Randomized Crossover Comparison of Adhesively Coupled Colostomy Pouching Systems
This study was sponsored by a clinical grant from ConvaTec, a Bristol-Myers Squibb Company, Princeton, NJ.
Personal well being and quality of life are important for an individual adjusting to life with an ostomy. Recovery is affected by appliance comfort and ease of use, maintaining skin integrity, security from leakage,1-4 access to a stoma care nurse,5 and capacity to engage in normal activities of daily living.6 Individuals with an ileostomy or a colostomy are especially concerned about odor; leakage; restricted leisure, social or sexual activities; loss of employment; and problems with emptying or cleaning the pouch.2 As a result, new developments in ostomy technology strive to improve patient comfort and accommodate patient concerns while minimizing peristomal skin damage.
Few published studies address the safety and effectiveness of ostomy products and systems. Although they may be bulky and inflexible and require manual dexterity or extra pressure to secure them to tender peristomal skin, traditional two-piece ostomy products have successfully provided skin protection, security, and versatility and are preferred by many persons with a stoma.7 On the other hand, more flexible and comfortable one-piece systems, with their discrete low-profiles, lack versatility. Moreover, removal (which is frequent) should be performed carefully and gently to avoid pain and irritation of sensitive peristomal skin2,8; the rate of peristomal complications ranges from 18% to 55%.1 This challenge to adapting to life with an ostomy has been documented.6 For example, one controlled study8 notes that the proportion of persons experiencing peristomal skin irritation while using a specific one-piece pouch product increased 18% after applying and removing 10 pouches. Overall, the pros and cons of traditional ostomy systems encourage the development of new technologies.
Adhesive Coupling Technology™ (ConvaTec, a Bristol-Myers Squibb Company, Princeton, NJ) combines a low-profile, flexible, comfortable one-piece pouching system with the versatility and reduced frequency of skin barrier removal associated with two-piece pouching systems. Uncomplicated pouch removal permits clinical inspection or pouch changes with minimal disruption of peristomal skin or activities of daily living; pouches may be resealed or changed leaving the skin barrier in place. The two adhesively coupled systems currently available differ in shape and other skin barrier and pouch characteristics and may consequently differ in ease of use, leakage, or other parameters, potentially affecting patient clinical safety, efficacy, preferences, and quality of life. To assess a new approach to this technology, a prospective, randomized, controlled study was conducted to compare subject preference and product performance of two adhesively coupled pouching systems used during routine self-care by persons with a colostomy.
Materials and Methods
Study centers and participant enrollment. Six outpatient ostomy care clinics in Germany participated in the study. Eligible study participants included current two-piece, closed-pouch users who were 18 years of age or older, had a colostomy of at least 3 months’ duration, and were able to provide written informed consent and attend clinic on three separate occasions. The study was conducted under the supervision of each clinic’s ostomy care nurse and principles of Good Clinical Practices for monitoring studies (managing patient care and recording, verifying, and analyzing data throughout the study) were applied. Participant informed consent was obtained in conformance with the Helsinki Accord. Ethics and other appropriate institution approvals were obtained for all centers participating in the study.
Participants were required to have intact peristomal skin on enrollment, the capability to care for their stoma on their own or with a consistent caregiver, and sufficient mental alertness to record the required study data. Current users of the test product, any convex product, or any product other than a two-piece pouching system were excluded from enrollment. The original goal was to enroll 80 individuals to ensure 60 with evaluable data - thus, meeting statistical power criteria sufficient for differentiating preferences of participants. However, the study was terminated early with IRB agreement at the clinical investigators’ requests because preferences for System E were so strong the investigators believed study continuation was of questionable clinical value to their patients during the periods requiring use of System F. The magnitude and consistency of System E preferences exceeded original assumptions in the statistical power calculations; the study remained adequately powered with only 39 subjects participating. Using a prospective, randomized, crossover, open-label study design, successively enrolled patients were randomly assigned using sealed envelopes to receive either System E or System F for five consecutive skin barrier changes or a maximum of 15 ± 2 days (Phase 1). Then participants used the alternative system for a similar period during Phase 2.
Both products were applied as single-use pouching systems. System E is CE marked (the European equivalent of “manufactured according to Good Manufacturing Processes”) as a single-use pouch. It was changed as needed or if discoloration covered two-thirds of the pouch adhesive ring, according to package insert instructions. System F is CE marked and allows more than one episode of use, but re-usage was deemed inappropriate in this study because multiple use is considered unsanitary practice in Germany.
