The prevalence and inaccessibility of Internet references in the biomedical literature at the time of publication.

OBJECTIVES: To determine the prevalence and inaccessibility of Internet references in the bibliography of biomedical publications when first released in PubMed. METHODS: During a one-month observational study period (Feb 21 to Mar 21, 2006) the Internet citations from a 20% random sample of all forthcoming publications released in PubMed during the previous day were identified. Attempts to access the referenced Internet citations were completed within one day and inaccessible Internet citations were recorded. RESULTS: The study included 4,699 publications from 844 different journals. Among the 141,845 references there were 840 (0.6%) Internet citations. One or more Internet references were cited in 403 (8.6%) articles. From the 840 Internet references, 11.9% were already inaccessible within two days after an article's release to the public. CONCLUSION: The prevalence of Internet citations in journals included in PubMed is small (<1%); however, the inaccessibility rate at the time of publication is considered substantial. Authors, editors, and publishers need to take responsibility for providing accurate and accessible Internet references.

The life and death of URLs in five biomedical informatics journals.

OBJECTIVE: To determine the decay rate of Uniform Record Locators (URLs) in the reference section of biomedical informatics journals. METHODS: URL references were collected from printed journal articles of the first and middle issues of 1999-2004 and electronically available in-press articles in January 2005. We limited this set to five biomedical informatics journals: Artificial Intelligence in Medicine, International Journal of Medical Informatics, Journal of the American Medical Informatics Association: JAMIA, Methods of Information in Medicine, and Journal of Biomedical Informatics. During a 1-month period, URL access attempts were performed eight times a day at regular intervals. RESULTS: Of the 19,108 references extracted from 606 printed and 86 in-press articles, 1112 (5.8%) references contained a URL. Of the 1049 unique URLs, 726 (69.2%) were alive, 230 (21.9%) were dead, and 93 (8.9%) were comatose. URLs from in-press articles included 212 URLs, of which 169 (79.7%) were alive, 21 (9.9%) were dead, and 22 (10.4%) were comatose. The average annual decay, or link rot, rate was 5.4%. CONCLUSION: The URL decay rate in biomedical informatics journals is high. A commonly accepted strategy for the permanent archival of digital information referenced in scholarly publications is urgently needed.

Use of a computerized C-reactive protein (CRP) based sepsis evaluation in very low birth weight (VLBW) infants: a five-year experience.

BACKGROUND: Serial C-reactive protein (CRP) values may be useful for decision-making regarding duration of antibiotics in neonates. However, established standard of practice for its use in preterm very low birth weight (<1500 g, VLBW) infants are lacking. OBJECTIVE: Evaluate compliance with a CRP-guided computerized decision support (CDS) algorithm and compare characteristics and outcomes of compliant versus non-compliant cases. Measure correlation between CRPs and white blood count (WBC) indices. METHODS: We examined 3 populations: 1) all preterm VLBW infants born at Vanderbilt 2006-2011 - we assessed provider compliance with CDS algorithm and measured relevant outcomes; 2) all patients with positive blood culture results admitted to the Vanderbilt NICU 2006-2012 - we tested the correlation between CRP and WBC results within 7 days of blood culture phlebotomy; 3) 1,000 randomly selected patients out of the 7,062 patients admitted to the NICU 2006-2012 - we correlated time-associated CRP values and absolute neutrophil counts. RESULTS: Of 636 VLBW infants in cohort 1), 569 (89%) received empiric antibiotics for suspected early-onset sepsis. In 409 infants (72%) the CDS algorithm was followed; antibiotics were discontinued ≤48 hours in 311 (55%) with normal serial CRPs and continued in 98 (17%) with positive CRPs, resulting in significant reduction in antibiotic exposure (p<0.001) without increase in complications or subsequent infections. One hundred sixty (28%) were considered non-compliant because antibiotics were continued beyond 48 hours despite negative serial CRPs and blood cultures. Serial CRPs remained negative in 38 (12%) of 308 blood culture-positive infants from cohort 2, but only 4 patients had clinically probable sepsis with single organisms and no immunodeficiency besides extreme prematurity. Leukopenia of any cell type was not linked with CRPs in cohorts 2 and 3. CONCLUSIONS: CDS/CRP-guided antibiotic use is safe and effective in culture-negative VLBW infants. CRP results are not affected by low WBC indices.

