INTRODUCTION
Most patients with spinal cord injury (SCI) have neurogenic lower urinary tract dysfunction (NLUTD), which may continuously pose medical, physical, and social challenges. For this reason, proper bladder management to prevent secondary complications is very important in patients with SCI [1-3].
NLUTD due to SCI can cause urinary tract infection (UTI), urinary stones, and renal impairment. To prevent such complications, it is important to perform periodic urodynamic studies (UDS) and maintain appropriate bladder pressure and capacity by choosing an appropriate bladder emptying method [4-8].
The management of neurogenic bladder has evolved in recent decades. After World War II, an indwelling catheter was commonly used because of its easy application [9], where as normal voiding, reflex voiding, and expression voiding were commonly used in patients not using an indwelling catheter. According to two Korean studies, between the 1980s and 1990s, the proportion of patients using voiding without catheter was 82.8% to 86.6%, the proportion of patients with indwelling catheter was 2.5% to 8.6% and the proportion of patients with intermittent catheterization was about 8% [10,11]. However, since the 1990s, indwelling catheter and voiding without catheter have been replaced by intermittent catheterization, as this technique leads to fewer upper urinary tract complications and higher patient satisfaction [4,5,12,13]. Since the mid-1990s, many rehabilitation hospitals in Korea, including our own center, have started to recommend intermittent catheterization as the first approach for bladder management. Thus, active patient education has enabled more patients to select intermittent catheterization. However, there has been a lack of studies on the changes in bladder emptying methods used in patients with SCI in Korea.
In addition, previous studies reported differences in bladder emptying methods according to the American Spinal Injury Association impairment scale (AIS), which are also associated with the somatic nerve recovery of bladder function [3,14,15]. However, to our knowledge, no study has addressed bladder emptying methods according to the AIS classification in Korea.
Additionally, because hand function in tetraplegia patients is frequently impaired, a different study reported differences in bladder emptying methods according to the level of injury (tetraplegia vs. paraplegia) [2].
Thus, in this study, we aimed to retrospectively analyze changes in the trend in bladder emptying methods according to the severity of injury in patients with SCI over the last 20 years in Korea.
MATERIALS AND METHODS
Patients and study design
This retrospective study was approved by the Institutional Review Board at the National Rehabilitation Center (No. NRC-2018-03-017) and included patients with SCI at a single center in Korea. Due to the retrospective nature of the study, the requirement for informed consent was waived. We retrospectively reviewed the medical records of patients with SCI admitted to the center between 1994 and 1998 (group 1) and between 2012 and 2016 (group 2). Among these patients, those aged 15 years or more and admitted within 2 years of the onset of injury were considered eligible to participate in the study. Patients with no or unclear information about AIS and bladder emptying methods were excluded from the final data. All patients were examined according to the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) guidelines. Collected data included sex, level of injury (tetraplegia/paraplegia), severity of the injury (AIS grade A, B, C, or D), length of hospital stay, duration of injury at admission, and bladder emptying method at admission and at discharge.
Bladder emptying methods
From medical records, we collected information on bladder emptying methods at admission and discharge from our center. Bladder emptying methods were categorized according to the International Spinal Cord dataset recommended by the International Spinal Cord Society (ISCoS) in 2018. In this study, we grouped patients according to normal voiding, bladder reflex triggering (voluntary/ involuntary), and bladder expression (straining/ external compression) as those who used voiding without catheter. Twenty years ago, the International Spinal Cord datasets regarding bladder emptying methods were not available, and patients with SCI often used a combination of bladder emptying methods. Thus, it was difficult to accurately classify bladder emptying methods according to the International Spinal Cord dataset recommended by ISCoS. For this reason, we used voiding without catheter to classify patients in this study. Consequently, we categorized bladder emptying methods into four groups— voiding without catheter, intermittent catheterization, urethral indwelling catheter, and suprapubic indwelling catheter.
