Clinicians required very high sensitivity of a bacteremia prediction rule

Diagnostic performance of food consumption for bacteraemia in patients admitted with suspected infection: a prospective cohort study

OBJECTIVES

A previous study reported that food consumption is useful to rule out bacteraemia in hospitalised patients. We aimed to validate the diagnostic performance of (1) food consumption and (2) a previously reported algorithm using food consumption and shaking chills for bacteraemia in patients admitted to hospital with suspected infection.

DESIGN

Prospective cohort study.

SETTING

Department of General Medicine in two acute care hospitals in Japan.

PARTICIPANTS

A total of 2009 adult patients who underwent at least two blood cultures on admission.

PRIMARY OUTCOME MEASURES

The reference standard for bacteraemia was judgement by two independent specialists of infectious diseases. Food consumption was evaluated by the physician in charge asking the patient or their caregivers the following question on admission: 'What percentage of usual food intake were you able to eat during the past 24 hours?'

RESULTS

Among 2009 patients, 326 patients were diagnosed with bacteraemia (16.2%). Diagnostic performance of food consumption was sensitivity of 84.4% (95% CI 80.1 to 88), specificity of 19.8% (95% CI 18 to 21.8), positive predictive value (PPV) of 16.9% (95% CI 15.2 to 18.9) and negative predictive value (NPV) of 86.8% (95% CI 83.1 to 89.8). The discriminative performance was an area under the curve of 0.53 (95% CI 0.50 to 0.56). The performance of the algorithm using food consumption and shaking chills was sensitivity of 89% (95% CI 85.1 to 91.9), specificity of 18.8% (95% CI 17 to 20.7), PPV of 17.5% (95% CI 15.7 to 19.4) and NPV of 89.8% (95% CI 86.2 to 92.5).

CONCLUSION

Our results did not show the usefulness of food consumption and the algorithm using food consumption and shaking chills for the diagnosis of bacteraemia in patients admitted to hospital with suspected infection.

How good is our diagnostic intuition? Clinician prediction of bacteremia in critically ill children

Background

Clinical intuition and nonanalytic reasoning play a major role in clinical hypothesis generation; however, clinicians’ intuition about whether a critically ill child is bacteremic has not been explored. We endeavored to assess pediatric critical care clinicians’ ability to predict bacteremia and to evaluate what affected the accuracy of those predictions.

Methods

We conducted a retrospective review of clinicians’ responses to a sepsis screening tool (“Early Sepsis Detection Tool” or “ESDT”) over 6 months. The ESDT was completed during the initial evaluation of a possible sepsis episode. If a culture was ordered, they were asked to predict if the culture would be positive or negative. Culture results were compared to predictions for each episode as well as vital signs and laboratory data from the preceding 24 h.

Results

From January to July 2017, 266 ESDTs were completed. Of the 135 blood culture episodes, 15% of cultures were positive. Clinicians correctly predicted patients with bacteremia in 82% of cases, but the positive predictive value was just 28% as there was a tendency to overestimate the presence of bacteremia. The negative predictive value was 96%. The presence of bandemia, thrombocytopenia, and abnormal CRP were associated with increased likelihood of correct positive prediction.

Conclusions

Clinicians are accurate in predicting critically ill children whose blood cultures, obtained for symptoms of sepsis, will be negative. Clinicians frequently overestimate the presence of bacteremia. The combination of evidence-based practice guidelines and bedside judgment should be leveraged to optimize diagnosis of bacteremia.

Clinical prediction rules: A systematic review of healthcare provider opinions and preferences

OBJECTIVE

The act of predicting clinical endpoints and patient trajectories based on past and current states is on the precipice of a technological revolution. This systematic review summarises the available evidence describing healthcare provider opinions and preferences with respect to the use of clinical prediction rules. The primary goal of this work is to inform the design and implementation of future systems, and secondarily to identify gaps for the development of clinician education programs.

METHODS

Five databases were systematically searched in May 2016 for studies collecting empirical opinions of healthcare providers regarding clinical prediction rule usage. Reference lists were scanned for additional eligible materials and an update search was made in August 2017. Data was extracted on high-level study features, before in-depth thematic analysis was performed.

RESULTS

45 articles were identified from 9 countries. Most studies utilised surveys (28) or interviews (14). Fewer employed focus groups (9) or formal usability testing (4). Three high-level themes were identified, which form the basis of healthcare provider opinions of clinical prediction rules and their implementation - utility, credibility and usability.

CONCLUSIONS

Some of the objections and preferences stated by healthcare providers are inherent to the nature of the clinical problem addressed, which may or may not be within the designer's capacity to change; however, others (in particular - actionability, validation, integration and provision of high quality education materials) should be considered by prediction rule designers and implementation teams, in order to increase user acceptance and improve uptake of these tools. We summarise these findings across the clinical prediction rule lifecycle and pose questions for the rule developers, in order to produce tools that are more likely to successfully translate into clinical practice.

Blood cultures and bacteraemia in an Australian emergency department: Evaluating a predictive rule to guide collection and their clinical impact

OBJECTIVE

The objective of the present study is to determine whether a predictive rule could safely reduce the number of negative blood cultures collected in an Australian ED and to assess the clinical impact of positive results from blood cultures taken in the ED.

METHODS

All positive blood cultures taken in the ED at a single facility were retrospectively identified for the calendar year 2012. Clinically significant bacteraemia episodes were assessed against a predictive rule using major and minor clinical and laboratory criteria gathered from medical records and pathology databases, and compared with a randomly generated sample of ED patient episode with negative blood cultures. The ED and final diagnoses and blood culture impact on clinical management were also collected.

