Predictors of catheter-free voiding after spinal cord injury

Abstract

Context

Despite a high prevalence of neurogenic bladder (NGB) in patients with spinal cord injury (SCI), clinicians are unable to predict long-term bladder outcomes due to variable phenotypes of bladder dysfunction. This study investigates if early bladder events, infections, and spinal cord injury characteristics during rehabilitation admission affect bladder outcomes one year after SCI.

Methods

This retrospective study included patients with SCI admitted to a tertiary rehabilitation center between 1 January 2016 and 1 January 2020. Data was collected on early bladder management, comorbidities, infections and injury characteristics; level of injury, American Spinal Injury Association Impairment Scale (AIS) classification, and International Standards for Neurological Classification of Spinal Cord Injury lower extremity motor score (LEMS).

Results

Seventy-two patients met inclusion criteria; 63% (45/72) patients had cervical SCI and 31% (22/72) were complete injuries. Twenty-two percent (16/72) did not use an internal catheter to empty the bladder, improving to 41% (29/72) at one year. On multivariate logistic regression accounting for age, sex, Charlson comorbidity index, LEMS, and infections during admission, higher LEMS (OR 1.104, 95%, CI 1.037–1.176, P = 0.002) associated with catheter-free voiding (CFV) at one year while male sex (OR 0.091, 95% CI 0.012–0.713, P = 0.0225), and non-urologic infections (OR 0.088, 95% CI 0.010–0.768, P = 0.0279) were negatively associated.

Conclusions

Preserved LEMS early after SCI associates with CFV at one year while male sex and early non-urologic infections such as pneumonia are associated with persistent urinary retention. This can be used to counsel SCI patients on expected bladder recovery and outcomes.

Introduction

Traumatic spinal cord injury (SCI) is a significant cause of morbidity in U.S. patients, with an estimated 12–17 000 new SCI cases each year representing the highest rates of any country globally (1). A high proportion (70–84%; 2) of these patients will develop some degree of lower urinary tract dysfunction because of their neurologic injury, broadly categorized as neurogenic bladder (NGB). NGB causes significant mortality and morbidity in this patient population as most re-hospitalizations in the first year after SCI are for genitourinary complications including urinary tract infections (UTI) (3). NGB and associated interventions are also a major driver of decreased quality of life in patients with SCI (2), and bladder function is consistently rated as among the highest priorities for recovery by patients (4).

Predicting bladder function recovery after SCI is critical to establishing rehabilitation goals for patients and initiating a successful bladder management program. It can help clinicians counsel patients on optimal long-term management strategies, classify patients into risk and surveillance tiers, and select possible clinical trials (5, 6). The anatomic level of neurologic injury as well as its severity are currently used to broadly predict the clinical presentation of NGB (2, 5, 7). However, the anatomic level and severity of SCI are not specific, resulting in significant heterogeneity in bladder outcomes (8). Kessler et al. (2016) proposed a model that predicted bladder function recovery using International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) lower extremity motor score (LEMS), S3 dermatome sensation, and spinal cord independence measure (SCIM) scores (9). This was further explored by Eliott et al. (2022) using the National Spinal Cord Injury Database who found that these established variables predicted voiding function, and also showed that early non-urologic infections reduced the odds of catheter-free voiding (CFV) by ∼20% (10). This novel finding is in keeping with evolving data suggesting that early infectious/inflammatory events such as wound infections and pneumonia may impact neurologic recovery from SCI; however, data on urologic infections was not available within this dataset (11, 12). Since urinary tract infections (UTIs) affect a majority of SCI patients early after injury, further evaluation is needed to see if UTIs impact functional recovery.

