Background

The EHP is the only condition-specific PRO designed from the patient’s perspective to assess health related quality of life in endometriosis. The EHP is available in various formats to suit users study requirements, the long-form core instrument, the EHP-30, the short-form core EHP-5 and a selection of 6 modules that can be used alongside the core instrument.

Published evidence concludes that the EHP is a reliable and valid instrument for assessing areas of concern to women with endometriosis that are not addressed by other condition-specific and generic questionnaires.

The EHP is particularly appropriate for use in clinical trials to assess the effectiveness of medical or surgical therapies for endometriosis on the HRQoL of affected women. For this reason the EHP has been used by four of the top twenty global pharmaceutical companies, supporting numerous clinical trials.

EHP-30 and 6 Modular PROs

The EHP consists of a core instrument, available as either a long-form 30 item instrument (the EHP-30), or the short-form (EHP-5) PRO.

The core instruments have five scale scores covering:

• Pain (11)
• Control and powerlessness (6)
• Social support (4)
• Emotional well-being (6)
• Self-image (3)

Numbers in brackets represent the number of items in each scale of the (long-form) core EHP-30.

In addition, there is the option of deploying alongside the core instrument six supplementary modules, a total of 23 items. These modular scales cover areas of health status that may not affect every endometriosis sufferer and are therefore provided as an option. The modules can be chosen by users (in any combination of entire modules) to assess areas of health status that may be particularly relevant to their study.The six separate modules cover areas of:

• Work (5 items)
• Relationship with child/children (2 items)
• Sexual relationship (5 items)
• Feelings about medical profession (4 items)
• Feelings about treatment (3 items)
• Feelings about infertility (4 items)

EHP-5 and Short Form Modular PROs

A short form of the core EHP, the EHP-5 has been developed using items taken from the larger instrument. The EHP-5 was created by taking one item from each of the 5 scales from the long-form EHP-30. The chosen item for each scale was selected on the basis of having the highest item to total correlation within the scale.

The short-form EHP-5 has been tested and shown to be highly correlated with the parent scale. The EHP-5 is a reliable and valid short-form PRO which can be supplemented with a short form version of the modular PRO when required. The short-form of the modular PROs has also been produced and tested, resulting in a single 6-item (one item from each module) short-form modular instrument. The single short-form modular PRO contains six dimensions. Item selection for the short-form modular PRO was based on the same selection protocol as the short-form EHP-5 core PRO, namely, the item with the highest item to total correlation in each module was chosen.

Example studies

• The EHP has been used by four of the global top twenty global pharmaceutical companies, supporting numerous clinical trials
• The EHP can be used to assess the efficacy of drugs and surgical interventions

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Development

The EHP system including the core and modular scales was developed in a 3 step approach:

Stage 1 – Item generation.

From qualitative in-depth interviews with 24 women who had laparoscopic diagnosis of endometriosis. This generated a large number (86) of candidate questionnaire items. This 86-item questionnaire was developed and piloted (Group 1) to test basic acceptability and comprehension.

Stage 2 – Item reduction and scale generation.

A second survey was administered using the 87-item questionnaire to 1000 women from the National Endometriosis Society, U.K. (Group 2). The items were reduced using factor analysis of the survey results to produce a shorter (53-item) questionnaire and enable the most salient dimensions of endometriosis which affect HRQoL to be identified.

Stage 3 – Establishing test-retest reliability and validity.

To establish test-retest reliability and validity, a third survey was administered to 83 women recruited from an out-patient gynaecology clinic at the John Radcliffe Hospital, Oxford, (Group 3) using the 53-item questionnaire generated at stage 2. Construct validity was assessed in a postal survey (n = 40) to women undergoing conservative surgery for endometriosis at the John Radcliffe Hospital (Group 4) who completed the EHP-30 and SF-36.

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Scoring system

The purpose of the EHP is to indicate the extent of self-reported ill health on each domain measured. Therefore, each scale is standardised on a scale of 0 – 100, where 0 indicates the best health status through to 100 worst health status. Scale scores for each scale are calculated from the total of the raw scores of each item in the scale divided by the maximum possible raw score of all the items in the scale, multiplied by 100.  Further details of the scoring system and administration procedures for the EHP are provided in the EHP User Manual.

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Administration Methods

Pen and Paper	eCOA – Electronic administration	Telephone Interview

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Authorised eCOA Vendors

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