Post-operative urinary retention (POUR) anecdotally occurs in a significant proportion of male patients following inguinal hernia repair. This has a potentially detrimental effect on both patients and services, due to the need for urinary catheterisation and admission.
The international literature reports an extremely wide range (0.4%–41.6%) of rates of acute urinary retention following inguinal hernia repair [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]. Potential peri-operative risk factors postulated from a mixture of prospective and retrospective studies are the choice of a laparoscopic approach [8, 5], the use of spinal anaesthesia [11, 12], bilateral inguinal hernia repair [1, 2], increased duration of operative time , increased volume of perioperative fluids , use of specific anaesthetic agents , and increased use of narcotic analgesia . Contradictory evidence surrounds many proposed risk factors, however, with some authors finding no statistically significant correlation of POUR with open versus laparoscopic approach , with choice of anaesthesia , with performance of synchronous bilateral IH repair , or with volume of intra-operative fluids infused . Some studies have assessed patient related risk factors and identified increased BMI  and increased patient age [1, 2] as being associated with higher rates of POUR. Again, some dispute exists, notably surrounding whether or not an existing diagnosis of benign prostatic hyperplasia (BPH) increases the risk of POUR [1, 3].
Whilst urinary catheterisation may be considered a minor intervention, it is far from inconsequential. The need for insertion of a catheter can cause patients significant distress, prolong their hospital stay, restrict mobilisation  and risk complications. A recent prospective multi-centre trial assessing outcomes of short-term catheterisation of hospitalised patients (catheter indwelling for ≤3 days in 76%) found that one or more catheter-related complication were described by 57% (1184/2076) of patients at 30 day follow up . Catheter associated UTIs (CAUTIs) are amongst the most common hospital acquired infections reported globally [16, 17, 18, 19], have been described as the most common identifiable source of secondary blood-stream infection in the hospital setting , and are associated with the culture of rising numbers of resistant organisms . Common non-infectious complications of short-term urinary catheters include blockage, leakage and haematuria . More concerningly, accidental removal, urethral stricture or erosion (3.4%–16.7%)  and iatrogenic trauma during insertion (0.3–3%) [23, 24, 25] may occur, causing significant morbidity with potentially life-long consequences for the patient.
Furthermore, urinary retention following inguinal hernia repair has a significant impact on hospital services. Elective inguinal hernia repair is typically planned as a day-case procedure. The development of acute urinary retention in a patient mandates placement of a urinary catheter. This generally requires admission to hospital, with the alternative being catheter training with short-interval follow-up by specialist services. Undiagnosed or later evolving POUR may require Emergency Department attendance and/or admission in the early post-operative days. All scenarios pose a significant financial and logistical burden to hospital services. Post-operative urinary retention has been identified as the cause for unplanned admission in 20–25% of ambulatory general surgical procedures [26, 27]. Whilst there is a lack of published data on the economic impact of this in the context of individual health systems, it inevitably distorts the internationally anticipated 36–65% cost saving expected with performing hernia repair as day-case surgery . Should a complication of catheterisation occur, costs are greatly amplified; US evidence suggests that total costs incurred in the management of a catheter associated UTI exceed $1,000  and estimates of €3,846–€9,064 per patient for the management of iatrogenic urethral trauma in Ireland have been declared [30, 24].
Post-operative urinary retention following elective inguinal hernia repair may have a significant impact on patient morbidity and a high cost to healthcare services. Rates of POUR have not been formally evaluated in a global context, it is unclear what effect the surgical approach and choice of anaesthesia have on the incidence of POUR, and no risk stratification system is in place to preoperatively identify patients most likely to experience this complication.
Our hypothesis is that POUR is a significant complication of IH repair internationally, in both its incidence and its consequences. We propose that a prospective audit of this will assess the magnitude of the problem, and may identify patient and surgical factors increasing its incidence. Such findings would have potential to inform future research, which may explore ways to minimise and manage the complication of POUR in high-risk patient groups.
The definition of the primary endpoint is the rate of post-operative urinary retention (POUR) following elective inguinal hernia in male patients, where POUR is defined as the need for insertion of a urinary catheter as determined by the treating clinician.
