Biomedical subjects

Anthony D Harris

Publications and source records attributed to Anthony D Harris.

At least 19 recordsLinked to original sources

PubMed2006

Fatigue increases the risk of injury from sharp devices in medical trainees: results from a case-crossover study.

BACKGROUND: Extreme fatigue in medical trainees likely compromises patient safety, but regulations that limit trainee work hours have been controversial. It is not known whether extreme fatigue compromises trainee safety in the healthcare workplace, but evidence of such a relationship would inform the current debate on trainee work practices. Our objective was to evaluate the relationship between fatigue and workplace injury risk among medical trainees and nontrainee healthcare workers. DESIGN: Case-crossover study. SETTING: Five academic medical centers in the United States and Canada. PARTICIPANTS: Healthcare workers reporting to employee healthcare clinics for evaluation of needlestick injuries and other injuries related to sharp instruments and devices (sharps injuries). Consenting workers completed a structured interview about work patterns, time at risk of injury, and frequency of fatigue. RESULTS: Of 350 interviewed subjects, 109 (31%) were medical trainees. Trainees worked more hours per week (P<.001) and slept less the night before an injury (P<.001) than did other healthcare workers. Fatigue increased injury risk in the study population as a whole (incidence rate ratio [IRR], 1.40 [95% confidence interval {CI}, 1.03-1.90]), but this effect was limited to medical trainees (IRR, 2.94 [95% CI, 1.71-5.07]) and was absent for other healthcare workers (IRR, 0.97 [95% CI, 0.66-1.42]) (P=.001).Conclusions. Long work hours and sleep deprivation among medical trainees result in fatigue, which is associated with a 3-fold increase in the risk of sharps injury. Efforts to reduce trainee work hours may result in reduced risk of sharps-related injuries among this group.

Academic Medical Centers↗

PubMed2006

Impact of empiric antibiotic therapy on outcomes in patients with Pseudomonas aeruginosa bacteremia.

The impact of appropriate empirical antimicrobial therapy for Pseudomonas aeruginosa bacteremia on patient outcomes has not been clearly established. We assessed the effect of appropriate empirical therapy on in-hospital mortality and length of stay (LOS) among patients with P. aeruginosa bacteremia. This was a retrospective cohort study of inpatients with a positive blood culture for P. aeruginosa between January 2001 and June 2005. Empirical therapy was defined as appropriate if the patient received an antibiotic the organism was susceptible to between 8 h before culture collection and the time the susceptibility results were available. The severity of the illness was measured 24 h before culture collection. The data were analyzed using logistic regression (in-hospital mortality) and linear regression (LOS). Overall, there were 167 episodes of P. aeruginosa bacteremia, 123 (86%) of which received appropriate empirical antibiotics. Sixty-one patients died (36.5%). The median time from culture collection to susceptibility results was 3.4 days. After we adjusted for age, severity of illness, and time at risk, we found that the appropriate empirical therapy was not significantly associated with mortality (odds ratio = 0.96; 95% confidence interval = 0.31 to 2.93). There was a 7% reduction in the mean LOS for patients who had received appropriate therapy at the time susceptibility results were available compared to those who did not (P = 0.74). These data suggest that the use of appropriate empirical therapy, i.e., before susceptibility results are known may not be as critical to patient outcomes as other studies have suggested.

Aged↗

PubMed2006

What infection control interventions should be undertaken to control multidrug-resistant gram-negative bacteria?

Multidrug-resistant gram-negative bacteria are an emerging problem. The present article addresses 2 relevant questions: (1) should active surveillance be performed to identify patients colonized with multidrug-resistant gram-negative bacteria, and (2) should contact isolation precautions be taken with patients colonized or infected with multidrug-resistant gram-negative bacteria? Data and variables that are needed to scientifically answer these questions are reviewed, as are existing data on Pseudomonas aeruginosa, Enterobacteriaceae (Escherichia coli and Klebsiella species in particular), and Acinetobacter baumannii.

Cross Infection↗

PubMed2006

Comorbidity risk-adjustment measures were developed and validated for studies of antibiotic-resistant infections.

