CD-FI

Developed by the International Spine Study Group (ISSG) in 2018, that comprises 40 health comorbidities and patient-reported measures to assess the severity of frailty specific to spinal deformity in CSD patients.

It is designed to capture physiological ageing rather than just chronological age, which is a better predictor of adverse events after surgery.

Calculation as a Ratio:

The CD-FI score is derived by calculating the mean score of all these deficits. This means it is expressed as a ratio of the number of health deficits present to the total number of deficits considered (40).
For instance, if a patient has 10 out of the 40 deficits present, their CD-FI score would be 10/40, or 0.25.

Categorisation of Frailty: Patients are then categorised into frailty levels based on their CD-FI score:

Not Frail (NF): Scores < 0.2.
Frail: Scores between 0.2 and 0.4.
Severely Frail (SF): Scores > 0.

Adult Cervical Spinal Deformity Frailty Index (CD-FI) VS Adult Spinal Deformity Frailty Index (ASD-FI) are not the same, but they are closely related.

The ASD-FI was developed and validated specifically for patients with adult spinal deformity (not limited to cervical, but including thoracolumbar and lumbar deformity). It comprises ~40 items covering multidisciplinary health deficits (medical, functional, psychosocial).
The CD-FI is a cervical-specific frailty index created for adults undergoing cervical deformity surgery. It is based on the methodology and many of the same deficits as the ASD-FI, but was recalibrated for the cervical spine patient population.

Clinical significance

Prediction of Postoperative Complications:

Severely frail (SF) patients (CD-FI score > 0.4 points) have significantly higher odds of experiencing major complications (Odds Ratio (OR) 43; 95% Confidence Interval (CI) 2.7–684; P < 0.01) compared to not frail (NF) patients (<0.2 points).
While it correlates with medical complications, initial studies noted it did not significantly correlate with surgical complications, length of hospital stay, or discharge disposition in some cohorts, though sample size limitations were noted.

Improved Patient Counselling and Surgical Planning: By assessing a patient's frailty status, clinicians can more effectively counsel patients on their individual risks of adverse outcomes and potentially modify the invasiveness of surgery accordingly.
Influence on Recovery and Mitigation Strategies:

Patients who achieve successful radiographic correction are associated with a greater reduction in their CD-FI score, suggesting it can reflect improvements in physiological status post-surgery.
It informs strategies to mitigate risk, such as preoperative "prehabilitation" protocols (e.g., physical therapy, pain management, nutrition guidance), which can lead to fewer complications and shorter hospital stays.
Frail patients may also require longer fusion constructs for better outcomes.

40 items that comprise the original Adult Cervical Spinal Deformity Frailty Index (CD-FI)

Lung disease (e.g., COPD, asthma)

BMI <18.5kg/m² or >30kg/m²

Diabetes

Depression

Liver disease

Rheumatoid arthritis

Venous disease

Unsteady gait

Bladder incontinence

Leg weakness

≥4 comorbid conditions

Anxiety (EQ-5D-3L)

Bowel incontinence

Difficulty sleeping >6 hours (SWAL-QOL 9B)

Inability to walk (EQ-5D-3L)

Cancer

Cardiac disease

Disability status

Hypertension

Osteoporosis

Peripheral vascular disease

Prior blood clot (DVT/PE/stroke)

Smoking status

Bladder incontinence (duplicate for severity or frequency)

Bowel incontinence (duplicate for severity or frequency)

Deteriorating health this year

Difficulty climbing stairs

Difficulty driving a car

Difficulty getting dressed

Difficulty getting in/out of bed

Difficulty walking 91 meters (100 yards)

Difficulty with light activity

Feeling downhearted/depressed most of the time

Feeling tired most of the time

Feeling worn out most of the time

Fair/poor general health

Inability to bathe without assistance

Inability to cheer up often

Inability to do normal work/schoolwork/housework

Inability to lift heavy objects

Inability to travel >1 hour

Need for assistive device to walk

Loss of balance

Personal care dependency

Restricted activity level

Restricted social life

Note:

Some items combine clinical comorbidities (e.g., diabetes, lung disease) with functional and patient-reported measures (e.g., mobility, mood, self-care, sleep, social participation).