In this work, we set out to examine how early bladder events and UTIs, in addition to recently proposed injury characterization using LEMS and S3 sensation (9, 10), predict which patients are likely to recover or maintain CFV at one year post-SCI. UTIs may disrupt bladder function but are difficult to evaluate in SCI cohorts, partially due to the difficulties of identifying true UTIs in patients with NGB (10). While Elliot et al. showed that wound and respiratory infections were associated with diminished neurologic recovery, the role of urologic infections was not examined as it is not available within the National Spinal Cord Injury Database (10). We also aimed to examine the role of early bladder management; clean intermittent catheterization (CIC, allowing for bladder cycling) could be beneficial for maintaining myogenic function though this has never been shown definitively. Conversely, overdistention from very high bladder volumes may lead to myogenic injury/failure, which has been shown in animal models but has not been directly studied in an SCI cohort. We hypothesized that urologic and non-urologic infections, overdistension injury, low LEMS score, failure to use CIC and male sex would be associated with a low likelihood of CFV in our cohort.

Materials and methods

Patient selection

This retrospective study included patients with traumatic SCI who were >18 years old and admitted to a tertiary rehabilitation center directly following their injury and any resultant hospital stay between 1 January 2016 and 1 January 2020. Patients were included if they had at least 6 months of follow-up data after discharge from their initial rehabilitation visit. Exclusion criteria were non-traumatic (ischemic, infectious) SCI, lack of follow-up data beyond six months, or if basic information about their injury was not available including AIS classification or LEMS score. Patients readmitted to the rehabilitation facility after their initial care episode was completed at an earlier timepoint were excluded. This study was approved by the local institutional review board under IRB 2020H0128.

Variable data collection

Patient and injury characteristics were recorded at the time of discharge from the rehabilitation center. In addition to the American Spinal Injury Association Impairment Scale (AIS) classification and the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) lower extremity motor score (LEMS), (13) and presence or absence of light-touch sensation in S3 was recorded. We recorded early bladder management strategy utilized during the acute post-injury hospitalization as a variable potentially predicting later outcomes. Clean intermittent catheterization (CIC), indwelling foley catheter, suprapubic tube (SPT) or catheter-free voiding (CFV) were possible options. External collectors such as condom catheters or suction devices were included in CFV. Bladder volumes obtained during rehabilitation hospital admission by ultrasonic bladder scan or catheterization were documented, and presence of an overdistension injury was noted for patients with documentation of greater than 1000 mL of urine at any point while admitted to the rehabilitation facility. We recorded whether patients were prescribed bladder medications during the rehabilitation hospital admission (anticholinergics, α-blockers or β3 antagonists). The number of symptomatic culture-proven UTIs (febrile or afebrile) experienced by each patient during rehabilitation admission was also recorded. UTI was defined as a positive urine culture with greater than 10⁵ colony forming units of a known uropathogen in association with urinary symptoms. Asymptomatic bacteriuria was not considered to be a UTI event. Information regarding other infectious complications such as pneumonia or wound infections was also extracted.

Outcome data collection

The primary outcome was recovery or maintenance of volitional bladder function at one year, defined as documentation of CFV (compared to CIC or indwelling catheter) as the bladder management strategy at one year after injury. CFV encompassed several methods of bladder emptying: spontaneous emptying without control into diapers, condom catheters or other collection devices; Valsalva, credé or tapping voiding; or sensation of full bladder leading to volitional and controlled emptying with full continence. Given the variable timing of patient follow-up, the office visit with relevant data collected at a time point closest to one year after discharge from the rehabilitation facility was used. Due to the retrospective nature of the study, documentation of continence/incontinence was not consistent enough to be evaluated formally in our analysis, and very few patients had urodynamic evaluation within the timeframe of the study.

Statistical analysis

Analysis was performed using SAS version 9.4 (SAS Institute, Cary NC). To determine the univariate association between CFV at one year and all other variables, Wilcoxon two-sample test and Chi-square test were used. For multivariable modeling, logistic regression with the Firth Panelized Maximum Likelihood Estimation technique was used to estimate regression coefficients. The significance of nested models was tested using Likelihood Ratio test, and overall model fit was determined using C-statistics and Hosmer–Lemeshow goodness of fit test. Multivariable logistic regression was applied accounting for age, sex, Charlson comorbidity index (Charlson CI), AIS classification, lower extremity motor score (LEMS), UTI, and non-urologic infections during rehabilitation admission or during follow up. LEMS was evaluated as a continuous variable. Several nested models were investigated, starting with an initial model that included all variables, including AIS classification, LEMS, and lesion location (cervical, thoracic, or lumbar). Standardized regression coefficients were also calculated to rank variables according to importance in predicting CFV at one year. AIS classification and lesion location were deemed to have significant multicollinearity and low tolerance, with lower standardized regression coefficients than other variables within our model. These attributes were then removed, and the resulting model showed equivalent predictive value with no significant chi-square difference test from the initial model (please see Table 3 for a statistical and graphical comparison of initial model with nested optimized final model). Using the remaining categories, we created a model to estimate the likelihood of CFV at one year (Table 2).

