Hospitalizations Associated with Disseminated Coccidioidomycosis, Arizona and California, USA - Vol. 18 No. 9 - September 2012 - Emerging Infectious Disease journal - CDC
Volume 18, Number 9—September 2012
Hospitalizations Associated with Disseminated Coccidioidomycosis, Arizona and California, USA
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We analyzed hospitalization databases from Arizona and California for disseminated coccidioidomycosis–associated hospitalizations among immunocompetent persons. Racial/ethnic disease ratios were characterized by a higher incidence of hospitalization among blacks compared with other groups. This finding suggests that HIV infection, AIDS, and primary immune conditions are not a major factor in this disparity.
Coccidioidomycosis is a fungal infection caused by inhalation of Coccidioides immitis or C. posadasii spores (1,2). Most (≈60%) persons infected with Coccidioides spp. are asymptomatic (3), but symptomatic primary pulmonary coccidioidomycosis develops in ≈40% (4). An estimated 1% of all infections, asymptomatic and symptomatic, progress to extrathoracic disseminated coccidioidomycosis infection (3,4), which is more common among persons with underlying immune conditions, such as advanced HIV/AIDS. Although disseminated coccidioidomycosis is most often found in immunocompromised persons, it can also occur among persons without known predisposing conditions (5). The epidemiologic association between ethnicity and disseminated coccidioidomycosis within disease-endemic regions has been described (6,7) but not specifically among persons with disseminated coccidioidomycosis without HIV/AIDS or primary immune deficiencies. In the United States, coccidioidomycosis is predominantly localized to specific areas of southern California and Arizona (8). We focused our analyses of racial/ethnicy disease ratios on these regions.
We used the Arizona and California State Inpatient Databases (SID) from the US Agency for Healthcare Research and Quality (AHRQ) to describe clinical and demographic characteristics of persons hospitalized for disseminated coccidioidomycosis who did not have known primary immune conditions, HIV infection, or AIDS. The SID contains state-level data, including information from 90% of community hospital in-patient stays, and is maintained as part of the Healthcare Utilization Project at AHRQ. We extracted records from the available annual datasets for Arizona (2000–2009) and California (2003–2008) that listed any diagnosis of disseminated coccidioidomycosis (code 114.3 from the International Classification of Diseases, 9th Revision, Clinical Modification [ICD-9-CM]). We excluded records that listed any diagnosis of HIV infection or AIDS (ICD-9-CM code 042) or primary immune deficiency (ICD-9-CM code 279.xx). This study was not considered human subject research by the National Institutes of Health Office of Human Subjects Protection.
We calculated the average annual incidence of hospitalizations as the average annual number of disseminated coccidioidomycosis hospitalizations divided by the midyear population, as determined by US Census estimates (9). By using the revisit files available from AHRQ, we assessed differences in readmissions by race by comparing the proportion of persons with only 1 disseminated coccidioidomycosis infection among race groups. We also calculated all-cause hospitalization rates for blacks and whites in our dataset by using total hospitalizations from HCUPnet (http://hcupnet.ahrq.gov). In years for which patient state of residency was available, we assessed the potential bias from hospitalizations of persons with out-of-state residency by determining the percentage of total admissions from out-of-state patients. We used the Mann-Whitney test for nonparametric comparisons; the significance level used for all statistical tests was α = 0.05. All analyses were completed in SAS version 9.2 software (SAS Institute, Cary, NC, USA).