RESEARCH ARTICLE

Hospitalization for Community-AcquiredPneumonia in Children: Effect of an AsthmaCodiagnosisKaren M. Wilson, MD, MPH,a Michelle R. Torok, PhD,b,c Russell Localio, PhD,d Lisa McLeod, MD, MSCE,a Rajendu Srivastava, MD, FRCP(C), MPH,e

Xianqun Luan, MS,f Zeinab Mohamad, DrPH,f Samir S. Shah, MD, MSCE,g for the Pediatric Research in Inpatient Settings (PRIS) Network

A B S T R A C T BACKGROUND AND OBJECTIVE: Community-acquired pneumonia (CAP) is a common andexpensive cause of hospitalization among US children, many of whom receive a codiagnosis of acuteasthma. The objective of this study was to describe demographic characteristics, cost, length of stay(LOS), and adherence to clinical guidelines among these groups and to compare health careutilization and guideline adherence between them.

METHODS: This was a multicenter retrospective cohort study using data from the Pediatric HealthInformation System. Children aged 2 to 18 who were hospitalized with uncomplicated CAP from July1, 2007, to June 30, 2012 were included. Demographics, LOS, total standardized cost, and clinicalguideline adherence were compared between patients with CAP only and CAP plus acute asthma.

RESULTS: Among the 25 124 admissions, 57% were diagnosed with CAP only; 43% hada codiagnosis of acute asthma. The geometric mean for standardized cost was $4830; for LOS, it was2.01 days. Eighty-four percent of patients had chest radiographs; CAP1acute asthma patients wereless likely to have a blood culture performed (36% vs 62%, respectively) and more likely not to havea complete blood count performed (49% vs 27%, respectively). Greater guideline adherence wasassociated with higher cost at the patient-level but lower average cost per hospitalization at thehospital level. CAP1acute asthma patients had higher relative costs (11.8%) and LOS (5.6%) withinhospitals and had more cost variation across hospitals, compared with patients with CAP only.

CONCLUSIONS: A codiagnosis of acute asthma is common for children with CAP. This could befrom misdiagnosis or co-occurrence. Diagnostic and/or management variability appears to be greater inpatients with CAP1asthma, which may increase resource utilization and LOS for these patients.

aSection of PediatricHospital Medicine,Children’s HospitalColorado and the

University of ColoradoSchool of Medicine,Aurora, Colorado;

bSection of PediatricHospital Medicine,Children’s HospitalColorado, Aurora,

Colorado; cChildren’sOutcomes Research,

University of ColoradoSchool of Medicine,Aurora, Colorado;dDepartment ofBiostatistics and

Epidemiology, PerelmanSchool of Medicine,

University ofPennsylvania,Philadelphia,

Pennsylvania; eDivision ofPediatric Inpatient

Medicine, Department ofPediatrics, Primary

Children’s Hospital andInstitute for Healthcare

Delivery Research,Intermountain

Healthcare, Salt Lake City,Utah; fHealthcare

Analytics Unit, PolicyLab,Children’s Hospital of

Philadelphia,Philadelphia,

Pennsylvania; andgDivisions of Hospital

Medicine and InfectiousDiseases, CincinnatiChildren’s Hospital

Medical Center,Cincinnati, Ohio

www.hospitalpediatrics.orgDOI:10.1542/hpeds.2015-0007Copyright © 2015 by the American Academy of Pediatrics

Address correspondence to Karen M. Wilson, MD, MPH, Section of Pediatric Hospital Medicine, Children’s Hospital Colorado, University ofColorado School of Medicine, 13123 E. 16th Ave, B302, Aurora, CO 80045. E-mail: Karen.wilson@childrenscolorado.org

HOSPITAL PEDIATRICS (ISSN Numbers: Print, 2154-1663; Online, 2154-1671).

FINANCIAL DISCLOSURE: Drs Wilson, Srivastava, and Shah were supported by the Children’s Hospital Association. The other authors haveindicated that they have no financial relationships relevant to this article to disclose.

FUNDING: A grant from the Children’s Hospital Association to the Pediatric Research in Inpatient Settings Network

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

Dr Wilson conceptualized the design and led the study and drafted the initial manuscript; Dr Torok helped with analytic planning and methods,completed statistical analyses, and helped draft the manuscript; Dr Localio led the analytic plan and advised on statistical procedures and studydesign, performed statistical analyses, drafted parts of the manuscript, and helped edit the manuscript; Mr Luan and Dr Mohamad completedstatistical analyses, assisted with study design, and helped edit the manuscript; Drs McLeod, Srivastava, and Shah participated in the studydesign, analytic planning, and data quality review and edited the manuscript; and all authors approved the final manuscript as submitted.

