Study design.
This is a study on the feasibility of a quality improvement intervention, with a before-after design.
Context/Study setting.
The study was conducted in three EDs: Hamilton Health Sciences (HHS) EDs (Hamilton General and Juravinski Hospitals, Hamilton, ON) and the Montfort Hospital, Ottawa, ON. These are teaching hospitals and are staffed with approximately 50 physicians (Hamilton hospitals) and 32 physicians (Montfort Hospital) who manage 100,000 and 55,000 patient visits per year, respectively. A chart review of HHS EDs 2013–2015 showed that 290 patients were investigated for PE in the HHS EDs every six months.
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Population studied.
This implementation study used electronic data to identify patients tested for PE in the ED. The population was consecutive adults (aged 18 years and older) with suspected PE, for whom a D-dimer blood test and/or imaging for PE (CTPA or VQ scan) was performed in the ED. When a patient books into the ED, the triage nurse assigns a chief complaint from a selection of predefined categories, classified based on the Canadian Emergency Department Information Systems (CEDIS)Presenting Complaint List.
10 D-dimer blood test is used to diagnose both deep vein thrombosis and PE, so to ensure we captured only patients tested for PE (and not deep vein thrombosis), we aimed to restrict our population to those who presented to the ED with the presenting complaint “chest pain” (cardiac and non-cardiac) and/or “shortness of breath.” To evaluate whether a sufficient proportion of all patients tested for PE were registered under these two presenting complaints, we retrieved a list of CTPAs ordered in the ED in 2018. We manually extracted the presenting complaints for each case. We aimed to capture a minimum of 80% of the CTPAs ordered in the ED.
Implementation.
We led a Canadian Association of Emergency Physician (CAEP) working group consisting of six emergency physicians from across Canada with expertise in PE diagnosis and knowledge translation. This knowledge broker group systematically reviewed the literature and identified all optimal PE diagnostic strategies for the ED, as well as optimal ways to encourage adherence to this diagnostic strategy. As a result, we decided to test a multimodal intervention aimed at promoting the uptake of D-dimer in everyday clinical practice. The implementation strategy is based on the knowledge translation recommendations from CAEP.
11 The components of the intervention are detailed in Table
1. This implementation strategy was discussed at each site by engaging with local champions, hospitals managers, nurses, diagnostic imaging staff, support staff, and physicians to identify and implement strategies to overcome local barriers.
Table 1
description of the components of the intervention.
Leadership endorsement We obtained approval from the clinical and managerial leads for the ED, radiology, hematology and thrombosis for a new protocol for the diagnosis of PE. |
Ordering D-dimer and CTPA/VQ scan We moved from the concept of ordering D-dimer or imaging for PE, to the broader concept of “testing for PE”. We created a new order set (Appendix A) which guides ED testing for PE. The new diagnostic PE pathway starts with D-dimer blood testing in all patients. We no longer asked the physician to calculate the Wells score to simplify the process and to avoid having physicians artificially increasing the score in order to avoid using D-dimer. The testing process has been semi-automated. If the D-dimer result is lower than the threshold, the attending physician is notified by the nurse and PE is excluded. If the D-dimer result is higher than the threshold, the patients goes directly for a CTPA without the need for physician reassessment. The physician is notified when the imaging report is available. We made the new PE diagnostic pathway attractive to use by enabling ordering of CTPA without the requirement to first discuss with a radiologist. |
Physicians education We met with the ED physicians and nurses with educational material to support the use of the proposed diagnostic workflow. |
Personalized confidential physician feedback We sent each physician a quarterly confidential personalized report containing the following: The proportion of eligible patients (based on the presenting complain) who had an imaging test, expressed as a percentage: (number of exams requested)*100/(total number of eligible patients) The proportion of imaging tests ordered without D-dimer or despite a negative D-dimer, expressed as a percentage: (number of cases in which the algorithm has not been followed in patients receiving imaging)*100/(total number of imaging test performed) These metrics were calculated for the individual physician, and compared to the average of all the physicians working in the same ED. The form was piloted with some of the study clinical investigators (the research manager and two ED physicians with expertise in quality improvement and knowledge translation) and then with a convenience sample of four physicians. The form was modified according to their feedback. |
Patients information We developed patient information about the testing process, as well as the risks and benefits of undergoing CT scanning. Moreover, the PE testing order set incorporated nurse facilitated identification of patient-specific goals (for example treatment of pain) so the treating ED physician can focus their treatment and advice on patient-specific needs. |
ED: emergency department; PE: pulmonary embolism; CTPA: computed tomography pulmonary angiography. |
Comparison and timelines
A flow chart describing the timeline is reported in Fig. 1. Data on baseline clinical practice were collected from January 1, 2018 to October 31, 2019. The intervention was implemented in November 2019. Data on the period after the comparison were collected starting in December 2019. For the purpose of this report, we present the post-implementation data up till the end of February 2020.
Outcomes
Primary outcome - feasibility:
Feasibility was described using 6 criteria:
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1. Implementation of the new diagnostic PE protocol at the participating hospitals (yes/no for each centre). To consider the intervention feasible, it should have been implemented in at least two of the three participating sites.
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2. Electronic identification of our population of interest capturing ≥ 80% of all CTPAs ordered in the EDs.
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3. Establishing access to the required electronic data with monthly data updates (yes/no).
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4. Timely manual chart data extraction. To be considered feasible, the data extraction had to be completed five days before the end of the following month ≥ 80% of the times.
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5. Implementation of individual emergency physician audit and feedback. To be considered feasible, we required that feedback data on the previous month was complete before the end of the following month ≥ 80% of the time.
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6. An estimate of the number of hours of research assistant time to extract the required data and synthesize the physician feedback reports (total number of hours per week). To be considered feasible if ≤ 2 days/week.
Secondary outcomes - preliminary estimates of effect:
The outcomes used for the preliminary estimate of the effect of the intervention were the following:
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a. Proportion of patients tested for PE among the whole study population.
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b. Proportion of patients tested for PE in adherence to the protocol among the total number of patients tested for PE.
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c. Proportion of eligible patients with an imaging test.
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d. Diagnostic yield of imaging tests requested: (number of exams positive for PE)*100/(total number of exams requested).
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e. Proportion of imaging tests ordered without D-dimer or despite a negative D-dimer: (number of cases in which the algorithm was not followed in patients receiving imaging)/(total number of imaging test performed)
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f. Proportion of imaging tests not ordered, despite D-dimer positivity: (number of cases in which imaging was indicated and not performed)/(total cases in which imaging was indicated)
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g. We also described the prevalence of PE, as follows: All PEs, central PE (segmental or more), and distal PE (Sub-segmental).
Balancing measure:
A before-after comparison of the number of D-dimer blood tests ordered in the ED.
Analysis
Baseline patient characteristics and the feasibility measures were reported using standard descriptors of central tendency and variability (mean and standard deviation or median and ranges as appropriate). The secondary outcomes regarding effect and balancing measure were reported descriptively, with the 95% confidence intervals (CIs) for the proportions’ differences. To facilitate visual inspection, the outcomes were also plotted against time with two regression lines, before and after the intervention. All the analyses were conducted with STATA/IC v. 16 (StataCorp LP, College Station, TX, USA).
Ethics
Research ethics approval was obtained from participating sites prior to commencing the study (Hamilton Integrated Research Ethics Board # 5339-C).