Tools

Hagar A. Algburi1, Mustafa Ismail1, Saad I. Mallah2, Linah S. Alduraibi3, Sama Albairmani4, Aanab O. Abdulameer1, Abdulaziz Saad Alayyaf5, Zaid Aljuboori6, Norberto Andaluz7, Samer S. Hoz7
  1. Department of Neurosurgery, University of Baghdad, College of Medicine, Al Risafa, Baghdad, Iraq,
  2. Department of Neurosurgery, School of Medicine, Royal College of Surgeons in Ireland - Bahrain, Busaiteen, Bahrain,
  3. Department of Neurosurgery, Sulaiman Al Rajhi University, College of Medicine, Al Bukayriyah, Saudi Arabia,
  4. Department of Neurosurgery, Al_Iraqia University, College of Medicine, Al Risafa, Baghdad, Iraq,
  5. Department of Neurosugery, Prince Sattam Bin Abdulaziz University, College of Medicine, Al Kharj - Riyadh, Saudi Arabia,
  6. Department of Neurosurgery, University of Wisconsin-Madison, Wisconsin, United States
  7. Department of Neurosurgery, University of Cincinnati, Cincinnati, Ohio, United States.

Correspondence Address:
Samer S. Hoz, Department of Neurosurgery, University of Cincinnati, Cincinnati, Ohio, United States.

DOI:10.25259/SNI_949_2022

Copyright: © 2023 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, transform, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.

How to cite this article: Hagar A. Algburi1, Mustafa Ismail1, Saad I. Mallah2, Linah S. Alduraibi3, Sama Albairmani4, Aanab O. Abdulameer1, Abdulaziz Saad Alayyaf5, Zaid Aljuboori6, Norberto Andaluz7, Samer S. Hoz7. Outcome measures in neurosurgery: Is a unified approach better? A literature review. 17-Feb-2023;14:61

How to cite this URL: Hagar A. Algburi1, Mustafa Ismail1, Saad I. Mallah2, Linah S. Alduraibi3, Sama Albairmani4, Aanab O. Abdulameer1, Abdulaziz Saad Alayyaf5, Zaid Aljuboori6, Norberto Andaluz7, Samer S. Hoz7. Outcome measures in neurosurgery: Is a unified approach better? A literature review. 17-Feb-2023;14:61. Available from: https://surgicalneurologyint.com/surgicalint-articles/12154/

Date of Submission
14-Oct-2022

Date of Acceptance
08-Feb-2023

Date of Web Publication
17-Feb-2023

Abstract

Background: Accurate assessment and evaluation of health interventions are crucial to evidence-based care. The use of outcome measures in neurosurgery grew with the introduction of the Glasgow Coma Scale. Since then, various outcome measures have appeared, some of which are disease-specific and others more generally. This article aims to address the most widely used outcome measures in three major neurosurgery subspecialties, “vascular, traumatic, and oncologic,” focusing on the potential, advantages, and drawbacks of a unified approach to these outcome measures.

Methods: A literature review search was conducted by using PubMed MEDLINE and Google scholar Databases. Data for the three most common outcome measures, The Modified Rankin Scale (mRS), The Glasgow Outcome Scale (GOS), and The Karnofsky Performance Scale (KPS), were extracted and analyzed.

Results: The original objective of establishing a standardized, common language for the accurate categorization, quantification, and evaluation of patients’ outcomes has been eroded. The KPS, in particular, may provide a common ground for initiating a unified approach to outcome measures. With clinical testing and modification, it may offer a simple, internationally standardized approach to outcome measures in neurosurgery and elsewhere. Based on our analysis, Karnofsky’s Performance Scale may provide a basis of reaching a unified global outcome measure.

Conclusion: Outcome measures in neurosurgery, including mRS, GOS, and KPS, are widely utilized assessment tools for patients’ outcomes in various neurosurgical specialties. A unified global measure may offer solutions with ease of use and application; however, there are limitations.