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Community-acquired pneumonia (CAP)ranks among the most common and costlyreasons for hospitalization of children.1

Children hospitalized with CAP often receivea diagnosis of asthma, a conditioncolloquially referred to as “asthmonia.”Distinguishing CAP occurring alone fromCAP occurring with an asthma exacerbationcan be challenging because viralrespiratory tract infections predispose tobacterial pneumonia and also triggerasthma exacerbations. In addition, althoughCAP is typically diagnosed by chestradiograph or focal lung findings, there isevidence that atelectasis can mimicinfiltrates,2 which could lead tomisdiagnosis of pneumonia in a patient withasthma. Children with asthma are atincreased risk for invasive pneumococcalinfections,3 including pneumonia. Animportant challenge in the management ofCAP occurring with an asthma exacerbationis that national guidelines focus treatmenton a single diagnosis (CAP alone or asthmaalone), and in some cases, the guidelinesconflict on ideal management.4,5

The guidelines for treatment ofuncomplicated CAP include obtainingbacterial cultures, viral testing,inflammatory markers, chest radiography,and the use of an aminopenicillin.Corticosteroids, a mainstay of asthmatherapy, have not been proven effective forthe treatment of CAP in randomized trialsinvolving adults6 and are not recommended.There is no role for bronchodilators in thetreatment of CAP. In contrast, managementof an acute asthma exacerbation includesadministration of oral corticosteroids andbronchodilators. Routine chest radiographsand viral testing are not recommended, andin fact, chest radiographs in pediatricasthma were chosen as one of the ChoosingWisely campaign’s procedures not to order.7

Previous studies of hospital-level adherenceto CAP guidelines have shown variability; theaverage percent of patients receivinga chest radiograph for CAP across 29children’s hospitals ranged from 54% to90%, whereas the average percent ofpatients with a documented blood cultureranged from 0% to 92%.8 Conversely,adherence to the asthma care guidelines of

using systemic corticosteroids andbronchodilators was high and consistentacross hospitals.9 Although therecommendations for management ofuncomplicated pneumonia alone or asthmaalone are well defined, they do not providedirection for a common clinical occurrence:treating patients who are diagnosed withboth. We hypothesized that this might leadto more diagnostic uncertainty, andtherefore decreased adherence to clinicalcare guidelines, increased health careutilization, and variation in the clinicalmanagement and treatment of thesepatients. Understanding how patients whohave pneumonia and asthma codiagnosesinfluence utilization might help to clarifymore appropriate patient selection forguidelines use, and allow systems ofcare–based interventions to moreaccurately measure patient and costoutcomes.

We used data from a national multihospitalcohort of children to determine thevariation in resource utilization andadherence to the pneumonia guidelines inchildren with CAP with and withouta concomitant diagnosis of asthma.

METHODSData Source and Study Design

We conducted a retrospective, multicentercohort study using data from the PediatricHealth Information System (PHIS), anadministrative database that containsinpatient data from .40 pediatric hospitalsin the United States. Detailed hospitalizationand resource utilization data, such asdemographic, diagnostic, procedural,outcome, and charge information, arecontained in PHIS. Data are deidentified;however, encrypted medical recordnumbers permit tracking of patients withinhospitals across hospitalizations. TheChildren’s Hospital Association andparticipating hospitals jointly ensure dataquality as previously described.10 This study,using deidentified data, was consideredexempt according to the policies of theCincinnati Children’s Hospital MedicalCenter Institutional Review Board.

