Development and Content Validation of the Insulin Pump Infusion Sets Satisfaction Scale (IPISS): A Self-Reported Questionnaire for Patients with Type 1 Diabetes and Caregivers

Abstract

Background: Patient satisfaction with diabetes technology is increasingly recognized as a key factor in therapeutic success. Patient-reported outcomes (PROs) are gaining importance in diabetes care and in the evaluation of advanced insulin delivery systems. Objectives: This study aimed to design and validate a new questionnaire, the Insulin Pump Infusion Sets Satisfaction Scale (IPISS), to assess satisfaction with insulin infusion sets among individuals with type 1 diabetes. Methods: The questionnaire was developed by our Diabetology Unit in two versions: one for patient self-reporting and one for caregivers when the patient is too young to complete it autonomously. Content validity was assessed by six healthcare professionals (three diabetologists and three nurses) based on Polit and Beck’s methodology. The Item Content Validity Index (I-CVI) was calculated for both relevance and comprehensibility and was considered satisfactory if expert agreement reached ≥83%. The Scale Content Validity Index (S-CVI) was computed as the average of I-CVIs, with a cut-off value > 90% deemed acceptable. Results: Almost all items achieved 100% positive agreement for both relevance and comprehensibility, except one item in the caregiver version, for which one rater did not provide a rating for comprehensibility (I-CVI = 83.3%). The S-CVI was 100% for relevance in both versions, 99.24% for comprehensibility in the caregiver version, and 100% in the patient version. Conclusions: The IPISS is a content-validated, self-reported tool, suitable for evaluating satisfaction with infusion sets in individuals using insulin pumps, with versions adapted for both patients and caregivers.

1. Introduction

Over the past two decades, the management of type 1 diabetes (T1D) has undergone a substantial technological transformation. Continuous subcutaneous insulin infusion (CSII) and continuous glucose monitoring (CGM) systems have become integral to modern diabetes care, significantly improving glycemic control and quality of life, especially among pediatric and adolescent populations [1,2,3,4,5]. Automated insulin delivery (AID) systems have further advanced the field by enhancing time-in-range and reducing hypoglycemia risk [6].

However, while algorithmic and sensor advancements have been central to recent progress, the success of these technologies relies also on the functionality and usability of each component of the system. Among them, the infusion set plays a critical role: serving as the interface between the device and the body, infusion sets are responsible for insulin delivery and are directly linked to patient comfort, therapeutic adherence, and safety [7,8,9].

Infusion set-related complications, including occlusions, kinking, catheter blockage, adhesive failures, skin irritation, and lipohypertrophy, are frequently reported in clinical practice [5,7,8,9,10]. In a large international survey of 14,015 CSII users, approximately 42% reported infusion site complications such as skin irritation and adhesive failures [11]. One Polish study using ultrasonography found lipohypertrophy in 94.9% of CSII users, compared to 49.4% detected by clinical examination [12], whereas two recent meta-analyses estimated lipohypertrophy prevalence to be 40% among T1D patients, with improper site rotation emerging as a significant risk factor [13,14]. These complications are frequently associated with hyperglycemia, premature infusion set failure, and reduced patient satisfaction [10].

The subcutaneous tissue response to infusion sets is also a growing concern. Both Teflon and steel cannulae may provoke inflammatory reactions, itchiness, redness, and scarring, with up to 90% of pediatric pump users reporting dermatological complications, including pruritus, skin lesions, or eczema [15]. Medical adhesives used to secure infusion sets may also trigger allergic or irritative reactions to materials such as colophonium, epoxy resins, or acrylates [16,17,18].

Patient-Reported Outcomes (PROs) Relevance

PROs have become essential in diabetes research and clinical practice, as they provide direct insight into individuals’ experiences, preferences, and treatment satisfaction. Regulatory bodies, such as the FDA, increasingly emphasize the inclusion of PROs in the evaluation of medical devices [19]. However, while several validated instruments exist to assess insulin pump-related quality of life [20], infusion sets are rarely evaluated as standalone elements in clinical studies or patient satisfaction surveys despite their clinical relevance.

Existing validated tools, including the Insulin Treatment Satisfaction Questionnaire (ITSQ) [21], the Insulin Delivery System Rating Questionnaire (IDSRQ) [22], and the Insulin Device Satisfaction Survey (IDSS) [23], assess broader aspects of insulin devices such as glycemic control, ease of use, or emotional burden, but do not specifically dissect infusion set satisfaction. Similarly, the INSPIRE questionnaire developed for AID systems covers expectations and overall device experience without focusing on infusion sets [24].