Table 3.

Comparison analyses of penalized maximum likelihood estimates of initial model compared to optimized nested models. Chi-square difference test (df) = 1.549 (2), P = 0.230.

Patient characteristics	OR (95% CI) Model 1	P value	Absolute standardized coefficient (Rank)	Tolerance	OR (95% CI) Model 2	P value	Absolute standardized coefficient (Rank)	Tolerance	OR (95% CI) Model 3	P value	Absolute standardized coefficient (Rank)	Tolerance
Age	0.94 (0.87–1.03)	0.188	0.584 (2)	0.323*	0.97 (0.90–1.04)	0.414	0.304 (6)	0.373	0.97 (0.90–1.04)	0.3702	0.342 (6)	0.377
Male sex	0.11 (0.01–0.82)	0.032	0.523 (3)	0.888	0.11 (0.02–0.81)	0.03	0.512 (3)	0.91	0.09 (0.01–0.71)	0.0225	0.559 (3)	0.913
Charlson CI	1.29 (0.66–2.50)	0.46	0.330 (6)	0.418	1.28 (0.70–2.34)	0.425	0.322 (5)	0.442	1.34 (0.72–2.51)	0.3575	0.386 (5)	0.443
Light sensation S3	3.01 (0.32–28.72)	0.339	0.302 (7)	0.405	3.88 (0.51–29.54)	0.191	0.372 (4)	0.548	4.57 (0.58–36.04)	0.1494	0.417 (4)	0.588
PVR > 1000	1.08 (0.20–5.74)	0.932	0.020 (13)	0.827	0.87 (0.17–4.54)	0.871	0.038 (8)	0.882	0.86 (0.17–4.33)	0.8534	0.042 (7)	0.925
UTI during admission	0.90 (0.13–6.33)	0.914	0.029 (10)	0.661	0.91 (0.15–5.41)	0.917	0.025 (9)	0.682	0.96 (0.17–5.53)	0.9601	0.012 (8)	0.713
Non-urologic infections	0.15 (0.02–1.37)	0.093	0.501 (4)	0.707	0.11 (0.02–0.87)	0.036	0.570 (2)	0.892	0.09 (0.01–0.77)	0.0279	0.635 (2)	0.909
LEMS	1.11 (1.02–1.21)	0.013	1.141 (1)	0.234*	1.10 (1.03–1.16)	0.003	0.977 (1)	0.458	1.10 (1.04–1.18)	0.0021	1.063 (1)	0.46
Injury location C vs. L	1.10 (0.04–33.17)	0.958	0.025 (12)	0.186*	0.91 (0.04–18.87)	0.953	0.025 (10)	0.197*
Injury location T vs. L	1.11 (0.04–30.08)	0.953	0.026 (11)	0.190*	0.74 (0.03–17.56)	0.853	0.078 (7)	0.196*
AIS score, B vs. A	1.94 (0.09–44.10)	0.679	0.142 (9)	0.465
AIS score, C vs. A	9.01 (0.45–181.94)	0.152	0.438 (5)	0.407
AIS score, D vs. A	2.21 (0.07–75.60)	0.659	0.210 (8)	0.166*
Goodness-of-fit	Value	Chi-square	df	P value	Value	Chi-square	df	P value	Value	Chi-square	df	P value
Likelihood ratio	–	45.12	13	<0.0001	–	43.95	10	<0.0001	–	45.6	8	<0.0001
Hosmer and Lemeshow	–	6.39	7	0.5	–	6.74	7	0.46	–	6.21	7	0.52
C-statistics	0.97	–	–	–	0.97	–	–	–	0.96	–	–	–
Difference test	–	–	–	–	–	1.17	3	0.24	–	1.55	2	0.23

LEMS, Lower extremity motor score; AIS, American Spinal Injury Association Injury Severity; CI, comorbidity index; UTI, Urinary Tract Infection, Injury location; C, cervical; T, thoracic; L, lumbar; PVR, post-void residual.