Study Cohort

We created a cohort of patients withuncomplicated CAP and CAP1asthma for

which the pneumonia guidelines wouldapply.4 We used a previously validatedalgorithm for identifying hospitalizedpatients with CAP from PHIS.11 Patients aged.3 months and ,18 years between July 1,2007, and June 30, 2012, with principal orsecondary diagnosis InternationalClassification of Diseases, Ninth Revision,Clinical Modification diagnosis codes ofpneumonia were eligible. We excludedpatients who were unlikely to havea diagnosis of uncomplicated CAP using thefollowing criteria: (1) receipt of antibioticsnot typically used for CAP on day 0, 1, or 212;(2) no charge for antibiotics on the firsthospital day; (3) an InternationalClassification of Diseases code for viralpneumonia; (4) complex chronic condition13;(5) age ,2 years (to avoid misclassificationwith bronchiolitis); (6) a charge for a chestcomputed tomography, ultrasound, ordecubitus films on the first hospital day (toexclude complicated pneumonia onpresentation); (7) a charge forhyperalimentation on the first hospital day;or (8) a charge for extracorporealmembrane oxygenation on the first hospitalday. Three clinicians reviewed all additionaldiagnoses and procedures and excludedpatients with diagnoses or proceduressuggesting a low likelihood of CAP (eg,motor vehicle traffic accident). To betterensure patients with a typical presentationof CAP, we excluded hospitalizations forwhich total costs were beyond the lowestand highest fifth percentile within eachhospital.1 For patients with multipleadmissions meeting the inclusion criteria,we selected the first hospitalization.

Exposure Measure

The main exposure was meeting inclusioncriteria for CAP and a codiagnosis of acuteasthma (CAP1asthma). Patients wereconsidered to have CAP1asthma if they hadany diagnosis code of asthma and a chargefor a short-acting bronchodilator use afterhospital day 1. Because 35% of childrenadmitted with a diagnosis of CAP in 1 largecohort had received corticosteroids14 andthis was more common in patients in theICU, we did not include steroid use asa specific marker for asthma to avoidconfounding by severity. Patients in theCAP1asthma exposure group were

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compared with the clinical group who hadCAP without acute asthma.

Covariables

Categorized age (,5, 5–11, $12 years),gender, race (white, black, Asian, other);insurance (government, nongovernment);geographic region (Midwest, Northeast,South, West), mean number of hospitalbeds, and ICU stay (yes/no) were included inthe analyses.

Outcome Measures

Measured outcomes were length of stay(LOS), total standardized cost, andguideline adherence. LOS in days wasmeasured as a continuous variable. Totalstandardized cost in US dollars wascalculated using a Cost Master Index (CMI)previously developed for research utilizingdata from PHIS hospitals.1 Briefly,standardized costs for an entire patienthospitalization are calculated by firstmultiplying the billed units of each item byits standardized per unit cost and thensumming these itemized costs, resulting ina total standardized hospital bill.15 Allstandardized costs were inflated to 2012dollars by using the medical care services

component of the Consumer Price Index. Ofthe 42 hospitals contained in the PHISdatabase, 2 were excluded from cost andLOS analyses due to missing data.

Adherence to the Pediatric InfectiousDiseases Society and the Infectious DiseasesSociety of America clinical guidelines for themanagement of children with pneumonia3

was the final outcome. The followingguidelines were assessed, based onavailability in the PHIS dataset: receipt ofchest radiograph (recommended), bloodculture (recommended), respiratory viralpanel testing (recommended), Mycoplasmapneumoniae testing when macrolide wasordered (recommended), complete bloodcount testing (not recommended), andChlamydophila pneumoniae testing (notrecommended). We considered all availablerecommendations regardless of strength ofevidence. Adherence to guidelines on theindividual level was depicted as a rate(number of guidelines followed/totalguidelines measured). Adherence toguidelines at the hospital-level was depictedas the mean number of guidelines followedper patient with CAP admitted to thatparticular hospital.

Statistical Analysis

We described variation in the totalstandardized costs within hospital using thegeometric mean and range. Bivariabledifferences between the exposure groupswere tested using x2 and Wilcoxon rank-sum tests for individual-levelcharacteristics. We used Cochran-Mantel-Haenszel statistics to test differences indemographic and clinical coursecharacteristics between the 2 clinicalgroups when stratified by hospital, and log-rank tests were used for stratified tests toevaluate differences between clinicalgroups for continuous but skewedcharacteristics accounting for hospital.Analysis of variance was used to testbivariable differences for hospital-levelvariables (region and number of beds).

