Bowel management and continence in adults with spina bifida: Results from the National Spina Bifida Patient Registry 2009–15

1. Introduction

As the most common permanently disabling birth defect, spina bifida (SB) has traditionally been considered a pediatric condition. Nearly 1,500 children are estimated to be born in the United States (US) with SB without anencephaly each year based on national prevalence studies from the Centers for Disease Control and Prevention (CDC) [1]. However, advances in medical care have enabled nearly all children with SB to now survive into adulthood. In fact, most Americans living with SB are currently adults [2]. Most individuals with SB suffer from neuropathic bowel dysfunction (NBD) manifesting as constipation and fecal incontinence and having a documented negative impact on quality of life [3]. Management of NBD in SB patients has traditionally been conducted by pediatric urologists, pediatric gastroenterologists, developmental pediatricians, and physiatrists, but with more patients reaching adulthood, transition to adult care has become increasingly relevant [4].

The National Spina Bifida Patient Registry (NSBPR), funded through the CDC, began collecting data from multidisciplinary SB clinics across the US in 2009. Its primary goals were to describe the patients who attend those clinics, to provide a foundation for research, and to improve clinical care [5]. This, in turn, has enabled collaborative research across multiple time points during patients’ lives. The data collected are comprehensive, covering multiple organ systems and complications of SB. The registry includes over 6000 patients, 22% of whom are adults, with sufficient granularity to study NBD management and continence outcomes [6].

Currently, there are little data about bowel management and continence outcomes in adults with SB, and these are primarily from single institutional series. The purpose of this descriptive analysis is to characterize current NBD management and associated continence outcomes in a large cohort of adults with SB from across the US. More information is needed to improve care and develop realistic expectations for adults as well as for children with SB and their families.

2. Methods

The NSBPR, a center-based registry implemented and maintained by the CDC, was designed to help describe characteristics of people with SB, processes of care, and health outcomes among a national sample of patients attending SB clinics. Between September 2008 and December 2015, 26 sites (29 multidisciplinary SB clinics) participated in the NSBPR. Through the use of a standardized data collection tool, longitudinal data were gathered, de-identified, and pooled from patients with 1 of 6 diagnoses: myelomeningocele (MMC), meningocele, lipomyelo- meningocele, split cord malformation, terminal myelocystocele, or fatty filum [7].

Local institutional review boards provided approval for study participation, and parents and patients provided informed consent (and assent, as indicated by age) as appropriate. Given that sites were encouraged but not required to enroll all eligible SB patients, aggregate and individual level demographic data on patients not enrolled were collected for comparison. Baseline demographic and diagnostic information was collected through an initial encounter form used at the time of patient enrollment. An annual visit form was used to collect updated information on time-varying demographic and clinical characteristics and treatments at enrollment and at each yearly visit. Patient data were obtained through medical record abstraction and patient interview; after de-identification, data were transmitted to the CDC for management and analysis.

3. Results

4. Discussion

Using data from the NSBPR, we herein report the largest analysis of bowel management and continence outcomes in adults with SB to our knowledge. The findings are important not only to evaluate care of SB adults but also to provide realistic expectations to SB children and their families about future management. Clinical care is continually evolving in all areas of medicine, and SB care is no different; we noted significant differences in management and outcomes in adults compared to school-aged children and adolescents, as newer procedures and management techniques have been developed.

The adult SB population is heterogeneous in terms of SB type and lesion level, so variation in NBD was expected. Our adult cohort had a larger proportion of individuals with the MMC form of SB and higher lesion levels than younger cohorts. It is unknown if this difference was related to the fact that adults with milder forms of SB are less likely to receive care at multidisciplinary SB clinics participating in the NSBPR or if there has been a recent trend to include more children with non-MMC diagnosis in SB clinics. The reported bowel continence rate for adults with SB was 58.3% (55.6% for MMC and 74.9% for non-MMC). An international on-line survey of 518 SB adults showed a lower bowel continence rate of 44.6% [9]. It is unclear if lower continence rates were due to the voluntary and private nature of the on-line survey. Nonetheless, it is clear that bowel continence is attainable for a large proportion of adults with SB.

