Biostatistics applications in surgery, anesthesiology, and emergency and critical care medicine Clinic Notes (2021)

2021 December 08

Melanie Whitmore, Pharmacy

  • This is a retrospective study assessing 2 groups - weight based versus non-weight based vasopressor doses (norepinephrine, epinephrine) - on time to achieve MAP goal, length of hospital stay, various other end points. Data collected and previously analyzed. Pursuing VICTR statistics voucher. VICTR Biostatistics voucher.
  • Meeting Notes:
    • Data has already been collected
    • Primary endpoint: time to achieve MAP goal (achieve MAP and keep it for 1 hour)
    • Secondary endpoints: all-cause mortality, length of ICU stay
    • Limitations: small sample size; confounders
    • Comparison: everyone used weight-based dosing, then everyone switched to non-weight-based dosing
  • Recommendations:
    • Can be a VICTR project
    • Consider the actual provider behavior (did they use weight-based when supposed to?)
    • Could do an interrupted time series analysis
    • Could just do a 2-group comparison (and not consider time)

2021 December 01

Clay Smith, Emergency Medicine

  • In the Vanderbilt Health Clinic at Walgreens locations in middle Tennessee, we employ medical assistants (MA) or patient service specialists (PSS) to staff the front desk and to welcome and register patients. The 14 locations follow a staffing model that includes only one MA/PSS and one advanced practice provider (APP). At times, the MA/PSS may not be available to work due to illness or other reason. In these cases, the APP works alone and has to perform the function of both registering patients and seeing them as the clinician. This creates the opportunity for a natural experiment: to compare average patient volume on days when an MA/PSS is present versus days in which only an APP is present. We have preliminary analytics QA data that indicates that patient volume is higher on days in which an MA/PSS is present. This has very important clinical and economic implications. There are currently no published analyses that address this. This could be beneficial for other health systems who operate retail health clinics as they consider various staffing models and the economic implications. VICTR Biostatistics voucher.
  • Meeting Notes:
    • Aim: Identify associations between the availability of an MA at a clinic and productivity metrics of satisfaction, wait times, walk out rates
    • Outcome: satisfaction
    • Primary predictor(s): clinic; MA or not; who the APP was
    • Covariates: wait times; walk outs
  • Recommendations:
    • Recommended to apply for VICTR voucher

Stephanie Patterson, Pediatric Critical Care

Previous clinic session Wednesday, November 17, 2021.
  • Going over statistics for PICS in children study. At previous clinic told to request Chris Lindsell.
  • Recommendations:
    • Either remove p-values from Table 1, or also add effect size to the table
    • For categorical variables, run 1 test (Fisher’s exact test is fine)

2021 November 17

Mary Cella (Jennifer Beavers, Susan Hamblin), Pharmacy

Previous clinic session Thursday, October 7, 2021.
  • Our project is titled “Safety of NSAID Use in Traumatic Brain Injury.” It is a retrospective study that will have a matched cohort. Our study question is “Does NSAID use within 14 days of injury in patients with TBIs lead to significant increase in intracranial bleed compared to patients who did not receive NSAIDs?” Data collection will be accomplished via chart review, Health IT data pull, TRACs, and Neurotrauma Registry (IT data pull points submitted to be collected). VICTR Biostatistics voucher. Mentor confirmed.
  • Meeting Notes:
    • Currently have an IT team working on a data pull at Vanderbilt
  • Recommendations:
    • Propensity score model for getting an NSAID
      • Then given someone is treated with NSAIDs, compare the outcomes
      • Need all variables that would be potential factors of provider reasoning for giving NSAIDs
    • Work on the statistical analysis plan and apply for a VICTR voucher
    • If looking for another data source, could look into Track TBI (

Ryan Stark (Stephanie Patterson), Pediatric Critical Care

  • We are assessing the correlation of an immunosuppressed phenotype in septic pediatric deaths compared to non-immunosuppressed septic deaths. We are looking at global demographic/location differences between the groups, prediction of labs values to development of immune phenotype and odds ratio of fungal infections. We have completed all the analysis but would like verification that we did the statistics right as well as a coauthorship for statistical credence. VICTR Biostatistics voucher.
  • Meeting Notes:
    • Has already done some stats, but would like to make sure the statistical approach is sound
  • Recommendations:
    • Many subjects without PICS are not eligible to have PICS (because they die before day 14), so a time-to-event analysis might not be the best approach
      • Want to focus on developing PICS, not morality
    • P-values in table 1: okay to include, but also include a difference in groups (absolute difference) and the confidence interval
    • Sign up for another clinic so we can look through more of the methods / statistical approach together

