Slashing Two-wheeled Accidents by Leveraging Eyecare — STABLE  

Myopia Clinical Trial

Official title: Slashing Two-wheeled Accidents by Leveraging Eyecare: a Stepped-wedge Cluster Randomised Controlled Trial to Assess Impact of Spectacles on Reducing Crash and Near-crash Events Among Myopic Motorcycle Drivers in Ho Chi Minh City Vietnam

Status Not yet recruiting

Clinical Trial Summary

STABLE is a stepped-wedge cluster randomised controlled trial and its primary aim is to determine whether the provision of spectacles for the correction of myopia can reduce the average number of crash-near-crash (CNC) events among eligible motorcycle drivers in Vietnam as measured under naturalistic driving conditions with the Data Acquisition System (DAS).

STABLE is designed to assess the impact of vision correction on the safety of road users in a a Low and Middle income countries (LMIC) setting. A positive trial outcome would demonstrate the safety benefits of vision correction and would create pressure for tighter regulation of drivers' vision and the promotion of vision correction.

The study will be conducted in the peri-urban universities in Ho Chi Minh City, Vietnam and 875 students from five universities will be recruited into the trial.

Before conducting the main trial, a pilot of 35 students will be recruited to test DAS and build CNC dictionary.

Duration of the trial is 33 months from enrolment to completion of primary analysis, with 18 months for data collection.

Study participants can be both male and female motorcycle drivers aged 18 to 25 years years with at least one year of driving experience; they must use their motorcycle as their primary means of transport; drive at least 50 km per week and present with un- or under-corrected myopia that can be corrected with spectacles.

Participants with any ocular or systemic abnormality affecting vision, other than un-or under-corrected myopia will be excluded from the trial.

STABLE's primary outcome is CNC events per 1,000 km driven the DAS mounted to the motorcycles of trial participants. An interim analysis of the primary outcome will take place 9 months after data collection begins. The interim analysis will be reviewed by the trial's Data Monitoring and Ethics Committee. Unless a change is needed because of this review, the trial's primary analysis will take place 18 months after the DAS units are fitted to participants' motorcycle).

Best-corrected visual acuity and compliance with study glasses; self-reported visual function (driving-adapted Visual Function Questionnaire-25 [VFQ-25]); Dula Dangerous Driving Index (DDDI), maximum abbreviated injury score (MAIS) for all crashes; self-reported CNC events for comparison with recorded CNC events and total delivery cost per CNC event avoided with the intervention (indicator of cost-effectiveness).

Clinical Trial Description

The primary aim of STABLE is to determine whether the provision of spectacles for the correction of myopia can reduce the average number of crash-near-crash (CNC) events among young motorcycle drivers in Vietnam.

Road traffic crashes kill more people aged 5 to 29 years worldwide than any other cause and are predicted to become the 7th leading global causes of death for all ages by 2030. The Southeast Asia has among the world's highest burdens of traffic mortality, with 20.7 fatalities per 100,000 population, trailing only Africa. The United Nations reports that motorcycles account for 93.3% of all motorized vehicles on the road in Vietnam, the highest number as a proportion of all motorized vehicles of any Association of Southeast Asian Nations country.

The investigators recently published a meta-analysis in Lancet Global Health which revealed that drivers with poor vision in Low and Middle-Income Countries (LMICs) had a 46% greater risk of experiencing a road traffic crash than those with good vision Risk Ratio (RR) 1·46, 95% Confidence Interval 1·20 to 1·78, p<0·001, 13 studies). Nevertheless, the impact of poor vision on the safety of young road users in LMICs, where many drivers do not undergo vision testing, remains poorly understood. There is a particular dearth of information for adolescent drivers, who are at greatest risk for crash-related death and the lack of reliable data has proven a significant barrier to inference of cause and effect.

Trials with robust measurement of CNC events with appropriate equipment under conditions of naturalistic driving are needed, and these have become possible only recently, due in part to falling costs and aggressive miniaturisation of GPS and on-board video systems.

