Table 2 Summary characteristics of included studies

Cloney et al 2015 [35]

frailty in patients with glioblastoma

Retrospective cohort study in elective surgery

243 patients

Age > 65

MFI 11

81% frail

-Association between mFI score and the decision to forego surgical resection -rate of postoperative complications,

-Length of hospital stay,

-Overall mortality;

-Frailer patients were less likely to undergo surgical resection, as opposed to a biopsy, had longer hospital stays, an increased overall risk of complications, and decreased overall survival;

Harland et al. 2020 [37]

frailty in patients undergoing tumour surgery

Prospective cohort study in elective surgery

260 patients

Age > 18

John Hopkins Frailty Instrument

25% frail

-Postoperative complications within 30 days of surgery, including mortality; -new neurologic deficit; -LOS; -discharge to a skilled nursing facility, acute rehabilitation facility, or hospice at 30 days when previously independent

-Preoperative frailty was associated with an increased risk for discharge to a location other than home, postoperative complications;

Henry et al. 2021 [38]

skull base procedures National Surgical Quality Improvement Program (NSQIP) database from 2005 to 2018

Retrospective cohort study—trauma cases were excluded

17912

Age > 18

5 Factor Modified Frailty Index

45% frail

Primary outcome variables included rates of overall complications and life-threatening complications within the 30-day postoperative period.

-Independent predictor of overall complications life-threatening complications, and mortality.

Huq et al. 2021 [15]

Frailty in brain tumor patients

Single-center retrospective cohort study primary brain surgery

1692

Age > 18

5 Factor Modified Frailty Index

57% frail

Total length of stay (LOS), intensive care unit (ICU) LOS, complications, charges, and 30-d readmissions)

-Mean intensive care unit (ICU) and total LOS were 1.69 and 5.24 days respectively.

Mean pulmonary embolism (PE)/deep vein thrombosis (DVT), physiological/metabolic derangement, respiratory failure, and sepsis rates were 7.2%, 1.1%, 1.6%, and 1.7%, respectively.

Mean total charges were $42,331;

Imaoka et al. 2018 [36]

Frailty in patients undergoing treatment for spontaneous cerebral hemorrhage

Single-center retrospective cohort study—no trauma cases

156

Age > 18

11 Factor Modified Frailty Index

75% frail

Outcome measures included an unfavorable outcome (modified Rankin Scale score of 4–6) or mortality at 6–8 months after hemorrhage.

-Higher mFI was significantly associated with an unfavorable outcome (p value = 0.004) and mortality

Shahrestani et al. 2020 [16]

Frailty in patients undergoing primary tumor surgery

Primary CNS neoplasm between 2010 and 2017 by using the Nationwide Readmission Database

13342

Age > 65

JHACG

50% frail

-Demographics and frailty were queried at primary admission, and readmissions were analyzed at 30-, 90-, and 180-day intervals; complications of interest included infection, anemia, infarction, kidney injury, CSF leak, urinary tract infection, and mortality;

-Mortality was increased compared to non-frail geriatric patients receiving the same procedure; frail patients had a significantly increased inpatient length of stay (p < 0.0001) and all-payer hospital cost (p < 0.0001) compared to non-frail patients at the time of primary admission.

Theriault 2020 [40]

Primary tumor surgery

Single-center retrospective cohort study of patients who underwent intracranial meningioma resection

76 patients

Age> 18

5 Factor Modified Frailty Index;

55% frail

LOS (length of stay), discharge location, readmission rates, and reoperation rates;

-Increased hospital LOS (p = 0.0218), increased reoperation rate (p = 0.029), and discharge to a higher level of care;

Sastry et al. 2020 [39]

Primary tumor surgery

Retrospective cohort 2012–2018 ACS-NSQIP participant

use file

20,333

Age> 18

5 Factor Modified Frailty Index

41% frail

incidence of major postoperative complications, discharge destination other than home, 30-day readmission, and 30-day mortality after elective craniotomy for brain tumor resection.

- Both low and medium-high frailty were associated with increased adjusted odds ratio of major complications, discharge destination other than home, and 30-day mortality;

Youngerman et al. 2017 [17]

Primary tumor surgery

NSQIP 2008–2012

9149

Age> 18

11 Factor

Modified

Frailty Index

49% frail

30-day mortality, 30-day severe medical complications, 30-day severe neurologic complications, 30-day any complication, extended length of stay (LOS), and unfavorable disposition

-mFI was associated with stepwise increases in the rates of mortality, severe medical complications, prolonged length of stay, and unfavorable discharge;