Statistical analysis
All statistical analyses were performed with SPSS version 20.0 (IBM SPSS Inc., Armonk, NY, USA). The level of statistical significance was set at p<0.05. Data are presented as means±standard deviations for continuous variables and as percentages for categorical parameters. We used the paired t-test to test for differences in length of hospital stay and the chi-square test for other demographic factors. Chi-square tests were also used for comparing changes in bladder emptying methods over time between the two groups.
RESULTS
Demographics
From 1994 to 1998 (group 1) and from 2012 to 2016 (group 2), 944 patients with SCI were admitted to our center. A total of 667 patients, 194 in group 1 and 473 in group 2, met the study criteria and were thus included in the study (Table 1).
The mean age was 32.8±11.9 years (range, 15–69 years) in group 1 and 49.1±15.9 years (range, 15–84 years) in group 2. Men comprised 77.4% of group 1 and 71.2% of group 2. Patients with tetraplegia comprised 49.7% of group 1 and 47.8% of group 2. The severity of injury was evaluated using AIS. AIS grade A was found in 51.0% of group 1 and 31.5% of group 2.
Compared to group 1, patients in group 2 had a significantly higher severity of injury, a higher non-traumatic rate, were older, had longer length of hospital stay, and had a shorter duration of injury at admission.
Changes in the trend inbladder emptying methods at discharge
Changes in the trend in bladder emptying methods at discharge were analyzed by comparing group 1 (1994– 1998) and group 2 (2012–2016). There was a significant change in the proportion of patients using different bladder emptying methods between group 1 and group 2 (p=0.001) (Table 2, Fig. 1).
The proportion of patients using voiding without catheter decreased over time from 67.0% in group 1 to 30.0% in group 2. The proportion of patients with intermittent catheterization increased over time from 26.8% in group 1 to 54.8% in group 2 (Fig. 1A).
We also analyzed data according to injury severity. Among patients with AIS-A and AIS-B, the proportion of those using voiding without catheter decreased from 61.9% to 3.7%. The proportion of patients with intermittent catheterization increased from 32.8% to 73.3% (Fig. 1B). In patients with AIS-C, the proportion of those using voiding without catheter decreased from 70.6% to 22.8%, and the proportion of those with intermittent catheterization increased from 14.7% to 60.9% (Fig. 1C). Similar trends were observed in AIS-A and AIS-B. However, in patients with AIS-D, the proportion of those using voiding without catheter decreased from 88.5% to 68.9%, and the proportion of those with intermittent catheterization increased from 11.5% to 26.8%. In patients with AISD in group 1, only 11.5% of patients used intermittent catheterization, and no patients used indwelling catheter at discharge. In contrast, in patients with AIS-D in group 2, 31.1% of patients used intermittent catheterization (26.8%) or indwelling catheter (4.3%) at discharge. Voiding without catheter was still the most frequently used method in AIS-D (Fig. 1D). There were significant changes in bladder emptying methods in all AIS grades between group 1 and group 2 (Fig. 1).
Changes in the trend in bladder emptying methods from admission to discharge according to severity of injury
Changes in the trend in bladder emptying methods were analyzed by comparing patient status at admission and at discharge (Table 2).
In patients with AIS-A and AIS-B in group 1, the proportion of those using voiding without catheter decreased from 67.9% at admission to 61.9% at discharge, while the proportion of those with intermittent catheterization increased from 20.9% to 32.8% at discharge. In contrast, the proportion of patients with indwelling catheter decreased from 11.2% to 5.3% at discharge.
In patients with AIS-A and AIS-B in group 2, the proportion of those using voiding without catheter decreased from 7.8% at admission to 3.7% at discharge. The proportion of those with intermittent catheterization increased from 48.9% to 73.3% at discharge, whereas the proportion of those with indwelling catheter decreased from 43.3% to 23% at discharge.
In patients with AIS-C in group 1, the proportion of those using voiding without catheter decreased from 76.5% at admission to 70.6% at discharge, while the proportion of patients with intermittent catheterization increased from 8.8% to 14.7% at discharge. Finally, the proportion of patients with indwelling catheter was 14.7% at both admission and discharge.