2021 November 10

Brad Guidry (Silky Chotai), Neurosurgery

  • Trends project using the National Inpatient Sample: Do neurosurgeons opt to perform surgery on elderly adults more often now than they did previously, after accounting for changes in disease incidence or life expectancy? Are the trends similar across different subspecialties, elective vs. emergent cases, and academic vs. urban vs. rural centers? VICTR Biostatistics voucher. Mentor confirmed.
  • Meeting Notes:
    • Main question: Do neurosurgeons opt to perform surgery in elderly adults (> 80 years old) more often now than they did previously, accounting for some covariates?
    • Using the National Inpatients Service (NIS) database from 2013 - 2018
    • Hypothesis: trends in neurosurgical intervention in elderly patients differ by disease process
  • Recommendations:
    • To look at the trends for each disease process, use graphical presentations
    • Recommended to apply for a VICTR voucher

Matthew Rohlfing, Otolaryngology/Vanderbilt Voice Center

  • Planning a randomized, controlled trial to determine the true efficacy of superior laryngeal nerve injection for treatment of chronic cough. This is a procedure routinely performed at the Voice Center. We plan to test against a placebo injection. Would like to discuss sample size and statistical plan. VICTR Biostatistics voucher.
  • Meeting Notes:
    • 2 surveys:
      • A weekly survey w/ 10 items
      • A survey every 3 weeks w/ 28 items
    • Expecting: around N = 15-20 per arm

  • Recommendations:
    • Reduce CSI survey to once every other week instead of weekly
    • Need to create a clear hypothesis
    • To get sample size calculations, need to think about minimum impact size

2021 November 03

Chiara Foster (Kristina Betters), Pediatric Critical Care

  • This project is a secondary cost analysis comparing the cost to hospital of each of the 2 arms (sedation weaning protocol and no sedation weaning protocol). One specific question is if the study is powered well enough with 49 in one arm and 47 in the other. Another question is the best way to compare the difference in cost. VICTR Biostatistics voucher. Mentor confirmed.
  • Meeting Notes:
    • Original analysis looked at the duration of days of weaning of sedation medicines with an interrupted time series
    • Now want to look at the comparison between price charged to hospital pre-intervention vs post-intervention
  • Recommendations:
    • Apply for a new VICTR voucher
    • Can use non-parametric tests for unadjusted analyses
    • Can use a proportional odds model for adjusted analyses

2021 October 27

Patricia Andrews (Jo Ellen Wilson), Psychiatry

  • Our project is a secondary data analysis in which we want to investigate if the presence of catatonia, delirium, coma, catatonia + delirium, catatonia + coma or none of the above (no brain dysfunction) during hospitalization in critically ill patients is associated with worsening depression or PTSD scores at 3 or 12 months. We want feedback on our proposed analysis plan to submit for a VICTR voucher application. VICTR Biostatistics voucher. Mentor confirmed.
  • Meeting Notes:
    • A daily assessment of catatonia is done on any day that a coma assessment or delirium assessment is done
    • Delirium and coma cannot occur at the same time
    • Catatonia can occur with delirium and with coma
  • Recommendations:
    • Need to define exposures explicitly
      • Combine coma + delirium on an ordinal scale (coma, delirium, neither)
    • This takes us to 2 independent variables instead of 3 and improves the ability to extract information about catatonia
    • Could calculate days alive without catatonia + delirium + coma and days alive without coma or delirium and compare models

Kevin Patel (Daniel Byrne), Neonatology

  • My project involves developing and validating a model that predicts the number of days until discharge. My project has IRB 210173, and have obtained raw data from the EHR. I am seeking assistance in processing the data into the final spreadsheet prior to developing the predictive model. VICTR Biostatistics voucher. Mentor confirmed.
  • Meeting notes:
    • Outcome: Days until discharge (continuous)
    • Historical cohort with ~800 patients and 66 variables believed to be important in this prediction
    • Some variables are measured daily, some only at baseline, some multiple times a day, and some only if the patient is in a certain condition
      • Issue: missingness is not random
    • Infants need to meet certain milestones before being considered for discharge
  • Recommendations
    • This is currently too much for a VICTR voucher
    • One idea is to try to understand the milestones first, before jumping into the full prediction model
    • Can also investigate how each variable affects each patient’s trajectory

