predictors of early hospital readmission for asthma among inner-city children

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  • Journal of Asthma, 43:3740, 2006Copyright C 2006 Taylor & Francis Group, LLCISSN: 0277-0903 print / 1532-4303 onlineDOI: 10.1080/02770900500446997


    Predictors of Early Hospital Readmission for Asthma AmongInner-City Children


    1Childrens Hospital at Montefiore, Department of Pediatrics, Albert Einstein College of Medicine, Bronx, New York, USA2Albert Einstein College of Medicine, Department of Epidemiology and Population Health, Bronx, New York, USA

    Factors associated with early asthma readmission have not been fully studied. To identify predictors of early readmission, we performed a matchedcase-control study of children discharged with primary diagnosis of asthma. Cases were readmitted with asthma within 30 days of discharge. Controlswere not readmitted. Conditional logistic regression analysis was used. History of asthma hospitalization within the past 12 months was an independentpredictor of early readmission (OR 1.89, p = 0.021). Modifiable factors such as medical treatment and management during and upon discharge fromthe index admission did not predict early asthma readmission.

    Keywords asthma, modifiable predictors, early readmission, inner-city, children

    INTRODUCTIONAsthma is one of the most frequent causes of hospital ad-

    missions among children (1). It accounts for almost 200,000childhood hospitalizations per year (2) and 1.6 billion dol-lars in annual medical costs for children in the United States(3). Asthma readmissions contribute substantially to this bur-den. Children residing in New York City have the highest ratesin the nation for hospitalization related to asthma, and theBronx, in particular, has the highest rates of asthma-relatedhospitalization and death (4).

    Twenty to fifty percent of children hospitalized for asthmawill be readmitted with the same diagnosis within the fol-lowing year (58). This late readmission has been related todemographic factors (7, 9), asthma severity at index admis-sion (9), and a history of previous hospitalizations for asthma(7). A number of children discharged with asthma will bereadmitted early, within 30 days of discharge. Factors associ-ated with early asthma readmission have not been fully stud-ied. Identifying these factors, especially if they are amendableto change, would allow physicians to recognize patients atrisk for early readmission and enhance their asthma manage-ment. Thus, the aim of this study was to identify modifiablepredictors of early readmission in inner-city children withasthma at one childrens hospital.

    METHODSDesign and Setting

    We conducted a matched case-control study of a cohortof children hospitalized for asthma at the Childrens Hos-pital at Montefiore (CHAM), Bronx, New York, between

    Presented in part at the Eastern Society for Pediatric Research AnnualMeeting, Old Greenwich, Connecticut, USA, March 2005 and PediatricAcademic Societies Annual Meeting, Washington, DC, USA, May 2005.

    Corresponding author: Philip O. Ozuah, M.D., Ph.D., ChildrensHospital at Montefiore, 3415 Bainbridge Avenue, Bronx, NY 10467;E-mail:

    January 1998 and December 2004, where the prevalence ofearly asthma readmission is three to four percent. Cases weredefined as children hospitalized with asthma exacerbationand readmitted with the same diagnosis within 30 days ofdischarge from the index admission. Controls were childrenhospitalized for asthma but not readmitted within 30 days ofdischarge. Index admission was defined as the subjects firsthospitalization for asthma during the study period.

    SubjectsWe used computerized health records to identify all pedi-

    atric patients (021 years of age) discharged with a primarydiagnosis of asthma (International Classification of Diseases,Ninth Revision, ICD-9 493.0) during the study period. Theelectronic records allowed us to retrieve data on subjectsgender, race, date of birth, medical record number, dischargedate of the index admission, and occurrence of asthma read-mission within a 30-day period. If a case had more than oneearly readmission during the study period, the first readmis-sion within 30 days of discharge from the index admissionwas selected; thus, each observation in the data representedan individual child.

    Of those children discharged with a primary diagnosis ofasthma during the study period (n = 5, 104), 173 subjectsmet the eligibility criteria for early readmission and wereidentified as cases. Of these, medical charts were unavailablefor 7 cases, and 14 cases had more than one early readmissionduring the study period and were excluded. Analysis included152 cases that were eligible for study entry.

