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. 2025 Jun 2;16(4):1303–1318. doi: 10.1007/s41999-025-01242-8

Table 3.

The association between frailty and hospital-related adverse events

Authors Type and incidence of AE n (%) Among non-frail and pre-frail patients (if reported) Type and incidence of AE n (%) Among frail patients Adjusted effect estimates for frailty as a predictor of AE Confounders
Deiner et al. [42]

Postoperative delirium (POD)

Frailty index (FI):

Non-frail 17/120

Pre-frail 32/190

Frailty phenotype (FP):

Non-frail 8/64

Pre-frail 58/280

Postoperative delirium (POD)

Frailty index (FI):

Frail: 60/195

Frailty phenotype (FP):

Frail: 43/160

Frailty index

RR 1.84 [95% CI 1.05–3.21], p-value = 0.06

Frailty phenotype

RR 1.33 [95% CI 0.63–2.80], p-value = 0.78

Adjusted for: age, sex, ASA class, surgical urgency, CCI, procedure complexity, and Modified Mini-Mental State
Esmaeeli et al. [27]

Postoperative delirium (POD)

Robust (frail 0): 7/174

Pre-frail (frail 1–2): 36/232

Postoperative delirium (POD)

Frail (frail 3–5): 37/151

OR 1.33 (95% CI 1.02–1.72), p-value = 0.03 Adjusted for: age, sex, marital status, cognitive score, Charlson comorbidity Index, falls in the past year, glomerular filtration rate, and ICU admission
Sieber et al. [29]

Postoperative delirium (POD)

Non-frail: 5/241

Postoperative delirium (POD)

Frail: 10/83

OR 3.5 (95% CI 1.1–11.5), p-value = 0.0007 Adjusted for: age and comorbidities
Joseph et al. [43]

Non-Frail and pre-frail

UTI: 9/217

Pneumonia: 7/217

Sepsis: 6/217

DVT/PE: 5/217

DIC: 2/217

Frail

UTI: 13/133

Pneumonia: 12/133

Sepsis: 5/133

DVT/PE: 7/133

DIC: 2/133

Not reported Not reported
Leung et al. [44]

Postoperative delirium (POD)

Pre-frail (frailty scores 1–2): 7/32

Postoperative delirium (POD)

Frail (frailty score ≥ 3): 9/21

OR 1.84 (95% CI 1.07–3.15), with a p-value of 0.028 Adjusted for: age, GDS score, and baseline cognitive function
Hanlon et al. [33] The population of this study consisted of all frail individuals, with 365/397 (91.9%) frail patients receiving ≥ 1 inappropriate medication prescribed Not reported  Not reported
McEvoy et al. [30]

Falls

0–1 deficit: 104/24,339

2 deficits: 181/8,717

3 deficits: 318/8,513

Pressure injury

0–1 deficit: 19/24,339

2 deficits: 17//8,717

3 deficits: 50//8,513

Delirium

0–1 deficit: 63/24,339

2 deficits: 202/8717

3 deficits: 426/8513

Pneumonia

0–1 deficit: 88/24,339

2 deficits: 104/8717

3 deficits: 219/8513

Thromboembolism

0–1 deficit: 33/24,339

2 deficits: 25/8717

3 deficits: 59/8513

4–12 deficits

Falls: 217/3152

Pressure injury: 54/3152

Delirium: 351/3152

Pneumonia: 189/3152

Thromboembolism: 31/3152

4–12 deficits

Falls:

RR 15.33 (95% CI 12.1–19.42, p < 0.001)

Pressure ulcers:

RR 21.28 (95% CI 12.53–36.16, p < 0.001)

Delirium:

RR 40.88 (95% CI 31.21–52.55, p < 0.001)

Pneumonia:

RR 16.46 (95% CI 12.74–21.27, p < 0.001)

Thromboembolism: RR 7.25 (95% CI 4.4–11.92, p < 0.001)

Adjusted for: age and sex
Thillainadesan J et al. [26]

Assessed by a FI

Delirium: 6/116

Functional decline: 17/116

Constipation: 64/116

Fall: 3/116

Pressure injury: 2/116

Assessed by CFS

Delirium: 6/105

Functional decline: 15/105

Constipation: 59/105

Fall: 3/105

Pressure injury: 2/105

Assessed by a FI

Delirium: 9/34

Functional decline: 11/34

Constipation: 16/34

Fall: 3/34

Pressure injury: 0/34

Assessed by CFS

Delirium: 10/45

Functional decline: 13/45

Constipation: 21/45

Fall: 3/45

Pressure injury: 0/45

Frailty Index (FI):