OBJECTIVES: Comorbidities are often included in risk-factor models for nosocomial antibiotic-resistant bacterial infections, and aggregate comorbidity measures are valuable because they allow one variable to represent many. This study aimed to develop new aggregate comorbidity measures based upon the Chronic Disease Score (CDS) for assessing the comorbidity-attributable risk of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) nosocomial infections. STUDY DESIGN AND SETTING: For each outcome, two retrospective cohort studies of hospitalized patients were conducted. Outcomes were a first MRSA or VRE positive clinical culture obtained 48 hours or more postadmission. Each cohort was divided into development (July 1998-2001) and validation (August 2001-2003) samples. New comorbidity measures were created for MRSA (CDS-MRSA), VRE (CDS-VRE), or any nosocomial infection outcome (CDS-ID) using logistic regression and subsequently validated. Model discrimination was measured using the c-statistic. RESULTS: Discrimination of the CDS-MRSA (c=0.60), CDS-VRE (c=0.65), and CDS-ID (MRSA: c=0.57; VRE: c=0.64) was greater than that of the original CDS (MRSA: c=0.52; VRE: c=0.57). CONCLUSION: The CDS-MRSA, CDS-VRE, and CDS-ID are new infectious disease specific comorbidity risk-adjustment measures that will be useful for the quality of future epidemiologic studies of MRSA, VRE, and other infectious diseases.

Comorbidity↗

PubMed2006

Impact of a computerized clinical decision support system on reducing inappropriate antimicrobial use: a randomized controlled trial.

OBJECTIVE: Many hospitals utilize antimicrobial management teams (AMTs) to improve patient care. However, most function with minimal computer support. We evaluated the effectiveness and cost-effectiveness of a computerized clinical decision support system for the management of antimicrobial utilization. DESIGN: A randomized controlled trial in adult inpatients between May 10 and August 3, 2004. Antimicrobial utilization was managed by an existing AMT using the system in the intervention arm and without the system in the control arm. The system was developed to alert the AMT of potentially inadequate antimicrobial therapy. MEASUREMENTS: Outcomes assessed were hospital antimicrobial expenditures, mortality, length of hospitalization, and time spent managing antimicrobial utilization. RESULTS: The AMT intervened on 359 (16%) of 2,237 patients in the intervention arm and 180 (8%) of 2,270 in the control arm, while spending approximately one hour less each day on the intervention arm. Hospital antimicrobial expenditures were $285,812 in the intervention arm and $370,006 in the control arm, for a savings of $84,194 (23%), or $37.64 per patient. No significant difference was observed in mortality (3.26% vs. 2.95%, p = 0.55) or length of hospitalization (3.84 vs. 3.99 days, p = 0.38). CONCLUSION: Use of the system facilitated the management of antimicrobial utilization by allowing the AMT to intervene on more patients receiving inadequate antimicrobial therapy and to achieve substantial time and cost savings for the hospital. This is the first study that demonstrates in a patient-randomized controlled trial that computerized clinical decision support systems can improve existing antimicrobial management programs.

Adult↗

PubMed2006

Identifying groups at high risk for carriage of antibiotic-resistant bacteria.

BACKGROUND: No simple, cost-effective methods exist to identify patients at high risk for methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci colonization outside intensive care settings. Without such methods, colonized patients are entering hospitals undetected and transmitting these bacteria to other patients. We aimed to develop a highly sensitive, simple-to-administer prediction rule to identify subpopulations of patients at high risk for colonization on hospital admission. METHODS: We conducted a prospective cohort study of adult patients admitted to the general medical and surgical wards of a tertiary-care facility. Data were collected using electronic medical records and an investigator-administered questionnaire. Cultures of anterior nares and the perirectal area were also collected within 48 hours of admission. RESULTS: Among 699 patients who enrolled in this study, 697 underwent nasal cultures; 555, perirectal cultures; and 553, both. Patient self-report of a hospital admission in the previous year was the most sensitive variable in identifying patients colonized with methicillin-resistant Staphylococcus aureus or with either organism (sensitivity, 76% and 90%, respectively). A prediction rule requiring patients to self-report having received antibiotics and a hospital admission in the previous year would have identified 100% of patients colonized with vancomycin-resistant enterococci. In the high-risk groups defined by the prediction rule, the prevalence of colonization by methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, or either organism were 8.1%, 10.2%, and 15.0%, respectively. CONCLUSION: Patients with a self-reported previous admission within 1 year may represent a high-risk group for colonization by methicillin-resistant Staphylococcus aureus or vancomycin-resistant enterococci at hospital admission and should be considered for targeted active surveillance culturing.

Carrier State↗

PubMed2005

Physicians' acceptable treatment failure rates in antibiotic therapy for coagulase-negative staphylococcal catheter-associated bacteremia: implications for reducing treatment duration.