In patients with AIS-C in group 2, the proportion of those using voiding without catheter decreased from 29.3% at admission to 22.8% at discharge. The proportion of those with intermittent catheterization increased from 39.1% to 60.9% at discharge, whereas the proportion of those with indwelling catheter decreased from 31.6% to 16.3% at discharge.
In patients with AIS-D, from admission to discharge, the proportion of those using intermittent catheterization decreased in group 1 but increased in group 2.
In patients with AIS-D in group 1, the proportion of those using voiding without catheter slightly increased from 84.6% at admission to 88.5% at discharge and the proportion of those using intermittent catheterization decreased from 15.4% to 11.5%. In patients with AIS-D in group 2, the proportion of those using voiding without catheter slightly increased from 67.7% at admission to 68.9% at discharge. From admission to discharge, the proportion of those with intermittent catheterization increased from 15.9% to 26.8%, whereas the proportion of patients with indwelling catheter decreased from 16.4% to 4.3%.
Switch in bladder emptying methods during hospitalization in patients with AIS-D
Switches in bladder emptying methods in patients with AIS-D were analyzed by following up patient status at admission and discharge (Table 3).
There were no patients with AIS-D in group 1 who switched from voiding without catheter to intermittent catheterization during hospitalization. However, in patients with AIS-D in group 2, 8 (7.2%) out of 111 patients switched from voiding without catheter to intermittent catheterization during hospitalization. According to the medical records of these 8 patients, 4 had small bladder volume (<300 mL), 4 had substantial residual urine (>200 mL), 1 had high detrusor pressure above 40 cmH2O (>68 cmH2O), 1 had low compliance below 10 mL/cmH2O (2.8 mL/cmH2O), 1 had uncontrolled incontinence, and 1 had urgency. All 8 patients switched from voiding without catheter to intermittent catheterization for one or more reasons.
Comparison of bladder emptying methods between patients with tetraplegia and paraplegia at discharge
To analyze the impact of the level of injury, we analyzed patients with tetraplegia and paraplegia separately. There was a significant difference in bladder emptying methods at discharge between groups (p=0.001) in both patients with tetraplegia and paraplegia.
In patients with tetraplegia, the proportion of those using voiding without catheter at discharge decreased from 71.7% to 31.1%, the proportion of those with intermittent catheterization increased from 23.7% to 45.8%, and the proportion of those with indwelling catheter increased from 5.1% to 23.1% (urethral, 12.4%; suprapubic, 10.7%) over the last 20 years. In patients with paraplegia, the proportion of those using voiding without catheter at discharge decreased from 62.9% to 29.0%, the proportion of those with intermittent catheterization increased from 29.9% to 62.9%, and the proportion of those with indwelling catheter increased from 7.2% to 8.0% over the last 20 years (Table 4).
DISCUSSION
Changes in the trend in bladder emptying methods over the study period
Very few studies have investigated changes in the trend in bladder emptying methods in recent decades in Korea. Up to the mid-1990s, patients with SCI mainly used percussion, Valsalva, or Crede methods in Korea and used a condom urine bag and vinyl urine sheath (Fig. 2) as collecting devices. Management by intermittent catheterization was rare, including at our center [10,11].
A study conducted in two United Kingdom spinal cord centers over a 20-year period, beginning in 1990, reported that the proportion of patients with intermittent catheterization increased from 4% to 18.8% and that the sum of voluntary control, straining/expression, and condom drainage, which is equivalent to the use of “voiding without catheter”, decreased from 82.3% to 50.6%. Further, the proportion of patients using indwelling catheters increased from 8.8% to 25.9% over this period, while the proportion of patients using indwelling urethral catheter did not differ significantly, increasing only from 6.3% to 10.6%. The use of a suprapubic indwelling catheter increased significantly from 2.5% to 15.3% [16].
