Abstract
Study Design
Retrospective cohort study.
Purpose
To investigate the association between preoperative nutritional status and postoperative in-hospital falls in patients undergoing surgery for cervical myelopathy.
Overview of Literature
In-hospital falls are common adverse events among surgical patients; however, the association between preoperative nutritional indices and postoperative in-hospital falls in patients undergoing spinal surgery for cervical myelopathy remains unclear.
Methods
We retrospectively reviewed clinical, laboratory, and surgical data of 649 patients who underwent surgery for cervical myelopathy at a single institution. Additionally, preoperative nutritional indices were assessed using the prognostic nutritional index (PNI), geriatric nutritional risk index, and controlling nutritional status score. Multivariable logistic regression and Cox proportional hazards regression analyses were performed to identify fall-related independent risk factors. Kaplan-Meier analysis was used to compare fall-free probability during hospitalization according to the PNI category.
Results
Among 649 patients, 48 (7.4%) experienced postoperative in-hospital falls. Patients who experienced falls had significantly lower nutritional status. PNI showed the strongest association with falls among the evaluated nutritional indices (odds ratio [OR], 0.91; p<0.001) and the highest predictive performance, although its discriminatory ability was modest (area under the curve=0.687). A PNI value of <50 (OR, 3.74; p=0.001) and cerebrovascular disease (OR, 5.22; p<0.001) were identified as independent risk factors of falls; this was confirmed in the Cox analysis (PNI <50: hazard ratio [HR], 3.11; p=0.008; cerebrovascular disease: HR, 4.82; p<0.001).
Conclusions
Preoperative PNI is a practical laboratory-based marker for identifying patients at high risk of postoperative falls, with low preoperative PNI (<50) associated with an increased risk of postoperative in-hospital falls in patients undergoing surgery for cervical myelopathy.
Keywords: Cervical myelopathy, Accidental falls, Nutritional status, Prognostic nutritional index
Graphical Abstract
Introduction
In-hospital falls are one of the most common adverse events occurring during hospitalization, representing a major patient safety concern [1,2]. Falls in turn lead to serious consequences, such as fractures, head injuries, delayed rehabilitation, prolonged hospital stay, and increased healthcare costs [3–5]. Therefore, identifying patients at high risk for falls is a critical component of perioperative patient management.
Several risk factors for in-hospital falls have been documented, including advanced age, impaired mobility, cognitive dysfunction, and the presence of comorbidities [6,7]. Previous studies investigating falls after spinal surgery have also identified older age and higher comorbidity burden as significant predictors of in-hospital falls [8]; however, these studies have largely evaluated heterogeneous cohorts and primarily focused on demographic or perioperative clinical factors rather than patient-specific physiological conditions.
Patients undergoing cervical spine surgery for cervical myelopathy tend to be more vulnerable to in-hospital falls because the disease itself is commonly associated with gait disturbances, impaired balance, and motor dysfunction. Frequent falls and fall-related neurological deterioration have often been reported in patients with degenerative cervical myelopathy [9,10]. Although surgical treatment may reduce fall frequency, postoperative recovery is often gradual, and gait instability may persist during the early postoperative period.
In recent years, increasing attention has been directed toward the role of nutritional status in surgical outcomes. Malnutrition is reported to be associated with impaired immune function, reduced muscle strength, delayed wound healing, and increased postoperative complications [11–13]. Several objective indices, such as prognostic nutritional index (PNI), geriatric nutritional risk index (GNRI), and controlling nutritional status (CONUT) score, have been developed to evaluate nutritional status [14–16]. Presumably, because nutritional status is closely related to muscle mass, physical performance, and frailty [17,18], it may also influence the risk of falls. However, the relationship between preoperative nutritional status and postoperative in-hospital falls has not been adequately investigated, particularly in patients undergoing cervical spine surgery.
Therefore, this study aimed to evaluate the association of preoperative nutritional status (assessed using PNI, GNRI, and CONUT scores) with postoperative in-hospital falls in patients undergoing cervical spine surgery for cervical myelopathy. We hypothesized that poor preoperative PNI would increase the risk of postoperative in-hospital falls.