Variables to be collected:
There is a significant need for better tools to measure what really matters to patients, increasingly recognised across surgical disciplines [32, 33]. A lack of standardised tools to measure patient reported outcomes limits research in this area. There is currently no validated tool specifically to record patient reported outcomes in inguinal hernia repair. This is particularly relevant in the context of the current focus on mesh use in inguinal hernia repair. Recruiting patients participating in part 1 of the RETAINER study to also be involved in development of a PROM for inguinal hernia repair presents an opportunity to develop and validate a meaningful tool for future research.
This study is designed to develop and evaluate the psychometric properties of a disease-specific PROM instrument for patients undergoing inguinal hernia repair. The evaluation and development of a disease-specific instrument will be carried out in accordance with current FDA guidelines for developing PRO measures, to ensure high quality and standardisation of the development of our PROM in inguinal hernia surgery [34, 35, 36, 37, 38].
The research design for RETAINER II is based on recommended guidelines and will be developed in three phases: 1) item generation; 2) pre-testing and 3) RETAINER II PROM evaluation.
Phase 1, Item Generation, will be developed by undertaking a systematic review and narrative analysis of health-related quality of life (HrQoL) outcomes literature relevant to patients with an inguinal hernia. Focus groups will be conducted with patients with an inguinal hernia to understand important relevant outcomes to patients. The information combined from the systematic review and qualitative interviews will produce a provisional conceptual framework. This will be scrutinised by the project steering group prior to finalising the conceptual framework.
Phase 2 of this project will be the development and pre-testing of the provisional RETAINER II questionnaire. Items (questions) will have been generated from the qualitative work carried out in phase 1. The aim of this phase is the refinement of the provisional RETAINER II tool, with review of the tool to ensure clarity and to achieve consensus, thus leading to the development of the pre-test version of the instrument. This provisional tool will be administered to a select number of patients with an inguinal hernia. Using cognitive interview techniques and the face validity score QQ-10 , the instrument will be refined by clarifying any ambiguities in item wording, reviewing the relevance and appropriateness of the question stem and response options, as well as the instruments time-frame. Based upon the responses gained, the provisional RETAINER II will be revised to produce a preliminary version ready for field testing.
Phase 3, a field test will be undertaken to evaluate the RETAINER II tool for reliability and validity using psychometric techniques from Classical Test Theory , to ensure rigour and scientific credibility.
An initial systematic review and narrative analysis will be undertaken to identify HrQoL issues relevant to patients with inguinal hernia, this will be used to identify themes and concepts to help inform the interview guide. Supplemental information using content analysis from five focus group consisting of 3–4 patients each will be used to develop a conceptual framework.
A traditional focus group will be used to identify issues important and relevant to patients with an inguinal hernia. The focus group will be guided by an interview guided generated from the systematic review to aid and stimulate discussion. Focus groups are an appropriate method for addressing a broad range of research questions across a variety of health-related domains. Focus group information is a reflection of the group dynamics and behaviour, with the advantage of memories and thoughts stimulated or prompted by comments made by other members of the group. The use of a focus group will enable data collection in an interactive manner.
A purposive sampling strategy will be employed to ensure all relevant patient and clinical characteristics have been captured to ensure generalisability of the findings to a wider population.
Patients will be excluded from the study in any of the following criteria apply. They:
The focus group recordings will be transcribed verbatim, with clear indication of pauses, emphasised words, expressions of emotion and unintelligible speech. Conversational norms such as interruptions and overlapping speech will be preserved. All transcripts will be reviewed by the focus group facilitator for accuracy and clarification of ambiguities.
Using the principles of content analysis, transcript data obtained from the focus group will be analysed to identify themes and codes. A combined approach will be used, using inductive methods to identify new categories arising from the transcripts and deductive methods to build on the categories identified by current literature.
The information combined from the systematic review and focus group will produce a conceptual framework. This conceptual framework will be scrutinised and refined by the study steering group.
The purpose of this phase is to reach consensus regarding the questionnaire format and structure to confirm that instructions and items are clear, understandable, relevant, and applicable. Face validity of the questionnaire will be assessed using the QQ-10 .
Patients fulfilling the eligibility criteria in for RETAINER II will be eligible to participate.