2021 October 06

Drew Johnson (Robert Tunney), Pharmacy

Previous clinic session Thursday, Sept 16, 2021.
  • This is an epidemiological, observational study to establish the prevalence of iron-deficiency in hospitalized advanced heart failure patients with elevated ferritin as assessed by reticulocyte hemoglobin equivalent. Hospitalized advanced heart failure patients who are being evaluated for or planned to undergo cardiac surgery will be followed via chart review to identify individuals with elevated ferritin (>300 ng/mL). Patients will be followed via chart review to identify the administration of intravenous iron and/or completion of cardiac surgery per the primary team. Final reticulocyte hemoglobin equivalent, ferritin, and transferrin saturation will be subsequently evaluated prospectively as a study procedure. We would like assistance in identifying and refining our statistical analysis plan in light of our discussion on 9/16. Mentor confirmed.
  • Meeting Notes:
    • Main research question: In patients with high ferritin levels, should we proceed with iron repletion based on another biomarker (reticulocyte hemoglobin)?
    • Hypothesis: the current iron screening is not catching everyone that is truly iron deficient
    • Have two different endpoint times for those who had surgery vs those who did not have surgery
  • Recommendations:
    • Might want to consider the subjects who have low ferritin levels in order to compare normal/abnormal ferritin with normal/abnormal reticulocyte hemoglobin
    • To address the different endpoints:
      • Could measure everyone at discharge, or
      • Can adjust for the time between baseline and follow up
        • This would not work if all non-surgery times are the same (ex. 5 days) and all surgery follow-up times are the same (ex. 28 days)

Morgan Sexton (Jo Ellen Wilson), School of Medicine/Psychiatry

  • While admitted to VUMC ICUs, patients were evaluated for presence of catatonia daily. At 3 and 12 months following hospital discharge, they returned to VUMC for an in-person assessment of cognitive impairment using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), which produces a global index score (outcome, continuous). Covariates that have been recorded and we hope to account for are age, race, education level, diagnosis at admission or reason for ICU admission, comorbidities (Charlson comorbidity index), baseline cognition (Short IQCODE), mean modified SOFA score, days of severe sepsis, duration of hypoxemia, days of delirium, and days of coma. The question we would like to address: Is a longer duration of catatonia (days) while in the ICU independently associated with more severe cognitive impairment at three and twelve months following discharge? VICTR Biostatistics voucher. Mentor confirmed.
  • Meeting Notes:
    • Hypothesis: A longer duration of catatonia while in the ICU is independently associated with more cognitive impairment during the first year following discharge
    • Exposure: days of catatonia
    • Outcome: cognitive status (based on a continuous scale) measured at 3 and 12 months
      • Do not have a baseline measurement
    • It is known that delirium is highly associated with catatonia

2021 September 29

Adam Evans (Salam Al Kassis), Plastic Surgery

  • We plan to use a national database of outpatient surgery data to investigate specific surgeries for complications and risk factors, disparities, and procedural cost. VICTR Biostatistics voucher. Mentor confirmed.
  • Meeting Notes:
    • Have a few different aims using the same data:
      • Risk factors of different complications
      • Disparities in access to health care
    • Focus is on two types of surgeries: gender affirmation surgery and migraine surgery
  • Recommendations:
    • Clearly lay out which projects/aims you want to focus on
    • Describe each of the outcomes
    • Prespecify any confounding variables and make sure you have them in your dataset
    • It is recommended to apply for a VICTR voucher

Sandra Kikano (Dan Byrne), Pediatric Cardiology

  • Analyzing genomic data in relation to acute kidney injury after congenital cardiac surgery. Best way to form a retrospective logistic regression model? Mentor confirmed.
  • Meeting Notes: There are 6 candidate genes for adults in cardiac surgery (from the literature), though there is not much known on pediatrics
  • Recommendations:
    • Prespecify a short list of genes to look at, but maybe a little longer list than the 6 currently selected
    • Can look at comparing AKI vs non-AKI with a logistic regression
    • Also look at non-genetic predictors of AKI

2021 September 22

Kimberly Rengel (Chris Hughes), Anesthesiology

  • I am conducting a study collecting ultrasounds of skeletal muscle in critically ill patients at multiple time points during their hospitalization. I would like to perform a correlation analysis between myself and another investigator for inter-rater reliability in both performing the ultrasounds and measurements. Mentor confirmed.
  • Meeting Notes:
    • Goal is to measure the replicability in both performing the ultrasounds and measurements
  • Recommendations:
    • Separate the study into the two main questions: ultrasounds and measurements
    • For the ultrasound question, have two people do ultrasounds with 1 third-party person doing the measurements
    • For the measurement question, have one third-party person do the ultrasound with 2 people doing the measurements
    • For both questions, can look at Bland Altman plots and use Deming regression
      • Can get the limits of agreements from Bland Altman
    • In general, the bigger the sample size, the narrower CIs you will get