Keywords: Oncologic neurosurgery, Outcome measures, Traumatic neurosurgery, Unified scale, Vascular neurosurgery

INTRODUCTION

The accurate assessment and evaluation of health interventions are a crucial component of evidence-based care.[ 9 ] The systematic monitoring and analysis of surgical outcomes were first proposed by Dr. Earnst Amory Codman in the early 1900s but was met by unwavering resistance. It was not until 1988 that the Outcomes Committee of the American Association of Neurological Surgeons was established.[ 11 ] Before the mid-1970s, outcome measures were mostly restricted to objective physiologic findings, such as lab values or mortality rates. However, the value of patients’ quality of life and subjective perception of their state of wellness later drew attention to patient-reported clinical outcome measures.[ 25 ]

The use of outcome measures in neurosurgery grew in popularity in 1974 with the introduction of the Glasgow Coma Scale. Since then, various outcome measures have appeared, some of which are disease specific — such as the subarachnoid hemorrhage outcome tool — while others are used more generally, such as the health utility index.[ 29 ] With time, specific sub-specialized fields in neurosurgery began to develop their own outcome measures, many of which have been validated and used interchangeably as per different physician, hospital, and national preferences. For instance, more than 10 outcome measures have been reported to be used in pediatric stroke studies alone. Meanwhile, nearly 100 different outcome measures have been reported for traumatic brain injuries.[ 6 ] With the popularity of different outcome measures, the choice of the tool has become a combination of accepted practice and personal preference.[ 23 ] In designing these outcome measures, a balance between two main aims is sought: the comprehensiveness of the outcome measure in accurately describing the patient’s status and the efficiency of the outcome measure for routine use in clinical practice. As a result, what was initially sought to be a standardized, global approach to outcome evaluation is now dispersed across practices and unstandardized. In this paper, we will address the most widely used outcome measures in three of the essential subspecialties of neurosurgery — vascular, traumatic, and oncologic — with a focus on the potential, advantages, and drawbacks of a unified approach to outcome measures across neurosurgical subspecialties.

MATERIALS AND METHODS

The PubMed MEDLINE and Google scholar databases were utilized to conduct a literature review. The Modified Rankin Scale (mRS), The Glasgow Outcome Scale (GOS), and The Karnofsky Performance Scale (KPS) data were retrieved and analyzed.

RESULTS

The original goal of establishing a uniform shared language for the precise categorization, quantification, and evaluation of patients’ results has been undermined. Furthermore, the KPS may provide a basis for establishing a unified approach to outcome measures. It may provide a straightforward, internationally standardized approach to outcome measurements in neurosurgery and elsewhere after clinical testing and customization. In addition, based on our analysis, the KPS may provide a basis for establishing a unified global measure.

DISCUSSION

Vascular neurosurgery – The mRS

Vascular neurosurgery is mainly concerned with managing aneurysmal disease, vascular malformation, and ischemic and hemorrhagic stroke. One of the commonly used tools in vascular neurosurgery and especially in stroke trials is the mRS.[ 31 ] In 1957, Rankin introduced the Rankin Scale to provide an ultimate prognosis for those suffering from a significant cerebrovascular accident.[ 32 ] The scale primarily had five gradings that ranged from “1: No significant disability despite symptoms, able to carry out all usual duties and activities” to “5: Severe disability, bedridden, incontinent, requiring constant nursing care, and attention.”[ 42 ] In 1988, the Rankin Scale was modified by the United Kingdom Transient Ischaemic Attack trial to include an additional score, “0: No symptom at all.”[ 34 , 41 ] A further score, “6: Dead,” was added in the 2000s for reliability purposes, delivering the mRS in its current final form.[ 44 ]

Primarily, the mRS has been used in adult cerebrovascular disease, particularly in stroke trials.[ 1 ] Furthermore, It also has minimal usage in aneurysmal pathologies.[ 33 ] On the other hand, other alternative applications for mRS include general brain injury, trials for targeted hypothermia, sarcopenia, spinal meningiomas, and in children with transverse myelitis.[ 5 , 10 , 17 , 20 , 21 , 24 , 35 ] The broad use of the mRS is likely due to its simplicity and transferability as a general measure for the extent of disability.

