Spanish version of the Parkinson’s Disease Questionnaire–Carer (PDQ-Carer)

Parkinson’s disease (PD) is a chronic and progressive neurodegenerative disorder characterised by physical and psychological symptoms that result in motor disability, neuropsychiatric symptoms and loss of autonomy [1, 2]. PD is the second most common neurodegenerative disorder after Alzheimer’s disease affecting approximately 1-2 % of the population over 60 years of age and 4 % of those aged 80 years worldwide [3]. According to disease prevalence projections, it is estimated that the number of patients with Parkinson’s disease in Western Europe will grow from 4 million in 2005 to 9 million in 2030 [4]. In Spain, around 6.400 individuals are affected by Parkinson’s disease each year and about 30 % of cases are diagnosed in advanced stages of the disease [5, 6]. This figure is expected to increase due to the growing elderly population, particularly in the group of individuals aged 70 and older [7].

As a consequence of the progressive nature of the disease most patients with PD are affected by a range of cognitive and behavioural disorders which are observed even in the early stages of the disease, as a result of the loss of dopaminergic neurons and the progressive decrease of the activity in several areas of the brain [8]. These cognitive deficits are often accompanied by clinical symptoms such as bradykinesia, rigidity and resting tremor, which has been reported to be prognostic of the progressive course of the disease, [9] making difficult for people with Parkinson to carry out basic and instrumental everyday activities without the assistance of family members and other non-informal caregivers [10]. Parkinson’s caregivers have been recognized to play an important role in supporting patients, particularly in advanced stages of the disease leading a reduction of the rates of institutionalization and number of hospitalizations [10, 11]. However, caring for a family member with PD has been considered as a stressful process that affects negatively physical, psychological and socioeconomic conditions of caregivers [12]. It has been reported that caring a patients with PD is strongly related to poor psychosocial outcomes including high levels of burden, depression, anxiety, mood disturbances and emotional distress [13‐15]. These common manifestations that affect the quality of life (QoL) of carers of individuals with PD are frequently associated with the severity of symptoms of patients, progression disease and patient disability [14]. Several studies examining the role of caregiving in Spain and other Western European countries have found that patient disability and mood disturbances contribute to caregiver’s burden and stress as well as placing strain on the family unit as a whole [1, 16, 17]. In addition, the demands of caring may result in an increase in marital dissatisfaction since caregiving may result in a lack of leisure activities, social isolation and low levels of perceived social support [18]. Given that the QoL of PD caregivers can be adversely affected by a range of factors, it is important to assess the areas of greatest impairment associated to role of caregiver. Awareness of the impact of PD on carers may enable effective interventions aimed at improving caregiver’s quality of life of patients and ameliorating the negative effects of caregiving [15].

Previous research has often measured QoL in carers of patients with Parkinson’s disease by using a variety of generic scales including the Zarit Caregiver Burden Inventory [19] and the World Health Organisation Quality of Life Scale (WHOQoL) [20] which were originally developed for caregivers of patients with dementia [21]. More recently several instruments such as the BELA-A-K [12] and the Scale of Quality of Life Care-Givers (SQLC) [22] have been specifically developed for caregivers of people with PD. Although these measures provide clinically important information of physical and psychological factors affecting to the role of caregivers, their feasibility has not formally been reported for English and Spanish speaking population [23]. In addition, the Scale of Quality of Life Care-Givers (SQLC) has been subject to criticism due to the complexity of both administration and scoring [23].

Recently, a short and easy to administrate health related quality of life questionnaire for use with carers of patients with PD have been developed in UK. The Parkinson’s Disease Questionnaire fore Carers (PDQ-Carer) attempts to quantify subjective experiences of caregivers by examining the main important domains that are adversely affected by the role of caring: Social and Personal Activities, Anxiety and Depression, Self-Care and Stress [23]. The PDQ-Carer has been shown to be valid, reliable and sensitive to change for English population. However, cross-cultural validation has not been reported in other cultures. Therefore, the purpose of this study was to examine the psychometric properties of the Spanish version of the PDQ-Carer. We examined the PDQ-Carer in terms of reliability and validity by examining a sample of 73 caregivers of patients with PD.

