Intermittent catheterisation with hydrophilic and non-hydrophilic urinary catheters: systematic literature review and meta-analyses

Normal bladder functionality can be lost due to neurogenic or non-neurogenic causes. Neurogenic bladder disorders are seen secondary to spinal cord injury (SCI), multiple sclerosis or spina bifida. Common non-neurogenic bladder disorders include outlet obstructions (e.g. benign prostate hyperplasia) and post-operative urinary retention.

Management of bladder dysfunctions aims to improve continence and bladder functionality, protect the upper urinary tract and improve patients’ quality of life. Antimuscarinic agents are the preferred treatment for patients with storage dysfunction, while intermittent catheterisation (IC) is the preferred choice for patients with significant voiding problems [1, 2].

Although antimuscarinic agents are effective, well tolerated and safe, they have no long-lasting therapeutic effects and bladder dysfunction recurs immediately after therapy suspension. As a result, treatment should be continued for the patient’s lifetime. Available alternative treatments include intra-detrusor injection of botulinum toxin and neuromodulation. Botulinum toxin causes a reversible chemical denervation, lasting for approximately 9 months, which can significantly improve bladder functionality. Electrical stimulation of peripheral nerves (e.g. sacral or pudendal nerve), interrupting inappropriate detrusor contractions, has proved to be effective in managing the idiopathic overactive bladder [3], but for patients with an underlying neurological disorder, its role still remains unclear [1].

In patients with bladder storage dysfunction, urinary catheterisation can be required in combination with antimuscarinic agents, botulinum toxin or neuromodulation if voiding problems occur. Incomplete bladder emptying can either be managed by a permanent urethral/suprapubic catheter or IC. European guidelines focusing on neurogenic lower urinary tract dysfunctions [4‐6] report that IC is the option of choice for patients resulting in high post-void residual volumes, especially for patients with SCI [7]. IC is a manual bladder emptying technique performed regularly about four to six times a day by a patient themselves or a caregiver; the catheter is inserted through the urethra and removed once the bladder has been drained from urine. This method limits the complications and improves the prognosis of the patients [8].

One of the major advantages of IC is the significant reduction in the risk of catheter-induced UTIs, resulting in maintenance of urinary tract health and protection of the kidneys [9, 10]. In 2010 the International Consultation on Incontinence concluded that IC is effective and safe for emptying the bladder both in the short and long terms, but that bladder and urethral complications increase in the long term [11]. These complications are mainly represented by recurrent UTIs, which are one of the most important problems of patients with lower urinary tract dysfunction. These infections, if not treated properly, can lead to kidney infections, resulting in kidney failure and risk of sepsis [12]. UTIs also cause high morbidity and result in frequent hospitalisations [13]. Moreover, repeated cycles of antibiotic therapy necessary in patients with a recurrent UTI cause the onset of “antibiotic resistance” in various strains of microorganisms involved in the infection [12]. For these reasons, UTIs impose in general a relevant economic burden on patients and their families as well as on the healthcare systems [14].

IC performed several times a day places the individual at risk also for urethral trauma, often measured by the occurrence of haematuria. Urethral trauma is associated with an increase in UTI risk [15, 16].

There are different catheters suitable for IC, for example, disposable catheters with a hydrophilic polymer surface coating, disposable catheters with pre-packaged water based lubricant, and uncoated catheters. Uncoated catheters may be discarded after use or washed and re-used for different days.

Two possible advantages of hydrophilic coated catheters over uncoated ones are the reduction of urethral trauma (e.g., haematuria) and the incidence of symptomatic UTIs. Currently, although there are trends in favour of hydrophilic coated catheters with respect to UTIs [17‐19] in the short term, there is little consensus on which type of catheter is best. Four meta-analyses have been previously published investigating the impact of hydrophilic coated catheters (and other catheter types) on UTI rate and urethral trauma among patients practicing IC [20‐23]. Two meta-analyses concluded that hydrophilic coated catheters are associated with a risk reduction of UTI [20, 23] and trauma [23] as compared to non-hydrophilic catheters, while two others were inconclusive and unable to differentiate between catheter types or techniques [21, 22]. According to Clark et al. [20] the effect size of UTI reduction were 21% in hospital setting and 53% in the long-term community setting [20] while Li et al. [23] reported a risk reduction of 64% [23] associated to hydrophilic coated catheters. The other two meta-analyses [21, 22] allowed more catheter types in the comparison and as such the included studies were more heterogeneous and, accordingly, they showed no treatment difference between catheter types or catheter techniques in terms of UTI rate. In addition, they concluded that the number of randomised controlled trials were too low and compromised by quality issues [21, 22]. Two studies added cost-effectiveness data based on the results of the meta-analyses [20, 22]; one study concluded that hydrophilic coated catheters is a cost-effective choice when considering long-term treatment of IC [20] while the other one concluded that there are no therapy or economic benefits associated to a specific catheter type or technique [22].

The aim of the present study was to confirm/reject the conflicting evidence of previously published meta-analyses and again try to compare complication rates (UTI and urethral trauma/haematuria) related to hydrophilic coated catheters as compared to non-hydrophilic catheters for users who practice IC. In addition, a separate analysis including reused uncoated catheters was performed to evaluate differences between catheter types and their use in IC.