RESULTS

The predictive rule has a high sensitivity (98.8%) and modest specificity (48.7%), and if applied stringently would have prevented almost half of all blood cultures in our ED but missed two positives. Blood cultures altered the clinical management of 94.3% bacteraemic patients, representing 3.4% of all ED patients with blood cultures performed. High discordance (54%) between ED diagnosis and discharge diagnosis of bacteraemic patients was noted.

CONCLUSIONS

Bacteraemia detected in the ED alters subsequent patient management. The predictive rule can be safely applied in the ED to determine need for blood culture collection. Blood cultures should not be omitted in the ED based entirely on preliminary diagnosis given the high discordance seen between ED and discharge diagnosis.

Identifying Patients with Bacteremia in Community-Hospital Emergency Rooms: A Retrospective Cohort Study

Objectives

(1) To develop a clinical prediction rule to identify patients with bacteremia, using only information that is readily available in the emergency room (ER) of community hospitals, and (2) to test the validity of that rule with a separate, independent set of data.

Design

Multicenter retrospective cohort study.

Setting

To derive the clinical prediction rule we used data from 3 community hospitals in Japan (derivation). We tested the rule using data from one other community hospital (validation), which was not among the three “derivation” hospitals.

Participants

Adults (age ≥ 16 years old) who had undergone blood-culture testing while in the ER between April 2011 and March 2012. For the derivation data, n = 1515 (randomly sampled from 7026 patients), and for the validation data n = 467 (from 823 patients).

Analysis

We analyzed 28 candidate predictors of bacteremia, including demographic data, signs and symptoms, comorbid conditions, and basic laboratory data. Chi-square tests and multiple logistic regression were used to derive an integer risk score (the “ID-BactER” score). Sensitivity, specificity, likelihood ratios, and the area under the receiver operating characteristic curve (i.e., the AUC) were computed.

Results

There were 241 cases of bacteremia in the derivation data. Eleven candidate predictors were used in the ID-BactER score: age, chills, vomiting, mental status, temperature, systolic blood pressure, abdominal sign, white blood-cell count, platelets, blood urea nitrogen, and C-reactive protein. The AUCs was 0.80 (derivation) and 0.74 (validation). For ID-BactER scores ≥ 2, the sensitivities for derivation and validation data were 98% and 97%, and specificities were 20% and 14%, respectively.

Conclusions

The ID-BactER score can be computed from information that is readily available in the ERs of community hospitals. Future studies should focus on developing a score with a higher specificity while maintaining the desired sensitivity.

A Critical Appraisal of the Role of the Clinical Microbiology Laboratory in the Diagnosis of Bloodstream Infections

The detection of bloodstream infections is one of the most important functions of clinical microbiology laboratories. Despite advances in blood culture technology and clinical studies that have focused on the detection of bacteremia and fungemia, perfection has not been achieved and uncertainties persist. This review provides perspectives on a number of areas, including the recommended number of blood cultures, duration of incubation of blood cultures, use of anaerobic, in addition to aerobic, blood culture media, value of the lysis-centrifugation method, processing and reporting of probable blood culture contaminants, and limitations of current blood culture methods and systems. We also address the handling of blood cultures in point-of-care locations that lack full microbiology capabilities.

Validation of the Acute Heart Failure Index

STUDY OBJECTIVE

Validate a clinical prediction rule prognostic of short-term fatal and inpatient nonfatal outcomes for heart failure patients admitted through the emergency department.

METHODS

We retrospectively studied a random cohort of 8,384 adult patients admitted to Pennsylvania hospitals in 2003 and 2004 with a diagnosis of heart failure as defined by primary discharge diagnosis codes. We reported the proportions of inpatient death, serious medical complications before discharge, and 30-day death in the patients identified as low risk by the prediction rule.

RESULTS

The prediction rule classified 1,609 (19.2%) of the patients as low risk. Within this subgroup, there were 12 (0.7%; 95% confidence interval [CI] 0.3% to 1.2%) inpatient deaths, 28 (1.7%; 95% CI 1.1% to 2.4%) patients survived to hospital discharge after a serious complication, and 47 (2.9%; 95% CI 2.1% to 3.7%) patients died within 30 days of the index hospitalization.

CONCLUSION

This prediction rule identifies a group of admitted heart failure patients at low risk of inpatient mortal and nonmortal complications. Our validation findings suggest the rule could assist physicians in making site-of-care decisions for this patient population and aid in analyzing presenting illness burden in study populations.

Diagnostic use of C-reactive protein in bacteraemic emergency department patients

OBJECTIVE

To assess C-reactive protein (CRP) as a marker of bacteraemia in ED patients.

METHODS

A retrospective review of a convenience sample of adult patients was conducted at an urban, tertiary care, academic ED. Patients were included in the present study if they had CRP and blood cultures taken during their ED assessment. Neutropenic patients were excluded. Sensitivity, specificity, predictive values and likelihood ratios for CRP in the detection of bacteraemia were calculated.

RESULTS

Over a 12 month period 1214 patients were included in the present study. Blood cultures were positive in 77 (6.3%, 95% confidence interval [CI] 5.0-7.6%), and contaminated in 33 (2.7%, 95% CI 1.8-3.6%). An elevated CRP was 94% sensitive (95% CI 86-98%) and 18% specific (95% CI 16-20%) for concurrent bacteraemia. The positive likelihood ratio for bacteraemia with an elevated CRP was 1.15 (95% CI 1.07-1.23), and the negative likelihood ratio was 0.33 (95% CI 0.23-0.49).

CONCLUSION

Although the present study has limitations, it appears to show that CRP has limited diagnostic utility for the detection of bacteraemia in ED patients.