2021 September 15

Amany Alshibli (Bantayehu Sileshi), Anesthesiology

  • We conducted a retrospective cohort study of surgical case data from two hospitals in Ethiopia to describe surgical care and outcomes during the initial COVID-19 lockdown. We are undergoing manuscript revision process and I wanted to clarify and confirm my interpretation of several items that were brought up including: my interpretation of a segmented regression analyses that we have performed, testing for interaction in subgroups, and adjusting for multiple comparisons. Thank you! Mentor confirmed.
  • Meeting Notes:
    • Goal of today’s clinic is to review some revisions from a manuscript submission to clarify interpretations on interactions terms, adjusted p-values, and a figure

  • Recommendations:
    • When looking at the interaction term in the Poisson model, exponentiate the coefficient to get a ratio. To check the interaction term, run 2 models: one with the interaction and one without, then run a Likelihood Ratio test to compare the 2 models
    • Although the reviewers suggested adjusting the p-values, Wu thinks it is still reasonable to defend not doing this in the limitations
    • For Figure 1, might be able to drop the segmented regression part and just plot 4 different time periods
      • For the model, include a categorical variable for the 4 time periods, and report the contrasts
    • Recommended to work with Wu outside of clinic on some answers for the revision

2021 September 08

Livia Linden (Julie Sinclair-Pingel), VCH Pharmacy

  • We’re comparing the effects of fenoldopam to low-dose dopamine on renal perfusion. We’d like to discuss power calculations and what statistical tests we might be able to run based on the data we’re planning to collect. Mentor confirmed.
  • Meeting Notes:
    • Fenoldopam has been the standard, but it is more expensive than dopamine
    • They have sent out some educational materials to the doctors showing how the drugs are similar (hoping this will get more doctors to prescribe dopamine)
    • Primary outcome: change in urine output
    • Guessing they will have about 20 patients for each drug by the end of data collection

  • Recommendations:
    • Need to justify the time interval you are collecting the urine for (hourly gives you more info)
    • Look at trajectory of the urine output and see what happens over time
    • Hypothesis: that the drugs are similar (instead of saying that one is better or worse)
      • Stated that a meaningful clinical difference would be .3 in urine output
      • Would need a standard deviation to calculate the sample size needed

2021 September 01

William Quach (Alexander Langerman), Center for Biomedial Ethics and Society

  • We are looking at what topics are most important to patients when it comes to residents involved in their surgery. We developed a survey and have piloted it on participants on mechanical turk and would like assistance with a statistical analysis plan and how to properly power the survey. VICTR Biostatistics voucher. Mentor confirmed.
  • Meeting Notes:
    • Research question: What are the most important topics that patients want to know about the residents involved in their surgery during the informed consent process?
    • Overall goal: educate surgeons on how to talk to patients about residents being in their surgery
    • An online survey asking people to rank how important questions about a resident are (on a scale of 0-100) and to pick their top 5 more important questions
  • Recommendations:
    • When presenting percentages, also include the numerator and denominator to clarify what the percentages are of
    • The online survey is most likely biased. Check to see if the respondents are a good reflection of the general US surgical population (if not, could do some matching)
    • Overall, this is mainly a descriptive study
    • Look at box plots or violin plots of each question ranking to view the distributions
    • Can do a non-parametric difference test (Wilcoxon sign rank test) to compare the comfort question pre and post quote
    • Recommended to apply for a VICTR voucher. Start by writing the protocol and laying out the core questions. We can help with the statistical analysis plan.

Caitlin Jacowski (Uchenna Anani), Neonatology

  • I have met before with the statisticians, but wanted to clarify questions about sample number. VICTR Biostatistics voucher. Mentor confirmed.
  • Meeting Notes: Surveys have already been sent out and responses are back. Among the 3 sub-specialties, the responses are N = 36, N = 36, and N = around 350. The survey questions are all Likert scale answers (some 4 point and some 5 point).
  • Recommendations:
    • Since the responses are already in, a power calculation is irrelevant. Instead, mention the kind of signal that can be found with the known sample size. While applying for a VICTR voucher, we can help with these specific numbers.
    • Start by writing out 3 or 4 key questions you want to answer
    • We can start with a Kruskal Wallis test to test for overall differences
    • Then we can look at scatterplots to evaluate associations for each pairing of sub-specialty

2021 August 18

Jed Maslow, Orthopaedic Surgery

  • Examine our institutional experience with pedicled groin flaps or upper extremity and hand soft tissue coverage. VICTR biostatistics request.
  • Clinic Notes:
    • Biggest question to answer: How many surgeries do these patients need? This tends to be many patients’ question; wanting to know how long to expect the full process to take.
    • Choose an outcome that is powerful and makes sense (maybe try creating an ordinal outcome starting with number of procedures and including amputation and death in the outcome). Try to avoid binary outcomes and rare outcomes.
    • Think about what variables you care about most. This will be important with the smaller sample size.
    • Can apply for a VICTR voucher for help.

