The goal of this observational study is to:

1. develop and validate a health behavior theory-based questionnaire to examine the older adults' and informal caregivers' determinants of deprescribing behavior
2. assess the psychometric properties of this new instrument
3. analyze the moderating influence of health literacy and locus of control on the effect of the determinants on deprescribing intention or behavior.

Participants will be involved in the validating process by completing the questionnaire to be validated, as well as the HLS19_Q12 for health literacy and the MHLC questionnaire for locus of control.

BIBLIOGRAPHIC REFERENCES Prescribing medication is an essential dimension in the care of the older adults (i.e. people aged 60 or 65 and over). However, the ageing process leads to physiological changes that can increase the risk of adverse drug events, and inappropriate polypharmacy can contribute to drug-drug interactions, lower medication adherence, significant costs to both the patient and the healthcare system, and also reduce people's ability to perform activities of daily living.

Therefore, it is important thinking about deprescription, defined by Reeve et al. (2022) as "a planned/ supervised process of dose reduction or the stopping of medicines that may be causing harm or conferring no additional benefit".

As implementation deprescribing requires a complexes changes to established patters of behaviors, understanding the cognitive mechanisms underlying patient's and caregiver's behavior with respect to deprescribing, seems essential to improve the collaborative work between the patient, or even the caregivers, and the health professionals, to achieve the best health outcomes for the patient.

In reality, health behavior theories provides a series of concepts deriving from social, cognitive and motivational psychology, that can be useful in understanding why people behave in certain ways in relation to their health.

Screening Tools The patients' attitudes towards deprescribing (PATD) questionnaire, and its revised version questionnaire (rPATD), and Beliefs about Medicines Questionnaire (specific section) (BMQ-Specific) are 2 instruments widely used. However, this questionnaires don't consider critical domains that can be relevant to deprescribing, such as self-efficacy beliefs, outcome expectations, subjective norms, health goals, environmental barriers and enablers, among others.

Hypothesis The investigators hypothesise that some of the gaps in existing tools will be filled by using health behaviour concepts in the development of an assessment tool.

STUDY DESIGN AND METHODOLOGY APPLIED Type of study: Questionnaire development and validation - older adult and informal caregiver version

Study configuration The initial questionnaire was developed considering the results of a previous systematic review (article currently being written), which was intended to identify (concepts included in) behavioral health theories (HBTs) that explain older adults' and informal caregivers' deprescribing intention and/or their actual deprescribing behavior, as well as the rPATD questionnaire and BMQ questionnaire.

The initial version for informal caregivers was developed by modifying the wording of the items, in the version for the older adults, adapting them for informal caregivers.

Another two questionnaires will be used in this study: one that measure health literacy (HLS19_Q12) and another one that assess the locus of control (Multidimensional Health Locus of control scale, MHLC).

The development and validation of the questionnaire comprise 4 main steps:

1. Item Development

2. Preliminary pilot testing

   1. Colleagues questionnaire feedback
   2. "Cognitive pre-test" performed with older adults and informal caregivers to check the linguistic and analytical construction of the items,
   3. First round with healthcare professionals and second round with older adults and informal carers for a self-administered questionnaire and focus group.

3. Pre-test of the questionnaire - older adult and informal caregiver version

4. Validation of the questionnaire - older adult and informal carer versions, using exploratory factor analysis

Strategies for recruiting participants To recruit participants, several organisations and institutions will be contacted.

Data Management Responsibilities The two questionnaire versions will be either a paper version for self-administration and an electronic version available online.

DISSEMINATION OF RESULTS AND PUBLICATION POLICY The progress and results of this study will be discussed with the Di-Prescribe research team. At the end of the study, a scientific publication will be written by the co-investigator (Sara Alves Jorge) under the supervision of the sponsor representative and Prof Van den Broucke. A paper will also be written for publication in a peer-journal. Acknowledgements will be made to all those who will make this work possible, including healthcare professionals, the different institutions and organizations that will be contacted, as well as the older adults and informal caregivers who will take part in the study. In addition, some people who will be indirectly involved, in particular by giving support and guidance, will also be recognized.

Inclusion Criteria:

Older adults

• Age 60 years or older;
• Taking at least 5 medications daily;
• Having at least one chronic condition.

Informal caregivers

• They self-identified as a caregiver (defined as having any role in a family member or friend's management of health and/ or medication management) of an older adult who has 60 years old or older, that are taking at least 5 medications daily;
• The care recipient lived in the community (at home with or without the caregiver) or in a NH.

Exclusion Criteria:

Older adults

• Suffering from psychiatric trouble;
• Past or present drug or alcohol dependency;
• Having a terminal illness;
• Inability to complete a written questionnaire in French due to a functional or cognitive impairment;
• Inability to understand and express oneself in French.

Informal cariegivers

• Caregiver age under 18 years old;
• Caregivers who are paid for the care they provide;
• Caregiver inability to give consent and complete a written questionnaire in French;
• Caregiver inability to understand and speak in French.

For the purposes of this study, older adult are people aged 60 or older. Take at least 5 regular medications: the ageing process is often accompanied by an increasing burden of chronic illness, and consequently by chronic medication use that can lead to polypharmacy, defined as taking 5 or more medications.

In this study informal caregiver refers to a family member, a friend that provide care or support to a dependent older person with physical or cognitive functions declines. The relationship between the informal caregiver and the care recipient is based on solidarity. Therefore, in this study those who provided informal care are: (a) working-age adults who care for older parents with disabilities, family members, neighbors or friends; (b) people of retirement age or older who care for their partner, family members, neighbors or friends