Whilst there have been multiple previous surveys which have assessed clinician opinions on driving regulations in brain cancer patients [13,14,15,16], including two surveys in Australian populations [17, 18], this is the first Delphi study to both assess clinician attitudes and then identify areas for change in driving guidelines. Moreover, the multidisciplinary nature of this study is unique, as previous studies [9, 19] did not include radiation oncologists or neurosurgeons as part of analysis. Among the strengths of this study are the proven credentials of the expert panel, as evidenced by the numbers of years practicing as a specialist, number of patients with brain tumours reviewed each year, and frequency of driving inquiries from patients with brain tumours each year. The expertise of the panelists in our study is highlighted by the near universal awareness of driving guidelines (96.2%), compared with 26.1% and 76% of panelists used in previous Australian surveys (16,17). Yet, despite this, over half advised difficulty answering driving restriction queries and only raised restrictions on an as-needed basis. Furthermore, nearly all believed there needed to be more specific driving guidelines. Interestingly, eight (72.7%) medical oncologists had difficulty answering queries relating to driving restrictions, whereas only three (50%) radiation oncologists, two neurosurgeons (33.3%), and one neurologist (33.3%) reported as such. These differences could be explained by the existence of separate guidelines for seizures and post-operative restrictions. Unfortunately, as suggested in our previous systematic review [6], there is limited evidence underpinning driving guidelines, and insufficient understanding of the risks in brain tumour patients driving.

There were several novel findings from this Delphi survey. Firstly, despite the lack of framework within current driving guidelines for clinicians when initially determining fitness to drive in patients with brain tumours, there was consensus among clinicians that taking a comprehensive neurological history, performing a neurological exam, and documenting baseline visual fields should form the basis of the assessment. Although taking a thorough neurological history and reassessing patients may be implied in the guidelines, they are not a requirement. The specific components of the neurological exam and visual fields were not assessed as part of the study, however possible exam findings were evaluated, as reflected in Table 3 and Appendix A. Beyond not mandating EEGs as part of the assessment, the study also affirmed the guideline’s stance on having a defined post-operative period of no driving; however current guidelines are advisory only, allowing neurosurgeons to have discretion with deciding duration. While there was disagreement regarding whether each tumour subtype needed its own specific guideline, there was consensus that specific tumour histology such as glioblastoma and brain metastases, did not prohibit driving [3]. However, in contrast to existing Australian guidelines, there was consensus agreement among panelists that stability on MRI or CT should be part of the assessment in patients with brain tumours. Stability on brain imaging was not defined as part of this study, however this should be based on the Response Assessment in Neuro-Oncology (RANO) criteria in which stable disease defined as clinically stable without evidence of progression or complete or partial response, and stable non-enhancing lesions, on the same or reduced dose of corticosteroids [20, 21]. RANO criteria do not advise fixed intervals for repeating scans but rather recommend an individualized approach based on the clinical scenario. The frequency of repeating scans was not assessed as part of this study and remains a complex decision requiring clinical discretion based on the patient’s symptoms, and future studies are needed to determine the optimal interval in cases where patients remain asymptomatic. Additionally, there was consensus that it is important to continually reassess fitness to drive, following the same principles as the original assessment. These are in line with the findings from the Swiss Delphi study reported in 2021, which suggested routine brain MRI, thorough history, and neurological examination, as well as neuropsychological and visual assessment when determining fitness to drive [9]. However, a more recent study by Mondia et al. formulated a wider multidisciplinary approach involving epileptologists, ophthalmologists, neuropsychologists and driving simulators to determining fitness to drive in brain cancer patients [19]. As part of their findings, Mondia et al. generated a decision tree which included some aspects of the current driving guidelines such as seizures, visual acuity impairment, visual field loss, diplopia, motor weakness, cognitive deficit, progressive disease, or concerns raised by patients or their families [19]. Nevertheless, these findings across studies highlight the wide range of clinically significant findings in determining fitness to drive, and the challenge of formulating a single driving guideline. There is important role for an Australian registry evaluating real world data, based on a previous Finnish study by Huuskonen et al., to quantify the true risks posed by patients with brain tumours [22]. Ultimately, further research into the true risks posed by patients with brain tumours driving, through a multidisciplinary lens, involving medical oncologists, radiation oncologists, neurologists, neurosurgeons, well as ophthalmologists, and occupational therapists is needed to resolve disagreements between guideline requirement and the expertise clinicians.