Traumatic neurosurgery – The GOS

Traumatic neurosurgery is mainly concerned with the management of all blunt and penetrating brain injuries. Outcome measures for traumatic brain injury (TBI) exceed any other neurosurgical sub-specialty, with close to 100 measures.[ 26 ] The tools used in TBI may differ regarding acute versus long-term outcomes and mild to severe TBI. Each class of outcome measures has a role in different research settings and patient conditions. However, one of the usually used measures is the GOS and GOS Extended (GOSE),[ 36 ] which has been argued to be a near complete instrument, in combination with neuropsychological tests, for the assessment of outcome after TBI.[ 43 ]

The GOS was first described in 1975 by Drs Bryan Jennet and Michael Bond.[ 13 ] It was intended as an objective description of functional recovery following severe brain damage. The original GOS was scored on a five-point scale: death, persistent vegetative state, severe disability, moderate disability, and good recovery.[ 45 ] The seven-point extended version of GOSE was introduced in 1998 as a more accurate classification of functional recovery post-TBI by dividing moderate and severe disability into upper and lower limbs.[ 13 ]

Moreover, the GOS and GOSE measures have continued to be used in line with their original aim, which is traumatic head injuries.[ 27 ] However, the generality of the scale and the broad involvement of TBIs has allowed for applying GOS in several other areas, such as intracranial aneurysms, tumors, strokes, and cranioplasties.[ 12 , 14 , 16 , 40 ]

Oncologic neurosurgery – The KPS

Oncologic neurosurgery is mainly concerned with the management of all intracranial neoplastic tumors. Outcome measures of this subspecialty are crucial to assess the patient’s response to different treatments. The KPS is one of the oldest, most widely used, and evaluated outcome measures in oncology. Its uses have ranged from treatment planning to prognostic assessments.[ 19 , 38 , 46 ]

In 1948, the KPS was introduced by Dr. David Karnofsky to evaluate patients undergoing treatment with nitrogen mustard for bronchogenic carcinoma.[ 15 , 39 ] KPS was intended as an indicator of performance status, an attempt to quantify general well-being and activities of daily living. Further, this was particularly useful when other objective measures, such as survival time, were not as easily measurable.[ 15 ] The inter-rater reliability of KPS proved high in several studies.[ 47 ] Its construct validity was also found to be strongly associated with measures of patients’ functioning.[ 28 ]

Primarily, the KPS has been widely used to measure cancer patients’ functioning and the extent of disability. This has ranged widely from the brain to prostate cancer.[ 18 ] As a generally applicable measure of disability, the KPS has found its way to settings of palliative care, geriatric population, musculoskeletal injury, and cerebrovascular surgery.[ 2 - 4 , 22 , 37 , 48 ]

A comparative analysis

All three discussed scales are the most popular outcome measures in the major subspecialties of adult neurosurgery (vascular, traumatic, and oncologic) as examples of common targets between them which are the consciousness status and the neurological deficit measures. The oldest one of these three measures is the KPS (1948) followed by mRS (1957) and finally GOSE (1998). In terms of simplicity, the mRS is relatively the least comprehensive of the three tools, scored on a 7-point scale of which two are ‘no symptoms and ‘death’, whereas the KPS, scored on a 10-point scale with specific criteria, is the most comprehensive one. The GOSE, in terms of simplicity versus comprehensiveness, is most closely similar to the mRS. However, the GOSE is the only scale of the three to differentiate between upper and lower limb disability, which may offer an advantage for an accurate assessment of these regions. For both the KPS and GOSE scales, a higher number indicates a better state, whereas for the mRS a higher number indicates worse status.

