Navigating Uncertainty in Clinical Practice: A Workshop to Prepare Medical Students to Problem-Solve During Complex Clinical Challenges

Introduction

Uncertainty is an inherent part of medicine. Prior work has trained medical students to better communicate diagnostic uncertainty; however, this work touches on only one aspect of the uncertainty students will face in practice. We developed a session to provide them with a taxonomy for categorizing the various types of uncertainty, as well as a framework to apply when navigating uncertainty during clinical challenges. These tools can help students make sense of uncertainty and determine actions in a complex health system.

Methods

We designed a virtual workshop for third-year medical students at the end of their core clerkships. It included a didactic session followed by a small-group immersive unfolding case experience with several challenge points during which we tasked students with applying the framework, classifying the uncertainty domain, and discussing how they would problem-solve each scenario.

Results

We conducted the workshop with 128 third-year medical students. We collected data through an anonymous postsession survey (86% response rate; 110 of 128 students). Most found the workshop useful (64%; 54 of 85), and a large number found the framework helpful in appraising uncertainty (47%; 42 of 89). A majority felt their perspectives on uncertainty changed after the workshop (66%; 73 of 110). Students integrated prior health systems science knowledge in their strategies to problem-solve each challenge.

Discussion

This session provides a novel application of a sense-making framework and taxonomy for medical students to classify uncertainty. It offers a simple, low-cost, interactive, virtual activity that can be implemented at other institutions.

Intolerance of uncertainty and attitudes towards persons living with disabilities in medical students: Is there a correlation?

Introduction

Patients living with a disability experience an illness trajectory that may be uncertain. While navigating clinical uncertainty has been well-researched, health professionals' intolerance of uncertainty for patients living with disabilities has yet to be explored. We examined the relationship between medical students' intolerance of uncertainty with their attitudes towards people living with disabilities to better inform curricular efforts.

Methods

We employed a survey-based design consisting of the Intolerance of Uncertainty Scale (IUS) and Disability Attitudes in Healthcare (DAHC) Scale to medical students upon completion of core clerkships (end of third-year of training). Data were de-identified. Mean DAHC and IUS scores were compared with published values via t-test. Linear regression was used to examine IUS/DAHC scores for anonymized students. Pearson correlation coefficient was calculated to assess correlation between IUS and DAHC scores.

Results

Response rate was 97% (268/275 students). Mean IUS score did not differ from previously cited medical student scores, but mean DAHC score was significantly higher than previously cited scores. We observed a statistically-significant relationship between IUS and DAHC scores. Students with greater intolerance of uncertainty had lower scores for disability attitudes [F(1,243) = 8.05, value of p < 0.01], with an R ²-value of 0.032, suggesting that 3% of DAHC score variance can be explained by IUS score changes.

Conclusion

We identified a weak negative correlation between IUS and DAHC scores in medical students. Further research is needed to clarify findings and identify best practices that equip trainees with skills to care for patients with uncertain illness trajectories and patients living with disabilities.

Phase II Single-arm Study of Durvalumab and Tremelimumab with Concurrent Radiotherapy in Patients with Mismatch Repair-proficient Metastatic Colorectal Cancer

PURPOSE

Immune checkpoint inhibition (ICI) alone is not active in mismatch repair-proficient (MMR-P) metastatic colorectal cancer (mCRC), nor does radiotherapy alone result in objective systemic benefit. However, combined radiotherapy plus ICI can induce systemic antitumor immunity in preclinical and clinical models.

PATIENTS AND METHODS

In this single-center, phase II study, patients with chemotherapy-refractory MMR-P mCRC received durvalumab 1,500 mg plus tremelimumab 75 mg every 4 weeks plus radiotherapy. The primary endpoint was objective response rate (ORR) in nonirradiated lesions. Treatment and efficacy were correlated with peripheral immune cell profiles.

RESULTS

We enrolled 24 patients, and report outcomes after a median follow-up of 21.8 (range: 15.9-26.3) months. The ORR was 8.3% (2 patients) [95% confidence interval (CI), 1.0-27.0]. The median progression-free survival was 1.8 (95% CI, 1.7-1.9) months, median overall survival was 11.4 (95% CI, 10.1-17.4) months. Twenty five percent of patients (n = 6) had treatment-related grade 3-4 adverse events. We observed increased circulating CD8⁺ T lymphocyte activation, differentiation, and proliferation in patients with objective response.