Table 2.

Analysis of penalized maximum likelihood estimates rank by absolute standardized estimates after removal of AIS classification and injury location.

Patient characteristics	Adjusted odds ratio	95% Confidence interval	P value	Absolute standardized coefficient rank	Tolerance	Variance inflation factor
LEMS	1.104	1.037–1.176	0.0021	1.063 (1)	0.46	2.172
Non-urologic infections	0.088	0.010–0.768	0.0279	0.635 (2)	0.909	1.1
Male sex	0.091	0.012–0.713	0.0225	0.559 (3)	0.913	1.095
Light sensation S3	4.568	0.579–36.035	0.1494	0.417 (4)	0.588	1.7
Charlson CI	1.342	0.717–2.512	0.3575	0.386 (5)	0.443	2.255
Age	0.967	0.898–1.041	0.3702	0.342 (6)	0.377	2.65
PVR > 1000	0.859	0.170–4.332	0.8534	0.042 (7)	0.925	1.081
UTI during admission	0.956	0.165–5.527	0.9601	0.012 (8)	0.713	1.403

Likelihood Ratio Chi-square (df) = 45.502 (8), P < 0.0001.

Hosmer–Lemeshow goodness of fit Chi-square (df) = 6.205, P = 0.516.

C-statistics = 0.962.

LEMS, Lower extremity motor score; Charlson CI, Charlson comorbidity index; UTI, Urinary Tract Infection; PVR, post-void residual.

Results

Data were analyzed from 72 patients who met inclusion criteria. Median age was 52 years (IQR 31–63), and 76% (55/72) were male. 78% of patients with data identifying race were Caucasian (45/58). Most patients had cervical spinal cord injuries (61% (44/72)) and 31% (22/72) were complete injuries. During rehabilitation admission, 47% (34/72) were managed with clean intermittent catheterization (CIC), 22% (16/72) were voiding without catheters, and 31% (22/72) had an indwelling catheter or SPT. At the time of discharge, 32% (23/72) utilized CFV. Patients were distributed through every AIS classification with A: 22 patients (31%), B: 12 patients (17%), C: 11 patients (15%), D: 27 patients (38%). Thirty-nine patients had LEMS score <20 (56%), 9 (13%) had LEMS score 20–30, and 22 (31%) had LEMS score >30. Forty patients out of 68 with data (58%) had the presence of S3 dermatome sensation, with either partially or fully preserved sensation. Forty-six patients (64%) had a UTI during admission and 22 (31%) had a non-genitourinary tract infection. Thirty-six patients (50%) had an overdistension injury as indicated by a documented PVR > 1000 mL Twenty-one patients (29%) were prescribed bladder medications during rehabilitation. There was no significant difference in age, BMI, or Charlson CI between the two groups. Demographic information is summarized in Table 1, with univariate associations between each factor and CFV.

Table 1.

Demographic and clinical characteristics of the patient population.