Secondly, this study highlights clinicians’ perspectives on aspects that are incompatible with driving. While several aspects align with the existing guidelines in terms of restricting patients with significant impairments in visuospatial perception, vision, memory, or executive function [3], consensus was not achieved regarding impairments in motor domains, sensory domains, or insight. Additionally, consensus was not achieved regarding current epilepsy guidelines for seizure-free period in brain tumours and following intracranial surgery. This suggests that existing guidelines may be too broad, and more granular information regarding deficits expected to impact the ability to drive safely should be incorporated into future guidelines. The study identified 19 statements which reached consensus, of which 12 align with existing Australian guidelines. The remaining seven statements signify opportunities to enhance clinical practice through future formal guideline revisions. Current guidelines do not entirely reflect the attitudes of practicing clinicians and further research is needed to resolve these disagreements with the current guidelines. Future studies at the local institutional level are necessary to validate these novel clinical assessment findings before they can be integrated into formal guidelines.

Thirdly, a striking finding from this Delphi survey was that over half of clinicians reported needing to impose restrictions on a patient, despite the patient previously receiving approval from a different doctor. All four specialties surveyed had between 45.5% and 66.7% of respondents needing to override previous clearance. Additionally, in cases of non-compliance, there is uncertainty around the most appropriate reporting with 50% contacting only the patient directly, and 50% also contacting a licensing authority. While this study focused on clinician attitudes towards assessing fitness to drive, patient perspectives were not specifically sought. A previous self-reported patient questionnaire by Mansur et al. identified that 88.4% of patients with brain tumours rated their driving as “good” or “excellent”, with only approximately 17.9% self-limiting their driving since their brain cancer with only one individual reporting concerns regarding their driving ability [23]. Beyond highlighting the possible directions for change in future driving guidelines, these findings amplify the challenges faced by clinicians who treat patients with brain tumours in balancing patient autonomy and confidentiality against clinical concern for their safety when driving. Future studies incorporating patient perspectives regarding driving restrictions or quality-of-life assessments would be valuable in ensuring patient-centered care when making these challenging decisions.

Finally, beyond the findings of the Delphi survey regarding assessing fitness to drive, the novel methodology of this study provides an innovative change for future Delphi studies. A laborious and time-intensive aspect of performing Delphi studies is analyzing, summarizing, and distributing the results between rounds in a timely manner [8]. R was a powerful tool in this study that accelerated the process of generating accurate results that are unique to each respondent. This study developed an automated methodology on R for inter-round analysis, that performed rapid data assessment, figure generation, and qualitive analysis. While previous Delphi studies have utilized R in scenario analysis, it does not appear that other Delphi studies have utilized R for the inter-round analysis [24]. This novel change to Delphi Methodology can be applied to future Delphi studies to more efficiently disseminate individualized inter-round summary results.

There are limitations to our Delphi survey. The total number of panelists that responded to both rounds is small (17), but nevertheless falls within the acceptable range for Delphi studies of eight to 20 panelists [25]. All the panelists work in Australia, and there appeared to be geographic selection bias as 88.5% respondents worked primarily in tertiary hospitals, with only 7.7% working in regional hospitals, which may limit the generalizability of the findings to rural populations. Yet current guidelines similarly do not distinguish between metropolitan and rural practice sites. There was an attrition of respondents between rounds one and two, with nine panelists not participating in round two. Although the experience level of non-responders was comparable to those who completed both rounds, 66.7% of neurosurgeons did not respond, which may have influenced the findings of round two. As most (27) statements did not achieve a consensus, the statements which did have consensus provide mostly a direction for possible improvements to guidelines. Unfortunately, the guidelines generated are broad and remain open to interpretation. Further studies are needed to refine the consensus statements, such as the frequency of follow up imaging required to establish stability. There may be a role for future multidisciplinary Delphi studies incorporating occupational therapists, to establish degrees of impairment. However, the strengths of our study include a multidisciplinary cross-section of clinicians involved in driving decision making and reasonably high response rates across both rounds at 70.3% for round one and 65.4% for round two.