Independent variable: Interprofessional teams with and without acute care nurse practitioners.

A dichotomous variable will be created to measure the inclusion of at least one ACNP within the interprofessional team. For patients under the care of an interprofessional team with ACNPs, an additional descriptive variable will measure the number of days where the ACNP was involved in the daily follow-up of the patient, on the entire hospitalization at the postoperative cardiac surgery unit.

Dependant variable: The level of adherence to best-practice guidelines by interprofessional teams.

A total of 12 best-practice guidelines will be included in this project (Fig 1). All best-practice guidelines are divided into three categories: 1) pharmacotherapy (n = 4), 2) laboratory tests (n = 4), and 3) postoperative assessment (n = 4).

Four best-practice guidelines are included in the category of pharmacotherapy. These guidelines are the prescription and relevant monitoring of medications including: 1) anticoagulants, 2) beta blockers, 3) lipid-lowering agents, and 4) anti-platelets, during hospitalization and at hospital discharge of the patient. The adherence to these four guidelines is defined by the prescription (e.g., beta blocker) and relevant monitoring (e.g., assessment of the blood pressure) of those four medications on a daily basis during the patient’s hospitalization and at discharge. For each best-practice guideline, two additional descriptive variables will be collected, including the type of medication prescribed and the presence of a contraindication, which precludes the possibility of achieving the guideline recommendation (e.g., allergy).

Four best-practice guidelines on laboratory tests are included, recommending the prescription and monitoring of the following: 1) potassium (K+), 2) magnesium (Mg+), 3) serum glucose, and 4) international normalized ratio (INR) by interprofessional teams during the patient’s hospitalization in the postoperative cardiac surgery unit. The achievement of each best-practice guideline recommendation will be confirmed if the laboratory result falls under the normal range supported by the current literature. The monitoring of laboratory tests also includes the interventions conducted by clinicians to ensure the laboratory test values remain within the normal range, such as routinely ordering laboratory tests, assessing laboratory tests to confirm normal values and detect any abnormal values, and performing pharmacological and clinical interventions to address abnormal laboratory test values. An additional variable called “no INR needed” will be added specifically for the best-practice guideline related to the prescription and management of INR, to take into consideration patient who don’t need a strict INR follow-up (e.g., administration of direct acting oral anticoagulant (DAOC)). A pilot-test will be performed to assess the characteristics of the patients hospitalized at the post-operative cardiac surgery unit and the feasibility of the data collection. The following three additional descriptive variables will be measured for each guideline: 1) number of prescriptions requested by interprofessional teams, 2) proportion of abnormal values below or above normal range, and 3) average of all values of laboratory tests.

Four best-practice guidelines are included in the category of the postoperative assessment performed by interprofessional teams. A daily assessment of the patient’s level of pain, surgical wound(s), nutrition, and mobilization will be measured. For each best-practice guideline recommendation, the achievement of the guideline will be confirmed if at least one postoperative assessment per day is performed by the ACNP or other members of the interprofessional teams during the patient’s hospitalization in the postoperative cardiac surgery unit. The postoperative assessments include the assessment of the clinical manifestations, signs, and symptoms experienced by the patient (e.g., patient’s decrease mobility), as well as the interventions conducted by clinicians following these assessments. Interventions include pharmacological interventions (e.g., prescription of analgesic), non-pharmacological interventions (e.g., prescription of a coronary diet), and clinician consultations (e.g., consultation with the nutritionist). Two additional descriptive variables will be measured for each best-practice guideline, including: 1) the total number of postoperative assessments performed by interprofessional teams during the hospitalization, and 2) the type of associated interventions conducted by clinicians (e.g., non-pharmacological, consultation, etc.).

A composite score will be developed to measure the level of adherence to best-practice guidelines by interprofessional teams with and without ACNPs. A composite score per patient per day of hospitalization in postoperative cardiac surgery will be developed and based on three consecutive steps. Firstly, for each best-practice guideline, a score on a scale of two will be created and points will be attributed for: 1) the achievement of the best-practice guideline recommendation, and 2) the associated intervention performed by clinicians. Points will be given based on the information contained in the patient’s health record and electronic databases. A missed intervention will be considered as a lack of adherence to best-practice guidelines, and no point will be given.

Secondly, an overall composite score will be calculated from the sum of all the scores of all best-practice guidelines (n = 12), ranging from zero to 24. The overall composite score will be transformed into a value in percentage ranging from 0 to 100% (i.e., composite score/24 * 100), such that 100% represents a complete adherence (24/24). An increase of the score will be associated with an increase of the level of adherence to best-practice guidelines by interprofessional teams. An overall score will be calculated per patient per each day hospitalized in the postoperative cardiac surgery unit.