    We selected up to two controls from the cohort of remain-ing 4,931 children discharged from CHAM with a primarydiagnosis of asthma but not readmitted within 30 days of in-dex admission. We identified 293 controls to match to our 152cases. Cases and controls were matched on age (2 years),gender, race, season, and year of index admission. Season wasdefined as winter (December, January, and February), spring(March, April, and May), summer (June, July, and August)


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  • 38 M. REZNIK ET AL.

    and fall (September, October, and November). If more thantwo matched controls were identified per case, controls withthe discharge date of the index admission closest to that of thecase were chosen. The institutional review board at Monte-fiore Medical Center, Bronx, New York, approved this study.

    Data CollectionOne of the authors (M.R.) performed medical chart reviews

    to abstract clinical and demographic data. Written recordsfrom the Emergency Department (ED), index hospital ad-mission, and discharge were also used. The variables of in-terest were chosen on the basis of literature review (510).Information was collected in the following four categories:demographics, variables related to past asthma history, vari-ables related to the index admission, and variables related todischarge from the index admission.

    Demographic data, including age at index admission, gen-der, race, and medical insurance (Medicaid-recipients, otherinsurance, or no insurance) were collected. Variables relatedto past asthma history included a history of asthma-relatedED visits and admissions to the hospital in the past 12 months,a prior history of an intensive care unit (ICU) admission forasthma, being premature at birth, prescription of inhaled cor-ticosteroids (ICS) before the index admission as per parentalreport of medications taken at home, and exposure to envi-ronmental triggers such as roaches and tobacco smoke.

    Variables related to the index admission included oxy-gen saturation level on presentation to the ED as mea-sured by pulse oximetry, length of hospital stay (LOS) indays, therapeutic management of asthma, including sub-cutaneous injection of epinephrine or intravenous (IV) in-jection of magnesium sulfate, and number and frequencyof aerosolized beta-agonist treatments, oxygen requirementduring the index admission, and receipt of a pulmonaryconsultation as initiated by the hospital physicians or sub-jects primary medical doctor (PMD). Variables related todischarge from the index admission included last recordedoxygen saturation level in the medical chart before dis-charge, presence of wheezing, and prescription of ICS as re-ported in the physicians discharge note and nurses dischargeinstructions.

    Statistical AnalysisData were maintained in SPSS version 11.5 (SPSS Inc,

    Chicago, IL) and STATA version 8.2 (STATA, College Sta-tion, TX) statistical softwares. Chi-square tests were per-formed to test for differences in categorical matching char-acteristics. For continuous variables, we used generalizedestimating equations (GEE) statistics to test for differ-ences in matched characteristics. GEE are methods of pa-rameter estimation well suited for the analysis of corre-lated data, as is the case in matched case-control studies(11, 12).

    We performed conditional logistic regression analyses formatched data to test for the association of independent vari-ables with early readmission status. Regression analyses fol-lowed model building strategies suggested by Hosmer andLemeshow (13). Univariate analysis was performed for eachvariable under consideration. Variables with a p value


    TABLE 1.Odds ratios for individual predictors of early asthma readmission.

    Predictors OR ( 95% CI) P value

    Hospital admission in the past 12 months 2.22 (1.403.50) 0.001ED visit in the past 12 months 3.28 (1.556.94) 0.002Prior ICU admission 2.18 (1.263.78) 0.005Pulmonary consultation during index admission 1.87 (1.123.10) 0.016Prescription of ICS before index admission 1.61 (1.022.52) 0.039Prematurity at birth 1.72 (.853.47) 0.129LOS 1.08 (.971.21) 0.221Roaches at home 1.36 (.852.17) 0.195Cigarette exposure at home 0.81 (.541.21) 0.306Receipt of subcutaneous epinephrine or IV

    magnesium sulfate on index admission1.49 (.852.60) 0.162

    Prescription of ICS on discharge 1.35 (.852.14) 0.200Presence of wheezing on discharge 0.98 (.641.51) 0.942Oxygen saturation on presentation for the index

    admission0.99 (.931.05) 0.727

    Oxygen saturation on discharge 1.00 (.871.15) 0.917Oxygen requirement during index admission 1.06 (.671.66) 0.816

    OR, odds ratio; CI, confidence interval; ED, Emergency Department; ICU, intensive careunit; ICS, inhaled corticosteroids; LOS, length of hospit


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