The KPS offers the most patient-friendly utility in terms of communication with patients and relatives. Moreover, this is due to its structure as a “percentage of ability” where 100% refers to a disease-free individual, 50% is a disabled person requiring hospitalization or the equivalent, unable to care for themselves, and 0% is a dead individual. As such, the KPS can be argued to be the most intuitive of the three. In addition, while the mRS focuses mainly on the ability to care for oneself and ambulate, the KPS and GOSE differentiate between various forms of “self-care” that fall under activities of daily living, such as being able to resume work and previous activities [ Table 1 ]. In one study done by Gaastra et al. where they performed an intersection and correlation analysis between mRS and GOS retrospectively in 3474 paired recordings of the patients.[ 8 ] They found that the two outcome scores are correlated, and they in optimal agreement when mRS is two and GOS is 4–5. In addition, mRS to GOS conversion was found to be superior to the reverse option when it was available.[ 8 ] This study enriches the discussion between outcome measures on a deeper level and shows variability between them in a detailed manner.


Table 1:

A comparative analysis of the most common outcome measures in the neurosurgical subspecialties.

 

Regarding the reliability and validity of each measure, it is difficult to compare and draw conclusions due to the wide variation in study designs and findings in the literature over the years. Therefore, to accurately compare each measure, validity and reliability study needs to be conducted for all three measures under the same conditions.

It is worth noting that all three scales serve the same purpose at the core: describing and classifying a patient’s functional and physical abilities. However, none of the scales measure psychosocial aspects of disease and recovery.

Potential, advantages, and disadvantages of a unified outcome measure

With over 100 different outcome measures in the literature, the original objective of establishing a standardized, common language for accurately categorizing, quantifying, and evaluating patients’ outcomes which have been eroded. For this reason, a call for a unified approach to outcome measures is warranted.

By reviewing the history of origin for the three commonest scales, it becomes clear that the main factor behind the use of these scales in a specific field can be traced back to their initial historical use. Naturally, when a researcher publishes within their field, their work is disseminated and most likely to influence other researchers and practitioners within the same field. As such, innovations tend to lag in transcending between specialties and sub-specialties, leading to their restricted adoption within the niche community, it was first intended.

As can be drawn from an analysis of the three scales, they are more similar than dissimilar and can be applied equally to each sub-specialty. The KPS, in particular, may provide a common ground for initiating a unified approach to outcome measures. In addition, this unification considers its comprehensiveness, tested reliability and validity, intuitiveness, broad uses, and clear, descriptive criteria. In addition, the KPS is already used diversely in various fields that deal with cancer and may have the highest tendency of success in new applications. With clinical testing and modification, it may offer a simple, internationally standardized approach to outcome measures in neurosurgery and elsewhere.

The unified global approach to outcome measures may have advantages in clinical practice and research; it facilitates communication, patient handover, and consultations across different sub-specialties and centers and allows for accurate comparisons between trials and patient populations. These considerations may prove highly rewarding concerning patient outcomes, neurosurgeons’ practice, and researchers’ efforts. On the other hand, a unified approach to outcome measures may not be appropriate in all settings, as subtle differences may be required according to the particular needs of each subspecialty. Moreover, the future direction of measuring the quality of life in neurosurgery is getting more specialized and focused, and there is a need for disease-specific outcome measures to ensure an accurate assessment of the patients.[ 7 ] The topic of this paper and its related discussion can be highlighted in the future in a comprehensive systematic review utilizing PRISMA guidelines.[ 30 ]

