Valid

The PDQ- Carer demonstrates good content and construct validity.

Reliable

The PDQ- Carer exhibits good internal consistency.

Acceptable

Pre-testing and high completion rates suggest that the PDQ-Carer is easy to complete and acceptable within the test population.

Easy to administer

The PDQ-Carer is a self-administered, paper based PRO. It is both short and easy to score.

Can be used with the developers’ corresponding patient questionnaire (the PDQ-39)

The PDQ-Carer can be used in conjunction with the established PDQ-39 to allow test administers to correlate quality of life scores of a person with PD and their respective carer.

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There are 29 items in the PDQ-Carer, representing four discrete scales:

• Social and personal activities (12 items)
• Anxiety and depression (6 items)
• Self-care (5 items)
• Stress (6 items)

The PRO asks about the influence of caring on specific areas of life over the past four weeks. Respondents are asked to select one of five response options: Never/Occasionally/Sometimes/Often/Always.

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The PDQ-Carer benefits from a simple scoring system. The raw score of each scale can be calculated and converted to a 0-100 metric where 0=no problem at all and 100=worst or maximum level of problem. The sum of the scale scores can provide a single figure used to assess the overall quality of life of the individual questioned.

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The procedure used to develop the PDQ-Carer replicated the methods used to develop the established PDQ-39 (also available from our clinical outcomes team) and follows recommendations for best practice.

The PDQ-Carer was developed and tested in a comprehensive three stage process:

Stage 1- Item generation (content validity)

Exploratory in-depth interviews were carried out with 21 carers of people with PD in order to generate a large number of questionnaire items reflecting the concerns of carers of people with PD. A 44 item questionnaire was subsequently developed and items were evaluated through cognitive testing. A pilot survey with 63 carers was carried out to assess acceptability and comprehension. Minor amendments resulted in a 45 item questionnaire.

Stage 2- Item reduction and scale generation

A postal survey of the 45 item questionnaire was conducted with 160 carers to refine items and assess the underlying domains within the questionnaire using appropriate psychometric methods. Exploratory factor analysis identified four scales (Social and personal activities/Anxiety and depression/Self-care/Stress) incorporating 29 items.

Stage 3- Establishing validity and reliability

A second postal survey was conducted using the 29 item questionnaire generated at stage two and a generic health measure (the SF-36), in order to test the validity and reliability of the new questionnaire. The 29 item questionnaire was completed by 236 carers. Construct validity was established by correlating dimensions tapping similar constructs of the PDQ-Carer with those contained in the SF-36. Internal validity was established with Cronbach alpha coefficients of 0.85 or above in all four scales.

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Previous studies have been forced to measure quality of life among carers of people with PD using generic measures. This recently developed PRO is feasible for use within a wide range of health care applications. It can be used in studies evaluating specific interventions aimed directly at carers of people with PD.

Poorer caregiver health has been linked to poorer outcomes for the people with PD whom they care for. Developers recommend that this PRO can also be used in trials of PD treatments where improved patient quality of life may impact the quality of life of their respective carers.

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Pen and Paper	ePRO/eCOA – Computer-based administration	Telephone Interview

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In collaboration with Mapi Research Trust, we would like to extend our acknowledgement of their continual work and support of synergistic Parkinson Disease measures. The PROQOLID™ database available through the ePROVIDE platform, currently houses over 2000 clinical outcome assessments, covering a range of therapeutic areas. Of those Clinical Outcome Assessments, 24 (including Oxford University Innovation’s PDQ-8, PDQ-39 and PDQ-Carer), are directly related to Parkinson Disease and available through the database. More specifically, Mapi Research Trust manage and distribute the following (potentially complimentary) COAs:

• King’s Parkinson Disease Pain Scale (KPPS), work of Dr K-Ray Chaudhuri (UK) and colleagues
• Parkinson’s Disease Sleep Scale (PDSS), work of Dr K-Ray Chaudhuri (UK) and colleagues
• Parkinson’s Disease Sleep Scale 2 (PDSS-2), work of Dr K-Ray Chaudhuri (UK) and colleagues
• Parkinson’s Disease Quality of Life Questionnaire (PDQL), work of Dr Angela De Boer (NL)

The choice of appropriate Clinical Outcome Assessments has a great effect on Patient-Centred Outcomes (PCO) Research. As such, COAs should be selected by the specific domains they measure along with the populations and therapeutic areas they cover. Implications such as; translations available, copyright and indeed access, are all important considerations to take on board.

To help assist you in finding the right COA that is fit for your study and in light of providing a tool for better knowledge, relevant use of COA, and to extend access to PCO resources for the scientific community, Mapi Research Trust created the PROQOLID™ database in 2002. It has grown exponentially over the years, based on recommended sources such as FDA (U.S. Food and Drug Administration), EMA (European Medicines Agency), and the Research and Development scientific community.

Access provided to the PROQOLID™ database does not constitute a licence for use of the COA measure. Please check with the copyright holder and ensure that you meet their conditions of use.

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