Characteristics	Total patients	Voiding at one year	Not voiding at one year	P value
Demographic characteristics
Age				0.231
18–34	22 (30.6%)	6 (20.7%)	16 (37.2%)
35–49	11 (15.3%)	3 (10.3%)	8 (18.6%)
50–64	23 (31.9%)	12 (41.4%)	11 (25.6%)
>64	16 (22.2%)	8 (27.6%)	8 (18.6%)
Sex				0.074
Female	17 (23.6%)	10 (34.5%)	7 (16.3%)
Male	55 (76.4%)	19 (65.5%)	36 (83.7%)
Race				0.035
White	45 (62.5%)	18 (62.1%)	27 (62.8%)
Minorities	13 (18.1%)	2 (6.9%)	11 (25.6%)
Unknown	14 (19.4%)	9 (31.0%)	5 (11.6%)
BMI				0.498
<18.5	3 (4.2%)	0 (0.0%)	3 (7.0%)
18.5–24.9	23 (31.9%)	9 (31.0%)	14 (32.6%)
25.0–29.9	17 (23.6%)	8 (27.6%)	9 (20.9%)
≥30	29 (40.3%)	12 (41.4%)	17 (39.5%)
Clinical Characteristics
Charlson CI				0.728
No comorbidities	21(29.2%)	7 (24.1%)	14 (32.6%)
1–3 comorbidities	27 (37.5%)	12 (41.4%)	15 (34.9%)
4–10 comorbidities	24 (33.3%)	10 (34.5%)	14 (32.5%)
Injury location				0.233
Cervical	45 (62.5%)	19 (65.5%)	26 (60.5%)
Thoracic	23 (31.9%)	7 (24.1%)	16 (37.2%)
Lumbar	4 (5.6%)	3 (10.3%)	1 (2.3%)
AIS classification				<0.001
Grade A	22 (30.6%)	1 (3.5%)	21 (48.8%)
Grade B	12 (16.7%)	2 (6.9%)	10 (23.3%)
Grade C	11 (15.3%)	6 (20.7%)	5 (11.6%)
Grade D	27 (37.5%)	20 (69.0%)	7 (16.3%)
LEMS				<0.001
≤20	40 (57.1%)	6 (21.4%)	34 (80.9%)
21–29	8 (11.4%)	5 (17.9%)	3 (7.1%)
≥30	22 (31.4%)	17 (60.7%)	5 (11.9%)
Light-touch sensation S3				<0.001
No	28 (41.2%)	3 (10.7%)	25 (62.5%)
Yes	40 (58.8%)	25 (89.3%)	15 (37.5%)
PVR > 1000				0.266
No	42 (59.2%)	20 (69.0%)	22 (52.4%)
Yes	29 (40.8%)	9 (31.0%)	20 (47.6%)
UTI during admission				0.001
No	26 (36.1%)	17 (58.6%)	9 (20.9%)
Yes	46 (63.9%)	12 (41.4%)	34 (70.1%)
Use of bladder medication				0.775
No	51 (70.8%)	20 (69.0%)	31 (72.1%)
Yes	21 (29.2%)	9 (31.0%)	12 (27.9%)
Other Infections during admission				0.011
No	50 (69.4%)	25 (86.2%)	25 (58.1%)
Yes	22 (30.6%)	4 (13.8%)	18 (41.9%)

BMI, Body Mass Index; AIS, American Spinal Injury Association Injury Severity; LEMS, Lower Extremity Motor Score; PVR, post-void residual; UTI, Urinary Tract Infection; Charlson CI, Charlson Comorbidity Index. For parameters without data available for every patient, percentages are calculated from the number of patients with available data.

At one year follow-up, 41% (29/72) patients were voiding without catheterization compared to 23% (16/72) during rehabilitation admission. Patients with CFV at follow-up had fewer UTIs (41.3% (12/29) vs. 73.9% (34/43), P = 0.001) and non-genitourinary tract infection (13.7% (4/29) vs. 41.8% (18/43), P = 0.011) during the early recovery period as compared to patients managed with CIC or indwelling catheter. Our model showed that LEMS (OR 1.104, 95%, CI 1.037–1.176, P = 0.002) associated with CFV at one year and was the single most impactful predictor in our model based on its standardized regression coefficient 1.063 and a rank of 1 utilizing the analysis of penalized maximum likelihood estimates rank by absolute standardized estimates (Table 2). Male sex (OR 0.091, 95% CI 0.012–0.713, P = 0.0225), and non-urologic infections (OR 0.088, 95% CI 0.010–0.768, P = 0.0279) during initial rehabilitation admission were associated with decreased likelihood of CFV at one year, although UTIs did not associate with CFV (Table 2). Also notable was the absence of a relationship with race and CFV on multivariate regression despite a univariate association (Table 1). Presence of overdistension injury (>1000 ml catheterized volume or ultrasonic PVR) and utilization of bladder medications during rehabilitation admission did not associate positively or negatively with CFV. Younger age, intact S3 sensation and low Charlson CI did not reliably predict bladder function though there were signals that these could be relevant and warrant further exploration in future studies (P = 0.37, 0.149, 0.36) (Table 3).

