Abstract

Background : cognitive limitations and lack of insight have been seen as barriers to self-reporting in quality of life (QoL) assessment of people with dementia. However growing evidence suggests that people with mild to moderate dementia may be able to complete standardised questionnaire items and articulate feelings, providing reliable evaluations of their health and QoL.

Objective : to examine the reliability of the item pool of a new measure of self-reported QoL, the Bath Assessment of Subjective Quality of Life in Dementia (BASQID)

Subjects : sixty people with mild to moderate dementia, recruited from a memory clinic.

Methods : participants completed 44 items from an initial draft of the BASQID and 30 completed the items on a second occasion, 2 weeks later. Item analytic criteria, including item facility, score distributions, tests of internal consistency and reproducibility, were used to reduce the item pool, and the reliability of the reduced pool was examined.

Results : twenty items were removed from the item pool. All retained items had at least moderate test-retest reliability (κ >0.41), with 13 items displaying good to very good reliability (κ >0.61). These 24 items were internally consistent (alpha = 0.91), and the total score had a good 2-week test-retest reliability with an intraclass correlation coefficient of 0.82 (0.66–0.91).

Conclusions : participants were able to complete items relating to feelings and evaluations of a range of QoL domains. The consistency of responses over a 2-week period suggests that self-reported QoL assessments are feasible and appropriate for people with mild to moderate dementia.

Introduction

Subjective evaluation of quality of life (QoL) by people with dementia may be influenced by their cognitive limitations and may reflect reduced insight, however they represent the best way of understanding the experience of life with dementia. Medical models of QoL have traditionally assumed that the more symptoms present, and the more advanced the disease, the poorer the QoL. However, people with chronically limiting conditions often report a high QoL [ 1 ]. Woods [ 2 ] suggests that there is an implicit assumption in many studies that increased independent function must be associated with a better QoL. He concludes that if well-being is to be increased through efforts to improve independent functioning, then there needs to be a better understanding of how the person with dementia cognitively processes these changes. Therefore, an understanding of people's perceptions, behaviours and experiences is needed if the concept of subjective QoL is to be adequately described.

People with dementia may have a range of cognitive and behavioural symptoms that can interfere with their ability to answer QoL questions. Communication, attention, memory and judgement are necessary skills to answer survey questions [ 3 ] and these are all cognitive areas that may be impaired in people with dementia. Similarly, altered psychological states such as depression, may impact on QoL assessment particularly when this involves reports about subjective well-being. Katschnig et al. [ 4 ] highlight the role of momentary affective states, reality distortion, and poor cognition in the distortion of responses to questions about functioning in social roles, and about material and social living conditions.

A further challenge for the direct assessment of QoL in people with dementia is the apparent lack of insight demonstrated by many individuals. This deficit can relate to awareness of specific memory/cognitive deficits, awareness of global memory/cognitive deficits, awareness of the impact of memory problems/dementia, or awareness of dementia as a whole [ 5 , 6 ]. Insight varies across domains such as self-care, memory, health status and language abilities [ 7 , 8 ]. However, Brod et al. [ 9 ] suggest that ‘awareness of feelings may be preserved, even in instances where awareness of cognitive deficits is impaired’ (p. 33). They cite evidence (e.g. [ 10 ]) that reports good correlations between patient and proxy measures, such as mood, energy, health and sense of self, alongside poor agreement on measures of memory and functional ability.

There is growing evidence to suggest that people with dementia can respond accurately to questions about QoL [ 9 , 11–16 ]. Although investigations of cognitively impaired individuals show that proxies consistently rate QoL lower for the patient than they would rate themselves [ 17 , 18 ], this lack of agreement is not entirely attributable to the level of patient cognitive impairment [ 19 , 20 ]. Case studies [ 11 ] and research [ 12–15 ] suggest that mild to moderately cognitively impaired individuals can articulate feelings, concerns and preferences, and provide evaluations of their health and QoL.