Quality of life as end-point

In modern-day practice, quality of life has become a critical target, particularly in the field of neurosurgery. Schwartz et al. pointed out in their study (they utilized mRS scale in the study) on the neurological outcome and quality of life in patients with world federation of neurosurgical societies Grades 4 and 5 aneurysmal subarachnoid hemorrhages in their center that younger ages (<53 years) and radiological absence of cerebral ischemia were significantly associated with favorable outcome in the quality of life.[ 36 ] In another study where disease-specific outcome measure was used, Foscolo et al. examined the quality of life in patients after vestibular schwannoma surgery.[ 7 ] They reached the conclusion that the quality of life of the selected patients after the surgery was acceptable in most of the domains, with other ones being more affected, such as hearing and balance. Vestibular rehabilitation programs and effective strategies to tackle hearing problems are recommended for postoperative cases with low scores.[ 7 ] The generated discussion in the literature is may pinpoint the need for disease-specific outcome measures to gain a more reliable measure of the intervention and future steps in patients’ management.

Limitations

The article represented a narrative review of the literature regarding the outcome measures in neurosurgery; however, a systematic review of the literature on this topic may redeem better cultivation of the subject. Our study focuses on the targets of consciousness status and neurological deficits in the outcome measures, mainly with examples applied in vascular, trauma, and oncology. Moreover, a suggested systematic review in the future that encompasses all the target measures in outcome in all possible sub-specialties within neurosurgery would add more clarification to the debates about the outcome measures.

CONCLUSION

Outcome measures in neurosurgery, like “The Modified Rankin Scale, The Glasgow Outcome Scale, and The Karnofsky Performance Scale” are commonly utilized assessment tools for patients’ outcomes in various neurosurgical diseases. A unified global measure may provide a solution with ease of use and application; however, there are limitations.

Declaration of patient consent

Patient’s consent not required as there are no patients in this study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

References

1. Banks JL, Marotta CA. Outcomes validity and reliability of the modified Rankin scale: Implications for stroke clinical trials: A literature review and synthesis. Stroke. 2007. 38: 1091-6

2. Belcaro G, Cesarone MR, Dugall M, Pellegrini L, Ledda A, Grossi MG. Efficacy and safety of Meriva®, a curcuminphosphatidylcholine complex, during extended administration in osteoarthritis patients. Altern Med Rev. 2010. 1: 337-44

3. Cho WS, Kim JE, Kim CH, Ban SP, Kang HS, Son YJ. Long-term outcomes after combined revascularization surgery in adult moyamoya disease. Stroke. 2014. 45: 3025-31

4. Crooks V, Waller S, Smith T, Hahn TJ. The use of the Karnofsky Performance Scale in determining outcomes and risk in geriatric outpatients. J Gerontol. 1991. 46: M139-44

5. Dankiewicz J, Cronberg T, Lilja G, Jakobsen JC, Bělohlávek J, Callaway C. Targeted hypothermia versus targeted Normothermia after out-of-hospital cardiac arrest (TTM2): A randomized clinical trial-rationale and design. Am Heart J. 2019. 217: 23-31

6. Engelmann KA, Jordan LC. Outcome measures used in pediatric stroke studies: A systematic review. Arch Neurol. 2012. 69: 23-7

7. Foscolo V, de Gennaro L, Murri A, Speranzon L, Signorelli F, Quaranta N. Postoperative impact of pontocerebellar angle surgery on the quality of life in patients with vestibular schwannoma. Audiol Res. 2022. 12: 635-43

8. Gaastra B, Ren D, Alexander S, Awad IA, Blackburn S, Doré S. Evidence-based interconversion of the Glasgow Outcome and modified Rankin scales: pitfalls and best practices. J Stroke Cerebrovasc Dis. 2022. 31: 106845

9. Glick HA, Polsky D, Willke RJ, Schulman KA. A comparison of preference assessment instruments used in a clinical trial: Responses to the visual analog scale from the EuroQol EQ-5D and the Health Utilities Index. Med Decis Making. 1999. 19: 265-75

10. Hansen PM, Lauridsen JT, Frandsen NS. Risk of delirium and impaired neurological outcome associated with delay in neurorehabilitation after acquired brain injury. Dan Med J. 2021. 68: A03210199