STABLE will be the first cluster randomised controlled trial to investigate whether there is a link between vision correction with glasses and road safety in a LMIC.

Rationale for Intervention: The intervention in STABLE is the provision of glasses for the correction of distance visual acuity < 6/12 in the better-seeing eye due to un- or under-corrected myopia following an eye examination. The intervention will be applied to male and female motorcycle users between ages 18 and 25 enrolled at universities in Ho Chi Minh City, Vietnam

Rationale for Comparator The comparator in STABLE is standard eyecare. For university students in Vietnam, this requires the individual to pay for eyecare services provided by trained ophthalmologists or optometrists and access to good-quality eyecare services amongst university students is low. This is illustrated by the high proportion either not wearing glasses, or having glasses with incorrect power in the unpublished study noted above.

STABLE is an investigator-masked mixed-methods naturalistic driving study using a stepped-wedge cluster randomised trial (SW-CRT) design. It uses a SW-CRT design because, in a conventional parallel group cluster randomised trial, half the clusters would be randomly assigned to the intervention condition and half to the control condition. This approach would necessitate identifying participants with un- or under-corrected myopia and withholding glasses from them if they were randomly assigned to the control group until after the completion of the trial. The STABLE investigators maintain that it would be unethical to withhold glasses from motorcycle drivers who have been identified as needing them through the trial's processes for this length of time. Therefore, working with local stakeholders in Vietnam they agreed on the use of the SW-CRT design, which balances the need to conduct a randomised evaluation of the intervention with the ethical demand to provide glasses to trial participants as soon as their need for vision correction is identified.

Primary objective: is to provide reliable estimates of the impact that vision correction with glasses has on the number of CNC events in a Low- and Middle-Income Country (LMIC) setting.

Secondary objectives: are to investigate the effects of study interventions on best-corrected visual acuity; self-reported visual function; spectacle compliance; maximum abbreviated injury score (MAIS) for all crashes, association between CNC events and roadway characteristics, self-reported CNCs for comparison with recorded CNCs and the total delivery cost per CNC event avoided.

Recruitment Methods: The research team will approach the Board of Executives of the five universities and explain the purpose of the study and invite them to join the study. If they agree to participate and depending on their assignment, trial partners Asia Injury Prevention Foundation will work with each university's Department of Student Affairs and/or the Student Unions to announce, advertise and follow up on trial recruitment activities. The trial will be advertised on posters, through email and through fan page of either the Department of Student Affairs or the Student Unions.

Informed consent: Informed Consent to participate in STABLE will be sought from students in 5 faculties from each university (a total of 25 clusters). Those who meet the inclusion criteria for DAS fitting and informed consent will undergo the informed consent procedure. 35 students will be recruited from the university to be involved in the pilot study, and 175 students (35 per cluster) will be recruited from each of the other five universities for the main trial. Of the 175 students enrolled at each university, the investigators anticipate that 20% (35) will have un- or under-corrected myopia.

Sequence generation: At each sequence (step), a centralised, password-protected web-based system will be used to randomly select five clusters from those that have not yet been assigned to STABLE's intervention group. The PI on site, or an individual with delegated authority, will access the system to generate the list of five randomly selected clusters.

Diversified Technical Systems (DTS) has developed the DAS for STABLE to support the research questions and objectives of the trial. The DAS will be connected to two colour, wide-angle view video cameras: forward-facing and driver-facing. Additional data streams include: 3-axis accelerometer, Geographic Positioning System (GPS), braking and ground speed.

DAS will be fitted to the motorcycles of eligible students who provide informed consent to participate in the trial. The DAS will be fitted on-site after completion of the informed consent procedure. For the pilot study this will take place in the week prior to the start of the pilot study. For the main trial this will take place in the month preceding the start of the trial. It will take approximately 7 days to complete DAS fitting at each university, and approximately 35 days to fit the DAS to the motorcycles of all 875 participants.