Evaluating the utility of syndromic surveillance algorithms for screening to detect potentially clonal hospital infection outbreaks.

OBJECTIVE: The authors evaluated algorithms commonly used in syndromic surveillance for use as screening tools to detect potentially clonal outbreaks for review by infection control practitioners. DESIGN: Study phase 1 applied four aberrancy detection algorithms (CUSUM, EWMA, space-time scan statistic, and WSARE) to retrospective microbiologic culture data, producing a list of past candidate outbreak clusters. In phase 2, four infectious disease physicians categorized the phase 1 algorithm-identified clusters to ascertain algorithm performance. In phase 3, project members combined the algorithms to create a unified screening system and conducted a retrospective pilot evaluation. MEASUREMENTS: The study calculated recall and precision for each algorithm, and created precision-recall curves for various methods of combining the algorithms into a unified screening tool. RESULTS: Individual algorithm recall and precision ranged from 0.21 to 0.31 and from 0.053 to 0.29, respectively. Few candidate outbreak clusters were identified by more than one algorithm. The best method of combining the algorithms yielded an area under the precision-recall curve of 0.553. The phase 3 combined system detected all infection control-confirmed outbreaks during the retrospective evaluation period. LIMITATIONS: Lack of phase 2 reviewers' agreement indicates that subjective expert review was an imperfect gold standard. Less conservative filtering of culture results and alternate parameter selection for each algorithm might have improved algorithm performance. CONCLUSION: Hospital outbreak detection presents different challenges than traditional syndromic surveillance. Nevertheless, algorithms developed for syndromic surveillance have potential to form the basis of a combined system that might perform clinically useful hospital outbreak screening.

Insulin resistance heralds positive cultures after severe injury.

BACKGROUND: Insulin resistance and hyperglycemia are common in acutely injured patients, and associated with poor outcomes. In the era of tight glucose control, measures of insulin responsiveness (IR) may provide a better indicator of patient status than does the serum glucose concentration. We hypothesized that measures of IR during tight glycemic control protocols are associated with infection and may be more predictive than the serum glucose concentration. METHODS: All critically injured, mechanically ventilated patients undergo protocolized tight glycemic control with the aid of a computer-based system that calculates the insulin dose using an adapting multiplier (insulin dose = [blood glucose - 60) x M). Consecutive patients on protocol were studied to identify the incidence of positive sterile-site or quantitative bronchoalveolar lavage cultures (>10(4) colony-forming units/mL). Patients were stratified by presence and number of positive cultures and analyzed by both serum glucose measures and measures of IR (average multiplier and average insulin infusion rate). RESULTS: During the six-month study period, 356 patients were placed on the tight glycemic control protocol. Of these, 101 patients had 192 positive cultures. Patients with positive cultures required significantly more hourly insulin than those without a positive culture (3.7 vs. 2.8 units/h; p = or<0.001). Logistic regression showed the insulin dose (odds ratio 2.1; 95% confidence interval 1.6, 3.0; p = <0.001) and the adapting multiplier to be independent predictors of the patient having a positive culture among other factors associated with nosocomial infection. CONCLUSIONS: Insulin resistance, quantified by hourly insulin dose and median multiplier, confers a higher risk of systemic nosocomial infection. Patients with positive cultures actually had lower admission and median blood glucose values over their intensive care unit stays, highlighting the decreased value of this measure as a predictor of outcome in the setting of tight glucose control. A greater insulin requirement suggesting resistance may be used as a marker of a higher risk of nosocomial infection.

Prevalence and inaccessibility of URLs in the biomedical literature.

The World Wide Web is a dynamic environment that does not guarantee permanent access or content stability. We determined the prevalence of URLs in forthcoming, biomedical papers when they are first released in MEDLINE(R) and prospectively evaluated the rate of inaccessible URLs during a 19-day period. Among 96,153 references from 2,614 forthcoming papers (739 journals) the prevalence of URLs was 0.59%. The rate of inaccessible URLs was 12.4% when first available to the public community.

The life and death of URLs in five biomedical informatics journals.

With the increased use of the World Wide Web has come an increase in the number of Uniform Resource Locator (URL) references cited in journals. Out of the 17,698 references we collected from five biomedical informatics journals between 1999 and 2005, 6.8% contained URLs. Overall, 22.6% of these URLs were inaccessible. In-press articles had 10.8% unavailable URLs. Approaches that guarantee permanent access to URL citations of scientific publications are needed.