Multivariate logistic regression showed adequate goodness of fit statistics (Hosmer–Lemeshow goodness of fit test Chi-square 6.39, P value 0.5) and good model discrimination (C-statistics 0.97).

Discussion

Lower extremity motor score (LEMS) associated with CFV (P = 0.002, OR 1.104) one year after SCI in this patient population. Male sex and non-urologic infections decrease the chances of CFV with respective adjusted odds ratios of 0.091 (95% CI 0.012–0.713, P = 0.0225) and 0.088 (95% CI 0.010–0.768, P = 0.0279). All three variables are clearly important and predictive of CFV, although LEMS had the highest rank of any variable tested using the analysis of penalized maximum likelihood estimates. Despite higher absolute values of the adjusted odds ratios for sex and non-urologic infections, LEMS therefore was the most important predictor of CFV within our model. This importance of LEMS corroborates the findings of the recently published study by Elliott et al. (2022), who similarly showed the negative impact of early systemic infection and male sex on bladder emptying (10). Other factors we examined showed signals of association, but none were significant. Age is an example where signals indicated possible relationships and a trend toward higher rates of CFV in older patients, but this relationship did not persist within our model. S3 sensation notably also had an adjusted odds ratio of 4.6 but did not associate strongly enough to meet our significance level of P = 0.05 (P = 0.149, Table 2).

These findings add to the growing body of work allowing providers to identify and counsel patients most likely to void without catheterization at one year. This will help set expectations for recovery early on and minimize invasive bladder management options in patients more likely to recover CFV. For patients with minimal odds of improvement, this data can allow for earlier pursuit of definitive surgical interventions designed to improve independence and outcomes. This also emphasizes that minimizing systemic infections during the early recovery period can have a significant positive impact on long-term bladder outcomes, healthcare costs, and patient quality of life in both the short- and long-term. The ability to prognosticate outcomes for these patients is a critical focus for improvement in research given its importance to patients (7).

The importance of LEMS in this population is concordant with the recent model created by Kessler et al. (2016) using LEMS to estimate the likelihood of CFV in a new SCI patient (9). Other groups have applied this model or variations to various patient populations and overall have validated its accuracy (6, 7, 10). Our study again supports the utility of LEMS as a marker associated with voiding function and additionally corroborates other characteristics associated with CFV, most notably non-urologic infections. Validating the applicability of this information is particularly important given quite mixed results with historic attempts to prognosticate voiding recovery (14, 15).

In this SCI cohort, non-urologic infections including pneumonia, cellulitis, and pressure ulcers were associated with decreased odds of CFV at one year (OR 0.088, 95% CI 0.010–0.768, P = 0.0279). Recent research has supported the idea that chronic inflammation is detrimental to overall neurologic recovery after SCI in patients and in animal models (12, 16), and that acute infections like those seen in our study are specifically associated with delayed or reduced neurologic recovery at one year in terms of mobility and improvement in AIS (11, 12). Our findings support recently published work examining this phenomenon in a large de-identified cohort showing that non-urologic infections correlate with reduced CFV (10). While there is a probable link between increased disability and odds of acquiring respiratory or wound infections, our model did adjust for injury characteristics and infection was clearly still an important predictor of CFV.

Even though UTIs are much more common in patients who manage their bladder with CIC or an indwelling catheter (73.9% vs. 26.1% with CFV; 17, 18), UTIs alone were not associated positively or negatively with CFV at one year after accounting for age, sex, injury characteristics, and patient comorbidities in our study. This theoretically could be because most UTIs are localized to the bladder and do not always lead to systemic inflammation or fever. Fever is associated with a deranged metabolic profile, lowered glucose levels and increased glutamate levels and lactate to glucose ratio at the spinal cord lesion site in patients (19). This coincides with impaired trophic support and signs of elevated excitatory neurotoxicity and aggravated lesion pathophysiology at the injury site, correlating with impaired recovery. This is in line with the interpretation that UTI and particularly afebrile UTI may induce a less severe systemic response, below the threshold to significantly impact neurologic function. However, the lack of significance could also be related to the size and power of our study and warrants further investigation (19).