To address this gap, we developed the Insulin Pump Infusion Sets Satisfaction Scale (IPISS), a structured, self-administered questionnaire designed specifically to assess satisfaction and experience with infusion sets among individuals with T1D. This paper presents the development, expert-based content validation, and structure of the IPISS questionnaire.

2. Materials and Methods

2.1. Questionnaire Design

The IPISS questionnaire was developed by our Diabetes Research Group to assess user satisfaction with insulin pump infusion sets in individuals with T1D. The questionnaire was designed to capture a comprehensive overview of the user experience, ranging from practical aspects of set use to subjective satisfaction and adverse events.

Two versions of the questionnaire were developed:

• A patient self-report version, intended for patients aged 12 years or older, considered able to complete the questionnaire independently.
• A caregiver version, to be completed by parents or caregivers when the patient is under 12 years of age or not capable of reliable self-reporting.

Both versions include a similar structure and item content, with adjustments in phrasing and perspective (first person vs. third person) to suit the respondent. The IPISS questionnaire is composed of six thematic sections, each targeting a specific area of relevance to infusion set use. These sections are summarized in

Table 1. Summary of Thematic Areas Covered by the IPISS Questionnaire.

Section	Description of Thematic Area
1. Demographics and Usage	Age group, type of infusion set used, and preferred insertion sites
2. Infusion Set Management	Frequency and duration of set changes, and level of autonomy in managing set changes
3. Problems and Complications	Difficulties encountered during set use, including pain, discomfort, and insertion ease
4. Skin Reactions	Occurrence, type, and timing of dermatological reactions related to set use
5. Adhesion and Glycemic Impact	Frequency of early set changes due to adhesive failure, hyperglycemia, leakage, or bleeding
6. Global Satisfaction	Overall satisfaction score and open comments on set performance and user experience

.

Items are predominantly close-ended, with either multiple-choice formats or numerical rating scales (e.g., 1–10). This structure allows for both quantitative analysis and user-friendly completion.

The questionnaire was originally developed and validated in Italian (full version available in Supplementary Table S1), while a non-validated English translation is provided in

Table 2. Non-validated English version of the Insulin Pump Infusion Sets Satisfaction Scale.