A pre-test questionnaire will be developed based on the conceptual framework devised in Phase I. Items from existing question banks will be mapped to the conceptual framework to devise a questionnaire. The pre-test questionnaire will be tested with a sample of patients. It is estimated that approximately 20–30 patients will be needed to reach saturation, with no new issues arising. A postal questionnaire will be administered to patients to self-complete. The pack will contain the RETAINER II questionnaire and the QQ-10 questionnaire.
Quantitative assessment of face validity of the measure will be undertaken using the QQ-10. This is a validated measure to assess the face validity, feasibility and utility of instruments designed to assess HrQoL.
Data collected will relate to feedback on participants understanding of each question and associated response category and instructions, and to verbalise how patients produced answers, with emphasis on memory retrieval and subsequent judgements and decision making. The QQ-10 consists of 10 quantitative questions scored on a Likert scale and 3 qualitative questions covering the domains of value and burden of questionnaire completion.
Review and analysis of information collected from cognitive interviews will be conducted as soon as possible after the interview, but as a minimum after every 3 interviews. This will enable any major flaws in the provisional questionnaire to be identified and revised before subsequent pre-testing with the revised version. This method of multiple rounds of pre-testing will determine whether the problem identified has been rectified and to ensure no new problems have been introduced.
The data from the QQ-10 questionnaire will be analysed both quantitatively and qualitatively. For quantitative analysis we used the QQ-10 scoring method. Likert ratings from strongly disagree to strongly agree (coded as 0–4) will be summed up separately for the first six questions comprising the value score (‘helped me communicate about my condition’, ‘relevant to my condition’, ‘easy to complete’, ‘included all the aspects of my condition I am concerned about, was enjoyable, would be happy to complete as part of routine care), and from the last four questions comprising the burden score (too long, embarrassing, complicated, upset me). Qualitative thematic analysis will be performed on comments received in response to the three free-text questions at the end of the QQ-10.
A postal questionnaire pack will be administered to patients to self-complete. The pack will include the RETAINER II tool, as well as additional measures selected for validation purposes. A select group of patients who have completed the baseline questionnaire, will have a second (re-test) questionnaire pack after initial questionnaire completion.
Patients fulfilling the eligibility criteria in for RETAINER II will be eligible to participate.
An approximate sample of 50–100 patients will be purposively sampled ensuring representation of all subgroups. There is no formal sample size calculation for the development of PRO measures, however, recommended guidelines state 5–10 patients should recruited per item within the questionnaire . We are aiming to develop a PRO measure with a maximum of 10 items, therefore our sample size is deemed to be sufficient. Consecutive patients will be identified and approached to participate. Qualitative analysis, using NVIVO 12 for Windows (QSR International Pty Ltd., Australia) will be performed independently (by NOSTRA and ISRC collaborative members D Harji and CA Fleming).
A test-retest will be undertaken with a sub-sample of participants recruited for the final field test. Consenting participants will complete a second questionnaire pack 5–7 days after the first questionnaire pack (approximately 50 patients). The length of the test-retest interval must be short enough to ensure that clinical change is unlikely to occur, but sufficiently long to ensure that participants do not recall their responses from their first assessment. A short test retest interval is necessary to ensure stability is being evaluated, and not clinical change, which will underestimate reliability.
Local collaborators will identify eligible patients. A record of those identified as eligible, approached to participate, refusals, consenting patients and questionnaires returned will be made. The recruitment and consent methods described in the preliminary field test will be used. Additionally, the Patient Information Leaflet will allow participants an option of completing second questionnaire 5–10 days later. For patients who have agreed to a second questionnaire, a second questionnaire booklet will be sent to their home address with a self-addressed envelope. Stamped, self-addressed envelopes will be provided for the patients to return completed questionnaires to their local hospital.
Study data will be recorded by members of the clinical teams and by patients on questionnaire packs. Data will be returned to the research office at RCSI.
Assessments will be undertaken as follows:
Baseline information will be recorded by:
The baseline questionnaire pack will include:
Prior to assessing the proposed scale structure of the RETAINER II the completeness of the data must be analysed to identify missing data at the item and scale level, distribution of responses and floor/ceiling effects and descriptive analyses of item items. Data completeness concerns the extent to which items are completed by the target population and the total number of available data sets from which total scores are computable. The criteria for acceptable levels of missing data is <10%, for computable total scores >50% and for maximum endorsement frequencies is <80% (floor/ceiling effects <80%).