This is one the first studies in Spain to examine the relative contributions of health related quality of life in caregivers of patients with Parkinson’s Disease. The aim of the current study was to examine the psychometric properties of the Spanish version of the PDQ-Carer, a new quality of life measure specifically developed for Parkinson’s caregivers. The preliminary findings of this study suggest that the PDQ-Carer Spanish version shows good psychometric properties in terms of cross-cultural adaptation, reliability and validity comparable to those reported in the original English version [23]. Overall, the PDQ-Carer Spanish version was found to be easy to understand for respondents and few linguistics changes were required after the first stage of the cross-cultural validation into Spanish.

In terms of reliability, both the item-total correlation and Cronbach’s alpha values were found to be satisfactory for the four domains measured by the PDQ-Carer (Personal and Social Activities, Anxiety and Depression, Self-care and Strain). The alpha coefficient values ranged from 0.80 to 0.95, comparable to those found by Jenkinson et al., [23] in the original development and validation of this measure. The most significant alpha scores were related to personal and social activities scale, which examines how caring for a patient with PD may affect relationships with others as well as the ability to maintain pastimes and hobbies. Studies examining the relationship between activity level, wellbeing and quality of life among caregivers of patients with PD, have demonstrated that a loss of activity level as a consequence of caring might lead to a decrease in quality of life and contribute to a major impact on physical and mental health problems in caregivers [34]. In the current study, most caregivers were patient’s spouses, retired or housewives with an average age of about 63 years and about half of sample were taking care of the PD patients full time, resulting in a high demand of caring. Also, around 12 % of caregivers had been forced to leave their job to take care of PD patient. These results concur with previous studies in Spain and other countries [35, 36] and suggest that family caregivers assume a considerable role in the demands of caring of patients.

In the current study, the related domains of the PDQ-Carer were found to be correlated with all dimensions of the generic SF-36, a widely used health related quality of life in different populations. For all scales, both measures were correlated at significant level, with coefficients values between -0.31 to -0.59 (the negative correlations are due to the fact the measures are scored in opposite directions with 100 being the best score on the SF-36 and the worst on the PDQ-Carer). The personal and social activities, mental health and the anxiety and depression subscales of PDQ-Carer were moderately correlated with the social functioning and general health perceptions of the SF-36. The moderate association found in our study between these measures were similar to those reported by Morley et al., [25]. They found that the PDQ-Carer and SF-36 were significantly correlated, particularly for the social functioning, vitality and mental health SF-36 domains with correlations ranging between -0.68, -0.67, -0.66 respectively. Also, the results of the construct validity of the Spanish version of the PDQ-Carer is comparable to the original English version. These initial findings support the use of the Spanish version of the PDQ-Carer by providing some evidence of the utility of this measure in non-professionals caregivers.

However, the current study has several limitations which require areas for future examination. Firstly, the cross-sectional design of this study provides preliminary evidence of the utility of the PDQ-Carer as a valid and feasible measure for assessing the negative effects on caregiver’s quality of life, but it does not allow to establish temporal consistency of findings across time. Secondly, although participants in our cohort were comprised from different Parkinson’s Associations across Spain, this sample cannot be considered as representative from all the Spanish caregivers since some associations could not be contacted. Consequently, this might limit the generalizability of the findings. Future studies would benefit from the inclusion a large sample size of participants from more diverse settings and regions in Spain. Also, future research should include the use of validated measures assessing the physical stage of the patient’s disease and the examination of caregivers with similar education level. Thirdly, while the focus of the present study was to examine the preliminary findings of Spanish version of the PDQ-Carer in terms of reliability and validity, we did not examine test-rest reliability over time. In addition, future work would benefit from including more sophisticated analysis such as structural equation modelling by considering how some potential moderators such as cognitive deficits, depression or severity of illness, can mediate the impact on caregiver quality of life.

Despite these limitations, this study provides evidence for the use of the PDQ-Carer scale in non-professional caregivers in Spain and to the best of our knowledge is one of the first health related QoL measures designed for caregivers of patients with PD. The use of the PDQ-Carer may have important implications for clinical practice. It may be important for targeting interventions focused on reducing the negative effects on health and social functioning of caregivers as well as to understand the effects of treatment, since those with a poor quality of life may require additional support from clinical and community services.

Due to the fact the PDQ-Carer is both short and easy to administer, it can be used in a wide range of clinical applications thereby providing important information about health related quality of life problems that need to be addressed in PD caregivers.