CONCLUSIONS

This combination of radiotherapy plus ICI study did not meet the prespecified endpoint criteria to be considered worthwhile for further study. However, rare instances of systemic immune augmentation and regression in nonirradiated lesions were observed (an abscopal response). Combination durvalumab and tremelimumab plus radiotherapy is feasible in MMR-P mCRC with a manageable safety profile. Further studies of novel immunotherapy combinations, and identification of biomarkers predictive of abscopal response are warranted.

Aluminum chloride pretreatment of elastin inhibits elastolysis by matrix metalloproteinases and leads to inhibition of elastin-oriented calcification

Calcification of elastin occurs in many pathological cardiovascular diseases including atherosclerosis. We have previously shown that purified elastin when subdermally implanted in rats undergoes severe calcification and aluminum chloride (AlCl(3)) pretreatment of elastin inhibits calcification. In the present study we investigated whether matrix metalloproteinase (MMP) binding to elastin and elastin degradation is prevented by AlCl(3) pretreatment. Subdermal implantation of AlCl(3)-pretreated elastin showed significantly lower MMP-9 and MMP-2 activity surrounding the implant as compared to the control implants. AlCl(3) pretreatment also significantly inhibited elastin implant calcification at the seven-day implant period (AlCl(3)-pretreated 4.07 +/- 1.27, control 23.82 +/- 2.24 microg/mg; p<0.0001). Moreover, elastin gel zymography studies showed that gel pretreatment with AlCl(3) inhibited elastolysis by MMP-9. We also demonstrate significant suppression of MMP-2 activity in aortic wall segments of AlCl(3)-pretreated porcine bioprosthetic heart valve implants as compared to control valve implants in sheep mitral valve replacement studies. AlCl(3) pretreatment also significantly inhibited calcification of elastin in this model. Thus, we conclude that aluminum ion binding to elastin prevents MMP-mediated elastolysis and thus prevents elastin calcification.

High reactivity of alkyl sulfides towards epoxides under conditions of collagen fixation--a convenient approach to 2-amino-4-butyrolactones

Epoxy crosslinking agents have been investigated for use in the fabrication of bioprosthetic devices, such as heterograft heart valve prostheses. It has been generally assumed that epoxy crosslinking takes place via amino-epoxy reactions. The present study investigated the hypothesis that the reactions of methionine residues with epoxides also can occur in biomaterial crosslinking. A series of model reactions were studied in which a mono-epoxide was combined with individual alkyl sulfides. In the present studies epoxides rapidly alkylate aliphatic sulfides, including methionine derivatives, in buffered aqueous solutions at room temperature and pH close to neutral, forming sulfonium compounds, which are stable at pH 5-7 at temperatures up to 50 degrees C, except for cases in which methionine derivatives with non-protected carboxy groups are used. The rate of reaction remains practically unchanged within the range of pH from 5 to 12, whereas in strongly alkaline media the reverse reaction occurs. This discovery can provide a better understanding of processes occurring in the fixation of bioprosthetic tissues with polyepoxides. It can also develop into a site-specific method to label methionine residues in proteins. The carboxy group-containing sulfonium betaines derived from N-protected methionines undergo cyclization in unexpectedly mild conditions, which can be used as an efficient method for preparation of N-protected 2-amino-4-butyrolactones with sensitive protective groups.