We modeled cost and LOS with a log g

model with patient-level factors ascovariates and accounting for clustering ofpatients by hospital. These modelsdecomposed the effects of the covariatesinto within-hospital and between hospitalcomponents to rule out possibleconfounding by hospital in theseassociations of interest.16,17 This

FIGURE 1 Cohort selection flow diagram. CT, computed tomography; ECMO, extracorporeal membrane oxygenation;

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decomposition permits 2 comparisons ofinterest: (1) the effects of the risk factor onoutcome when applied to otherwise similarchildren within a hospital (eg, do 2 similarpatients at the same hospital have differentoutcomes depending on guideline

adherence in their management) and (2)the effects when moving from a hospitalwith 1 average level of a risk factor toa hospital with a different average level ofthe same factor (eg, do similar patientsadmitted to 2 hospitals with varying average

guideline adherence across their patientpopulations have different outcomes).18

Results from this decomposed model of thewithin hospital comparison were thenconfirmed with models in which hospitalwas a fixed effect. We also evaluated the

TABLE 1 Bivariable Comparison of Characteristics Between Clinical Groups

Characteristics Overall (n 5 25 124) Range AmongHospitals (n 5 42) (%)

CAP (n 5 14 390) CAP1acuteasthma (n 5 10 734)

P a P b

Age, y (median, SD) 5.0 (3.6) 4.0 (3.7) 5.0 (3.4) ,.0001

Age, y ,.0001 ,.001

,5 12 490 (49.7) 39.8–68.9 7478 (52.0) 5012 (46.7)

5–11 10 463 (41.7) 25.4–50.0 5566 (38.9) 4897 (45.6)

$12 2171 (8.6) 5.4–14.7 1346 (9.4) 825 (7.7)

Female 12 051 (48.0) 40.0–54.9 7136 (49.6) 4915 (45.8) ,.0001 ,.001

Principal payer, governmentc 10 514 (41.9) 6.5–67.0 5639 (39.2) 4875 (45.4) ,.0001 ,.001

ICU stay 1936 (7.7) 1.4–27.9 519 (3.6) 1417 (13.2) ,.0001 ,.001

Race (n 5 24 231) ,.0001 ,.001

White 13 200 (54.5) 9.5–99.0 8670 (62.5) 4530 (43.7)

Black 6630 (27.4) 1.7–71.4 2696 (19.5) 3934 (37.9)

Asian 718 (3.0) 0.2–34.8 498 (3.6) 220 (2.1)

Other 3683 (15.2) 0.9–70.1 2000 (14.4) 1683 (16.2)

Region ,.0001 N/A

Midwest 7306 (29.1) 4046 (28.1) 3260 (30.4)

Northeast 2683 (10.7) 1357 (9.4) 1326 (12.4)

South 9620 (38.3) 5882 (40.9) 3738 (34.8)

West 5515 (21.9) 3105 (21.6) 2410 (22.5)

Number of beds ,.0001 N/A

#200 beds 3191 (12.7) 1695 (11.9) 1496 (13.9)

201–300 beds 8220 (32.7) 4730 (32.9) 3490 (32.5)

301–400 beds 6621 (26.4) 4037 (28.1) 2584 (24.1)

.400 beds 7092 (28.2) 3928 (27.3) 3164 (29.5)

Metrics

% with chest radiograph 20 973 (83.5) 50.0–94.1 11 906 (82.7) 9067 (84.5) .0003 .002

% with blood culture 12 829 (51.1) 27.3–83.3 8931 (62.1) 3898 (36.3) ,.0001 ,.0001

% without CBC 9170 (36.5) 6.1–62.6 3957 (27.5) 5213 (48.6) ,.0001 ,.0001

% with respiratory viral panel testing 7935 (31.6) 8.6–87.9 4477 (31.1) 3458 (32.2) .06 .17

% with macrolide withmycoplasma testing

1693 (6.7) 0.4–55.0 992 (6.9) 701 (6.5) .26 .18

% without Chlamydophilapneumonia testing

25 087 (99.9) 99.42–100.0 14 362 (99.8) 10 725 (99.9) .02 .03

LOS, d geometric mean (range), dd 2.0 1.3–2.6 1.9 (1.2–2.5) 2.1 (1.5–2.8) ,.0001 ,.0001

ICU LOS, geometric mean (range), de 1.6 1.0–2.3 1.6 (1.0–2.3) 1.6 (1.0–2.8) .28 ,.0001

Total standardized cost,geometric mean (range), US$d

4830.4 3291.5–6547.3 4519.3 (3024.9–6477.4) 5269.7 (3418.2–7474.5) ,.0001 ,.0001

CBC, complete blood count.a x2 and Wilcoxon rank-sum test used to test individual-level variables; analysis of variance used to test hospital-level variables (region and number of beds).b Controlling for hospital: Cochran-Mantel-Haenszel statistics used for categorical variables; log-rank test used for continuous variables.c Defined as Charity, In-State Medicaid (managed care), In-State Medicaid (other), Medicare, Other Government, Out-of-State Medicaid (all), TRICARE.d LOS and total cost data missing for 2 hospitals (n 5 1181).e Patients with an ICU stay, n 5 1936.