In addition, from a national database containing bladder emptying methods data from 1972 to 2005 in the United States [17], the proportion of patients with intermittent catheterization increased from 12.6% between 1972 and 1975 to 49.6% between 2001 and 2006. Conversely, the proportion of those using condom catheters steadily decreased from 34.6% between 1972 and 1975 to 1.5% between 2001 and 2006. Meanwhile, the use of an indwelling catheter initially decreased from 33.1% between 1972 and 1975 to 16.5% between 1991 and 1995 but increased to 23.1% between 2001 and 2006.
Hansen et al. [18] reported that the proportion of patients with intermittent catheterization increased from 26% at discharge to 44% at follow-up after 10 or more years. Intermittent catheterization is currently the most commonly used method in Denmark.
Over the last 20 years at our center, the proportion of patients using voiding without catheter decreased dramatically from 67.0% to 30.0%, and the proportion of those with intermittent catheterization increased from 26.8% to 54.8%. This may be because, after the mid- 1990s, many studies on the safety of intermittent catheterization were published, and intermittent catheterization was recommended as the treatment of choice for bladder emptying management [19]. Thus, due to the risk of upper urinary tract impairment, the percussion, Valsalva, and Crede methods used in the mid-1990s were no longer recommended [13]. Hence, all patients at our center underwent UDS within 3 months of admission, and we have actively recommended the use of intermittent catheterization since the mid-1990s. This treatment protocol might explain the differences between group 1 and group 2. Conversely, the proportion of those with indwelling catheters increased from 6.2% to 15.2% over the last 20 years.
Changes in the trend in bladder emptying methods according to severity of injury (AIS)
To our knowledge, there has been no study on the differences in bladder emptying management according to severity of injury (AIS) in Korea. In a 2012 Japanese study, the proportions of patients with AIS-B using the bladder emptying methods voiding without catheter, intermittent catheterization, and indwelling catheter were reported to be 13%, 26.1%, and 60.9%, respectively, whereas patients with AIS-C and AIS-D showed corresponding percentages of 37.8%, 34.5%, and 27.7% and 80.2%, 13.2%, and 6.6%, respectively. Only patients with AIS-D used voiding without catheter in over 50% of cases [3].
Furthermore, ischemic patients with SCI classified as AIS-D may have fewer urodynamic abnormalities and a greater possibility of having normal voiding [20]. Similarly, our center also showed differences in bladder emptying methods, which varied according to the severity of injury (AIS). Intermittent catheterization was more prominent in patients with AIS-A, AIS-B, and AISC. Conversely, in patients with AIS-D, voiding without catheter was the most frequently used bladder emptying method (68.9%). However, 31.1% of patients still used intermittent or indwelling catheter at discharge.
A Japanese study comparing bladder emptying methods at patient admission and discharge found that the use of intermittent catheterization increased at discharge. A comparison between bladder emptying methods at admission and discharge from 2003 to 2009 in a Japanese hospital [3] indicated that the proportion of intermittent catheterization use, voiding without catheter use, and indwelling catheter use at admission were 8.1%, 42.7%, and 49.2%, respectively, whereas the rates at discharge were 22.7%, 57.2%, and 20.1%, respectively. Thus, the proportion of patients using an indwelling catheter decreased, while the proportion of patients with intermittent catheterization increased at discharge.
This trend is in line with the trends observed in our study, except for the proportion of patients using “voiding without catheter”. In our study, in patients with AIS-A, AIS-B, and AIS-C in group 2, the use of indwelling catheter and voiding without catheter decreased, whereas the use of intermittent catheterization increased at discharge. However, in patients with AIS-D in group 2, the use of voiding without catheter and intermittent catheterization increased, while the use of indwelling catheter decreased at discharge compared to that used at admission. The reason for the differences between patients with AIS-A, AIS-B, and AIS-C and patients with AIS-D may be that due to low urodynamic abnormality exhibited by patients with AIS-D many patients continue to use voiding without catheter [20]. However, even in patients with AIS-D, some patients switched from voiding without catheter to intermittent catheterization at discharge. Among patients with AIS-D in group 2, 8 (7.2%) out of 111 patients switched from voiding without catheter to intermittent catheterization as the bladder emptying method during hospitalization.
