TY - JOUR
T1 - Influence of referral bias on the clinical characteristics of patients with Gram-negative bloodstream infection
AU - Al-Hasan, M. N.
AU - Eckel-Passow, J. E.
AU - Baddour, L. M.
PY - 2011/11
Y1 - 2011/11
N2 - Referral bias can influence the results of studies performed at tertiary-care centres. In this study, we evaluated demographic and microbiological factors that influenced referral of patients with Gram-negative bloodstream infection (BSI). We identified 2919 and 846 unique patients with Gram-negative BSI in a referral cohort of patients treated at Mayo Clinic Hospitals and a population-based cohort of Olmsted County, Minnesota, residents between 1 January 1998 and 31 December 2007, respectively. Multivariable logistic regression analysis was used to determine factors associated with referral. Elderly patients aged ≥80 years with Gram-negative BSI were less likely to be referred than younger patients [odds ratio (OR) 0·43, 95% confidence intervals (CI) 0·30 - 0·62] as were females (OR 0·63, 95% CI 0·53 - 0·74). After adjusting for age and gender, bloodstream isolates of Escherichia coli (OR 0·50, 95% CI 0·43 - 0·58) and Proteus mirabilis (OR 0·49, 95% CI 0·30 - 0·82) were underrepresented in the referral cohort; and Pseudomonas aeruginosa (OR 2·26, 95% CI 1·70 - 3·06), Enterobacter cloacae (OR 2·31, 95% CI 1·53 - 3·66), Serratia marcescens (OR 2·34, 95% CI 1·33 - 4·52) and Stenotrophomonas maltophilia (OR 17·94, 95% CI 3·98 - 314·43) were overrepresented in the referral cohort. We demonstrated that demographic and microbiological characteristics of patients with Gram-negative BSI had an influence on referral patterns. These factors should be considered when interpreting results of investigations performed at tertiary-care centres.
AB - Referral bias can influence the results of studies performed at tertiary-care centres. In this study, we evaluated demographic and microbiological factors that influenced referral of patients with Gram-negative bloodstream infection (BSI). We identified 2919 and 846 unique patients with Gram-negative BSI in a referral cohort of patients treated at Mayo Clinic Hospitals and a population-based cohort of Olmsted County, Minnesota, residents between 1 January 1998 and 31 December 2007, respectively. Multivariable logistic regression analysis was used to determine factors associated with referral. Elderly patients aged ≥80 years with Gram-negative BSI were less likely to be referred than younger patients [odds ratio (OR) 0·43, 95% confidence intervals (CI) 0·30 - 0·62] as were females (OR 0·63, 95% CI 0·53 - 0·74). After adjusting for age and gender, bloodstream isolates of Escherichia coli (OR 0·50, 95% CI 0·43 - 0·58) and Proteus mirabilis (OR 0·49, 95% CI 0·30 - 0·82) were underrepresented in the referral cohort; and Pseudomonas aeruginosa (OR 2·26, 95% CI 1·70 - 3·06), Enterobacter cloacae (OR 2·31, 95% CI 1·53 - 3·66), Serratia marcescens (OR 2·34, 95% CI 1·33 - 4·52) and Stenotrophomonas maltophilia (OR 17·94, 95% CI 3·98 - 314·43) were overrepresented in the referral cohort. We demonstrated that demographic and microbiological characteristics of patients with Gram-negative BSI had an influence on referral patterns. These factors should be considered when interpreting results of investigations performed at tertiary-care centres.
KW - Bacteraemia
KW - Gram-negative
KW - Rochester Epidemiology Project
KW - epidemiology
KW - population-based
KW - selection bias
UR - http://www.scopus.com/inward/record.url?scp=80053567510&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=80053567510&partnerID=8YFLogxK
U2 - 10.1017/S095026881100001X
DO - 10.1017/S095026881100001X
M3 - Article
C2 - 21281552
AN - SCOPUS:80053567510
SN - 0950-2688
VL - 139
SP - 1750
EP - 1756
JO - Epidemiology and Infection
JF - Epidemiology and Infection
IS - 11
ER -