11. Harbaugh RE. History of outcomes measures in neurosurgery. Neurosurg Clin N Am. 2001. 12: 217-21

12. Hofman M, Jamróz T, Jakutowicz I, Jarski P, Masarczyk W, Niedbała M. Endovascular treatment of complex intracranial aneurysms. Pol J Radiol. 2018. 83: 109-14

13. Jennett B, Bond M. Assessment of outcome after severe brain damage: A practical scale. Lancet. 1975. 305: 480-4

14. Junior AC, Filho PT, Gonçalves MP, Neto AA, Zanini MA. Cranioplasty: An institutional experience. J Craniofac Surg. 2018. 29: 1402-5

15. Karnofsky DA, Abelmann WH, Craver LF, Burchenal JH. The use of the nitrogen mustards in the palliative treatment of carcinoma: With particular reference to bronchogenic carcinoma. Cancer. 1948. 1: 63

16. Kasner SE. Clinical interpretation and use of stroke scales. Lancet Neurol. 2006. 5: 603-12

17. Katsuki M, Suzuki Y, Kunitoki K, Sato Y, Sasaki K, Mashiyama S. Temporal muscle as an indicator of sarcopenia is independently associated with hunt and kosnik grade on admission and the modified rankin scale score at 6 months of patients with subarachnoid hemorrhage treated by endovascular coiling. World Neurosurg. 2020. 137: e526-34

18. Kelly WK, Scher HI, Mazumdar M, Vlamis V, Schwartz M, Fossa SD. Prostate-specific antigen as a measure of disease outcome in metastatic hormone-refractory prostate cancer. J Clin Oncol. 1993. 11: 607-15

19. Khalid MA, Achakzai IK, Khan SA, Majid Z, Hanif FM, Iqbal J. The use of Karnofsky Performance Status (KPS) as a predictor of 3 month post discharge mortality in cirrhotic patients. Gastroenterol Hepatol Bed Bench. 2018. 11: 301-5

20. Kohli A, Chao E, Spielman D, Sugano D, Srivastava A, Dayama A. Factors associated with return to work Postinjury: Can the modified Rankin scale be used to predict return to work?. Am Surg. 2016. 82: 95-101

21. Kwee LE, Harhangi BS, Ponne GA, Kros JM, Dirven CM, Dammers R. Spinal meningiomas: Treatment outcome and long-term follow-up. Clin Neurol Neurosurg. 2020. 198: 106238

22. Laing RJ. Measuring outcome in neurosurgery. Br J Neurosurg. 2000. 14: 181-4

23. Liao Z, Quintana Y. Challenges to global standardization of outcome measures. AMIA Jt Summits Transl Sci Proc. 2021. 2021: 404-9

24. Lim J, Hamouda ES, Fortier MV, Thomas T. Antecedent minor trauma and hyperacute presentations in childhood transverse myelitis. J Child Neurol. 2021. 36: 1034-41

25. Lorig K, Stewart A, Ritter P, Gonzalez V, Lynch J, Laurent D, editors. Outcome Measures for Health Education and Other Health Care Interventions. California, United States: Sage; 1996. p.

26. McCauley SR, Wilde EA, Anderson VA, Bedell G, Beers SR, Campbell TF. Recommendations for the use of common outcome measures in pediatric traumatic brain injury research. J Neurotrauma. 2012. 29: 678-705

27. McMillan T, Wilson L, Ponsford J, Levin H, Teasdale G, Bond M. The glasgow outcome scale-40 years of application and refinement. Nat Rev Neurol. 2016. 12: 477-85

28. Mor V, Laliberte L, Morris JN, Wiemann M. The Karnofsky performance status scale: An examination of its reliability and validity in a research setting. Cancer. 1984. 53: 2002-7

29. Nobels-Janssen E, van der Wees PJ, Verhagen WI, Westert GP, Bartels RH, Boogaarts JD. Patient-reported outcome measures in subarachnoid hemorrhage: A systematic review. Neurology. 2019. 92: 1096-112

30. Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD. The PRISMA 2020 statement: An updated guideline for reporting systematic reviews. BMJ. 2021. 372: n71

31. Pistoia F, Sacco S, Ornello R, Degan D, Tiseo C, Carolei A. Composite scores and other outcome measures in stroke trials. Right Ther Neurol Disorders. 2016. 39: 60-70

32. Rankin J. Cerebral vascular accidents in patients over the age of 60: II. Prognosis. Scott Med J. 1957. 2: 200-15

33. Rinaldo L, Johnson DM, Vine RL, Rabinstein AA, Lanzino G. Differences between patient-and professional-reported modified Rankin Scale score in patients with unruptured aneurysms. J Neurosurg. 2018. 131: 397-402

34. Savio K, Pietra GL, Oddone E, Reggiani M, Leone MA. Reliability of the modified Rankin Scale applied by telephone. Neurol Int. 2013. 5: e2

35. Schaefer PW, Huisman TA, Sorensen AG, Gonzalez RG, Schwamm LH. Diffusion-weighted MR imaging in closed head injury: High correlation with initial Glasgow coma scale score and score on modified Rankin scale at discharge. Radiology. 2004. 233: 58-66

36. Schwartz C, Pfefferkorn T, Ebrahimi C, Ottomeyer C, Fesl G, Bender A. Long-term neurological outcome and quality of life after world federation of neurosurgical societies grades IV and V aneurysmal subarachnoid hemorrhage in an interdisciplinary treatment concept. Neurosurgery. 2017. 80: 967-74

37. Shukla D, Devi BI, Agrawal A. Outcome measures for traumatic brain injury. Clin Neurol Neurosurg. 2011. 113: 435-41

38. Silva CH, Morais SS, Sarian LO, Derchain SF. Association of the Karnofsky Performance Scale with the quality of life of Brazilian women undergoing palliative care. J Palliat Care. 2011. 27: 164-9

39. Timmermann C. ‘Just give me the best quality of life questionnaire’: The Karnofsky scale and the history of quality of life measurements in cancer trials. Chronic Illn. 2013. 9: 179-90

40. Tobias S, Jahshan S, Grober Y, Soustiel JF. Skull base hemangiopericytomas. Acta Neurol Belg. 2021. 126: 1537-45

41. Uk-Tia Study Gro. United Kingdom transient ischaemic attack (UK-TIA) aspirin trial: Interim results. Br Med J (Clin Res Ed). 1988. 296: 316-20

42. Van Swieten JC, Koudstaal PJ, Visser MC, Schouten HJ, Van Gijn J. Interobserver agreement for the assessment of handicap in stroke patients. Stroke. 1988. 19: 604-7

43. Wilde EA, Whiteneck GG, Bogner J, Bushnik T, Cifu DX, Dikmen S. Recommendations for the use of common outcome measures in traumatic brain injury research. Arch Phys Med Rehabil. 2010. 91: 1650-60

44. Wilson JL, Hareendran A, Hendry A, Potter J, Bone I, Muir KW. Reliability of the modified Rankin Scale across multiple raters: Benefits of a structured interview. Stroke. 2005. 36: 777-81

45. Wilson JL, Pettigrew LE, Teasdale GM. Structured interviews for the Glasgow Outcome Scale and the extended Glasgow Outcome Scale: Guidelines for their use. J Neurotrauma. 1998. 15: 573-85

46. Witteler J, Schild SE, Rades D. Palliative radiotherapy of primary glioblastoma. In Vivo. 2021. 35: 483-7

47. Yates JW, Chalmer B, McKegney FP. Evaluation of patients with advanced cancer using the Karnofsky performance status. Cancer. 1980. 45: 2220-4

48. Yip CM, Hsu SS, Liao WC, Liu SH, Lin YS, Hsu YH. Intracranial solitary fibrous tumor/hemangiopericytoma-A case series. Surg Neurol Int. 2020. 11: 414

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