In our study, women were more likely to void without catheterization at one-year post-SCI than men. In previous reports examining the impact of sex, the majority show no difference in terms of CFV or continence (20, 21), though some recent studies have shown higher rates of spontaneous voiding in women in agreement with our findings (7, 9, 10). The failure to show sex differences in earlier studies may be due to the low proportions of female patients in most SCI cohorts. The observed lower rates of CFV in men may be anatomic in nature due to higher outlet resistance secondary to the prostate and longer urethra. Urodynamic evaluation would be needed to establish true return of function to better understand sex-based differences in bladder function.

Acute urinary retention is often found in patients with SCI during spinal shock and may be permanent in some patients. Bladder injury is known to occur with even a single episode of severe retention, postulated to occur via mechanical damage to the urothelium and detrusor muscle and through ischemia-reperfusion injury after decompression, though this mechanism has not been shown in humans (22, 23). While acute dysfunction and pathologic changes have been well-documented, the chronicity of these effects is not well known, nor have these impacts been well-studied in an SCI cohort. In our work, overdistention injury was hypothesized to predict worsened bladder function though it was not shown to be statistically significant. This is potentially due to the power of our study, though could also be related to confounding effects with more severe SCI in patients with severe retention. Additionally, patients in our study were closely monitored during their rehabilitation and only had brief episodes of overdistention before decompression. Thus, it may be not the overdistention event but the total duration of time in retention with high volume that results in myogenic or neurogenic failure. Chronicity and repetition of retention worsening bladder outcomes have been shown in patients managed on CIC where overdistension occurred recurrently and chronically (24).

While the data used for our analysis is significantly more granular compared to prior national cohort studies, the primary limitation of our study is its retrospective design along with a small sample size. Our definition of CFV was subjective as continence details were not documented for most patients, and our definition of S3 sensation included both partially and fully preserved sensation. In addition, the absence of urodynamic data precludes assessment of bladder safety with CFV methods in our cohort. A larger study is needed to better outline the associations between early clinical events after injury and recovery of voiding function, ideally with a formal evaluation of bladder function parameters at one year of follow-up with urodynamic studies. Additionally, obtaining patient-reported outcome measures with a validated questionnaire such as Qualiveen for neurogenic bladder-related quality of life (25), and the Neurogenic Bladder Symptom Score (26) would be of key importance to counseling efforts. It would also be helpful to isolate patients who regain CFV after inability to void in the acute setting, as these patients are most in need of counseling and potentially more aggressive rehabilitative therapies. Elliott et al. (2022) attempted to examine infection’s impact on this “conversion” and found signals of an effect but without significance, highlighting the importance of further study on this important subset of patients (10). A larger prospective study would be better able to examine specific factors associated with voiding function in this key patient population.

Conclusions

This study continues to support the association between LEMS and catheter-free voiding function, strengthening initial studies of this parameter (6, 7, 9, 10). In addition, we showed associations between poor voiding function at one year and male sex and non-urologic infections, emphasizing the role of systemic inflammation in early SCI recovery and the need for aggressive infection prevention protocols. Taken together with recommended urologic evaluation and urodynamics assessments as per the American Urological Association guidelines (27), these findings can help guide physicians in predicting bladder outcomes in the long-term and anticipating care needs in a poorly understood and critically important time for patients with SCI. This may allow some patients to move on to more definitive bladder management strategies sooner after injury and may motivate others at a high likelihood of improvement to pursue CIC while monitoring bladder function.

Ethics of approval statement

This study was approved by the local institutional review board (IRB) at Ohio State University Wexner Medical Center under IRB 2020H0128.

Data availability statement

Data generated for this research article is available for review upon reasonable request.

Disclaimer statements

Contributors None.

Funding None.

Conflicts of interest Authors have no conflict of interests to declare.