Test systems. System E was an adhesively coupled, two-piece, closed-end ostomy appliance, Esteem synergy®. It was designed to replace the standard two-piece flange and locking system with a flangeless Adhesive Coupling Technology (ACT)™ surface on the pouch, allowing users to locate and seal the new pouch in place on the Stomahesive® Skin Barrier (Esteem synergy, Adhesive Coupling Technology (ACT), and Stomahesive are manufactured by ConvaTec, a Bristol-Myers Squibb Company, Princeton, NJ, and are registered trademarks of E. R. Squibb & Sons, LLC, Princeton, NJ). The Skin Barrier and pouch flanges were available to subjects in matching small, medium, and large sizes, with a central opening that could be enlarged to accommodate stoma diameters up to 48 mm (1 7/8"). The closed-end pouches were available in standard length and short length. System E minimizes skin distortion, requiring less than half the pressure applied to the tender peristomal skin area to establish a secure connection than is applied with traditional two-piece systems.9 The pouch may be removed from the gelatin/pectin-based skin barrier with the same pouch repositioned up to 25 times10 or new or different pouches may be successively re-attached without removing the square skin barrier from the peristomal skin (see Figure 1). This design combines the benefits of a two-piece system8,11 with those of a one-piece system.
System F utilized the Assura® AC (US — EasiFlex® in Germany) pouching system with a supporting Alterna/Assura® grooved base plate to which the pouch is adhesively coupled using an Easy-Removal™ adhesive (EasiFlex, Alterna/Assura, and Easy-Removal are trademarks of Coloplast Corporation, Marietta, Ga.). A security channel on the pouch side, designed to guard against leakage, adds slightly to the thickness of the System F coupling device. The base plate was available to participants in small, medium, and large sizes, with a central opening that could be cut to fit ostomy sizes up to 58 mm (2 1/3") to match the pouch flange opening.
The main differences between the two systems are different skin barrier adhesive compositions, the channel and grooved base plate-pouch interface in System F, and base plate shape (System E features a square base plate and System F is circular).
For the study, skin barrier sizes were selected to match the clinical needs of the patients and were based on stoma size and site. All products were stored at normal room temperature and skin barriers and pouches were cleaned, applied, and removed according to manufacturers’ instructions.
Assessment and study variables. After obtaining informed consent and determining study eligibility, participant demographic variables (age, sex), stoma history and assessment (reason for surgery, stoma duration, diameter, protrusion), and stoma care variables (usual skin barrier/pouch wear time, accessory products used) were recorded. Peristomal skin condition was assessed by the investigator using a 4-point Skin Rating Scale where 0 = intact skin, no redness; 1 = minimal redness without breakdown of skin; 2 = extensive redness without skin breakdown; 3 = reddened and blistered without skin breakdown; and 4 = reddened with skin breakdown. Stoma diameter was measured (mm) and categorized as protruding >2 cm, <2 cm, or flush. All study participants received a diary card on enrollment and were asked to record the date and time of all pouch and skin barrier changes and to describe skin appearance and reasons for pouch or skin barrier removal as “routine” or “non-routine.” The latter was further classified as removal due to incidental leakage (gradual leakage, possibly a time to change indicator) or significant leakage (sudden leakage without warning, partial detachment, or other reason). Participants also were asked to record the appearance of peristomal skin (normal, better, or worse than normal) and whether the skin barrier or pouch provided adequate wear time. Pouching system safety was assessed by the study investigators and defined by the incidence and nature of the reported peristomal skin problems and the number of subject withdrawals and adverse events.
End-of-study phase participant evaluations. When each study phase was completed, participants were asked by the investigator to rate pouching systems on security and adhesive performance variables (excellent, good, fair, or poor); ease of use (very easy, easy, difficult, very difficult); amount of residue remaining on the skin after barrier removal (none, minimal, moderate, excessive); comfort (very comfortable, comfortable, uncomfortable but acceptable, uncomfortable and unacceptable); flexibility (very flexible, flexible, not flexible, rigid), and discreteness of pouching system (very discrete, fairly discrete, noticeable, very noticeable). The peristomal skin condition was rated as: “no redness,” “minimal redness without breakdown of skin,” “extensive redness without skin breakdown,” “reddened and blistered without skin breakdown,” or “reddened with breakdown of skin.”
End-of-study participant and investigator final comparisons. At the completion of Phase 2, participants returned to the clinic to complete the End-of-Study Phase Evaluation and a Final Evaluation. Investigators asked participants to compare the two systems with respect to usage learning curve, ease of application and removal, comfort, flexibility, wear time, and overall performance. Participants who indicated a preference also were asked to provide comments on their choices. Investigators also were asked to compare both systems using the same usage criteria.