Materials and Methods
Ethics statement
This study was conducted in compliance with the principles of the Declaration of Helsinki. The study protocol was approved by the Institutional Review Board of Osaka Rosai Hospital (approval no., 2025-103). The requirement for informed consent was waived because of the retrospective design of this study.
Study design
In this retrospective cohort study, we screened 809 consecutive patients who underwent cervical spine surgery at Osaka Rosai Hospital between December 2015 and December 2025. Patients were identified through the institute’s surgical database, and clinical data were obtained from electronic medical records. As per study objectives, only patients who underwent cervical spine surgery for cervical myelopathy were included. Patients undergoing cervical spine surgery for conditions other than cervical myelopathy, concomitant thoracolumbar surgery, or additional cervical surgery during the same hospitalization were excluded. Patients undergoing revision cervical surgery for cervical myelopathy were included only if the revision procedure was the index surgery. Accordingly, 649 patients were included in the final analysis (Fig. 1).
Fig. 1.
Patient selection flowchart. A total of 809 patients who underwent cervical spine surgery were screened, and 649 patients were included in the final analysis cohort.
The primary study outcome was the occurrence of in-hospital falls during the postoperative hospitalization period, which was defined as unexpected or unintentional events in which a patient came to rest on the floor or another lower level during postoperative hospitalization, regardless of whether the event was witnessed [6,8]. Events judged as intentional sitting or lying on the floor were not classified as falls. Fall events were identified through institutional incident reports and confirmed by a review of medical records and the hospital’s fall-risk assessment sheets. Based on this data, patients were categorized into two groups according to the occurrence or non-occurrence of in-hospital falls.
Data collection
Data regarding the following demographic and clinical variables were collected: age, sex, body mass index (BMI), American Society of Anesthesiologists (ASA) physical status classification, diagnosis, preoperative functional status, preoperative Japanese Orthopaedic Association (JOA) score for cervical myelopathy, surgical approach, surgical procedure, operative time, estimated blood loss, postoperative intravenous patient-controlled analgesia (IV-PCA) postoperative length of hospital stay (LOS), and discharge destination. Patients with ASA physical status ≥III were considered to have severe systemic disease [19].
Preoperative functional status was classified as independent, partially dependent, or totally dependent according to the NSQIP functional status scale [20]. “Independent” was defined as requiring no assistance from another person for activities of daily living, regardless of the use of assistive devices; “partial dependence” was defined as requiring some assistance from another person for activities of daily living; “total dependence” was defined as requiring complete assistance for all activities of daily living. Additionally, comorbidities, including congestive heart failure, pulmonary disease, hypertension, diabetes mellitus, cerebrovascular disease, cardiovascular disease, dialysis, rheumatoid arthritis, and psychiatric disease, were recorded.
Frailty status was assessed using the modified frailty index (mFI-5), which includes five comorbid conditions, namely congestive heart failure, chronic obstructive pulmonary disease or pneumonia, diabetes mellitus, hypertension requiring medication, and non-independent functional status [21]. Patients with an mFI-5 score of ≥2 were classified as frail [22].
Preoperative nutritional assessment
Preoperative laboratory data obtained within 30 days prior to surgery were reviewed to obtain data for serum albumin, total cholesterol, C-reactive protein (CRP), white blood cell count (WBC), lymphocyte count, estimated glomerular filtration rate (eGFR), blood glucose level, and hemoglobin level. The following nutritional indices were calculated using these laboratory parameters: PNI: 10×serum albumin (g/dL)+0.005×total lymphocyte count (/μL) [14]. GNRI: 14.89×serum albumin (g/dL)+41.7×(present body weight/ideal body weight) [15]. Ideal body weight was calculated using the Lorentz formula; when the ratio of present body weight to ideal body weight exceeded 1, the value was set to 1. CONUT score: calculated using serum albumin, total lymphocyte count, and total cholesterol level [16]. The score ranges from 0 to 12, with higher scores indicating poor nutritional status.
Statistical analysis
All analyses were performed using JMP ver. 19.1.0 (SAS Institute Inc., Cary, NC, USA). A p-value of 0.05 was considered statistically significant for all statistical analyses. Continuous variables were described as mean±standard deviation, and categorical variables as frequency and percentages. Between-group (patients with and without in-hospital falls) differences were assessed using Student t-test for continuous variables and the chi-square test for categorical variables.