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effect of codiagnosis on cost and LOSwithin hospitals by hospital, by comparingthe likelihood ratios from 2 models. Thefirst was the same model as describedearlier, with hospital as a fixed effect. Thesecond included an interaction termbetween hospital and clinical group (CAPor CAP1asthma). A likelihood ratio testwas performed to examine cost and LOS byhospital. Data were analyzed using SASv9.3.

Finally, we investigated the relativecontribution to interhospital variance instandardized costs attributable to CAP andCAP1asthma using a mixed effects modelwith separate hospital-level randomintercepts for the 2 groups. We comparedthese 2 variance components with totalvariance (including the residual, within-hospital component), using Stata version 13.Because log g models for this questionwould not converge, we opted for identitylink models for this estimation.

RESULTSPatient and Hospital Characteristics

Of the 112 441 admissions eligible for studyinclusion, 25 124 with CAP remained afterapplying exclusion criteria (Fig 1); of these,43% had an additional diagnosis of andtreatment of acute asthma.

The median age was 5.0 years (Table 1). Thedistribution of age group, insurance, ICUstay, and race varied widely acrosshospitals. When comparing the 2 clinical

groups, patients hospitalized with CAP1asthma had a greater median age and weremore likely to be male, to be black or“other” race/ethnicity, and to havegovernment insurance than those with CAPonly. Because patient characteristics areknown to differ by hospital, we compareddemographic and clinical coursecharacteristics between the 2 clinicalgroups adjusting for hospital. The differencein the number of ICU days by clinical groupreached statistical significance whenaccounting for hospital; other results weresimilar to the unadjusted results (Table 1).Patients with CAP1asthma were more likelyto have received a macrolide antibiotic thanthose with CAP alone (59% vs 37%; P, .001)and to have received corticosteroids (87%vs 12%; P , .001).

Resource Utilization

Standardized cost varied between hospitals,from $3292 to $6547, with an overallgeometric mean of $4830. Figure 2 displaysthe cost distribution by hospital and clinicalgroup. Thirty-eight of the 40 hospitals hadhigher costs for the CAP1asthma patientscompared with CAP alone. CAP1asthmapatients had higher geometric mean costcompared with CAP alone ($5270 vs $4519)(Table 1). Multivariable analysis of totalstandardized cost within hospitals indicatedthat CAP1asthma patients were morecostly compared with CAP alone (Table 2).We estimated cost variances not explainedby patient-level factors between patients

with CAP compared with those with CAP1asthma, and found that unexplainedinterhospital variation as a percentage oftotal variation in costs was 7.6% for CAPand 12.3% for CAP1asthma. The likelihoodratio test for within hospital cost wasstatistically significant, suggesting thatthere was some variation in totalstandardized cost between CAP1asthmaand CAP only patients across hospitals.However, the data suggest that for the vastmajority of hospitals, cost is higher amongCAP1asthma patients.

The overall geometric mean for LOS was2.01, with a range of 1.3 to 2.6 betweenhospitals. For ICU days, the overall meanwas 1.63 with a range between hospitalsfrom 1.0 to 2.3 (Table 1). Figure 3 shows thedistribution of LOS by clinical group andhospital. Although 7 of 40 hospitals hadlonger LOS for CAP alone, the majority hadlonger LOS for CAP1asthma. Patients withCAP1asthma had longer LOS (2.1 vs 1.9);however, ICU LOS was similar (1.6 vs 1.6,P 5 .28). Multivariable analysis indicatedthat patients with CAP1asthma had a 6%longer LOS compared with CAP patientswithout acute asthma (Table 2). Thelikelihood ratio test for within hospital LOSwas statistically significant, suggesting thatthere was some variation in LOS betweenCAP1asthma and CAP-only patients acrosshospitals. For the majority of hospitals, LOSwas longer for CAP1asthma compared withCAP only patients.

FIGURE 2 Distribution of total standardized cost by clinical group and hospital (n 5 40).