BACKGROUND: Decreasing the duration of antimicrobial therapy is an attractive strategy for delaying the emergence of antimicrobial resistance. Limited data regarding optimal treatment durations for most clinical infections hinder the adoption of this approach and impair optimal physician-patient communication under the shared decision-making model. We aimed to identify acceptable failure rates among infectious disease consultants (IDCs) for treatment of central venous catheter-associated bacteremia. METHODS: A case scenario involving a representative patient who developed central venous catheter-associated bacteremia caused by coagulase-negative staphylococci and who received standard-of-care therapy was distributed to all nonpediatric IDC members of the Infectious Diseases Society of America's Emerging Infections Network in August 2003. Each member was suggested 1 of 10 treatment failure rates and asked whether he or she would accept or reject the given value. Logistic regression was used to evaluate the relationship between specific failure rates offered to respondents and their willingness to accept them using a methodology derived from contingent valuation. RESULTS: Among the 374 respondents (response rate, 54%), the median acceptable failure rate was 6.8%. Thus, one-half of the IDCs would have found a failure rate of 6.8% to be acceptable. Seventy-five percent of IDCs would have found a failure rate of 1.6% to be acceptable, and 25% of IDCs would have found a failure rate as high as 11.9% to be acceptable. CONCLUSIONS: The quantified acceptable failure rates, when used to interpret clinical trial or cohort study results, will help select optimal antimicrobial therapy durations for this specific condition. These findings are a critical step in the development of effective shared decision-making models.

Anti-Bacterial Agents↗

PubMed2005

The use and interpretation of quasi-experimental studies in medical informatics.

Quasi-experimental study designs, often described as nonrandomized, pre-post intervention studies, are common in the medical informatics literature. Yet little has been written about the benefits and limitations of the quasi-experimental approach as applied to informatics studies. This paper outlines a relative hierarchy and nomenclature of quasi-experimental study designs that is applicable to medical informatics intervention studies. In addition, the authors performed a systematic review of two medical informatics journals, the Journal of the American Medical Informatics Association (JAMIA) and the International Journal of Medical Informatics (IJMI), to determine the number of quasi-experimental studies published and how the studies are classified on the above-mentioned relative hierarchy. They hope that future medical informatics studies will implement higher level quasi-experimental study designs that yield more convincing evidence for causal links between medical informatics interventions and outcomes.

Evaluation Studies as Topic↗

PubMed2005

A systematic review of quasi-experimental study designs in the fields of infection control and antibiotic resistance.

We performed a systematic review of articles published during a 2-year period in 4 journals in the field of infectious diseases to determine the extent to which the quasi-experimental study design is used to evaluate infection control and antibiotic resistance. We evaluated studies on the basis of the following criteria: type of quasi-experimental study design used, justification of the use of the design, use of correct nomenclature to describe the design, and recognition of potential limitations of the design. A total of 73 articles featured a quasi-experimental study design. Twelve (16%) were associated with a quasi-experimental design involving a control group. Three (4%) provided justification for the use of the quasi-experimental study design. Sixteen (22%) used correct nomenclature to describe the study. Seventeen (23%) mentioned at least 1 of the potential limitations of the use of a quasi-experimental study design. The quasi-experimental study is used frequently in studies of infection control and antibiotic resistance. Efforts to improve the conduct and presentation of quasi-experimental studies are urgently needed to more rigorously evaluate interventions.

Drug Resistance, Microbial↗

PubMed2005

Utility of the Chronic Disease Score and Charlson Comorbidity Index as comorbidity measures for use in epidemiologic studies of antibiotic-resistant organisms.

Comorbidity is a known risk factor for antibiotic-resistant bacterial infections. Although aggregate comorbidity measures are useful in epidemiologic research, none of the existing measures was developed for use with this outcome. This study compared the utility of two comorbidity measures, the Charlson Comorbidity Index and the Chronic Disease Score, in assessing the comorbidity-attributable risk of nosocomial infections with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE). Two case-control studies were conducted at the University of Maryland Medical System in Baltimore, Maryland. Cases were inpatients with a first positive clinical culture of MRSA or VRE at least 48 hours postadmission (July 1, 1998-July 1, 2001). Three inpatient controls were randomly selected per case. The MRSA study included 2,164 patients, and the VRE study included 1,948. The scores' discrimination and calibration were measured by using the c statistic and Hosmer-Lemeshow chi-square test. The Charlson Comorbidity Index (c = 0.653) and Chronic Disease Score (c = 0.608) were similar discriminators of MRSA and VRE (c = 0.670 and c = 0.647, respectively). Calibration of the scores was poor for both outcomes (p < 0.05). A revised comorbidity measure specific to resistant infections would likely provide a better assessment of the comorbidity-attributable risk of antibiotic-resistant infections.