Lee recommended that the bladder emptying method be chosen according to the AIS grade [21]. In particular, intermittent catheterization should be selected for patients with AIS-A, AIS-B, and AIS-C, and natural voiding training should be attempted for patients with AIS-D. Furthermore, even patients with AIS-D are often required to choose intermittent catheterization rather than voiding without catheter due to uncontrolled incontinence or urgency, deformity of the bladder, or increased detrusor pressure, which is a risk factor for vesicoureteral reflux. Thus, patients with AIS-D who present with these risk factors (urgency, uncontrolled incontinence, deformity of bladder, and/or high detrusor pressure) should be recommended for intermittent catheterization.
Comparison of bladder emptying methods between patients with tetraplegia and paraplegia at discharge
In a 2017 Dutch study, suprapubic indwelling catheter was the most commonly used method (20.7%) in patients with tetraplegia, while intermittent catheterization was the most commonly used method (60%) in patients with paraplegia [2]. In addition, Cameron et al. [17] reported that female sex, age >43 years at injury, and presence of tetraplegia significantly increased the proportion of patients managed with an indwelling catheter versus intermittent catheterization at initial discharge from rehabilitation.
In this study, differences in bladder emptying methods at discharge were significant over a 20-year period in both patients with tetraplegia and with paraplegia with a decrease in the use of voiding without catheter and an increase in the use of intermittent catheterization. Furthermore, consistent with previous studies, the proportion of indwelling catheter use in patients with tetraplegia was higher than that in patients with paraplegia, which may be due to impaired hand function in patients with tetraplegia who require assistance for intermittent catheterization.
In addition, among patients with tetraplegia in group 2, a similar proportion of patients was managed with transurethral and suprapubic indwelling catheters at discharge. Currently, suprapubic indwelling catheters are recommended more often than transurethral indwelling catheters because they lead to fewer complications, such as epididymitis and urethral stricture [4]. However, transurethral indwelling catheters are still frequently used, potentially because patients usually have negative opinions on the intervention necessary for the use suprapubic indwelling catheters.
This study has several strengths. First, to our knowledge, this was the first study to report on changes in bladder emptying methods among patients with SCI in Korea over a period of 20 years. Second, our study evaluated bladder emptying methods according to severity of injury (AIS) in patients with SCI. This study will provide fundamental data to aid clinicians in choosing the most suitable bladder emptying method for patients with SCI according to severity of injury (AIS). Third, this study reported that among patients with AIS-D in group 2, approximately 26.8% chose the intermittent catheterization approach at discharge, indicating a direction away from “voiding without catheter”.
This study has several limitations. First, it was a singlecenter study and so, multicenter studies are required in the future. Second, because of its retrospective design, follow-up data after discharge were unavailable. A previous study showed that compliance with intermittent catheterization after discharge was 85.5% in our center [22]. Compliance with other methods may also require future study. Third, in addition to the comparison of AIS grade and level of injury, it is necessary to make a comparison according to whether there is an intermittent catheterization capable hand function. Fourth, there were differences in several demographic factors between the two groups. According to a recent study analyzing patients who visited a single center in Japan from 1995 to 2013, the proportion of older and non-traumatic injury patients has increased over the years [23]. For this reason, the length of stay and duration of injury might be affected and such differences might have impacted the results of this study in unknown ways.
In conclusion, during the study period, the use of voiding without catheter decreased, whereas the use of intermittent catheterization increased. This was especially prominent in patients with AIS-A, AIS-B, and AIS-C. In patients with AIS-D, voiding without catheter was still the most frequently used bladder emptying method. However, the proportion of patients with intermittent catheterization increased in recent decades in Korea. These results will be helpful for clinicians in choosing the most suitable bladder emptying method according to the severity of injury (AIS).
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