Multi-trait scaling will be used to determine whether the items of the RETAINER II will fit in with the proposed scale structure. The grouping of items into subscales and scales and the calculation of summated scores is based on four scaling assumptions:
If the first and second criteria are fulfilled the current grouping of items is supported. If the third and fourth criteria are fulfilled the items can be summed without weighting; if not, weighting is normally suggested to achieve equal item-to-total correlations and equal variances [38, 45, 46, 47]. Multitrait scaling will include analysing item frequencies, item and scale descriptive statistics including mean, standard deviation and variance, estimates of scale internal consistency, item intercorrelations and item-to-total correlations.
Item internal consistency is determined by analysing the correlations between all items within a scale (item intercorrelations) and correlations between each item and the total scale (item-to-total correlations). Item intercorrelations indicate the extent to which the items are related. The recommended mean item-intercorrelation for a scale should exceed 0.30. However, items that are highly correlated may indicate redundancy, therefore it is recommended that item intercorrelations exceeding 0.70 should be removed. Item-to-total correlations indicate the strength of the relationship between individual items and the construct being measured and should exceed 0.3, this is also known as Item Convergent Validity.
Item discriminant validity gauges the extent to which items correlate more highly with the concept they are hypothesised to represent than with other concept. Item discriminant validity is supported and a scaling success declared when the item-to-total correlations for an item and its hypothesised scale is more than two standard errors higher than its correlations with another scale [38, 45, 46]. Item discriminant validity is also supported when item-scale correlations of <0.4 between an item and other scales in the questionnaire are observed.
Items can be summed without weighting to generate scores when they are substantially linearly related to the total score computed from all items in that group; measure at similar points on the scale, contribute equally to the total score variance and contribute equal proportions of information to the total score. These four criteria are satisfied when the items are internally consistent, have similar mean scores, variances and item-total correlations. However, when item-total correlations exceed the 0.30 criterion, the criteria of equivalent item means, variances and item-total correlations are considered satisfactory.
Following revision and finalisation of the scale structure of the LRRC-QoL tests of reliability and validity of the scales will be undertaken.
Reliability is the degree to which the questionnaire is free from random error. This is measured by the internal consistency of a scale and reproducibility of the questionnaire using the test-retest measure. Internal consistency measures the homogeneity of a scale ensuring all items are sufficiently similar, thus ensuring scale reliability using alpha coefficients (Cronbach’s Alpha). Cronbach’s Alpha indicates the extent to which items in a scale are interrelated by comparing the variance of the total score to the sum of the variances of the individual items. As the correlations between the items increase, the variance for the total score increases and alpha coefficients approximate unity. Internal consistency is considered to be good when Cronbach’s alpha co-efficient exceeds 0.70.
The test-retest measure assesses the stability of the questionnaire over a period of time during which the patients clinical state remains stable. The Intraclass coefficient (ICC) is used to measure the strength of agreement between repeated measures, by assessing the proportion of total variance of an observation that is associated with the between patient variability. If the ICC is large this suggests the random variability is low and a high proportion of the variance is attributable to the variation between patients. The measurements are thus described to have high reliability. Conversely, if the ICC is low, the random error variability dominates and the measurements have low reliability. A ICC score of 0.7 is recommended to ensure good test-retest reliability. The ICC will be calculated using a fixed-effects analysis of variance (ANOVA) model.
Convergent validity reflects the correlation between individual assessment tools measuring the same phenomenon. Pearson’s product moment correlation will be used to analyse correlation between items and scales of RETAINER II, and HERQL, CCS and EuraHS-QoL questionnaires. Pearson’s values of greater than 0.4 are considered to be highly correlated. It is hypothesised that the scales in the RETAINER II questionnaire will not correlate with the HERQL, CCS and EuraHS-QoL unless they address similar themes.
The method of known-groups comparison will be used to assess the ability of the RETAINER II to distinguish between patients differing in clinical status. The clinical parameter hypothesised to form mutually exclusive patients for subgroup comparison included hernia type (primary and recurrent), hernia location (unilateral and bilateral) and surgical approach (open or laparoscopic). The independent student t-test will be used to examine differences in mean scores in 2 groups and the one-way analysis of variance (ANOVA) for more than 2 groups.
The following definitions will be used for this study:
The authors have no competing interests to declare.
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