Adolescent↗

PubMed2005

Impact of severity of illness bias and control group misclassification bias in case-control studies of antimicrobial-resistant organisms.

BACKGROUND: Case-control studies often analyze risk factors for antibiotic resistance. Recently published articles have illustrated that randomly selected control-patients may be preferable to those with the susceptible phenotype of the organism. A possible methodologic problem with randomly selected control-patients is potential bias due to control group misclassification. This occurs if some control-patients did not have clinical cultures performed and thus might have been unidentified case-patients. If this bias exists, these studies might be expected to report lower odds ratios (ORs) because control-patients would be more like case-patients. OBJECTIVE: To analyze potential biases that might arise due to control group misclassification and potentially larger selection biases that may be introduced if control-patients are required to have at least one clinical culture. PATIENTS: One hundred twenty case-patients, 770 control-patients in group 1, and 510 control-patients in group 2. METHODS: Two case-control studies. Case-patients had clinical cultures positive for imipenem-resistant Pseudomonas aeruginosa. The first group of control-patients were random. The second group of control-patients were identical to those in group 1 except being required to have at least one clinical culture. RESULTS: Univariate analyses showed higher ORs for case-patients versus control-patients in group 1 (imipenem [OR, 12.5], piperacillin-tazobactam [OR, 3.7], and vancomycin [OR, 4.7]) as compared with case-patients versus control-patients in group 2 (imipenem [OR, 8.0], piperacillin-tazobactam [OR, 2.5], and vancomycin [OR, 3.0]). CONCLUSION: Requiring control-patients to have at least one clinical culture introduces a selection bias likely because it eliminates patients with less severe illness.

Anti-Bacterial Agents↗

PubMed2005

The case-case-control study design: addressing the limitations of risk factor studies for antimicrobial resistance.

OBJECTIVE: There are significant limitations of the standard case-control study design for identifying risk factors for resistant organisms. The objective of this study was to develop a study design to overcome these limitations. DESIGN: Theoretical analysis of different types of study designs that can be used in risk factor studies for resistant organisms. RESULTS: We developed the case-case-control study design, which uses two separate case-control analyses within a single study. The first analysis compares patients infected with resistant bacteria (resistant cases) with control-patients without infection caused by the target organism, who are therefore representative of the source population; and the second analysis compares patients infected with the susceptible phenotype of the target organism (susceptible cases) with the same control-patients without infection caused by the target organism. These two analyses provide risk models for (1) isolation of the resistant phenotype of the target organism as compared with the source population and (2) isolation of the susceptible phenotype of the organism as compared with the source population. When these two risk models are compared and contrasted, risk factors specifically associated with isolation of the resistant phenotype can be identified. CONCLUSIONS: The case-case-control study design is an effective method for identifying risk factors for antimicrobial-resistant pathogens. Although the case-case-control study design has limitations, it is, in our opinion, more informative and less flawed than the standard case-control study design.

Anti-Bacterial Agents↗

PubMed2005

Test characteristics of perirectal and rectal swab compared to stool sample for detection of fluoroquinolone-resistant Escherichia coli in the gastrointestinal tract.

Among 63 patients enrolled in a prospective cohort study of gut colonization with fluoroquinolone-resistant Escherichia coli, the sensitivity of perirectal swab compared to stool sample was 90% (95% confidence interval [CI], 70 to 99%) and the specificity was 100% (95% CI, 91 to 100%). For rectal swab, the sensitivity was 90% (95% CI, 68 to 99%) and the specificity was 100% (95% CI, 91 to 100%).

Adult↗

PubMed2005

Multilocus sequence typing versus pulsed-field gel electrophoresis for characterization of extended-spectrum beta-lactamase-producing Escherichia coli isolates.

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli strains are emerging pathogens. Molecular typing of ESBL-producing E. coli is useful for surveillance purposes, to monitor outbreaks and track nosocomial spread. Although pulsed-field gel electrophoresis (PFGE) is the current "gold standard" for bacterial molecular typing, multilocus sequence typing (MLST) may offer advantages. Forty ESBL-producing E. coli isolates were selected at random from a cohort of intensive care unit patients who had active surveillance perirectal cultures done. PFGE identified 19 unique PFGE types (PT) among the 40 isolates; MLST identified 22 unique sequence types. MLST had greater discriminatory ability than PFGE for ESBL-producing E. coli. Simpson's indices of diversity for PFGE and MLST were 0.895 and 0.956, respectively. There were five clonal complexes (CCs) (isolates with differences of no more than two loci) that each contained multiple PT, but each PT was found in only one CC, indicating genetic consistency within a CC. MLST has clear utility in studies of ESBL-producing E. coli, based on a greater discriminatory ability and reproducibility than PFGE and the ability to a priori define genetically related bacterial strains.