Additionally, univariate logistic regression analyses and receiver operating characteristic (ROC) curve analysis were conducted to assess the predictive performance of each nutritional index. The area under the curve (AUC) was calculated, and optimal cutoff values were determined using the Youden index [23].
Next, multivariable logistic regression analysis was performed to identify independent risk factors for in-hospital falls. Based on clinical relevance and available evidence [8], age, ASA physical status ≥3, mFI-5 score ≥2, cerebrovascular disease, PNI <50, and preoperative JOA score were also included in the multivariable model. Dialysis was excluded from multivariable analyses because of the small number of patients affected.
Kaplan-Meier analysis was performed to compare the probability of fall-free survival during hospitalization between patients with PNI ≥50 and PNI <50; between-group differences were assessed using the log-rank test. Cox proportional hazards regression analysis was performed to account for differences in observation time during hospitalization. Time to fall was defined as the number of days from surgery to the first in-hospital fall; patients who did not experience a fall were censored at the time of hospital discharge.
Results
Patient characteristics
Among the 649 patients who underwent surgery for cervical myelopathy during the study period, 48 (7.4%) experienced postoperative in-hospital falls, with fall events predominantly occurring around midnight and late morning (Fig. 2A). Most falls occurred while getting up from the bed, which was followed by standing up, walking, and toileting (Fig. 2B). No fall-related injuries required treatment.
Fig. 2.
Characteristics of in-hospital falls. (A) Distribution of fall events by time of day. (B) Distribution of circumstances at the time of fall.
Patients who experienced falls were significantly older (mean age: 75.1±7.7 years vs. 69.8±12.3 years; p=0.003) and had a significantly lower BMI (21.8±3.6 kg/m2 vs. 23.9±4.2 kg/m2; p=0.001) than those who did not. In addition, the fall group had a higher proportion of patients with ASA physical status ≥III (35.4% vs. 18.1%, p=0.003), dependent functional status (p=0.002), and frail patients with mFI-5 ≥2 (62.5% vs. 39.1%, p=0.001). Mean preoperative JOA scores were also significantly lower in the fall group than in the non-fall group (8.9±2.5 vs. 10.5±2.7, p<0.001).
Among comorbidities, cerebrovascular disease was significantly more prevalent in the fall group (20.8% vs. 4.3%, p<0.001), as was the prevalence of dialysis (8.3% vs. 1.3%, p<0.001). The mean postoperative LOS was also significantly longer in the fall group than in the non-fall group (29.0±19.2 days vs. 19.6±11.7 days, p<0.001). Patients who experienced falls were more frequently discharged to another hospital or rehabilitation facility rather than directly home (58.3% vs. 20.6%, p<0.001) (Table 1).
Table 1.