Peter Edmonds (Carla Sevin), Pulmonary/CC

  • Retrospective cohort of pulmonary function after COVID-19. Data includes lung volumes, diffusion and comorbidities. VICTR Biostatistics request. Mentor confirmed.
  • Clinic Notes: Currently have a very selective group of subjects (those with a PFT sometime before they got COVID and at least one after COVID). Main research question: Is decreased lung function associated with having COVID?
  • Recommendations:
    • A case-control study by getting a matched cohort that looks the same as the N = 88 COVID cohort, but without COVID
    • Recommended to apply for a VICTR voucher.

2021 July 21

Kristina Betters, Pediatric Critical Care

  • Pilot RCT assessing the effects of dexmedetomidine (sedative) on sleep architecture. Subjects will be enrolled for 2 nights with sleep study performed both nights, will increase dose of dexmedetomidine on study night and assess changes in time in different sleep phases. VICTR biostatistics request.

2021 June 30

Alex Wells (Austin Kirschner), Radiation Oncology

  • Renal Cell Carcinoma (RCC) is a cancer originating from the renal epithelium that accounts for 85-90% of cancers in the kidney. Patients with localized RCC are often primarily treated with surgery, however patients with metastatic RCC often require other treatment modalities, such as immunotherapy and radiation. RCC was previously believed to be a radio-resistant cancer with conventional radiation therapy techniques demonstrating little success in the treatment of primary and metastatic disease. However, advances in radiation therapy, namely the use of stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT), have emerged as effective treatment options for patients with metastatic RCC. Recent studies have demonstrated that SRS and SBRT provide strong local control and pain palliation rates in the treatment of patients with metastatic RCC.
  • Despite the use of radiation therapy in the management of metastatic RCC, consensus on optimal dose and fractionation schedules has not been well-established. This study aims to analyze existing patient data from ~50 patients treated at Vanderbilt University Medical Center (VUMC) with stereotactic radiotherapy for metastatic RCC to compare how radiotherapy treatment parameters influence both local control rates, disease progression, and side-effect profiles.
  • VICTR Voucher, mentor confirmed
  • Dandan and Wu attended the clinic. Here is a summary:
    • For the aim to compare local control rates, we suggest to derive a survival outcome (time to first control failure) instead of using a binary outcome aggregated over the follow-ups. This will capture potential temporal differences between the treatment arms.
    • For the aim to compare side-effect profile, we suggest to extract date of clinic visit so that the data will be in longitudinal format (a patient might have multiple clinic visits)
    • For the exploratary aim to associate treatment paramters to outcomes, we suggest to only using the local control rates outcome. This is because similar to the local control rates, the treatment parameters are specific to each site. We also suggest to look at some of the parameters instead of all of the parameters.
    • This project is a good fit for VICTR Voucher.

2021 June 23

Ankita Patro (Elizabeth Perkins), Otolaryngology

  • Cochlear implantation (CI) is the standard treatment for moderate-profound bilateral or profound unilateral hearing loss in patients who no longer derive significant benefit from hearing aids. Prior to CI surgery, the patient has evaluation with audiology, undergoes imaging scans, and meets with the surgeon. From initial referral to surgery, the process can be burdensome for the patient. Vanderbilt surgeons have thus developed and implemented a novel service delivery model for qualifying patients to have appointments and CI surgery on the same day. In efforts to streamline care and improve quality, video supplementation to the traditional informed consent process has been shown to decrease patient anxiety and increase knowledge in orthopedic and ophthalmology literature . However, video education in CI care has not been reported in the literature. The goal of this prospective study is to evaluate the effects of video education on patient attitudes and knowledge regarding CI using survey questionnaires. Patients undergoing CI evaluation will be randomly assigned to the intervention group (videos) or the control group (no video). Per current standards of care at Vanderbilt, all patients in the study will receive face-to-face discussion with the surgeon and an informational brochure pre-operatively. Mentor confirmed. VICTR biostatistics voucher.

David Xiao (Jill Streams), General Surgery

  • Characterize the penetrating injuries in Nashville and evaluate a community based intervention program.
    • Mentor confirmed. VICTR biostatistics voucher.

