Devising a New PROM

We devised a new questionnaire, the Patient Perception of Prolapse Condition (PPPC), based on adaptation of the PPBC. The PPPC is a single-question, six-point global scale in which patients rate their current impression of their prolapse (Fig. 1). Patients are asked to describe their prolapse on a six-point scale ranging from 1, corresponding to “does not cause me any problems at all” to 6, which corresponds to “causes me severe problems”.

Fig. 1

Patient Perception of Prolapse Condition questionnaire

Content Validity

To ensure content validity the pilot PROM was developed within the urogynaecology multidisciplinary environment of a tertiary referral centre. This was assessed by a lay person in order to ensure ease of reading and understandability. The pilot PROM was then assessed via interviews with 20 patients who had agreed to provide feedback; these patients were recruited from the urogynaecology outpatient clinic. The questions were then modified following the feedback provided, which mostly related to ease of understanding, and a final draft created. The questionnaires were ratified once more by the urogynaecology multidisciplinary team prior to distribution.

Determining the Mode of Administration

The mode of administration of the PROM is important, as changing the mode may lead to a variation in the responses. It has been suggested that intimate questions might better completed when self-administered rather than interviewer administered as the patient may not feel able to express her true thoughts out loud to the interviewer [1]. Also, as our PROM is to assess the bother caused by prolapse at any stage in the patient’s care, i.e. before or after interventions, the patient may feel obliged to show appreciation for the efforts made by the clinician to treat her and not provide a true response. There is also the risk of the interviewer leading the patient by the wording of their questions during completion of the PROM, or even through unintended intonation of their voice. As such, it was decided that the PROM would be self-administered.

The mode of self-administration was also taken into account. A questionnaire that is completed with a pen and paper may theoretically elicit different responses when the same questionnaire is administered via a screen and mouse or touchscreen device [8]. The initial thought was to create an electronic PROM; however, assessing the demographics of our patient population and our decision that it would best be self-administered, we deemed that an electronic PROM would exclude a section of our population. As such, the questionnaire would be conducted via pen and paper.

Formal Validation

As this was a novel questionnaire, the validity of the original questionnaire (PPBC) did not apply. To ensure that the information gained via this PROM was clinically useful, the PPPC needed to be validated in women with POP.

The International Consultation on Incontinence (ICI) states that the development of a PROM requires a multistep, structured process, with studies that demonstrate the measure's validity, reliability and responsiveness [1]. To validate the PPPC questionnaire, we needed to evaluate criterion validity, test/re-test reliability and its responsiveness. The psychometric validation of PROMs is described within the literature [9]. The ICI was utilised as a manual to conduct the validation of the PPPC and the definitions used are from those guidelines.

Validity refers to the ability of an instrument to measure what it is intended to measure.

Criterion validity reflects the correlation between the new questionnaire, PPPC and an accepted reference, or gold standard [1]. In this regard, we decided to assess the criterion validity looking at both subjective and objective measures. For the subjective measure we utilised the Prolapse Quality of Life (P-QOL) and for the objective criterion validity we utilised detailed examination of prolapse by the Pelvic Organ Prolapse Quantification (POP-Q) ordinal staging system. When criterion validity is to be established using an existing measure, the correlation, assessed using Spearman’s rank correlation should be 0.40 to 0.70 [10]. It has been stated that correlations approaching 1.0 indicate that the new questionnaire is too similar to the gold standard and as such is not required.

Reliability or test–retest reliability is defined as the ability of a PROM to produce similar results when undertaken under the same circumstances repeatedly. To assess test–retest reliability, the same patient completes the questionnaire more than once, at baseline and again after a period of time during which the impact of the symptoms is unlikely to change (e.g. a few days or weeks) [11]. Cronbach’s alpha is used to demonstrate reproducibility and α between 0.7 and 0.9 is considered “good”, whereas α greater than 0.9 is considered “excellent” [1].

Responsiveness indicates whether the measure can detect change (improvement or deterioration) in a patient's condition. To assess this the patients are utilised as their own controls and the PROM conducted once more after undergoing an intervention.

To undertake validation of the PPPC a prospective case-controlled study was conducted. Women were recruited from a tertiary urogynaecology clinic over an 8-month period. All women over the age of 18 years, literate in English, presenting with urogynaecological symptoms and able to provide informed written consent were invited to participate. There were no exclusion criteria.

At visit 1, prior to seeing a clinician for history and assessment, the patients referred for prolapse concerns completed the P-QOL and PPPC questionnaires. During the assessment they underwent a POP-Q examination in both the lying and the standing position at maximum Valsalva. The most severe extent of their prolapse was recorded. This enabled assessment of criterion validity comparing PPPC with P-QOL for subjective assessment, whereas objective assessment was conducted comparing the PPPC with the POP-Q. As the scores did not follow a normal distribution, criterion validity was assessed using Spearman’s rank correlation (rho) of the PPPC against the validated subjective and objective outcomes.

At visit 2, between the next 4 to 8 weeks, the PPPC was repeated to assess test/re-test reliability using Cronbach's-alpha (α).

Some of the women went on to undergo surgery for POP. In those undergoing pelvic floor surgery, the responsiveness of the PPPC was assessed at visit 3 by correlating PPPC and P-QOL scores 6 weeks post-operatively.

Statistical analysis was carried out using MedCalc Statistical Software version 12.7.8.