Patient characteristics according to postoperative in-hospital falls
| Characteristic | In-hospital falls (n=48) | Non-fall (n=601) | p-value |
|---|---|---|---|
| Age (yr) | 75.1±7.7 | 69.8±12.3 | 0.0038** |
| Sex, female | 14 (29.2) | 192 (32.0) | 0.69 |
| Body mass index (kg/m2) | 21.8±3.6 | 23.9±4.2 | 0.0012** |
| Diagnosis | 0.12 | ||
| CSM | 31 (64.6) | 424 (70.5) | |
| OPLL | 10 (20.8) | 93 (15.5) | |
| Disc herniation | 2 (4.2) | 58 (9.7) | |
| AAS | 5 (10.4) | 26 (4.3) | |
| Revision surgery | 1 (2.1) | 19 (3.2) | 0.68 |
| Surgical approach | 0.18 | ||
| Anterior | 5 (10.4) | 121 (20.1) | |
| Posterior | 41 (85.4) | 468 (77.9) | |
| Combined anterior and posterior | 2 (4.2) | 12 (2.0) | |
| Surgical procedure | 0.11 | ||
| ACDF or ACCF | 5 (10.4) | 121 (20.1) | |
| C1–2 fusion | 4 (8.3) | 15 (2.5) | |
| Occipitocervical fusion | 1 (2.1) | 9 (1.5) | |
| Laminoplasty or laminectomy | 35 (72.9) | 420 (69.9) | |
| Posterior fusion | 1 (2.1) | 24 (4.0) | |
| Combined surgery | 2 (4.2) | 12 (2.0) | |
| Fusion performed | 13 (27.1) | 182 (30.3) | 0.64 |
| ASA physical status | 0.0033** | ||
| 1 | 0 (0) | 52 (8.7) | |
| 2 | 31 (64.6) | 440 (73.2) | |
| 3 | 17 (35.4) | 109 (18.1) | |
| ASA physical status ≥3 | 17 (35.4) | 109 (18.1) | 0.0036** |
| Operation time (min) | 146.6±94.5 | 129.8±72.7 | 0.13 |
| Estimated blood loss (mL) | 61.6±103.7 | 59.9±116.6 | 0.92 |
| Postoperative IV-PCA use | 45 (93.6) | 545 (92.4) | 0.48 |
| Preoperative functional status | 0.0027** | ||
| Independent | 14 (29.2) | 326 (54.2) | |
| Partially dependent | 22 (45.8) | 193 (32.1) | |
| Totally dependent | 12 (25.0) | 82 (13.6) | |
| Comorbidities | |||
| Congestive heart failure | 1 (2.1) | 10 (1.7) | 0.83 |
| Pulmonary disease | 7 (14.6) | 43 (7.2) | 0.063 |
| Hypertension | 31 (64.6) | 292 (48.6) | 0.033* |
| Diabetes mellitus | 11 (22.9) | 147 (24.5) | 0.81 |
| Cerebrovascular disease | 10 (20.8) | 26 (4.3) | <0.001*** |
| Cardiovascular disease | 9 (18.8) | 88 (14.6) | 0.47 |
| Dialysis | 4 (8.3) | 8 (1.3) | <0.001*** |
| Rheumatoid arthritis | 0 (0) | 17 (2.8) | 0.24 |
| Psychiatric disease | 2 (4.1) | 14 (2.3) | 0.43 |
| mFI-5 | <0.001*** | ||
| 0 | 3 (6.3) | 140 (23.3) | |
| 1 | 15 (31.3) | 226 (37.6) | |
| 2 | 23 (47.9) | 167 (27.8) | |
| 3 | 5 (10.4) | 65 (10.8) | |
| 4 | 2 (4.2) | 3 (0.50) | |
| mFI-5 ≥2 | 30 (62.5) | 235 (39.1) | 0.0015** |
| Preoperative JOA score | 8.9±2.5 | 10.5±2.7 | <0.001*** |
| LOS after surgery (day) | 29.0±19.2 | 19.6±11.7 | <0.001*** |
| Discharge destination | <0.001*** | ||
| Home | 20 (41.7) | 477 (79.4) | |
| Transfer | 28 (58.3) | 124 (20.6) |
Values are presented as mean±standard deviation or number (%).
CSM, cervical spondylotic myelopathy; OPLL, ossification of the posterior longitudinal ligament; AAS, atlantoaxial subluxation; ACDF, anterior cervical discectomy and fusion; ACCF, anterior cervical corpectomy and fusion; ASA, American Society of Anesthesiologists; IV-PCA, intravenous patient-controlled analgesia; mFI-5, 5-factor modified frailty index; JOA, Japanese Orthopaedic Association; LOS, length of hospital stay.
p<0.05.
p<0.01.
p<0.001.
Preoperative laboratory findings and nutritional indices
Patients who experienced in-hospital falls demonstrated poorer nutritional status than those who did not (serum albumin levels: 3.9±0.45 g/dL vs. 4.1±0.42 g/dL, p=0.001; total lymphocyte counts: 1,400.8±587.1/μL vs. 1,676.7±657.8/μL, p=0.005). Hemoglobin levels were also significantly lower in patients who experienced falls (13.0±1.8 g/dL vs. 13.6±1.7 g/dL, p=0.010). Correspondingly, all nutritional indices were significantly lower in the fall group than in the non-fall group (GNRI: 96.5±8.5 vs. 101.2±7.2, p<0.001; PNI: 46.0±5.1 vs. 49.5±5.8, p<0.001; CONUT score: p<0.001) (Table 2).