Finally, an average composite score will be calculated from the average of all overall scores during the patient’s hospitalization at the postoperative cardiac surgery unit. An average composite score will be calculated for all patients included in the retrospective cohort.

Variables influencing the effect of acute care nurse practitioner practice related to patient characteristics.

Eleven influencing variables related to patient characteristics will be measured. For each patient, sociodemographic characteristics (e.g., sex, age) will be measured. The total length of stay at the hospital will be measured, which includes the stay in the ICU and postoperative cardiac surgery unit. The type of cardiac surgery will be collected from a categorical variable with three categories: 1) CABG, 2) valve repair, and 3) CABG/valve repairs. Comorbidities will be measured and operationalized from the Charlson Comorbidity Index (CCI) [44, 45]. A total score of 24 points will be calculated for each patient based on the 17 clinical conditions included in the CCI (S4 Appendix). The length of stay in the postoperative cardiac surgery unit will be collected for each patient. The hospital 30-days readmission at the postoperative cardiac surgery unit after discharge will be measured for each patient from a dichotomous variable.

Four influencing variables related to the patient characteristics in the ICU setting will be measured. The total number of hours hospitalized in the ICU will be measured from the time (in hours) of admission to the ICU after the surgery and the time (in hours) of discharge of the patient. The postoperative prolonged mechanical ventilation will be measured from a dichotomous variable. A prolonged mechanical ventilation will be confirmed if the time under mechanical ventilation exceeds 24 hours. The failed extubation of the patient and reintubation after first extubation will be measured with a dichotomous variable. The number of episodes of ICU readmission after initial discharge will be measured for each patient.

Variables influencing the effect of acute care nurse practitioner practice related to interprofessional teams’ characteristics.

Two influencing variables related to interprofessional teams’ characteristics will be measured. First, the cardiac surgeon who performed the surgery and ensured the follow-up of the patient’s recovery will be noted. A confidential code will be created for each surgeon practising in the UHC. Second, a discrete variable will be created to measure the number of consultations conducted by clinicians from different professional groups (e.g., nutrition, rehabilitation team) during the patient’s hospitalization in the postoperative cardiac surgery unit. A categorical descriptive variable will be created to measure each clinician’s professional group, including the following: 1) rehabilitation team (e.g., physical therapist, occupational therapist), 2) respiratory therapist, 3) social worker, 4) skin and wound care therapist, 5) nutritionist, and 6) speciality consultation (e.g., internal medicine, nephrology).

Data collection for the content validation.

Content validation will be performed to assess the clinical relevance and the representativeness of the practice of interprofessional teams in post-operative cardiac surgery setting of the items of the extraction tool. Content validation will follow two steps [46]. First, an expert committee will be recruited from clinicians, managers, and researchers who have expertise in postoperative cardiac surgery. The identification and recruitment of experts will be conducted by our research team and will include experts in Canada. A total of 10 experts will be recruited, including at least the following five: 1) an ACNP who worked a minimum of one year within a postoperative cardiac surgery unit outside of our associated UHC, 2) a cardiac surgeon or fellow in cardiac surgery who worked at least two years in an acute care centre outside of our associated UHC, 3) a nurse manager who has led for at least one year, a postoperative cardiac surgery unit, within our associated UHC, 4) a healthcare professional who worked in the data warehouse of our associated UHC for at least one year, and 5) a researcher in nursing or healthcare sciences with an expertise in measurement instruments and/or cardiac surgery.

Second, an electronic survey [47] will be created and sent to each expert of the committee. The survey will be composed of all items of the extraction tool (best-practice guidelines and confounding variables). For each item, experts will assess its relevance using a 5-points Likert scale [48, 49]. Additional spaces for qualitative comments and suggestions will be included in the survey. Two rounds of revision are planned. After the first round, our team will update the extraction tool and revise any unclear items based on the experts’ recommendations, and an updated version will be resubmitted to the expert committee.

Data collection for the criterion validation.

The criterion validation of the extraction tool will follow two consecutive steps. Firstly, the best-practice guidelines of The Society of Thoracic Surgeons (STS) have been selected as the gold standard of comparison for this study. For many years, the STS has been a leading healthcare organization in the development and validation of best-practice guidelines and performance measures in the care of patients in cardiac surgery settings [10]. In 2007, the STS developed and validated 21 performance measures for the delivery of high quality of care for patients who underwent CABG, valve repair, and CABG/valve repairs [50, 51]. For this project, five performance measures were selected, including: 1) prolonged mechanical ventilation higher than 24 hours in the ICU; 2) a 30-day readmission rate at the postoperative cardiac surgery unit after hospital discharge; and prescription of the 3) anti-platelet, 4) beta blocker, 5) and lipid-lowering agent, during the hospitalization at the postoperative cardiac surgery unit and at discharge. Each performance measure is operationalized as the proportion of patients who achieved the outcome (e.g., proportion of patients who were under prolonged mechanical ventilation) over the total sample size [46, 47].