2021 June 02

John Stokes (Whitney Gannon), Thoracic Surgery

  • Extracorporeal membrane oxygenation (ECMO) is a technology that provides cardiopulmonary support to patients with acute and chronic heart and lung failure. ECMO circulates blood outside the patient’s body through a membrane oxygenator, where exchange of carbon dioxide (CO2) and oxygen occurs. Capnometry is a relatively low-cost technology for non-invasively monitoring the concentration of CO2 in a gas. It is primarily used in health care settings to measure CO2 concentration in exhaled gas during invasive and non-invasive ventilation applications.1,2 As in the native lung, the gas flow leaving the gas outlet of the membrane oxygenator in ECMO circuits (exhaust gas) has a measurable concentration of CO2. Several clinical applications of ECMO exhaust capnometry and capnography have been proposed. Exhaust CO2 measurements are the gold standard for defining membrane oxygenator CO2 transfer3, which can provide insight into efficiency and health of the oxygenator.4 Changes in exhaust CO2 concentration may predict increasing clot formation within the membrane oxygenator.5 Exhaust CO2 concentration has also been proposed as an non-invasive parameter that can inform titration of sweep gas flow has been applied for autoregulatory control of sweep gas flow in large animals.6 Continuous exhaust capnography could also serve to immediately detect sweep gas flow source disruptions, facilitating earlier detection of this life-threatening complication during ECMO. Despite great theoretical potential of this non-invasive measurement, ECMO exhaust capnography is not routinely monitored during ECMO. The concentration of CO2 in the exhaust gas varies relative to numerous ECMO circuit and patient factors, including but not limited to the rate of sweep gas flow, circuit blood flow, CO2 tension in the pre-oxygenator blood, and efficiency of the membrane oxygenator.5,7 At present the relationships between these factors and exhaust CO2 concentration are inadequately defined to support useful clinical applications of ECMO exhaust capnometry and capnography. Additionally, while the relationship between venous and arterial blood gas values has been described in critically ill patients8,9, there are no published studies examining the relationships between venous blood gas results and arterial blood gas measures of Co2 tension in patients receiving ECMO. Additional characterization is needed to derive useful clinical applications for this low-cost, non-invasive measurement during ECMO. Primary Aim: To describe the relationships between ECMO CO2 clearance and other variables that may impact CO2 clearance, including hemoglobin concentration, patient arterial CO2 concentration, sweep gas flow rate, ECMO blood flow rate, membrane oxygenator device type (manufacturer and model), and duration of membrane oxygenator use. Secondary Aim: To evaluate the degree to which CO2 clearance (concentration of exhaustion CO2 x sweep gas flow) could be used to predict a patient’s arterial PaO2. Hypothesis 1: The concentration of CO2 in ECMO exhaust gas correlates with arterial PaCO2. Hypothesis 2: Peripheral venous blood gas measures (results drawn from a peripheral intravenous catheter) of PCo2 and pH will correlate with arterial blood gas measures of PCo2 and pH in patients receiving venovenous ECMO. Mentor confirmed. VICTR biostatistics voucher.

2021 May 26

Lin Cao (Wenliang Song), School of Medicine

  • We are looking at cholesterol, TG, HDL, and LDL levels in heart transplant patients collected at 4 time points around the time of transplant. We would like to compare lipid values and trends in patients receiving hep C positive donor hearts and non-hep C positive donor hearts. We would love advice on what statistical tests to use to achieve this! Mentor confirmed.

2021 May 19

Sofia Mendieta (Isaura Diaz), Pediatric Critical Care

  • Previous clinic session: 04/07/2021
  • How can we analyze our simulation recordings of our leaders? Can we say that our simulation has increased fellow/NP knowledge? Mentor confirmed. VICTR biostatistics voucher.

Michael Freeman (David Haynes), Otolaryngology - Head and Neck Surgery

  • We would like to know how the size of an acoustic neuroma tumor (1) changes hearing loss and (2) changes complications with surgery. We have a database of hundreds of these tumors with volumes measured on multiple MRIs. We need help with doing the statistical analysis for this. Mentor confirmed. VICTR biostatistics voucher.

2021 May 12

Seth Davis (Sarah Rohde), Otolaryngology

  • Free flap reconstruction of the tongue can be negatively impacted by atrophy of transplanted tissue over time. We have collected volumetric measurements at various time points following reconstruction, as well as long-term functional outcomes in patients. Questions: What is the average amount of atrophy to be expected post-transplant? Is there a difference in patients undergoing post-transplant radiation? What amount of atrophy correlates with long-term functional deficits? Mentor confirmed. VICTR biostatistics voucher.
  • Dandan Liu and Gong Wu attended the clinic. For this project, it is not feasible to collect baseline measure of transplanted tissue volume. The investigator mentioned there might be some approaches that can approximate the baseline tissue volume. In addition, days from baseline for the follow-ups varies across patients. It is suggested that trajectories of atropy be visualized before making a decision on the most appropriate model. In general, nonlinear mixed effect model might be the best choice. Inclusion/Exclusion criteria needs to be articulated around the first follow-up date/time since baseline.

2021 May 05

Whitney Gannon (Jonathan Casey), Allergy, Pulmonary, and Critical Care Medicine

  • Using a national database of patients who received ECMO for COVID-19 we’d like to generate a prognostic tool/prediction rule for in-hospital mortality. Mentor confirmed. VICTR biostatistics voucher.

