The NSBPR uses a standardized tool to collect longitudinal data from patients with spina bifida at 26 sites with 6 diagnoses, including MMC, meningocele, lip-omyelomeningocele, split cord malformation, terminal myelocystocele and fatty filum.⁸ After local institutional review board approval parents and patients gave informed consent. Enrollment of all eligible patients was encouraged but not required. Baseline demographic and diagnostic information was collected at enrollment, and updated demographic and clinical data were gathered yearly. The data used were obtained at the most recent clinic visit through medical record abstraction and patient interview.

This analysis of bladder management and continence outcomes in SB represents the largest cohort of adults described to date. These data are helpful not only to evaluate current care, but also to provide realistic expectations to younger individuals about future management and outcomes. Furthermore, we noted significant differences among adults compared to younger patients.

Variation in neuropathic bladder dysfunction was expected as the neuropathy associated with SB is a spectrum. Our adult cohort had a greater prevalence of the MMC form of SB and higher lesion level than younger cohorts. This difference could be explained by a tendency of adults with milder forms of SB to be less likely to receive care at multidisciplinary SB clinics.

Overall usage of CIC among adults was 76.8% (79.5% for MMC and 59.5% nonMMC) and bladder continence was 48.2% (45.8% and 63.1% for MMC and nonMMC, respectively). Liu et al noted a similar rate of CIC usage, at 71% in 225 adults with SB, of whom 87% had MMC.¹⁰ Another study of 65 individuals with SB at 2 adult clinics revealed nearly identical rates of continence (48%) and CIC (77%).⁵ An international online survey of 518 adults with SB showed similar CIC usage (76%), although bladder continence was notably lower at 23.7%.¹¹ It is unclear if the lower continence was due to the voluntary and private nature of the online survey or a different definition of continence. Nonetheless, these studies demonstrate that most adults with SB utilize CIC, even with nonMMC defects, and that bladder continence is attainable for a large proportion.

Our adult cohort had a higher proportion of females compared to younger cohorts. This group was less skewed than the adult SB group reported by Liu et al, which was two-thirds female.¹⁰ Perhaps females are more likely than males to seek treatment at NSBPR clinics, or males with SB have decreased longevity compared to females. Nonetheless, no continence differences were associated with gender. We also noted that the racial and ethnic mix of the population with spina bifida in the US has been changing through time, as seen in the 26 NSBPR sites in 20 states. The younger 2 cohorts had proportionally fewer nonHispanic white patients and more Hispanics/Latino patients. This finding likely reflects increased immigration of Hispanic/Latino individuals to the US in recent decades, and this population has a higher incidence of SB and higher birth rates.¹²

Usage of daily antibiotics was greater in adults. It is not known if this strategy to prevent UTI was begun in these patients when such practice was more common or if they indeed have more UTIs. However, use of antimuscarinic medication was decreased in adults despite improved continence rates and was similar to usage reported by Liu et al (49%).¹⁰ This finding could be related to a higher proportion of patients with a history of bladder augmentation, which typically obviates the need for such medication. The higher proportion of adults who had undergone bladder augmentation may be a reflection of increasing surgical indications with age due to bladder hostility, increasing desire for continence or prior practice patterns that more aggressively relied on augmentation.

The proportions of patients undergoing specific surgeries also could have been affected by prior surgical choices. For instance patients with a vesicostomy do not undergo bladder augmentation and vice versa. Adults underwent fewer surgeries to create continent catheterizable channels compared to adolescents, likely due to the fact that these operations have come into favor only in the last 2 decades. Summers et al noted a similar rate for prior bladder augmentation in their adult clinics (29%).⁵ Patients with SB have a greater risk of urolithiasis compared to the general population that increases with age,¹³ so an increased incidence of stone surgery in adults was not unexpected. The higher proportion of adolescents undergoing bladder outlet surgery for continence may be a reflection of an evolution of more aggressive efforts to help patients with spina bifida attain continence.

The proportion of individuals with no bladder management decreased with age. This finding may explain why bladder continence improved with age, from 36.9% in school-age children to 48.2% in adults. Bladder continence was significantly greater in adults with nonMMC compared to MMC SB. Adults were more likely to perform CIC and less likely to void spontaneously but CIC was less frequently used by adults with nonMMC SB. However, nearly 7% of all adults had an indwelling catheter or urostomy bag. It is unclear if this finding reflects older practice patterns or aging related sequelae such as progression of incontinence, declining mobility, inability to manage the bladder independently and increasing incidence of pressure ulcers.¹⁴ Regardless, as more individuals with SB survive further into adulthood, it will be important to determine if forms of bladder management change due to SB related factors or changes in practice paradigms. Inclusion of urodynamic parameters (added to phase 2 of the NSBPR) in future studies should further our understanding of the bladder pathology underlying these findings.

Our socioeconomic findings have implications for the social, educational and vocational development of individuals with SB. We previously analyzed socioeconomic factors in the same adult cohort of patients in the NSBPR and found bowel continence to be associated with higher employment rates and educational attainment on univariate analysis and with employment only on multivariable logistic regression analysis.¹⁵ In the current analysis of urinary parameters similar statistically significant associations were found between bladder continence and educational attainment/employment status. These associations were not appreciated on the initial analysis before excluding those with incontinent forms of management.¹⁵

These findings add to the growing body of literature investigating the impact of continence on QOL. Szymanski et al noted that QOL of adult patients with spina bifida was more negatively affected by any bowel incontinence than by low volume bladder incontinence.¹¹ Similarly Liu et al found that QOL outcomes in 66 adults with SB did not differ based on bladder management techniques.³

Our study has several potential limitations. As with any large database, errors in patient recall and data entry could have occurred. The NSBPR carefully standardizes data components and collection and has ongoing data quality monitoring.⁷ There is potential for selection bias at NSBPR clinics but analyses have revealed no significant differences in eligible, but not enrolled, patients in these clinics.¹⁶ Adults in the registry may not be representative of all adults with SB because they may be receiving more intensive and systematic care in selected clinics than patients receiving care elsewhere. Furthermore, adults attending these clinics may have a higher level of SB related disease burden than those not attending selected clinics. The age distribution of adults in the NSBPR is skewed toward young adults, so these findings may not be representative of older adults with SB. Finally, refinement of the definition of continence during the study period could have impacted the continence outcomes findings.

This analysis, which is the largest to date of bladder management and continence outcomes in adults with SB, found significant differences compared to adolescents and younger children. Management and outcomes varied by SB type but overall more than three-fourths of adults performed CIC. Bladder continence improved with age for patients with MMC and was significantly associated with employment status. These findings may help guide management of neuropathic bladder in adults with SB and provide realistic goals for younger individuals.