Secondly, 30 patient health records will be reviewed independently by two reviewers on two occasions, including the first author and a research assistant. For the first round of revision, the patient’s health record will be reviewed with the extraction tool. For the second round of revision, the records will be reviewed with the five performance measures from the STS.

Data collection for the pilot-test.

A pilot-test will be conducted to assess the feasibility of using the tool, standardize data collection among reviewers, examine the quality and accessibility of the retrospective data, and update the tool if needed. Four iterative steps will be included in the pilot-test [52–55]. First, two reviewers will conduct the pilot-test and data collection. Training sessions and documentation will be given to the reviewers.

Secondly, 30 patient health records from hospitalized patients in the postoperative cardiac surgery unit between January 1, 2019, and January 31, 2020, will be randomly selected. These patients will not be included in the retrospective cohort. Data will be collected by the two reviewers with the extraction tool. Inter-rater reliability will be assessed and a Cohen kappa higher than 0.60 will be targeted [55].

Thirdly, a triangulation of the available data will be performed to assess the quality and accessibility of the data. Multiple data sources will be screened between the electronic databases and patient health records. Items from the extraction tool with a high quantity of missing data or low quality of available data will be modified or removed.

Finally, frequent meetings among all research team members will be conducted to discuss divergences, reinforce convergences, and establish a consensus. The extraction tool will be updated after the pilot-test if needed [52].

A calibration session among the reviewers will be conducted during the data collection from the main retrospective cohort. A total of 30 patient health records will be reviewed by two independent reviewers [49, 50]. Inter-rater reliability will be assessed and a Cohen Kappa value higher than 0.60 will be targeted [55].

Objective 1.

For the content validation [56, 57], a Fleiss Kappa will be calculated for each round of revision and a value between 0.60 and 0.80 will be targeted [48, 49]. The content validity index (CVI) of each individual item of the extraction tool will be calculated from the proportion of experts who rated a score of 4 or 5 on the Likert scale [58]. A CVI of 0.80 will be targeted for each item and items with a value below 0.80 will be removed or modified. Then, the proportion of items with a CVI value above 0.80 will be calculated to determine the overall CVI of the extraction tool. A value higher than 0.80 for the overall CVI of the extraction tool will be targeted [46]. Qualitative comments and recommendations by experts will be analyzed by content analysis [59].

For the criterion validation, Spearman correlation will be calculated to assess the correlation between the measures of the gold standard (e.g., the performance measures of the STS), and the measures of the extraction tool. Values of Spearman correlation higher than 0.70 will be targeted [48, 49].

Objective 2.

Descriptive analysis will be performed to assess the level of adherence by interprofessional teams with and without ACNPs, as well as the confounding variables for patients under the care of both teams [60]. A graphic illustration will be created to visualize the tendency and distribution of the level of adherence to best-practice guidelines by interprofessional teams with and without ACNPs. An analysis of missing data will be conducted to examine the quality and distribution of missing data within patient health records and electronic databases. Team meetings and consultations with clinicians and statisticians will be held to discuss and identify potential causes of missing data, as well as to conduct a statistical analysis to manage them [61]. Bivariate analysis will be conducted, and the statistical significance will be based on a p-value of 0.05 [60]. The Bonferroni correction will be applied for the examination of each confounding variable related to the patient and interprofessional teams’ characteristics [62].

Objective 3.

A multivariate linear regression model will be developed to examine the association between interprofessional teams with and without ACNPs and the level of adherence to best-practice guidelines [63–65]. An examination of the distribution of the data will be performed. In the case of an abnormal distribution of the data, a transformation will be conducted to adjust the statistical model based on the observed data. The independent variables will include the interprofessional teams with and without ACNPs, as well confounding variables. A correlation matrix will be developed, and tolerance value lower than 0.2 and a variance inflation factor (VIF) value higher than 5 will be used to identify multicollinearity between independent variables [63–65]. Independent variables with multicollinearity will be removed one at the time and a new regression will be calculated. The dependent variable of the regression model will be the average composite score (%) of the level of adherence to best-practice guidelines. Statistical significance will be based on a p-value of 0.05. Sensitivity analysis will be conducted based on a selection of confounding variables related to the characteristics of the patient (e.g., length of stay, ICU readmission). The selection of these confounding variables will be based on the observed data and descriptive analysis. The residual analysis and the analysis of the R² will be conducted to assess the goodness-of-fit of the multivariate linear regression model.