2021 April 28

Jessica Turnbull, Pediatric Critical Care

  • Evaluation of a previously-validated resilience curriculum (PRISM) to increase resilience (Connor-Davidson Resilience Scale (CD-RISC)(Connor KM et al 2003) and decrease moral distress, stress and anxiety ((Measure of Moral Distress –Healthcare Professionals (MMD-HP) (Epstein EG et al 2019), the Perceived Stress Scale (PSS-10) (Cohen S et al 1988) and the 7-item Generalized Anxiety Disorder Scale (GAD-7) (Lowe B et al 2008), respectively) in pediatric critical care nurses. VICTR biostatistics voucher.

2021 April 07

Sofia Mendieta (Isaura Diaz), Pediatric Critical Care

  • Implement a simulation program for fellows and nurse practitioners (NPs) working in our PCICU to enhance knowledge and increase comfort level in managing cardiac patients. Our objectives were the following: Determine how many PICU programs around the nation have cardiac simulation curriculums in place. Identify the perception of usefulness of simulation curriculum. Determine confidence and preparedness fellows and NPs feel in managing cardiac patients before and after implementation of cardiac simulation curriculum. We conducted a national survey to determine cardiac simulations that are in place. Perception of usefulness of these simulations and gauge comfort level in leading and/or managing different scenarios often faced in the cardiac ICU. Questions we would like to answer: Descriptive analysis and statistical significance of our data. Mentor confirmed.

2021 March 10

Tanya Marvi (Todd Rice), Internal Medicine

  • The aim of our study is to determine if thromboelastography parameters are associated with the development of venous thromboembolism in critically ill patients with COVID-19 and respiratory failure. We prospectively enrolled 98 patients and measured thromboelastography parameters and other routine coagulation parameters on days 0, 3, 5, and 7 of ICU admission. We followed patients to hospital discharge and our primary outcome was time to first VTE. We built a competing risk regression using the maximum TEG parameter from the 4 measures with death as a competing risk accounting for anticoagulation dose and antiplatelet exposure. We are also running a GEE model using the panel data to assess the association between the thromboelastography parameters and the development of VTE. I have questions about the competing risk regression and the GEE model. VICTR biostatistics voucher. Mentor confirmed.

2021 March 03

Amany Alshibli (Bantayehu Sileshi), Anesthesiology

  • Previous clinic sessions: 12/17/2020 (Thursday), 01/07/2021 (Thursday), 02/03/2021 (Wednesday)
  • This meeting is for questions related to our analysis of estimated case volume. See prior notes for details. We would like to go over our analysis and interpretation of estimated case volume with the data we have. Mentor confirmed.

Annmarie Mede (Michael Topf), ENT

  • Dr. Topf and I are working on a project to increase awareness amongst providers of HPV vaccination and the connection between HPV and oropharyngeal cancer. We will be lecturing residents and administering a pre- and post-lecture Redcap survey on their perspectives and knowledge of HPV. We are looking for input on design and analysis of our data. Mentor confirmed. VICTR biostatistics voucher.

2021 February 24

CANCELLED: Jennifer Walker (Ann Sweeney), Pediatric Critical Care

  • Previous clinic session 1/20/2021
  • Implementation of a sedation weaning protocol - follow up meeting. To be scheduled with Christopher Lindsell - please let me know if he is not available. Mentor confirmed. VICTR Biostatistics voucher.

Jose Gomez, Medicine/Clinical Pharmacology

  • I am requesting access to BioVU data and need assistance with statistics plan.

2021 February 17

Courtney Sutton, Pharmacy

  • My project is a retrospective review of pharmacologic therapies used in extremely low birth weight infants to close a patent ductus arteriosus. I would like to compare those with successful closure vs. those without successful closure by a handful of variables and need guidance in selecting appropriate statistical tests based on the data I have collected.

Melanie Whitmore, Pharmacy

  • Assessing weight based versus non-weight based vasopressor doses (norepinephrine, epinephrine) on time to achieve MAP goal, length of hospital stay, various other end points.

2021 February 03

Amany Alshibli (Bantayehu Sileshi), Anesthesiology

  • Previous clinic session: 12/17/2020 (Thursday), 01/07/2021 (Thursday)
  • This meeting is for questions related to an expanded analysis of this previous project to include data from multiple hospitals. See prior notes for details. We are proposing a retrospective analysis of previously collected perioperative data from six hospitals across three countries in East Africa. We received feedback from the review board about our data analysis plan, and would like to go over our proposed analysis plan to determine if it is appropriate to answer our research questions with the collected data. This includes questions about the use of a log-linear model to determine changes in surgical case volume (# cases performed/week) during the COVID lockdown at different facilities. Mentor confirmed.