Delirium: OR = 5.64 (95% CI 1.47–21.68)

Functional decline: OR = 2.08 (95% CI 0.73–5.91)

Clinical frailty scale (CFS):

Delirium: OR = 4.21 (95% CI 1.14–15.50)

Functional decline: OR = 1.39 (95% CI 0.50–3.88)

Adjusted for: age, sex, Charlson comorbidity index (CCI), admission type and surgical management approach
Hubbard et al. [31]

The study did not explicitly report the exact numbers of AE per frail vs non-frail patients

Inpatient fall: 83/1418

Inpatient delirium: 321/1418

Inpatient pressure ulcer: 42/1418

Inpatient functional decline: 96/1418

 Inpatient Falls: OR 1.29 (95% CI: 1.10–1.50) Per 0.1 FI increase. Delirium: OR 2.34 (95% CI: 2.08–2.63) Per 0.1 FI increase. Pressure Ulcers: OR 1.51 (95% CI: 1.23–1.87) Per 0.1 FI increase. Functional decline: OR 1.20 (95% CI: 1.04–1.40) Per 0.1 FI increase. Adjusted for: age, gender, comorbidities, and baseline cognitive function 
Chan et al. [37]

CFS 1–3

Delirium: 21

Venous thromboembolism: 1

Pneumonia: 2

UTI: 7

Myocardial injury: 11

Need for transfusion: 14

Pressure ulcer: 8

Fall: 1

CFS 4–9

Delirium: 240

Venous thromboembolism: 12

Pneumonia: 28

UTI: 49

Myocardial injury: 104

Need for transfusion: 121

Pressure ulcer: 116

Fall: 22

(CFS 4)

OR 1.0 (95% CI 0.5–2.2), p-value: 0.974

(CFS 5)

OR 2.1 (95% CI 0.9–4.8), p-value: 0.076

(CFS 6–9)

OR: 4.8 (95% CI 2.1–10.8), p-value: < 0.001

Adjusted for: age, sex, time to surgery, and mode of anaesthesia
Dasgupta M et al. [41]

Having at least one complication:

EFS < 4: 5/51

EFS 4–7: 48/183

Having at least one complication:

EFS > 7: 9/16

EFS > 7

Cardiac complication:

OR 3.75 (95% CI 1.04–13.51)

Pulmonary complication:

OR 6.61 (95% CI 1.51–28.29)

Delirium:

OR 2.43 (95% CI 0.65–9.07)

Adjusted for: age
Jung et al. [34]

For CFS < 5

Total non-frail patients = 637

Delirium 1/637

Pressure ulcers 0/637

Falls 1/637

For CFS ≥ 5

Total frail patients = 379

Delirium 49/379

Pressure ulcers 26/379

Falls 5/379

Falls: OR = 1.39 (95% CI 0.74–2.60)

Pressure ulcers: OR = 2.77 (95% CI 1.94–3.96)

Delirium: OR = 2.56 (95% CI 1.98–3.31)

Adjusted for: age and sex
Kim et al. [36]

The study reported the total incidence of adverse events but did not specify the breakdown between non-frail and frail groups

Total incidence of complications = 85

Poor oral intake 16/85

Voiding difficulty 14/85

Urinary tract infection 4/85

Delirium 3/85

Pneumonia 3/85

Postoperative hematoma 2/85

Acute kidney injury 1/85

Electrolyte imbalance 1/85

Sepsis 1/85

Cardiac arrest 1/85

Superficialwoundinfection1/85

, p

 K-FRAIL scale and any postoperative complication:OR = 0.130 (95% CI 0.039–0.222), p = 0.006  Adjusted for: age, surgical invasiveness, and CCI
Nowak et al. [35]

Non-frail:

Bleeding 9/54

Infection 6/54 arrhythmia 5/54

Acute kidney injury (AKI) 11/54

Delirium 2/54

Stroke/transient ischaemic attack (TIA) 1/54

Liver injury 0/54

Hypoglycaemia 1/54

Pre-frail:

Bleeding 14/52

Infection 16/52

Arrhythmia 19/52

Acute kidney injury (AKI) 15/52

Delirium 6/52

Stroke/transient ischaemic attack (TIA) 2/52

Liver injury 6/52

Hypoglycaemia 0/52

Frail:

Bleeding 31/68

Infection 37/68

Arrhythmia 54/68

Acute kidney injury (AKI) 39/68

Delirium 36/68

Stroke/transient ischaemic attack (TIA) 3/68

Liver injury 12/68

Hypoglycaemia 7/68

Bleeding: not reported

Infection: OR = 3.3 (95% CI 1.6–7.0)

Pneumonia/LRTI: OR = 2.5 (95% CI 1.1–5.8)

UTI: OR = 4.8 (95% CI 1.8–12.5)

Arrhythmia (only atrial fibrillation): OR = 3.5 (95% CI 1.3–9.3)

AKI: OR = 2.6 (95% CI 1.2–5.3)

Delirium: OR = 11.7 (95% CI 4.8–28.7)

Adjusted for: age, BMI, atrial fibrillation, left ventricular ejection fraction, haemoglobin on admission, and invasive vs. conservative treatment
Chen et al. [39]

Postoperative pulmonary complications (PPC) = 56

Non-frail: 20/56

Postoperative pulmonary complications (PPC) = 56

Frail: 30/56

Frailty: OR 6.33 (95% CI 2.45–16.37) Adjusted for: age, sex, body mass index, current drinker, current smoker, hypertension, diabetes, coronary artery disease, asthma, chronic obstructive pulmonary disease, obstructive sleep apnoea, bronchiectasis, respiratory infection within the last month, forced expiratory volume in the first second (FEV1), FEV1/forced vital capacity (FVC), preoperative SpO2, haemoglobin, creatinine, operation time
Aceto et al. [40]

Postoperative pulmonary complications (PPC)

Non-frail: 1/11

Postoperative pulmonary complications (PPC)

Frail: 10/11

Logistic regression showed that mFI were a predictor of PPCs (p = 0.0001) but the study did not report the OR Not reported
Welch et al. [28]

Postoperative delirium (POD)

Fit (CFS 1–3):

15 out of 468

Postoperative delirium (POD)

Frail (CFS 4–6):

134/796

Very frail (CFS 7–9):

67/201

Frail (CFS 4–6): OR = 4.80 (95% CI 2.63–8.74)

Very frail (CFS 7–9): OR = 9.33 (95% CI 4.79–18.17)

Adjusted for: age, sex, Charlson Comorbidity Index (CCI), admission type, and baseline cognitive status
Birkelbach et al. [38]

Non-frail and pre-frail

Pneumonia: 23/1051

Pulmonary embolism: 6/1051

Acute kidney injury: 57/1051

Cerebrovascular accident: 2/1051

Coma: 2/1051

Superficial wound infections: 26/1051

Deep wound infections: 15/1051

Urinary tract infection: 172/1051

Sepsis: 14/1051

Deep vein thrombosis: 12/1051

Myocardial infarction: 2/1051

Cardiac arrest: 3/1051

Frail

Pneumonia: 5/135

Pulmonary embolism: 0/135

Acute kidney injury: 12/135

Cerebrovascular accident: 1/135

Coma: 2/135

Superficial wound infections: 8/135

Deep wound infections: 3/135

Urinary tract infection: 33/135

Sepsis: 4/135

Deep vein thrombosis: 2/135

Myocardial infarction: 2/135

Cardiac arrest: 4/135

Frail OR 2.08 (95% CI 1.21–3.60) p-value, 0.008 Adjusted for: age, sex, body mass index, American Society of Anaesthesiologists Physical Status (ASA PS), surgical risk, type of anaesthesia, Charlson comorbidity index (CCI), surgical discipline, smoking status, polypharmacy, as well as preoperative creatinine levels and glomerular filtration rates (GFR)
Joosten et al. [32]

Non-frail and pre-frail by CHS

Delirium: 14/132

Fall: 10/132

Non-frail and pre-frail by SOF

Delirium: 14/138

Fall: 12/138

Frail by CHS

Delirium: 10/88

Fall: 8/88

Frail by SOF

Delirium: 6/66

Fall: 5/66

CHS index

Delirium

OR 0.64 (95% CI 0.25–2.08)

Fall

OR 0.94 (95% CI 0.31–2.91)

SOF index

Delirium

OR 0.81 (95% CI 0.21–3.2)

Fall

OR 0.71 (95% CI 0.21–2.4)

Adjusted for: age, sex, education, number of comorbidities, ADLs, cognitive impairment, main diagnosis, haemoglobin, depression, and estimated Glomerular Filtration Rate