More recently, direct assessment of QoL in people with mild to moderate levels of cognitive impairment has been carried out using assessments specifically designed for this purpose. Logsdon et al. [ 16 ] administered a 13-item QoL measure (QoL-AD) to 177 people with Alzheimer's disease and showed that the assessment was valid and reliable for people with mild to moderate levels of cognitive impairment. Of 177 respondents, 155 could complete the assessment. All of those who were unable to complete the QoL-AD had Mini Mental State Examination scores of 10 or below (MMSE; [ 21 ]). Similarly the DQoL is a QoL measure [ 9 ] that is administered directly to the person with dementia, and contains 29 questions relating to their self-esteem, positive and negative effect, feelings of belonging, and sense of aesthetics. Administering the measure to 99 patients with mild to moderate stage dementia (MMSE > 11), Brod et al. found that 95% were able to complete the DQoL and they concluded that ‘it is feasible to assess directly QoL from most dementia patients with a MMSE score greater than 12’ (p. 34).

This paper reports on the preliminary stages of the development of the Bath Assessment of Subjective Quality of Life in Dementia (BASQID), which is a new measure of self-report QoL designed for use by people with mild to moderate dementia. The properties of the final BASQID measure, including validity and responsiveness to changes in QOL, have been reported elsewhere [ 22 ]. This paper focuses on the process of item reduction, where issues of item reliability were explored.

Method

Design

A cross-sectional design with a single follow-up was employed. Item-reduction was conducted through field-testing the item pool and application of standard psychometric criteria [ 23–26 ].

Participants

Sixty people with a diagnosis of dementia according to DSM-IV [ 27 ], and a MMSE score of 12 or above, were recruited as consecutive admissions to a memory clinic (Table 1 ). Participants were excluded from the study if English was not their first language. A sample size of 60 people was sufficient for item analysis, allowing detection of significant correlations (>0.3) between BASQID items. Thirty participants were reassessed 2 weeks later, to assess temporal stability of BASQID items, as this number would allow the detection of significant correlations (>0.7) between the two administrations of the measure. This sub-sample was obtained through quota sampling, whereby consecutive participants recruited to the study were invited to undergo a second assessment. This process continued until 30 people had been recruited to the retest.

Table 1

Sample characteristics

   Total sample ( n  = 60)   Test-retest subsample ( n  = 30)  
Probable Alzheimer's/mixed 49 (82%) 26 (87%) 
Diagnosis Vascular 8 (13%) 3 (10%) 
 Frontotemporal 3 (5%) 1 (3%) 
Cognitive MMSE mean (s.d.) 18.44 (4.07) 19.07 (3.43) 
Ability MMSE median (range) 18.00 (12–26) 19.50 (12–26) 
Living Living alone 8 (13%) 3 (10%) 
Arrangement Living with spouse 45 (75%) 24 (80%) 
 Living with relative/other 5 (8%) 2 (7%) 
 Residential accommodation 2 (3%) 1 (3%) 
Sex Male 28 (47%) 13 (43%) 
 Female 32 (53%) 17 (57%) 
Age <65 7 (12%) 3 (10%) 
 65–74 24 (40%) 13 (43%) 
 75–84 19 (32%) 8 (27%) 
 >85 10 (16%) 6 (20%) 
   Total sample ( n  = 60)   Test-retest subsample ( n  = 30)  
Probable Alzheimer's/mixed 49 (82%) 26 (87%) 
Diagnosis Vascular 8 (13%) 3 (10%) 
 Frontotemporal 3 (5%) 1 (3%) 
Cognitive MMSE mean (s.d.) 18.44 (4.07) 19.07 (3.43) 
Ability MMSE median (range) 18.00 (12–26) 19.50 (12–26) 
Living Living alone 8 (13%) 3 (10%) 
Arrangement Living with spouse 45 (75%) 24 (80%) 
 Living with relative/other 5 (8%) 2 (7%) 
 Residential accommodation 2 (3%) 1 (3%) 
Sex Male 28 (47%) 13 (43%) 
 Female 32 (53%) 17 (57%) 
Age <65 7 (12%) 3 (10%) 
 65–74 24 (40%) 13 (43%) 
 75–84 19 (32%) 8 (27%) 
 >85 10 (16%) 6 (20%) 