Table 2.
Preoperative laboratory findings according to postoperative in-hospital falls
| Variable | In-hospital falls (n=48) | Non-fall (n=601) | p-value |
|---|---|---|---|
| Serum albumin (g/dL) | 3.9±0.45 | 4.1±0.42 | 0.0013** |
| Total cholesterol (mg/dL) | 182.5±37.3 | 193.7±38.8 | 0.054 |
| CRP (mg/dL) | 0.45±1.1 | 0.40±1.4 | 0.79 |
| WBC (×103/μL) | 6.37±1.75 | 6.59±1.95 | 0.45 |
| Lymphocyte (/μL) | 1,400.8±587.1 | 1,676.7±657.8 | 0.005** |
| eGFR (mL/min/1.73 m2) | 64.9±29.1 | 69.0±21.4 | 0.21 |
| Glucose (mg/dL) | 124.0±42.1 | 122.3±40.8 | 0.78 |
| Hemoglobin (g/dL) | 13.0±1.8 | 13.6±1.7 | 0.010* |
| GNRI | 96.5±8.5 | 101.2±7.2 | <0.001*** |
| PNI | 46.0±5.1 | 49.5±5.8 | <0.001*** |
| CONUT score | <0.001*** | ||
| 0–1 | 16 (33.3) | 380 (63.2) | |
| 2–4 | 29 (60.4) | 194 (32.3) | |
| 5–8 | 1 (2.1) | 24 (4.0) | |
| 9–12 | 2 (4.2) | 3 (0.5) |
Values are presented as mean±standard deviation or number (%).
CRP, C-reactive protein; WBC, white blood cell count; eGFR, estimated glomerular filtration rate; GNRI, geriatric nutritional risk index; PNI, prognostic nutritional index; CONUT, controlling nutritional status.
p<0.05.
p<0.01.
p<0.001.
Results of univariate logistic regression analysis
According to this analysis, nutritional indices and related parameters were significantly associated with in-hospital falls. PNI and GNRI were inversely associated with fall risk (odds ratios [ORs], 0.91; p<0.001, and p=0.93, p<0.001, respectively). The CONUT score was also associated with an increased risk of falls (OR, 1.27; p=0.001). Likewise, lower serum albumin level, BMI, and hemoglobin levels were also significantly associated with an increased risk of in-hospital falls. The ROC curve analysis demonstrated that PNI had the highest predictive performance among the evaluated nutritional indices, although its discriminatory ability was modest (AUC=0.687). The optimal cutoff value for PNI was observed as 49.7 (sensitivity=0.85; specificity=0.49) (Table 3).
Table 3.
Univariate logistic regression and receiver operating characteristic analysis of nutritional parameters for postoperative in-hospital falls
| Variable | OR (95% CI) | p-value | AUC | Cutoff | Sensitivity | Specificity |
|---|---|---|---|---|---|---|
| PNI (per 1-point increase) | 0.91 (0.87–0.96) | <0.001*** | 0.687 | 49.7 | 0.85 | 0.49 |
| GNRI (per 1-point increase) | 0.93 (0.90–0.96) | <0.001*** | 0.676 | 99.3 | 0.58 | 0.68 |
| CONUT score (per 1-point increase) | 1.27 (1.10–1.47) | 0.0018** | 0.656 | 2.0 | 0.67 | 0.63 |
| Serum albumin (per 1 g/dL increase) | 0.37 (0.20–0.69) | 0.0015** | 0.635 | 3.9 | 0.48 | 0.72 |
| BMI (per 1 kg/m2 increase) | 0.87 (0.79–0.94) | <0.001*** | 0.652 | 22.1 | 0.65 | 0.65 |
| Hemoglobin (per 1 g/dL increase) | 0.81 (0.69–0.95) | 0.011* | 0.596 | 13.4 | 0.67 | 0.56 |
OR, odds ratio; CI, confidence interval; AUC, area under the curve; PNI, prognostic nutritional index; GNRI, geriatric nutritional risk index; CONUT, controlling nutritional status; BMI, body mass index.
p<0.05.
p<0.01.
p<0.001.