Elastin calcification and its prevention with aluminum chloride pretreatment

Elastin, an abundant structural protein present in the arterial wall, is prone to calcification in a number of disease processes including porcine bioprosthetic heart valve calcification and atherosclerosis. The mechanisms of elastin calcification are not completely elucidated. In the present work, we demonstrated calcification of purified elastin in rat subdermal implants (Ca(2+) = 89.73 +/- 9.84 microgram/mg after 21 days versus control, unimplanted Ca(2+) = 0.16 +/- 0.04 microgram/mg). X-ray diffraction analysis along with resolution enhanced FTIR spectroscopy demonstrated the mineral phase to be a poorly crystalline hydroxyapatite. We investigated the time course of calcification, the effect of glutaraldehyde crosslinking on calcification, and mechanisms of inhibition of elastin calcification by pretreatment with aluminum chloride (AlCl(3)). Glutaraldehyde pretreatment did not affect calcification (Ca(2+) = 89.06 +/- 17.93 microgram/mg for glutaraldehyde crosslinked elastin versus Ca(2+) = 89.73 +/- 9.84 microgram/mg for uncrosslinked elastin). This may be explained by radioactive ((3)H) glutaraldehyde studies showing very low reactivity between glutaraldehyde and elastin. Our results further demonstrated that AlCl(3) pretreatment of elastin led to complete inhibition of elastin calcification using 21-day rat subdermal implants, irrespective of glutaraldehyde crosslinking (Ca(2+) = 0.73-2.15 microgram/mg for AlCl(3) pretreated elastin versus 89.73 +/- 9.84 for untreated elastin). The AlCl(3) pretreatment caused irreversible binding of aluminum ions to elastin, as assessed by atomic emission spectroscopy. Moreover, aluminum ion binding altered the spatial configuration of elastin as shown by circular dichroism (CD), Fourier transform infrared (FTIR), and (13)C nuclear magnetic resonance (NMR) spectroscopy studies, suggesting a net structural change including a reduction in the extent of beta sheet structures and an increase in coil-turn conformations. Thus, it is concluded that purified elastin calcifies in rat subdermal implants, and that the AlCl(3)-pretreated elastin completely resists calcification due to irreversible aluminum ion binding and subsequent structural alterations caused by AlCl(3).

Mechanisms of bioprosthetic heart valve failure: fatigue causes collagen denaturation and glycosaminoglycan loss

Bioprosthetic heart valve (BPHV) degeneration, characterized by extracellular matrix deterioration, remodeling, and calcification, is an important clinical problem accounting for thousands of surgeries annually. Here we report for the first time, in a series of in vitro accelerated fatigue studies (5-500 million cycles) with glutaraldehyde fixed porcine aortic valve bioprostheses, that the mechanical function of cardiac valve cusps caused progressive damage to the molecular structure of type I collagen as assessed by Fourier transform IR spectroscopy (FTIR). The cyclic fatigue caused a progressive loss of helicity of the bioprosthetic cuspal collagen, which was evident from FTIR spectral changes in the amide I carbonyl stretching region. Furthermore, cardiac valve fatigue in these studies also led to loss of glycosaminoglycans (GAGs) from the cuspal extracellular matrix. The GAG levels in glutaraldehyde crosslinked porcine aortic valve cusps were 65.2 +/- 8.66 microg uronic acid/10 mg of dry weight for control and 7.91 +/- 1.1 microg uronic acid/10 mg of dry weight for 10-300 million cycled cusps. Together, these molecular changes contribute to a significant gradual decrease in cuspal bending strength as documented in a biomechanical bending assay measuring three point deformation. We conclude that fatigue-induced damage to type I collagen and loss of GAGs are major contributing factors to material degeneration in bioprosthetic cardiac valve deterioration.

Coronary perfusion pressure during cardiopulmonary resuscitation

Currently, there is no way to measure the effectiveness of cardiopulmonary resuscitation in humans. The literature suggests that minimum aortic diastolic and estimated coronary perfusion pressures during cardiopulmonary resuscitation (CPR) in the animal model correlate with higher resuscitation rates. Six patients were studied during CPR to determine the arterial diastolic and estimated coronary perfusion pressures (arterial minus right atrial diastolic pressures). Mean arterial pressures were 27/11 mm Hg, central venous pressures were 32/10 mm Hg, and the mean estimated coronary perfusion pressure was only 1 mm Hg. None of the six patients survived. This study demonstrates that the techniques of measuring hemodynamic values during CPR is practical. Poor estimated coronary perfusion pressures were obtained from the six patients studied. This study should be extended to include a large number of patients to determine whether these hemodynamic parameters can be used as prognostic indicators of successful resuscitation in humans.