Data and statistical analysis. All study data were entered as coded on the case report forms and verified by double key entry into a SAS Release 8.2 database of the SAS® System for Microsoft Windows (SAS Institute Inc., Cary, NC). Data from all participants enrolled in both study phases were included in the comparative analysis. Descriptive statistics (mean, median, range, and standard deviation) were calculated for all continuous variables measured on all subjects enrolled in at least one phase of the study. Skin barrier and pouch wear time were calculated as removal time minus application time. For comparisons of “reasons for wafer/pouch removal or adequacy of wear time,” a logistic regression model for repeated measures data was used. Comparisons between System E and System F were performed using a mixed model, repeated measure Analysis of Variance with skin barrier numbers as a random effect. Chi-square analysis compared proportions for responses with numbers less than 10. For rating variables such as ease of use, frequencies and percentages of each rating were presented. For analysis of final evaluation questionnaires, the percentages of subjects preferring System E were tested against the null hypothesis of equal preferences to determine whether significantly more patients preferred this system. An original sample size of 60 subjects was based on statistical power calculations assuming modest but clinically important differences in participant preferences. All statistical tests were deemed statistically significant at <0.05.
Results
Participant demographic and stoma characteristics. Thirty-nine volunteers with a permanent colostomy were enrolled in the study in six centers in Germany (see Table 1). Average age was 64.7 years (SD 9.8; range 37 to 81). The majority of the participants (15, 39%) had an ostomy as a result of rectal carcinoma. Ostomy surgery had been performed an average of 3.5 (SD 3.6) years before the study. Usual wear time for two-piece systems before enrollment was reported as 2.4 days (SD 0.5; n = 38) for the wafer and 10.1 hours (SD 4.7; n = 39) for the pouch. No significant differences in participant characteristics were found between those assigned System E and System F during the first phase of the study (see Table 1). Of the 39 participants, 33 completed Phase 1 and 31 of these completed both phases of the study. Collectively, 1,645 pouches and 342 skin barriers were used.
Wafer wear times for System E and System F were 2.0 days (SD 0.9) and 1.8 days (SD 0.8), respectively. Pouch wear times were 9.7 hours (SD 6.4) and 8.8 hours (SD 5.0) for System E and System F, respectively. These wear times were similar to corresponding pre-enrollment reports from the participants.
The study was terminated early with IRB agreement at the request of the clinical investigators because the magnitude and consistency of preferences for System E rendered study continuation of questionable clinical value to participants during the periods requiring them to use System F. The study was adequately powered to support statistical significance of the participant preferences reported.
System safety. Participant withdrawal was comparable in both groups. Six withdrew during Phase 1, evenly divided between participants using System E and System F. Two more withdrew during Phase 2. One, using System E, experienced a non-serious episode of mild diarrhea that resolved without treatment, was not considered related to any study product. The second withdrawal was a 63-year- old man who discontinued study participation during Phase 2 while using System F because “stool went under wafer.”
Skin assessments for all study participants were normal/intact at baseline. No episodes of skin breakdown were observed. Participant diary records of most participants (95% during use of System E and 98% during use of System F) reported a normal skin appearance during the 173 System E skin barrier and 169 System F wafer changes. At the end-of-phase assessment, four participants (11%) in the System E group reported patchy redness and one had extensive redness without skin breakdown.
Assessment after each study phase. System E was rated significantly (P <0.04) better on 10 of the 17 participant-rated parameters on the end-of-phase assessment. The systems were rated as comparable on seven parameters. System F was not rated significantly better on any parameter. The System E skin barrier received significantly higher ratings for ease of application, comfort on application and during wear, adherence to skin on application, during/following bathing/showering, and overall adhesive performance adhering to skin. The System E pouch also was rated significantly higher on ease of removal from skin barrier landing zone, flexibility and discretion during wear, and adhesion to the skin barrier landing zone during/following bathing/showering. No significant differences in ratings were noted with regard to ease of learning how to apply and remove the two systems, ease of pouch application to the skin barrier landing zone, skin barrier ease of removal from the skin, level of skin residue after skin barrier removal, comfort during skin barrier removal, adherence of pouch to landing zone on application, or overall adherence of pouch to landing zone (see Table 2).
System performance: participant diary records. Based on participant diary records, the average wear time was 2.0 (SD 0.9) days (N = 173) and 1.8 (SD 0.8) days (N = 169) for the System E and System F wafers, respectively. Although this difference was not statistically significant (P = 0.06), participants underscored its clinical significance by noting that System E skin barrier wear time was adequate 87.3% of the time, a significantly greater proportion of the time than the 75.1% reported for System F (P = 0.017). More System E (83%) than System F (60%; P = 0.001) skin barrier changes were recorded as “routine”(see Figure 2); however, significantly more incidental leakage was recorded as the reason for System F wafer changes (11.8%) than for System E (2.9%; P = 0.002). The other significant difference in reasons for non-routine skin barrier changes was partial skin barrier or wafer detachment — 11 episodes (6.4%) occurred with System E and 41 episodes (24.3%) with System F (P < 0.001). Skin appearance was recorded as “normal” more than 95% of the time for both systems.