Introduction	This questionnaire aims to collect the experience and satisfaction of patients or parents/caregivers with insulin infusion sets, the devices that connect the pump to the body through a small cannula inserted under the skin.
Question	Possible Answers
0. How old is the patient?	Under 12 years 12 years or older If the patient is under 12 years old, the CAREGIVER completes the questionnaire. If the patient is 12 years or older, the PATIENT completes the questionnaire.
Caregiver questionnaire
1. Which infusion set does the patient use?	Medtronic 7-day set (Medtronic Extended®) Medtronic 3-day set (MiniMed Mio Advance®) Tandem with angled insertion (Autosoft 30®) Tandem with vertical insertion (Autosoft 90®) Ypsopump Orbit® Omnipod®
2. What is the patient’s most frequently used placement * site? * insertion on skin	Arm Abdomen Buttocks Thigh
3. If multiple insertion sites are used, which others? (multiple answers allowed)	Arm Abdomen Buttocks Thigh
4. How often is the infusion set usually changed?	Every 1–2 days Every 3 days Every 4 days Every 5–6 days Every 7 days More than 7 days
5. How much time is usually needed to change the set?	1–5 min 5–10 min 10–15 min 15–20 min More than 20 min
6. Does the patient change the set independently?	Entirely independently With help from another person Entirely by another person
7. How often are there problems during set change requiring a new set within 24 h?	Never Less than once a month 1–3 times a month Once a week Several times a week
8. How easy is it to place * the infusion set? * insert on skin	Visual scale from 1 (very difficult) to 10 (very easy)
9. How painful is the infusion set placement * for the patient? * insertion on skin	Visual scale from 1 (no pain) to 10 (very painful)
10. How uncomfortable is the set once in place *? * once inserted on skin	Visual scale from 1 (no discomfort) to 10 (very uncomfortable)
11. Has the infusion set ever caused a skin reaction in the patient?	Yes No If Yes, continue to questions 11a, 11b, 11c. If No, go to question 12.
11a. What type of skin reaction? (multiple answers allowed)	Itching Redness Swelling Infection Burning Scarring Other: _______
11b. How often does the skin reaction occur?	Less than once a month Once a month 2–3 times a month Once a week Every 2–3 days
11c. When is the reaction noticed?	While the set is in place * After removing the set * inserted on skin
12. How often do you need to replace the infusion set before its intended replacement time due to a skin reaction?	Never Less than once a month More than once a month but less than once a week Once a week Several times a week
13. How often do you need to replace the infusion set before its intended replacement time due to poor adhesive retention?	Never Less than once a month More than once a month but less than once a week Once a week Several times a week
14. How often do you need to use extra adhesive products to keep the infusion set attached to the skin?	Never Less than once a month More than once a month but less than once a week Once a week Several times a week
15. How often do you need to replace the infusion set before its intended replacement time due to unexplained persistent hyperglycemia *? * high blood glucose for a long time without knowing why	Never Less than once a month More than once a month but less than once a week Once a week Several times a week
16. How often do you need to replace the infusion set before its intended replacement time due to insulin leakage/loss?	Never Less than once a month More than once a month but less than once a week Once a week Several times a week
17. How often do you need to replace the infusion set before its intended replacement time due to bleeding?	Never Less than once a month More than once a month but less than once a week Once a week Several times a week
18. Overall, how satisfied are you with the infusion set used?	Visual scale from 1 (not at all satisfied) to 10 (very satisfied)
19. Additional comments on the infusion set	Free text
Patient questionnaire
1. Which infusion set do you use?	Medtronic 7-day set (Medtronic Extended®) Medtronic 3-day set (MiniMed Mio Advance®) Tandem with angled insertion (Autosoft 30®) Tandem with vertical insertion (Autosoft 90®) Ypsopump Orbit® Omnipod®
2. What is your most frequently used placement * site? * insertion on skin	Arm Abdomen Buttocks Thigh
3. If you use multiple sites, which others? (multiple answers allowed)	Arm Abdomen Buttocks Thigh
4. How often do you usually change the infusion set?	Every 1–2 days Every 3 days Every 4 days Every 5–6 days Every 7 days More than 7 days
5. How long does a set change usually take?	1–5 min 5–10 min 10–15 min 15–20 min More than 20 min
6. Do you change the set by yourself or with someone’s help?	I do it completely on my own I do it with help It is done completely by someone else
7. How often do you have problems that require changing the set within 24 h?	Never Less than once a month 1–3 times a month Once a week Several times a week
8. How easy is it to place * the infusion set? * insert on skin	Visual scale from 1 (very difficult) to 10 (very easy)
9. How painful is the infusion set placement * for you? * insertion on skin	Visual scale from 1 (no pain) to 10 (very painful)
10. How uncomfortable is the set once in place *? * once inserted on skin	Visual scale from 1 (no discomfort) to 10 (very uncomfortable)
11. Has the infusion set ever caused a skin reaction for you?	Yes No If Yes, continue to questions 11a, 11b, 11c. If No, go to question 12.
11a. What kind of skin reaction? (multiple answers allowed)	Itching Redness Swelling Infection Burning Scarring Other: _______
11b. How often does the skin reaction happen?	Less than once a month Once a month 2–3 times a month Once a week Every 2–3 days
11c. When do you notice the skin reaction?	While the set is in place * After removing the set * inserted on skin
12. How often do you need to replace the infusion set before its intended replacement time due to a skin reaction?	Never Less than once a month More than once a month but less than once a week Once a week Several times a week
13. How often do you need to replace the infusion set before its intended replacement time due to poor adhesive retention?	Never Less than once a month More than once a month but less than once a week Once a week Several times a week
14. How often do you need to use extra adhesive products to keep the infusion set attached to the skin?	Never Less than once a month More than once a month but less than once a week Once a week Several times a week
15. How often do you need to replace the infusion set before its intended replacement time due to unexplained persistent hyperglycemia *? * high blood glucose for a long time without knowing why	Never Less than once a month More than once a month but less than once a week Once a week Several times a week
16. How often do you need to replace the infusion set before its intended replacement time due to insulin leakage/loss?	Never Less than once a month More than once a month but less than once a week Once a week Several times a week
17. How often do you need to replace the infusion set before its intended replacement time due to bleeding?	Never Less than once a month More than once a month but less than once a week Once a week Several times a week
18. Overall, how satisfied are you with the infusion set you use?	Visual scale from 1 (not at all satisfied) to 10 (very satisfied)
19. Additional comments on the infusion set	Free text

for reference purposes.

2.2. Content Validation Procedure

To ensure robust content validity, a two-round expert evaluation process was conducted based on the framework proposed by Polit and Beck [25].

