofultrasounds with appendixvisualization (Supplemental Fig 6).The other inputs had little impact onICERs, meaning that within the rangeof the input that was simulated, theICER did not vary substantially.

A 2-way sensitivity analysis (Fig 3)demonstrated little effect of theproportion of visualized ultrasounds

on optimal strategies even whenvisualization is low. Strategy I(discharge all) is the optimal strategywhen the pretest probability ofhaving appendicitis is ,∼16%.Strategy E is optimal when the pretestprobability is between 16% and 67%.With higher pretest probability(67%–95%), strategy D is optimal(all nonvisualized appendices onultrasound are followed by CT). Whenthe pretest probability is .95%, thenstrategy J (surgery without imaging)is optimal.

Because the absence of secondarysigns of inflammation in the RLQwhen the ultrasound does notvisualize the appendix has a lowersensitivity than a negative ultrasoundresult when the appendix is seen, it isonly cost-effective to forego a CT witha nonvisualized ultrasound if thereare no secondary signs of RLQinflammation and the patient hasa lower risk of appendicitis. Tomaximize cost-effectiveness, when

a patient has a higher risk ofappendicitis, all ultrasounds that donot visualize the appendix should befollowed by CT. The sensitivity of anultrasound that visualizes theappendix is high enough that a CTafter a negative ultrasound result isonly cost-effective when theproportion of nonvisualizedultrasounds is high. Furthermore, wefound that if the patient has a lowor high pretest probability ofappendicitis, it is cost-effective forpatients to forego imaging entirely.

DISCUSSION

In this study, we provide guidance toclinicians regarding the most cost-effective imaging strategies forpediatric patients with suspectedappendicitis, with particularconsideration on risk stratifyinga patient’s pretest probability ofappendicitis and a hospital’sproportion of ultrasounds that areunable to visualize the appendix. The

FIGURE 3Two-way sensitivity analysis. a Probability of appendicitis can be estimated by using examination, ancillary tests, or scoring systems.

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most cost-effective strategy is highlydependent on a patient’s riskstratification. At a prevalence ,16%and .95%, patients can foregoimaging entirely. For patients witha risk of appendicitis between 16%and 67%, it is cost-effective toperform an initial ultrasound andforego additional imaging if theultrasound does not visualize theappendix but shows no secondarysigns of inflammation. When thepretest probability of appendicitis is.67%, it is cost-effective to follow-upall nonvisualized ultrasounds witha CT even without secondary signs ofinflammation on ultrasound.

We found that even when theappendix is rarely visualized,ultrasound as the initial imagingmodality for intermediate-riskpatients is cost-effective. This isimportant because most quality-improvement initiatives thatexamined the ultrasound-firstapproach have been conducted inchildren’s hospitals, but mostpediatric patients are seen in generalEDs,48 where the proportion ofultrasounds that visualize theappendix may be lower. Our resultssuggest all hospitals should adoptrisk stratification followed byeventual ultrasound in patientswith intermediate probability ofappendicitis. It is important to notethat our results were sensitive tochanges in the specificity ofultrasound with visualization of theappendix; when ultrasound is notread by a pediatric radiologist, it mayhave a lower specificity, which wouldimpact the cost-effectiveness ofultrasound-first approaches.

The optimal imaging strategy ishighly dependent on a patient’spretest probability of appendicitis;therefore, imaging strategies shouldbe tailored on the basis ofa provider’s assessment of anindividual patient’s risk ofappendicitis. Providers can estimatea patient’s appendicitis risk usingancillary tests or scores such as the

Pediatric Appendicitis RiskCalculator49 or Pediatric AppendicitisScore.50 Our findings are consistentwith previous studies and Europeanguideline recommendations.18,19,51

The risk thresholds for imaging weidentified are similar to those derivedfrom risk prediction tools. ThePediatric Appendicitis Risk Calculatorscoring tool identifies patients withmedium risk of appendicitis from15% to 85%, similar to our model’srecommendation of imaging at a risklevel of 16% to 95%.49 Furthermore,our results align with previousfindings that patients with a lowlikelihood of appendicitis can bedischarged with an ultrasound thatdoes not visualize the appendixbut has no secondary signs ofinflammation given the high negativepredictive value of an ultrasoundwithout secondary signs in low-riskclinical settings.9,32 It is important tonote that many of these baselineestimates of pretest probability arefrom studies at children’shospitals.18,50 The advantage of usingour model to establish test thresholdsis that it can accurately estimate rareoutcomes, such as missed diagnosisleading to increased perforation risk,and identify precise pretestprobabilities at which differentimaging approaches are mostcost-effective.