Pouch wear times for the 827 recorded System E pouch changes were 9.7 hours (SD 6.4) compared to 8.8 hours (SD 5.0; P < 0.001, adjusted for effects of treatment sequence and study stage) for the 818 System F pouches. Although more than 97% of diary records for both systems indicated adequate wear time, System F pouch changes were noted as not providing adequate wear time in 19 (2.3%) instances as compared to seven (0.8%) System E changes (P = 0.01). Partial pouch detachment was recorded for 10 System E and 46 System F changes (P < 0.001). No significant differences in incidental or significant leakage (six for System E and 16 for System F) were noted.
Final participant and investigator evaluations. The 33 participants who completed both study phases sufficiently to compare the systems preferred System E on all seven Final Evaluation parameters, with statistical significance in five (ease of removal, P = 0.015; comfort, P = 0.003; flexibility, P = 0.004; wear time, P = 0.005; and best overall performance, P < 0.001) (see Figure 3). No significant differences were noted for the two other patient preferences. Five of the six investigators had sufficient experience with both systems to provide Final Evaluation ratings — five investigators unanimously rated System E better than System F on comfort and flexibility dimensions; no other unanimous preferences were noted. The number of investigators was not sufficient for these unanimous ratings to be statistically significant (P = 0.061).
Discussion
Participants rated both pouching systems high on safety and ease of mastery. However, System E was consistently rated higher by participants on non-routine skin barrier and pouch changes, comfort, adequacy of wear time, ease of pouch removal, adhesive performance of both pouch and skin barrier during/following bathing or showering, discretion of the pouching system, and flexibility. These variables are associated with improved clinical well being and quality of life for an individual with an ostomy.1,2,5,8,11
The participant diary record results were confirmed in the final evaluation preferences. Both systems were easy to learn and apply but System E was easier to remove and more comfortable to wear — potential benefits for individuals with recent ostomy surgery who experience significant abdominal tenderness. For these patients, greater comfort can improve the humanistic outcome experienced during ostomy surgery recovery. System E’s technology combines these benefits with the low profile, flexibility, simplicity, and ease of use of a one-piece pouching system, performance measures validated by Marquis et al as contributing to quality of life for individuals with an ostomy.1
Pouch wear times reported in this study are shorter than those reported in the US — characteristic of certain European countries where higher frequencies of ostomy product usage are reimbursed. In the US, an individual with an ostomy often reuses ostomy pouches, wearing them for up to approximately 5 days. This practice is considered unsanitary in Germany where the study was conducted; individuals with an ostomy discard used ostomy pouches and wafers. Effects of cultural differences and varying reimbursement regulations on such differences in ostomy care practice are worthy of future research.
Limitations
This type of study makes comparing ostomy appliances in a double-blind fashion virtually impossible. A technique for surmounting this limitation that was proven statistically powerful in the past8 is to use a prospective, randomized crossover design that allows patients and investigators to experience comparative pouching systems fully without sampling differences or selection bias. Another limitation is that only five investigators reported their Final Evaluation preferences — one of the six investigators had insufficient experience with one of the pouching systems to provide a representative response. Responses from five investigators were not enough to detect statistically significant differences, even though they unanimously preferred System E on comfort and flexibility.
The magnitude and consistency of the reported preferences for pouching System E were so pronounced that the clinical investigators asked to terminate the study before the intended finish date. Such consistent preferences for System E rendered study continuation of questionable clinical value to participants during the periods requiring them to use System F. Although this limited the number of observations recorded in the study, statistical power remained sufficient to uphold the conclusions regarding preferences reported by the participants.
Conclusion
This study confirms important differences between pouching systems and the importance of clinical studies to help differentiate between currently available ostomy products. The study design may help future researchers contribute to the field of ostomy research. The study results, methodology, and variables used to assess product acceptance and preference can be applied in clinical practice to aid in the selection of a pouching system.
Acknowledgment
The authors wish to thank Laura Bolton, PhD, and Geraldine Mayoros. Dr. Bolton served as US scientific/clinical manuscript facilitator. Ms. Mayoros is Dr. Bolton’s administrative assistant and helped prepare the manuscript.
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9. ConvaTec R&D Testing Laboratory Report Number A2-0089. To determine the minimum application force necessary to create a leak-free coupling. March 12, 2002. Data on file.
10. ConvaTec R&D Testing Laboratory Report Number A1-11CB19KJ03. To evaluate repeated coupling and uncoupling of the Esteem Synergy™ product. June 21, 2002. Data on file.
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