Global Volunteerism for Orthopaedic Surgeons-A Primer

The burden of unmet surgical need is heavily weighted toward low-income and middle-income countries. North American orthopaedic surgeons are increasingly interested in volunteer activities in resource-limited areas around the globe. There are multiple avenues through which an orthopaedic surgeon can positively contribute to improving musculoskeletal care around the world. Unfortunately, short-term missions are at risk of undermining local long-term development efforts if they do not mitigate harm and optimize benefit for host communities. Work in this area should be grounded in beneficence and sustainability with an emphasis on mutual respect, exchange, and a commitment to capacity building. All of the necessary information for adequate preparation for these activities is beyond the scope of this chapter, but the goal is to introduce a range of volunteer options, ethical considerations, cultural competence and volunteer preparedness principles, considerations when including trainees in global health work, and some nuts-and-bolts details on trip planning.

Abstract WP398: Impact of a Direct Ambulance-to-CT Stroke Protocol on Race, Sex, and Language Disparities in Stroke Treatment Times

Introduction: Prior studies have documented disparities in key acute stroke care metrics, with women and minorities more likely to have treatment delays and less likely to receive IV tPA.

Objective: To evaluate whether implementation of a direct ambulance-to-CT stroke protocol reduces race, sex, and primary language disparities in stroke treatment times.

Methods: We identified patients with confirmed strokes that had been transported by ambulance to our emergency department before and after implementation of a direct ambulance-to-CT protocol for suspected stroke at our urban safety-net hospital. We used the Mann-Whitney U test to compare median door-to-CT (DTC) and door-to-needle (DTN) times by sex, race, and primary language during the pre- and post-intervention periods.

Results: A total of 106 stroke patients in the pre-intervention group and 119 in the post-intervention group were included in this analysis. The pre-intervention group included 57 (53.8%) women, 20 (18.9%) whites, and 68 (64.2%) English-speaking patients. The post-intervention group included 58 (48.7%) women, 26 (21.9%) whites, and 77 (64.7%) English-speaking patients. A total of 48 pre-intervention patients and 47 post-intervention patients received tPA. Overall, median DTC and DTN times were significantly lower in the post-intervention group compared to the pre-intervention group (21 minutes vs. 10, p<0.0001; 39 vs. 30, p=0.006). There were no significant differences in DTC or DTN times by sex, race, or primary language in the pre-intervention group, but women had longer median DTN times than men (34 vs. 24, p=0.02) in the post-intervention group.

Conclusions: While no significant disparities in stroke treatment times by sex, race, or primary language were identified in the pre-intervention period, implementation of a direct ambulance-to-CT protocol was associated with greater improvements in DTN times for men than for women.

Prolonging herd immunity to cholera via vaccination: Accounting for human mobility and waning vaccine effects

BACKGROUND

Oral cholera vaccination is an approach to preventing outbreaks in at-risk settings and controlling cholera in endemic settings. However, vaccine-derived herd immunity may be short-lived due to interactions between human mobility and imperfect or waning vaccine efficacy. As the supply and utilization of oral cholera vaccines grows, critical questions related to herd immunity are emerging, including: who should be targeted; when should revaccination be performed; and why have cholera outbreaks occurred in recently vaccinated populations?

METHODS AND FINDINGS

We use mathematical models to simulate routine and mass oral cholera vaccination in populations with varying degrees of migration, transmission intensity, and vaccine coverage. We show that migration and waning vaccine efficacy strongly influence the duration of herd immunity while birth and death rates have relatively minimal impacts. As compared to either periodic mass vaccination or routine vaccination alone, a community could be protected longer by a blended "Mass and Maintain" strategy. We show that vaccination may be best targeted at populations with intermediate degrees of mobility as compared to communities with very high or very low population turnover. Using a case study of an internally displaced person camp in South Sudan which underwent high-coverage mass vaccination in 2014 and 2015, we show that waning vaccine direct effects and high population turnover rendered the camp over 80% susceptible at the time of the cholera outbreak beginning in October 2016.

CONCLUSIONS

Oral cholera vaccines can be powerful tools for quickly protecting a population for a period of time that depends critically on vaccine coverage, vaccine efficacy over time, and the rate of population turnover through human mobility. Due to waning herd immunity, epidemics in vaccinated communities are possible but become less likely through complementary interventions or data-driven revaccination strategies.