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Guideline Adherence

When comparing the 2 clinical groups at thepatient level, .80% of patients in bothgroups received chest radiographs(Table 1). CAP1asthma patients were lesslikely to have a blood culture performed(36% vs 62%) and more often did not havea CBC performed (49% vs 27%). Fewpatients in either group receiveda macrolide with M pneumoniae testing(close to 7% in each group), and fewpatients in either group had C pneumoniae

testing. Approximately 30% in each groupreceived respiratory viral panel testing.Across hospitals, the range of the percent ofguideline adherence was wide for all of theguidelines except testing for M pneumoniaeand C pneumoniae. At the patient-level,greater guideline adherence was associatedwith higher cost. However, contrastingadherence across hospitals, greaterhospital-level guideline adherence wasassociated with lower average cost perhospitalization (Table 2).

DISCUSSION

We found a high percentage of cases ofpneumonia that had a codiagnosis of andtreatment for asthma exacerbation;although we used an algorithm foridentifying CAP that has been validated withchart review and radiology data, thepresence of an infiltrate on a chest x-raymay not always represent pneumonia butmay in fact be atelectasis in a case ofprimary asthma. In addition, we may beoveridentifying cases of asthma in whichalbuterol is being used inappropriately.Regardless of whether these cases aremisdiagnoses or are truly patients withpneumonia and asthma, this studydemonstrated the challenge of measuringguideline adherence in the face ofcodiagnoses and diagnostic uncertainty,particularly in the management of common,acute pulmonary processes in children. Inthis cohort of patients admitted to 42children’s hospitals, codiagnosis resulted inbroader variation in management andhigher cost. These results also highlight thecomplexity of implementing guidelineswhere there is true codiagnosis ordiagnostic uncertainty in carefullyidentifying the appropriate targetpopulation for guideline development andmanagement so that when comparingoutcomes, hospitals are using the clinicalgroups of patients.

Overall, CAP1asthma patients within thesame hospital had higher costs and longerLOS than those with CAP alone. There wassignificant variability in cost and LOS amongthe hospitals for both CAP and CAP1asthma. Although having a second diagnosismay inherently increase overall cost,a secondary diagnosis of asthma alsoincreased observed variation in costsacross hospitals, suggesting that theaddition of the second diagnosis mayincrease uncertainty. This could bediagnostic uncertainty, managementuncertainty, or both.

Inappropriate diagnosis with a seconddisease process could result in overuse ormisuse of nonrecommended care, andtherefore higher costs. Increasing diagnosticprecision and standardizing treatment ofcodiagnoses such as CAP1asthma may

TABLE 2 Multivariable Regression Results for Total Standardized Cost and LOS

95% CI P

Total Standardized Cost (n 5 22 853)a Relative Cost per UnitChange in Variable

Across hospital contrast of effect of diagnosis oncosts per 10% increase in the proportion ofCAP1acute asthma patientsb

0.650 0.439–0.962 .03

The difference between CAP-only vs CAP1acuteasthma groups within each hospitalc

1.118 1.083–1.155 ,.0001

LOS (n 5 22 853)d Relative LOS per UnitChange in Variable

Across-hospital contrast of effect of diagnosis onLOS per 10% increase in proportion of CAP1acute asthma patients

0.953 0.585–1.553 .85

The difference between CAP-only vs CAP1acuteasthma groups within each hospitale

1.056 1.012–1.101 .01

Total Standardized Costs and Guideline Adherence(n 5 23 054)f,g

Relative Cost per UnitChange in Variable

Number of guidelines adhered to

1–2 Reference

3–4 1.201 1.152–1.252 ,.0001

5 1.407 1.308–1.513 ,.0001

Mean no. of guidelines to which hospital adheredfor CAP1acute asthma patients

0.823 0.683–0.991 .04

Mean no. of guidelines to which hospital adheredfor CAP-only patients

0.844 0.710–1.003 .05

Proportion of patients who have CAP1acuteasthma

1.166 0.733–1.857 .52

Sample sizes do not add up to 25 124 due to missing data (see Table 1). Estimates are from a log-g model.a Adjusted for gender, insurance, age group, race, ICU stay, mean number of hospitals beds, and mean LOS.b A relative cost of 0.650 means that across hospitals, a 10% increase in CAP1acute asthma patients isassociated with a 35% relative decrease in total standardized cost when controlling for the othervariables in the model.

c A relative cost of 1.118 means that within hospitals there is a 11.8% relative increase in cost among CAP1acuteasthma patients compared with CAP-only patients when controlling for the other variables in the model.