Materials

BASQID item pool

Through previous in-depth interviews with people with mild to moderate-stage dementia ( n  = 45), a conceptual framework for subjective QoL in dementia was developed which contained nine domains of QoL, reflecting recurrent themes in the interview data (Table 2 ). An initial item pool was written so as to include all of the dimensions (facets) of QoL contained within these domains. These items were standardised to conform to two types of question stem and response scale (satisfaction and capacity/intensity). Each response scale contained five response options, scored 0–4 where high scores represented good QoL. Questions beginning with the stem ‘how satisfied are you …’ were given a response scale: ‘not at all satisfied–a little satisfied–satisfied–very satisfied–extremely satisfied’; items beginning with ‘to what extent …’ were given a response scale: ‘not at all–a little–a moderate amount–quite a lot–a great deal’. Each item was written on an individual card 18 × 6 cm, in a large sans serif font (Arial 26 pt), and response scales on cards 30 × 10 cm with the same font. Response scales were set out horizontally, with vertical lines separating scalar points. The scale contained only the words defining each point on the scale, not the scores associated with each response. This item pool was pre-tested, using a simplified version of an item-by-item probing technique [ 28 ] on 15 participants in order to investigate problems with language and item format. Revisions resulted, and a second draft of 44 items was written.

Table 2

Quality-of-life domains and facets

QoL domain QoL facet 
Health Satisfaction with physical health 
 Satisfaction with mental health 
 Feelings of pain or discomfort 
 Feeling unwell 
Social Satisfaction with relationships 
interaction Ability to interact 
 Opportunity to interact 
 Social confidence 
 Satisfaction with treatment by others 
 Appearance to others 
 Satisfaction with role 
Function Satisfaction with self-care performance 
 Satisfaction with ADL & IADL performance 
 Satisfaction with level of independence 
 Confidence in ability 
 Frustration with ability 
Mobility Satisfaction with mobility around the home 
 Satisfaction with community mobility 
 Availability of transport 
 Satisfaction with ability to get out of the home 
 Feelings of restriction 
Being Satisfaction with leisure 
occupied Opportunity for leisure 
 Meaningful time use 
 Boredom 
Energy Bothered by feelings of fatigue 
 Satisfaction with motivation/enthusiasm 
 Satisfaction with activity levels 
 Satisfaction with energy levels 
Sleep Satisfaction with amount of sleep 
 Bothered by sleep disturbance 
Psychological Contentment and happiness 
 Depression 
 Anxiety 
 Feeling important 
 Feeling useful 
 Feeling in control 
Environment Adequacy of home 
 Adequacy of possessions 
 Satisfaction with financial status 
 Availability of support 
 Satisfaction with support 
 Privacy 
 Feelings of comfort 
 Feelings of security 
QoL domain QoL facet 
Health Satisfaction with physical health 
 Satisfaction with mental health 
 Feelings of pain or discomfort 
 Feeling unwell 
Social Satisfaction with relationships 
interaction Ability to interact 
 Opportunity to interact 
 Social confidence 
 Satisfaction with treatment by others 
 Appearance to others 
 Satisfaction with role 
Function Satisfaction with self-care performance 
 Satisfaction with ADL & IADL performance 
 Satisfaction with level of independence 
 Confidence in ability 
 Frustration with ability 
Mobility Satisfaction with mobility around the home 
 Satisfaction with community mobility 
 Availability of transport 
 Satisfaction with ability to get out of the home 
 Feelings of restriction 
Being Satisfaction with leisure 
occupied Opportunity for leisure 
 Meaningful time use 
 Boredom 
Energy Bothered by feelings of fatigue 
 Satisfaction with motivation/enthusiasm 
 Satisfaction with activity levels 
 Satisfaction with energy levels 
Sleep Satisfaction with amount of sleep 
 Bothered by sleep disturbance 
Psychological Contentment and happiness 
 Depression 
 Anxiety 
 Feeling important 
 Feeling useful 
 Feeling in control 
Environment Adequacy of home 
 Adequacy of possessions 
 Satisfaction with financial status 
 Availability of support 
 Satisfaction with support 
 Privacy 
 Feelings of comfort 
 Feelings of security 

For the field test, an additional item was added to the item pool so that it could be used in analysis of the validity of BASQID items. This global item asked, ‘How would you rate your overall QoL?’ and was scored on a five-point response scale (very poor/poor/fair/good/very good).