Bacterial Typing Techniques↗

PubMed2005

Methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci co-colonization.

We assessed the prevalence, risk factors, and clinical outcomes of patients co-colonized with vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) upon admission to the medical and surgical intensive care units (ICUs) of a tertiary-care facility between January 1, 2002, and December 31, 2003. Co-colonization was defined as a VRE-positive perirectal surveillance culture with an MRSA-positive anterior nares surveillance culture collected concurrently. Among 2,440 patients, 65 (2.7%) were co-colonized. Independent risk factors included age (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.01-1.05), admission to the medical ICU (OR 4.38, 95% CI 2.46-7.81), male sex (OR 1.93, 95% CI 1.14-3.30), and receiving antimicrobial drugs on a previous admission within 1 year (OR 3.06, 95% CI 1.85-5.07). None of the co-colonized patients would have been identified with clinical cultures alone. We report a high prevalence of VRE/MRSA co-colonization upon admission to ICUs at a tertiary-care hospital.

Aged↗

PubMed2004

Risk of mortality with a bloodstream infection is higher in the less severely ill at admission.

RATIONALE: Health care-associated bloodstream infections are common in critically ill patients; however, investigators have had difficulty in quantifying the clinical impact of these infections given the high expected mortality among these patients. OBJECTIVE: To estimate the impact of health care-associated bloodstream infections on in-hospital mortality after adjusting for severity of illness at critical care admission. METHOD: A cohort of medical and surgical intensive care unit patients. MEASUREMENTS: Severity of illness at admission, bloodstream infection, and in-hospital mortality. MAIN RESULTS: Among the 2,783 adult patients, 269 developed unit-associated bloodstream infections. After adjusting for severity of illness, patients with a lower initial severity of illness who developed an infection had a greater than twofold higher risk for in-hospital mortality (hazard ratio [HR] = 2.42, 95% confidence interval [CI] 1.70, 3.44) when compared with patients without infection and with a similar initial severity of illness. In contrast, patients with a higher initial severity of illness who subsequently developed an infection did not have an increased risk for in-hospital mortality (HR = 0.96, 95%CI 0.76, 1.23) when compared with patients without infection but with a similar initial severity of illness. CONCLUSIONS: These results suggest that these infections in less ill patients have a higher attributable impact on subsequent mortality than in more severely ill patients. Focusing interventions to prevent bloodstream infections in less severely ill patients would be expected to have a greater benefit in terms of mortality reduction.

APACHE↗

PubMed2004

The use and interpretation of quasi-experimental studies in infectious diseases.

Quasi-experimental study designs, sometimes called nonrandomized, pre-post-intervention study designs, are ubiquitous in the infectious diseases literature, particularly in the area of interventions aimed at decreasing the spread of antibiotic-resistant bacteria. Little has been written about the benefits and limitations of the quasi-experimental approach. This article outlines a hierarchy of quasi-experimental study design that is applicable to infectious diseases studies and that, if applied, may lead to sounder research and more-convincing causal links between infectious diseases interventions and outcomes.

Communicable Diseases↗

PubMed2004

Projected benefits of active surveillance for vancomycin-resistant enterococci in intensive care units.

Hospitals use many strategies to control nosocomial transmission of vancomycin-resistant enterococci (VRE). Strategies include "passive surveillance," with isolation of patients with known previous or current VRE colonization or infection, and "active surveillance," which uses admission cultures, with subsequent isolation of patients who are found to be colonized with VRE. We created a mathematical model of VRE transmission in an intensive care unit (ICU) using data from an existing active surveillance program; we used the model to generate the estimated benefits associated with active surveillance. Simulations predicted that active surveillance in a 10-bed ICU would result in a 39% reduction in the annual incidence of VRE colonization when compared with no surveillance. Initial isolation of all patients, with withdrawal of isolation if the results of surveillance cultures are negative, was predicted to result in a 65% reduction. Passive surveillance was minimally effective. Using the best available data, active surveillance is projected to be effective for reducing VRE transmission in ICU settings.

Anti-Bacterial Agents↗