Results of multivariable logistic regression analysis
After adjusting for covariates, PNI <50 (OR, 3.74; 95% CI, 1.65–9.71; p=0.001) and cerebrovascular disease (OR, 5.22; 95% CI, 2.13–12.24; p<0.001) remained independently significantly associated with in-hospital falls. The PNI cutoff was set at 50 because it approximated the optimal ROC-derived threshold of 49.7 and was clinically interpretable. Age, mFI-5 ≥2, ASA physical status ≥III, and preoperative JOA score were not independently associated with falls (Table 4).
Table 4.
Multivariable logistic regression analysis of risk factors for postoperative in-hospital falls
| Variable | OR (95% CI) | p-value |
|---|---|---|
| Cerebrovascular disease | 5.22 (2.13–12.24) | <0.001*** |
| PNI <50 | 3.74 (1.65–9.71) | 0.001** |
| Age (per 10-year increase) | 1.18 (0.85–1.72) | 0.12 |
| mFI-5 ≥2 | 1.52 (0.78–3.02) | 0.21 |
| ASA physical status ≥3 | 1.25 (0.62–2.46) | 0.52 |
| JOA score (per 1-point decrease) | 1.08 (0.95–1.21) | 0.23 |
OR, odds ratio; CI, confidence interval; PNI, prognostic nutritional index; mFI-5, 5-factor modified frailty index; ASA, American Society of Anesthesiologists; JOA, Japanese Orthopaedic Association.
p<0.01.
p<0.001.
Kaplan-Meier survival and Cox proportional hazards regression analysis
Kaplan-Meier analysis demonstrated that patients with PNI <50 had a significantly lower probability of remaining fall-free during hospitalization compared with those with PNI ≥50 (p<0.001) (Fig. 3). Cox proportional hazards regression analysis also showed that PNI <50 and cerebrovascular disease were independently associated with an increased risk of in-hospital falls. Patients with cerebrovascular disease had a significantly higher hazard of falls (hazard ratio [HR], 4.82; 95% CI, 2.33–9.97; p<0.001). In terms of nutritional status, patients with PNI <50 were at a significantly greater risk of in-hospital falls compared with those with PNI ≥50 (HR, 3.11; 95% CI, 1.34–7.22; p=0.008). Age, mFI-5 ≥2, ASA physical status ≥III, and preoperative JOA score were not significantly associated with falls (Table 5).
Fig. 3.
Kaplan-Meier curves for fall-free probability. Patients with prognostic nutritional index (PNI) <50 had a significantly lower fall-free probability during postoperative hospitalization than those with PNI ≥50 (log-rank p<0.001). Patients without a fall were censored at discharge.
Table 5.
Cox proportional hazards regression analysis of risk factors for postoperative in-hospital falls
| Variable | HR (95% CI) | p-value |
|---|---|---|
| Cerebrovascular disease | 4.82 (2.33–9.97) | <0.001*** |
| PNI <50 | 3.11 (1.34–7.22) | 0.0083** |
| Age (per 10-year increase) | 1.25 (0.91–1.78) | 0.19 |
| mFI-5 ≥2 | 1.53 (0.82–2.86) | 0.18 |
| ASA physical status ≥3 | 1.27 (0.69–2.37) | 0.44 |
| JOA score (per 1-point decrease) | 1.01 (0.90–1.13) | 0.85 |
HR, hazard ratio; CI, confidence interval; PNI, prognostic nutritional index; mFI-5, 5-factor modified frailty index; ASA, American Society of Anesthesiologists; JOA, Japanese Orthopaedic Association.
p<0.01.
p<0.001.
Discussion
The present study investigated the association between preoperative nutritional status measured using laboratory-based nutritional indices and in-hospital falls in patients undergoing cervical spine surgery for cervical myelopathy. We observed that preoperative PNI was significantly and independently associated with postoperative in-hospital falls (with the highest AUC) as compared to other nutritional indices like GNRI and CONUT scores.