Study Instruments: Trial data collection instruments will be used to capture the outcome measures. Data collection from DAS will begin after each DAS unit has been installed on the motorcycles of consenting participants. In the main trial, the first eye examination will take place 12 weeks after the last DAS unit is fitted. After the first eye examination DAS data will only be collected from those who:

• are in a cluster that has not yet been randomly selected for transition from the control period, or

• have undergone an eye examination and been diagnosed with uncorrected myopia or under-corrected myopia (and thereby entered the intervention group) The DAS systems will be removed from the motorcycles of those participants who have had an eye examination and do not meet the inclusion criteria for assignment to the intervention group. This process will be repeated at each sequence, until DAS data are being collected from only those who meet the inclusion criteria for assignment to the intervention group (myopes only). DAS data will be collected from these DAS units up until the time they are removed from the motorcycles. Data collection from all 35 clusters will cease after the final 5 clusters in the sequence have completed 12 weeks of follow up.

Prospective participants will be contacted by email and Short Messaging Service and asked to complete a screening questionnaire to know their age, ownership of bike.

Participants who meet the inclusion criteria for DAS fitting and informed consent will be contacted again and asked to provide the following information by questionnaire:

• self-reported driving risk assessment (Dula Dangerous Driving Index)30

• self-reported number of violations in the last 5 years for speeding

• self-reported number of violations in the last 5 years for failure to wear a helmet while driving

• urban or rural residence

• access to local eyecare services

• history of uptake of eyecare services Students who have given consent to take part in the trial and who have had DAS fitted to their motorcycles will be invited to receive a free eye examination in accordance with the timing determined by the randomisation sequence.

Participants who meet the inclusion criteria for assignment to the intervention group will be interviewed on-site and Visual Function (VFQ-25) will be administered four weeks after receiving eyeglasses:

Assessments in the event of a crash: Maximum Abbreviated Injury Score (MAIS) will be collected from each participant involved in a crash event that results in hospitalisation. During the main trial, research assistants will maintain contact with participants by Short Messaging Service (SMS) on a twice monthly basis to retrieve DAS data and ensure that they are motivated to continue with the study.

Statistical Methods: Baseline demographic and clinical characteristics will be reported for all participants who are eligible for the intervention group for whom the data is available. Baseline characteristics will be summarised by means and standard deviations, medians and inter-quartile ranges, or numbers and percentages as appropriate.

The primary outcome measure for STABLE is the number of CNC events per 1,000km driven. CNC events for each participant will be assessed from trial entry to closure and recorded in the trial database. In STABLE, the definition of a CNC event is the definition used in the Strategic Highway Research Program (SHRP) 2: "Any circumstance that requires a rapid, evasive manoeuvre by the participant vehicle, or any other vehicle, pedestrian, cyclist, or animal to avoid a crash. A rapid, evasive manoeuvre is defined as a steering, braking, accelerating, or any combination of control inputs that approaches the limit of the vehicle capabilities.

Null hypotheses and analyses for secondary outcomes take a similar form to that for the primary outcome. Mean differences for continuous outcomes and risk differences for binary outcomes will be reported (all adjusting for cluster, secular and time effects).

The 12 subscales and total scores of VFQ-25 will be calculated following the scale guidelines, ranging from 0 to 100. A multilevel longitudinal linear regression model with mixed effects will be applied to compare the total scores of VFQ-25 between control and intervention conditions. ;

Related Conditions & MeSH terms

• Myopia

• NCT number: NCT05466955
• Study type: Interventional
• Source: Queen's University, Belfast
• Contact: Nathan G Congdon, MD, MPH
• Phone: +44(0)289097
• Email: n.congdon@qub.ac.uk
• Status: Not yet recruiting
• Phase: N/A
• Start date: March 2024
• Completion date: November 2025