d Adjusted for gender, insurance, age group, race, proportion of blacks at the hospital, and ICU stay.e There is a 5.6% relative increase in LOS among CAP1acute asthma patients compared with CAP onlypatients when controlling for the other variables in the model.

f Adjusted for gender, insurance, age group, race, ICU stay, and mean number of hospital beds.g Controlling for other factors in the model, when 3–4 vs 1–2 guidelines are adhered to, there is a relativeincrease in total standardized cost of ∼20%. When 5 guidelines vs 1–2 guidelines are adhered to, thereis a 40% relative increase in cost. As the mean number of guidelines adhered to at a hospital increases,the relative cost of CAP1acute asthma patients decreases by ∼18%; for CAP-only patients, the relativetotal standardized cost decreases 16%.

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help to decrease interhospital variability incost. In particular, adhering to therecommendation not to get a chestradiograph in children admitted withclinical asthma exacerbations mightsignificantly decrease the overall cost andvariation in care. The mean LOS for CAP1asthma of 2.1 days was longer than thatreported in another PHIS study fornoncomplex asthma alone (1.8 days),19 alsosupporting the idea that the additionaldiagnosis adds complexity. Future studiesexamining the impact of a pneumoniadiagnosis on variation in care for asthmaexacerbations may provide corollaryinformation.

Overall, hospitals that had greateradherence to the CAP guidelines acrosstheir patient population had lower theoverall costs for CAP and CAP1asthma,suggesting that although some guidelinesmay be applied inappropriately, especiallyfor CAP1asthma, standardization of carehas some association with lower costs ofcare. Because adherence to guidelines forboth CAP and asthma are being used asquality metrics in some institutions, it maybe helpful to use these as metrics forpatients only when a codiagnosis is notpresent.

Studies using administrative data areinherently limited by the quality of the dataprovided by the hospitals, and there are

many potential explanatory variables thatare not available to us in PHIS. AlthoughPHIS has excellent quality control standards,its data are not routinely validated withchart review. We used an algorithm fordiagnosing CAP that has been validated withchart review,11 but it is nonetheless possiblethat there was misclassification for both theCAP and asthma diagnoses. In addition, weused antibiotic choice to select out cases ofCAP, which meant that we could not includeantibiotic selection in our analysis ofguideline adherence. Our definition of acuteasthma exacerbation may cause us tounderestimate such cases. We did notinclude corticosteroid administration in ourdefinition because corticosteroids,particularly at some hospitals, may beadministered to children with CAP.14 Thisapproach would bias the results to the nullhypothesis. We also had a significantnumber of exclusions to create our finalcohort; some of these may have biased ourdata. Although the pneumonia guidelineshave recommendations related toM pneumoniae and C pneumoniae testing,the lack of timely availability of results forthese tests at many institutions is likely tobe an important barrier to their use. Thedata are retrospective, and thus we cannotassume causation. Because we limited ouranalyses to children .2 years of age, thismay have increased the potential forasthma codiagnoses. Finally, our data may

not be generalizable outside of freestandingchildren’s hospitals.

CONCLUSIONS

A codiagnosis of acute asthma is commonfor children with CAP, adding a layer oftreatment complexity that may increaseresource utilization and LOS, regardless ofwhether there is diagnosticmisclassification or whether there are truly2 disease processes. There is still a highdegree of uncertainty surrounding the mosteffective and efficient way to treat CAP1asthma, and the appropriateness of existingguidelines to address the co-occurrence ofthese conditions. Clinicians should be clearabout which diagnosis they are treating,which guideline should be applied when theclinician is unsure, or whether 2 diagnosesare clearly present. Patients with 2diagnoses deserve to have both diagnosestreated according to evidence-basedprotocols. In the interim, hospitals canexamine their practice patterns for CAP1asthma and if they are outliers, work tostandardize and streamline care. As weincreasingly rely on guidelines for the careof children hospitalized with commondiseases, it is important to remember thatthey often have .1 diagnosis, and theseguidelines should incorporate evidenceabout common co-occurring conditions aswell as provide recommendations on theirtreatment.

FIGURE 3 Distribution of length of stay by clinical group and hospital (n 5 s40).

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Research in Inpatient Settings (PRIS) NetworkSrivastava, Xianqun Luan, Zeinab Mohamad, Samir S. Shah and for the Pediatric

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