In the present study, a PNI value of <50 remained significantly associated with in-hospital falls after adjustment for covariates, whereas the JOA score, which is used to assess the severity of clinical symptoms, was not independently associated with falls. This does not suggest that myelopathy severity is irrelevant, but rather highlights the role of other factors beyond neurological impairment that may affect fall risk. Previous studies have also reported that while cervical JOA score was associated with falls in patients with degenerative cervical myelopathy, handgrip strength was identified as an independent predictor in multivariable analysis [9]. Similarly, low muscle mass, rather than JOA score, was independently associated with postoperative falls in patients with lumbar spinal stenosis [7]. These findings suggest that fall risk is influenced not only by neurological impairment but also by patient characteristics like muscle strength, muscle mass, and systemic vulnerability. Since malnutrition is closely linked to sarcopenia, reduced muscle strength, and impaired physical performance [17], PNI may be a better indicator of fall-related vulnerability beyond neurological severity (JOA score) alone, along with muscle weakness and reduced physiological reserve.
Cerebrovascular disease was also noted as an independent factor affecting the risk of postoperative falls. Patients with cerebrovascular disease tend to have residual motor weakness, impaired balance, sensory disturbance, or reduced coordination [24]; these deficits may become more clinically relevant postoperatively when pain, fatigue, reduced activity, and changes in mobility interact. Therefore, the occurrence of cerebrovascular disease may be considered a marker of persistent neurological vulnerability in patients undergoing surgery for cervical myelopathy.
PNI can be easily calculated from routine laboratory data and reflects modifiable nutritional vulnerability, making it a practical screening tool for identifying patients at high risk of postoperative in-hospital falls. Accordingly, patients with low PNI may benefit from targeted perioperative strategies, including nutritional optimization, closer monitoring, and fall prevention measures. Although this study does not establish causality, our findings suggest that fall prevention strategies after cervical spine surgery should consider patient-specific physiological vulnerability in addition to disease-related factors. No fall-related injury occurring in the present cohort required treatment. Therefore, the present findings should be interpreted with regard to the risk of postoperative in-hospital fall events and not as evidence that low PNI predicts severe fall-related injury. Further studies are needed to evaluate the association between nutritional status and the severity of fall-related injuries.
This study has several limitations. First, the retrospective, observational, single-center design may limit the generalizability of the findings. In addition, the 10-year period for data collection may have encompassed changes in perioperative management, rehabilitation protocols, staffing, and fall prevention practices at the hospital level, potentially influencing the incidence and reporting of in-hospital falls. Second, other relevant factors, such as postoperative medication use, delirium, environmental factors, nursing workload, and rehabilitation protocols, were not evaluated. Third, because the observation period was limited to the postoperative hospital stay, patients with longer hospitalization may have exhibited a greater proportion of falls. Although we tried to address this issue using Cox proportional hazards modeling, the possibility of residual bias could not be completely excluded. Fourth, the small number of patients with certain comorbidities, such as a need for dialysis, may have limited the assessment of their independent effects.
Conclusions
PNI is a practical laboratory-based marker independently associated with an increased risk of postoperative in-hospital falls in patients undergoing spinal surgery for cervical myelopathy. A low PNI value of <50 is useful for identifying patients at high risk of in-hospital falls and should be used in implementing targeted perioperative fall prevention strategies.
Key Points.
Prognostic nutritional index (PNI) represents a practical laboratory-based marker for perioperative fall-risk assessment.
Low preoperative PNI (<50) was significantly associated with in-hospital falls after surgery for cervical myelopathy.
PNI value of <50 remained an independent risk factor of postoperative in-hospital falls after adjustment for age, frailty, American Society of Anesthesiologists physical status, cerebrovascular disease, and preoperative Japanese Orthopaedic Association score.
Footnotes
Conflict of Interest
No potential conflict of interest relevant to this article was reported.
Author Contributions
Conceptualization: TF, TK. Methodology: TF, KN, MT, DY, YS. Data curation: TF, KN, MT, DY, YS. Formal analysis: TF. Visualization: TF. Writing–original draft: TF. Writing–review & editing: TK. Supervision: TK, SO. Final approval of the manuscript: all authors.
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