Our cohort of adults had a higher proportion of females compared to younger cohorts. This was less skewed than others have reported; Liu et al. [10] had a two-thirds female distribution in their analysis of 225 adults with SB. Females are known to be more diligent about routine health care [11], and this may explain the greater preponderance of females attending SB clinics in the registry. Alternatively, females may simply be more likely than males to seek treatment at NSBPR or other SB clinics, or males with SB may be more likely to expire at younger ages than females. Despite this difference, no difference in bowel continence was associated with gender. We also noted that the racial and ethnic mix of the population of SB patients in the US has been changing over time, as seen in our 26 sites in 20 states. The younger two cohorts in the registry had proportionally fewer non-Hispanic whites and more Hispanics/Latinos. This likely reflects increased immigration of Hispanics/Latinos to the US in the past several decades, and this population is known to have a higher incidence of SB and higher birth rates [12].

Management of NBD showed different care patterns across age groups. Interestingly, continence was similar at 58% in both adults and adolescents. Use of timed evacuation, suppositories, and mini-enemas all declined with increasing patient age; it may be that these interventions may become less effective or require greater assistance as individuals age. Digital stimulation and disimpaction were used more frequently by adults and could be a reflection that these are older forms of management or that adults are less bothered by these techniques. Colostomy is typically a last resort in bowel management and is often done to manage severe sacral skin ulcers; its greater prevalence in adults was not unexpected as adults are known to have significant morbidity and mortality from skin ulcers [13, 14]. The use of antegrade enema was significantly greater in adolescents, and the higher rates of procedures to allow this was accordingly higher in this cohort. These age differences are likely explained by the fact that these procedures only came into widespread practice over the last two decades. Further study is needed to see if this surgical trend will lead to improved bowel continence rates in adults in the future.

The unique socio-economic findings of this analysis have many important implications for the social, educational, and vocational development of individuals with SB, as well as their daily personal hygiene. Adults with SB were less likely to have private insurance compared to younger patients. This is not unexpected as patients are no longer covered by their parents’ insurance at older ages. Furthermore, SB appears to negatively affect educational and employment attainment which is a major determinant of health insurance status for adults. We found that 46% of participants aged 25 years or older had attended some college, and 19% had at least a college degree; this compares to 59% of all American adults aged 25 or older attending some college and 33% achieving a bachelor’s degree [8]. Educational attainment in adults with SB was further noted to significantly impact employment and insurances status. Conversely, we noted that the more severe end of the SB spectrum manifested in MMC and higher levels of lesion was associated with lower educational attainment. A total of 38.4% of our adult SB cohort reported full or part time employment which was similar to 34% noted by Liptak et al. [15]. Finally, we noted an association between educational status and bowel continence. To investigate the association of socioeconomic and disease factors with bowel continence, controlling for confounding variables, we used multivariable logistic regression. The only statistically significant association noted was between bowel continence and employment status. In a similar analysis of bladder continence in the same cohort, we found no association with these same factors [16]. It has been suggested that bladder incontinence (particularly low-volume) may be less impactful than bowel incontinence. Szymanski et al. [9], in fact, noted that quality of life of adult SB patients was more negatively affected by bowel than bladder incontinence. The directionality of the relationship between bowel continence and educational attainment and employment is not known; are people that are more motivated to successfully use a bowel program to attain continence also more motivated to complete college and gain employment or does the presence of the bowel incontinence reflect social and/or disease-related factors that prevent college attendance/completion or employment? Clearly, further study is needed.

Our study was subject to limitations. As with any large database, errors in patient recall and data abstraction and entry may have occurred. The NSBPR carefully standardized data components and collection and has ongoing data quality monitoring between participating clinics and CDC staff [5]. There is a potential for selection bias within the enrolled clinics, but sensitivity analyses have shown no significant differences in eligible, but not enrolled, patients in these clinics. (manuscript in preparation) Adults enrolled in the registry may not be representative of all adults with SB in the US because they may be receiving more intensive and systematic care in multidisciplinary clinics selected by the CDC to participate in the NSBPR than patients receiving care at other SB clinics or elsewhere. It is not known if the type of SB clinic matters as the NSBPR includes a mix of pediatric only, adult only, and all age clinics. Furthermore, adults attending these clinics may have a higher level of SB-related disease burden than those not attending specialty clinics. This may be more pronounced for less affected non-MMC patients who may not seek medical care if having no problems. The age distribution of adults studied is skewed towards young adults, so these findings may not be representative of older adults with SB.

5. Conclusions

This largest analysis to date of NBD bowel management and continence outcomes in adults with SB revealed significant differences compared to adolescents and younger children with SB, as well as differences based on SB type. Bowel continence was noted to be superior in adults and better in those with less severe forms and lower lesion level of SB. Bowel continence was significantly associated with employment status and educational attainment on univariate analysis, but only employment on multivariable logistic regression analysis. These findings should help guide management of NBD in adults with SB and provide realistic goals for counseling of younger patients.