2021 January 27

Callie Jewett (Jed Maslow), Orthopaedic Surgery

  • Survey of patients who have sustained isolated upper extremity trauma (fracture, soft tissue disruption, neurovascular injury, and completion amputation) to determine predictive model of what patients experience sexual dysfunction as a result of their injury. Mentor confirmed. VICTR biostatistics voucher.

Jed Maslow, Orthopaedic Surgery

  • I am designing a randomized, prospective study evaluating perioperative steroid administration in reducing post-operative stiffness in elbow fractures. We have discussed with our pharmacy having a matched placebo. I wanted to review our statistical proposal and sample size calculations in preparation for a VICTR voucher, studio, and plan to submit this as a grant proposal. VICTR biostatistics voucher.

2021 January 20

Shannon Markus (Sean Collins, Alan Storrow), Emergency Medicine

  • The goal of this study is to identify whether there are racial/ethnic differences in rates of SARS-COV-2 infection, hospitalization, and critical illness in multiple large metropolitan populations in the STAR Clinical Data Network, while controlling for multiple sociodemographic factors, including age, sex, household income, insurance status, place of residence (population density and deprivation index), and baseline comorbidities (including Elixhauser score, hypertension, CAD, CHF, PVD, COPD, asthma, obesity, diabetes, malignancy). Mentor confirmed. VICTR biostatistics voucher.

Jennifer Walker (Ann Sweeney), Pediatric Critical Care

  • Sedation weaning protocol was implemented in the Pediatric Cardiac Intensive Care Unit with the goal of reducing time of weaning, total dose exposure and number of patients discharged on a wean. Would like to discuss biostatistical analysis and organization of data prior to applying to VICTR for statistical grant/support. Mentor confirmed. VICTR biostatistics voucher.

2021 January 13

Kelsey McNew (Dan Moore), Molecular Pathology and Immunology

  • We are performing image analysis of FFPE placenta sections. We will receive output with number of cells per tissue section (8 kinds of cells). While we could make a prediction based on mouse data, we are unable to estimate what the range of cell numbers in human tissue may be as this is the first study of its kind. Dr. Lindsell's preliminary review of our VICTR application stated "They do not state what the main variable is, nor do they provide a characterization in a sense of mean/median and range/SD. The approach to statistical testing is fine, but ignores the issue of 'multiplicity' - the possibility of concluding differences when there are really none simply because of chance. The investigators should provide a more complete description of the key variables, what differences they want to be able to find because they are of sufficient magnitude to be meaningful, and how they will handle the multiple testing problem." I would love advice addressing Dr. Lindsell's concerns within the constraints we have. Mentor confirmed.

Kelly Vittetoe (Amy Whigham), Otolaryngology

  • We are planning a retrospective case control study comparing patient outcomes in tonsillectomy vs. tonsillectomy + pharyngoplasty. Our primary outcome will be post-operative AHI, a measure of obstructive sleep apnea. We are asking for help with matching our case and control groups with regard to age, BMI, and pre-operative AHI. Mentor confirmed.

2021 January 06

Brandon Esianor (Alexander Gelbard), Otolaryngology-Head and Neck Surgery

  • Acute Laryngeal Injury (ALgI), characterized by ulceration and granulation formation, occurs in over 50% of individuals following intubation. Endotracheal tube (ETT) size has been identified as a modifiable risk factor for development of ALgI. Our project is geared towards creating strategies to decrease ETT size (educating stakeholders and making access to larger tubes > or equal to 7.5 more difficult). Our primary question is, How long/How many intubations do we need to track to appreciate a statistically significant change in tube size selection? We are able to easily extract information on prior intubations and will need to evaluate ETT size selection X months prior to intervention, X weeks-months following intervention #1 (education initiative), and X weeks-months after initiative 2 (limiting access to larger ETT size). Mentor confirmed. VICTR biostatistics voucher.

Cullen Moran (Joshua Lawrenz), Orthopeadic Surgery

  • We have data on the accuracy of various biopsy methods for soft tissue sarcomas. We would like to consult on how to analyze the accuracy of these biopsies for distinguishing benign vs. malignant tumors. We also are interested in investigating whether MRI diagnosis can distinguish between benign and malignant tumors. It is our anticipation that the data we have collected could also lend itself to a predictive model for diagnosing soft tissue tumors as benign of malignant. Mentor confirmed.
Topic revision: r2 - 30 Dec 2021, CassieHennessy

This site is powered by FoswikiCopyright © 2013-2022 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding Vanderbilt Biostatistics Wiki? Send feedback