Given the high cost of surgery andhospitalization relative to imaging inthe ED, we found that it is only cost-effective to forego imaging whenthere is a high risk for appendicitis.Our own personal experience is thatthere is much variation in theapproaches that providers use withhigh-risk patients. This exemplifieswhy decision models using virtualcohorts are helpful for informingclinical practice.

Many hospitals have adopted quality-improvement initiatives aimed atreducing CT use for suspectedappendicitis to reduce exposure toionizing radiation. Given highuncertainty about long-term effects of

radiation levels seen with a singleabdominal CT,52 we did not modelpotential future cases of radiation-induced cancer. Importantly, the CT-only protocol was not cost-effectiveeven without considering radiation.Therefore, an ultrasound-firstprotocol would not only reducepatients’ exposure to ionizingradiation but also improve value.

Because the appendicitis treatmentand recovery period is brief, therewere only minor differences inQALYs. It remains important toconsider the effect QALYs have on ourresults because ICERs identifydominant approaches (both moreeffective and less costly). A cost-onlyanalysis would mask these dominantscenarios. With a higher sensitivityand specificity than CT, MRI-basedimaging strategies have minimallyhigher QALY gains than do CT-basedstrategies. Because of the higher costof MRI, the ICERs for MRI-basedstrategies are significantly higherthan accepted willingness-to-paythresholds. New short-duration,appendix-specific MRI protocolscould make MRI more cost-effective ifthose protocols reduce costssubstantially.13

There has been recent interest in thetreatment of assumed uncomplicatedappendicitis with antibiotics withoutsurgery.53,54 Wu et al43 demonstratedthat this approach can be cost-effective. Because this approach costsless than operative management,54 itmay affect the cost-effectiveness ofdiagnosis. Recent studies havesuggested some cases ofuncomplicated appendicitis mayresolve spontaneously,53 suggestingthere may be a risk of overtreatingmild appendicitis detected byultrasound or CT. Furthermore, somepatients with false-negative diagnosisof appendicitis may have spontaneousresolution of their mild appendicitis.

This analysis was subject tolimitations. We did not account for allpossible costs and consequences

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related to imaging and outcomes.Perforated appendicitis can lead toabdominal strictures and scarring,leading to obstruction and potentialfuture surgeries. Imaging can lead toincidental findings with unclearclinical significance, which maynecessitate further imaging andinvasive procedures. We did notaccount for sedation when assessingMRI costs and morbidity. Many inputparameter estimates are based onstudies performed at children’shospitals. As is common in decision-analytic models, we made multiplemodeling assumptions. However,sensitivity analyses providerobustness checks on ourassumptions and results. Finally, wecould not extract imaging costs fromtotal hospital costs; therefore, costsfor patients with appendicitis include2 imaging modalities. However,imaging represents a fraction of totaltreatment costs, and this change isunlikely to affect our results.

CONCLUSIONS

Accurate diagnosis of appendicitiscan be challenging, withconsequences for both false-positiveand false-negative diagnoses. It isimportant to minimize potentialnegative consequences of imaging,including radiation, incidentalfindings, and costs. We demonstratethat for patients with a risk ofappendicitis ,16% or .95%,imaging is not cost-effective. Forpatients at moderate risk .16%,an ultrasound without secondarysigns of RLQ inflammationcan be sufficient even if theappendix is not visualized andeven in settings where theappendix is infrequently visualized.For patients with higher riskof appendicitis, providersshould tailor their imagingapproach for patients on the basisof a patient’s pretest probabilityof appendicitis.

ACKNOWLEDGMENTS

We thank Wren Haaland, MPH, ofSeattle Children’s Hospital, whocreated early iterations of themodel and Matthew Dellinger, MD,and Joel Tieder, MD, MPH, ofSeattle Children’s Hospital andthe University of WashingtonSchool of Medicine, who reviewedthe article.

ABBREVIATIONS

CPT: Current ProceduralTerminology

CT: computed tomographyED: emergency departmentICER: incremental cost-

effectiveness ratioKID: Kids’ Inpatient DatabasePedsQL: Pediatric Quality of Life

InventoryQALY: quality-adjusted life-yearRLQ: right-lower quadrant

PEDIATRICS (ISSN Numbers: Print, 0031-4005; Online, 1098-4275).

Copyright © 2020 by the American Academy of Pediatrics

FINANCIAL DISCLOSURE: The authors have indicated they have no financial relationships relevant to this article to disclose.

FUNDING: Funded by the University of Washington and Seattle Children’s Hospital Quality Improvement Scholars Program.

POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose.

COMPANION PAPER: A companion to this article can be found online at www.pediatrics.org/cgi/doi/10.1542/peds.2019-3349.

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Cost-effectiveness of Imaging Protocols for Suspected Appendicitis

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