A panel of six professionals with extensive experience in diabetes care—three diabetologists and three diabetes-specialized nurses—was recruited to evaluate both versions of the IPISS questionnaire (patient and caregiver). Each expert independently assessed every item for relevance and comprehensibility, using a 4-point Likert scale:

• Not relevant/not clear;
• Somewhat relevant/somewhat clear;
• Quite relevant/clear;
• Highly relevant/very clear.

A scale not including the ambivalent middle rating was adopted in order to facilitate the estimate of a meaningful CVI [25,26]. Ratings of 3 or 4 were considered positive, and the Item Content Validity Index (I-CVI) was calculated as the proportion of experts assigning a positive rating to each item. An I-CVI ≥ 0.83 (i.e., allowing for at most one negative rating) was considered acceptable for a six-member panel, corresponding to the proportion of expert whose positive judgements was required to obtain a statistically significant estimate at the traditional 0.05 threshold for the type I error [26]. The Scale Content Validity Index (S-CVI) was computed as the average I-CVI across all items, with values > 0.90 indicating adequate scale-level validity [25].

In the first round, experts evaluated the initial versions of the questionnaires and provided both quantitative scores and qualitative suggestions. Based on their feedback, some items were revised to improve clarity, simplify language, and eliminate ambiguities.

The revised versions were then resubmitted to the same expert panel for a second round of validation, during which all modified items were re-evaluated. Final I-CVI and S-CVI values were calculated based on this second round.

2.3. Face Validity Evaluation

Face validity was evaluated administering the content-validated questionnaire to a convenience sample of the target population, which included eight patients and eight parents. Participants were asked to provide their judgment about relevance and comprehensibility of the questionnaire using the same approach adopted for the content validity, in line with recommended practices for scale development [27].

3. Results

3.1. Content Validity

3.1.1. First Round of Evaluation

In the first round, the initial versions of both the patient and caregiver questionnaires were independently assessed by all six experts.

While most items received uniformly positive ratings, a few were flagged for potential ambiguity or overly technical phrasing.

Based on expert suggestions, several refinements were introduced to improve the structure and wording of the questionnaire without altering its conceptual content. In particular:

• A copyright symbol (^®) was added to each branded infusion set name (e.g., Medtronic Extended^®, Autosoft 30^®).
• The order of the questions was revised to enhance thematic continuity: the original item 17 (on skin reactions) was moved to position 12 to be grouped with related items.
• Minor spelling and formatting corrections were applied to improve consistency.

3.1.2. Second Round of Evaluation

The revised questionnaires were then resubmitted to the same panel of experts for a second round of validation. In this phase, all modified items received uniformly positive ratings from the six evaluators, confirming the effectiveness of the refinements.

The I-CVI reached 100% for all items in the patient version, for both relevance and comprehensibility.

In the caregiver version, all items also reached 100% agreement, with the exception of one item (item 7) for which one expert did not provide a positive rating for comprehensibility. This resulted in an I-CVI of 0.833.

3.1.3. Scale-Level Validity

Following the second round of expert review, the S-CVI for relevance reached 100% for both versions. As for comprehensibility, the patient version also achieved an S-CVI of 100%. In the caregiver version, the S-CVI for comprehensibility was slightly lower, reaching 99.24%. CVIs for both versions are shown in

Table 3. Content Validity Indices (I-CVI and S-CVI) for the relevance of IPISS Questionnaire.

Version	Round	I-CVI (Min)	I-CVI (Max)	Items with I-CVI < 0.833	S-CVI
Patient	Round 1	0.83	1.00	1	0.9924
Caregiver	Round 1	0.83	1.00	1	0.9924
Patient	Round 2	1.00	1.00	0	1.00
Caregiver	Round 2	1.00	1.00	0	1.00

for the relevance and in

Table 4. Content Validity Indices (I-CVI and S-CVI) for the comprehensibility of IPISS Questionnaire.

Version	Round	I-CVI (Min)	I-CVI (Max)	Items with I-CVI < 0.833	S-CVI
Patient	Round 1	0.83	1.00	1	0.9924
Caregiver	Round 1	0.83	1.00	2	0.9848
Patient	Round 2	1.00	1.00	0	1.00
Caregiver	Round 2	0.833	1.00	1	0.9924

for the comprehensibility.

3.2. Face Validity

Out of the 22 items included in each version of the questionnaire, 77% of caregiver items (17/22) and 86% of patient items (19/22) were rated positively for comprehensibility, while the remaining items were judged unclear by at least two raters. Similarly, most items were considered relevant (73% in the caregiver version and 55% in the patient version), with negative judgments assigned only to a minority of items.