The aim of the present study was to confirm or reject the conflicting evidence of previously published meta-analyses [20‐23] and again try to evaluate complication rates (UTI and urethral trauma/haematuria) related to hydrophilic coated catheters as compared to non-hydrophilic catheters for users who practice IC. In addition, a separate analysis including reused uncoated catheters was included to evaluate the possibility to further differentiate between catheter types and their use in IC.

The results from the study showed that hydrophilic coated catheters are associated with a reduced risk of UTIs among patients performing IC. The estimated risk reduction was 16% considering both single-use and single-use plus reused catheters scenarios. No difference in the results is due to the low number of patients involved in the two additional studies considering reused devices, which accounted for low study weights (0.2% each) in the overall analysis.

As regards the second considered outcome, haematuria, the meta-analyses were not able to verify a risk reduction associated to hydrophilic coated catheters. However, the results from the two meta-analyses suggest that there may be differences related to types of hydrophilic coated catheters. It should be noted that hydrophilic catheters considered in the single-use scenario all referred to the same brand (i.e. Coloplast), while both additional studies included to consider the extended scenario referred to another brand (i.e. LoFric). The inclusion in the analysis of these hydrophilic coated catheters with high osmolality [35] seemed to lower the risk of haematuria, although statistical significance could not be verified.

The present study provided objective data to support the use of hydrophilic catheters in clinical practice to reduce UTIs; however, the opinion of the patient regarding the choice of the type of device should also be taken into account; he/she has to find the product agreeable, corresponding to his/her needs, handy, and easy to use.

The present review has some limitations, first of all, the heterogeneity regarding the clinical outcomes and their definitions in the included studies. The proposed definitions of symptomatic UTI were: significant bacteriuria (≥10⁵ CFU/mL) plus at least one sign or symptom suggestive of UTI [17], clinical definition of symptomatic UTI (antibiotic treatment prescribed), and strict definition of symptomatic UTI (antibiotic treatment prescribed, bacteriuria, at least one of seven symptoms based on consensus guidelines–fever, autonomic dysreflexia, increased spasticity, discomfort or pain over the kidney or bladder or during micturition, onset and/or increase in incontinence episodes, cloudy urine with increased odour, malaise, lethargy, or sense of unease; dipstick test positive for leukocyte esterase) [18], clinical infection with symptoms of UTI and for which treatment was prescribed [19], >10⁴ CFU/mL [33], infection of the urinary tract that requires the insertion of a Foley catheter [30], >10⁵ CFU/mL [34]. With regard to haematuria, no precise definition was given but the studies referred to microscopic haematuria [34], gross haematuria [33], urethral bleeding [18, 31] and haematuria in general [19, 32].

Secondly, nearly half of the trials presented attrition biases that can greatly influence the strength of the reported results. Moreover, dropouts occurred early and were more frequent in the arm related to hydrophilic catheters, thus resulting in an imbalance and a potential bias in favour of the latter. This means that patients who didn’t continue the study may have been less satisfied with hydrophilic catheters than those who completed the study.

Thirdly, effectiveness data were derived from few RCTs with less than 50 participants. Although systematic reviews can be performed in practice with any number of studies, when few studies are used, the heterogeneity point estimate I² should be interpreted cautiously, even replaced with confidence intervals as reported by von Hippel [36].

Another limitation of the current study is that UTIs and episodes of haematuria are not the only complications that can occur in users performing ICs, However, the former are the most frequent complications in this type of users, while the latter occur regularly in one-third of them on a long-term basis [37].

In spite of the limitations of the current review and meta-analyses, the results from two previously published reviews [20, 23] in terms of UTI risk reduction associated to the use of hydrophilic coated catheters were verified. It should be noted that the meta-analyses of this study were limited to randomised clinical trials only to ensure high level of evidence but this is a limitation per se since few high quality trials exist and the available ones are compromised by quality issues [21]. On the other hand, the results from this study also verify the results by several observational studies that focused on the frequencies of UTIs [38, 39], urethral trauma [39], urethral complications [38], microscopic haematuria, and pain [40].

The management of UTIs with systemic symptoms requiring medical intervention is associated with significant costs. Findings can be summarised by a wide cost span between €523 and €4167 [41‐46] and it is likely that more complicated UTIs are associated with higher costs. A catheter that could lower UTI frequencies and other types of complications is likely to limit the burden for patients using IC, resulting in increased quality of life. The combination of both economic and quality of life aspects can be evaluated through a cost-effectiveness analysis comparing hydrophilic catheters to non-hydrophilic catheters.

The meta-analyses results confirmed that hydrophilic coated catheters are associated with a reduced risk of UTI among patients using IC. On the other hand, a risk reduction for haematuria associated to hydrophilic coated catheters in general was not demonstrated. The conclusions from the study are however compromised by several limitations, such as the heterogeneity of outcomes and definitions, the lack of available high quality randomised controlled trials as well as a higher dropout rate in the arms related to hydrophilic catheters. In view of these limitations, uncoated catheters may still maintain a place in the clinical practice.

Further studies are crucial to provide more direct evidence of the comparison between hydrophilic versus non-hydrophilic coated catheters and could be used to integrate a cost-effectiveness model. In the meantime, it is important also to consider the evidence from observational data when assessing the effectiveness of hydrophilic-coated catheters.

In conclusion, there is still further work to be performed in order to assess incremental cost and effectiveness of hydrophilic versus standard catheters to optimise informed policy decisions.