In both questionnaires, a negative judgment for the relevance was often expressed for the same items that received a negative rate for the comprehensibility. Closer examination showed that difficulties were mainly associated with specific terms such as “in sede” (“in place”) and “posizionamento/posizionare” (“placement”), which were perceived as ambiguous by both patients and caregivers. To improve clarity, synonymous or explanatory notes were added without altering the original wording of the items. In addition, a brief introductory statement was incorporated at the beginning of the questionnaire to clarify what is meant by “infusion set,” thereby reducing the risk of misinterpretation.

A detailed overview of all modifications, including cumulative changes made after the two rounds of expert content validation and the final face validation round with patients and parents, is provided in Supplementary Table S2.

4. Discussion

This study describes the development and Italian content validation of the IPISS, a novel self-report instrument specifically designed to assess satisfaction with insulin infusion sets in individuals with T1D.

While infusion sets are essential components of insulin pump therapy, their practical and psychological impact is rarely evaluated in routine care, despite being frequent sources of technical issues, discomfort, and user dissatisfaction. Most validated instruments, such as the Insulin Pump Attitudes Questionnaire (IPA) [28] and the IDSRQ [22], address attitudes toward insulin pumps in general—focusing on factors like glycemic control, ease of use, device functionality, and treatment burden. Broader surveys like the IDSS [23], the ITSQ [21], and the INSPIRE scales [24] include device-related satisfaction or expectations as a domain but do not dissect specific components such as infusion sets. By contrast, the IPISS addresses this gap by offering a structured, infusion-set–focused tool that examines both practical usage (e.g., frequency of changes, insertion ease, complications) and experiential aspects (e.g., comfort, skin reactions, device satisfaction).

The development process followed a rigorous two-step content validation procedure, ensuring iterative refinement of the items and maximizing both relevance and clarity across all content domains. The resulting scale demonstrated excellent content validity indices, with all final I-CVI values ≥ 0.83 and S-CVI values well above the 0.90 threshold for both versions of the questionnaire.

To complement this, a subsequent round of face validity was conducted with a small group of patients and parents, aimed at further assessing comprehensibility and relevance from the perspective of end-users. While most items were judged positively, a few terms (e.g., “placement”, “in place”) were perceived as unclear and were therefore clarified with a synonymous or by adding brief explanatory notes. This strategy allowed us to preserve the original wording—previously approved by experts—while improving the accessibility of the items for patients and caregivers. According to DeVellis [29], we have decided to preserve the content structure of the questionnaire considering judgments on item relevance provided by the target population less pertinent than those expressed by the pool of experts.

The dual-format design of the IPISS enhances its applicability in pediatric and adolescent diabetes care. The thematic structure, covering six key areas (summarized in Table 1), offers a comprehensive yet user-friendly tool suitable for clinical practice and research purposes.

Some limitations should be acknowledged. The content validation process was conducted with a panel of six experts, which may appear relatively small in number. However, the group encompassed a high level of professional diversity and experience, including a senior diabetologist with over 40 years of practice, two endocrinologists and three diabetes-care nurses trained in advanced insulin delivery systems. This multidisciplinary composition strengthens the reliability and clinical relevance of the judgments expressed. Moreover, the panel size aligns with established methodological standards: Lynn [26], as cited by Polit & Beck [25], recommends a minimum of three and a maximum of ten experts, while Boateng et al. [27] suggest that 5–7 experts are generally sufficient for content validation in health research. Accordingly, our six-member panel can be considered both appropriate and methodologically sound for the purposes of this validation study.

Nevertheless, the IPISS demonstrates strong content validity and represents a promising instrument for capturing patient- and caregiver-reported satisfaction with insulin infusion sets. Although the present study focused on content validity, further psychometric evaluation of the IPISS is warranted. In particular, we plan to assess the reliability of IPISS by estimating the internal consistency of the items and evaluating the test–retest reliability in a large patients’ cohort. The responsiveness to change will also be assessed. Construct validity will be performed, including the evaluation of the dimensionality of the scale. Finally, a stratification of the IPISS score into three or four levels will also be performed applying an unsupervised clustering approach.

Another important step for the future development of the IPISS after its complete validation will be its translation into English and, hopefully, into other languages, followed by formal cross-cultural validation.

5. Conclusions

To our knowledge, the IPISS is the first questionnaire specifically developed to evaluate satisfaction with insulin pump infusion sets in patients with T1D. It has demonstrated strong content validity through expert review and is available in two parallel versions for patients and caregivers. While further psychometric evaluation is warranted, the IPISS represents a promising tool for both clinical research and practice in the field of diabetes technology.