Procedure

Written informed consent was obtained from all participants. The BASQID item pool was administered to participants either at home or in the memory clinic, depending on the participant's preference. Administration began with the presentation and explanation of the response scale; respondents were asked if they could see the response scale clearly, and if they were able read all points on the scale. Questions were then laid one at a time underneath the appropriate response scale, in front of the respondent, and read aloud by the interviewer. The respondent was asked to select an appropriate response, and this was recorded on a standardised interviewer score sheet. Where a respondent encountered difficulties, the interviewer provided limited assistance but did not suggest an appropriate response to a question. The forms of assistance available for use included repetition of questions and response options, clarification of words and phrases (where standardised prompts were available) and provision of reassurance that respondents should answer questions to reflect their own feelings and opinions. Thirty participants were reassessed using the same procedure.

Analysis

The first analysis phase involved examining the properties of individual items. Response distributions were examined for frequency of endorsement, such that items with two or more adjacent scale points showing an average of less than 10% of the responses were deemed to have frequency problems [ 25 ]. Item facility indices were calculated, and a value within one point of the scale anchor values indicated a skewed distribution. Item discrimination was assessed by examining item-total correlations. Item validity was examined through the correlation between each item, and the global QoL question. Spearman's correlations were used throughout, due to the ordinal nature of the data. A correlation coefficient of 0.3 or above, between individual items and total score is evidence of internal consistency [ 26 ], and is also a suitable criterion for examining the correlation between individual items and the global rating of QoL. Finally, weighted kappa (κ) was used to assess the test-retest reliability of each item across 2 weeks. The strength of agreement between the responses using κ was defined as poor (<0.2), fair (0.21–0.4), moderate (0.41–0.6), good (0.61–0.8), and very good (0.81–1.0) [ 23 ].

Items were flagged for possible deletion from the item pool where they had either: an item-total correlation of <0.30; an item-global QoL correlation of <0.30; test-retest weighted κ of 0.4 or less; or κ of 0.41–0.60 in conjunction with a poor response distribution (characterised by a failure to meet both the item facility and the response endorsement criteria). Internal consistency of the remaining items was calculated using Cronbach's alpha and item-total correlations, in order to identify whether the items formed a cohesive scale. An intraclass correlation coefficient explored the test-retest reliability of summed item scores.

Results

All except one of the participants were able to complete the 44-item pool. Missing data was minimal: question (Q) 20 had the highest level (6.7%), whereas Q25 and Q39 had missing data in 5% of cases. The retest was completed by 29 of the 30 participants.

Item analysis of the BASQID item pool highlighted problems with 20 of the 44 items (rows marked with † in Table 3 ). These items were rejected from the item pool as none of the problems associated with these questions could be corrected through minor alterations to wording, and there were no obvious outliers in the data that may explain their poor performance. Thirteen of these items displayed poor validity, with correlations of <0.3 with the global QoL question, while five rejected items displayed poor association with other items ( r  < 0.3). Only one item (Q40) from the entire pool displayed poor-fair test-retest reliability (κ < 0.4). Nineteen of the 44 items displayed good test-retest reliability with values of κ ranging from 0.61 to 0.85. Moderate test-retest reliability in conjunction with poor response distributions accounted for the rejection of nine items.

Table 3

Criteria for reduction of BASQID item pool

No. Item  Valid
n  
Facility index Range  Item-total r
n  = 53  
Item-global r  Weighted Kappa (S.E.)
n  = 29  
Q1 How satisfied are you with your health? 60 2.83  1–4 a  0.71 **  0.46 ** 0.72 (0.13) 
Q2 How satisfied are you with your memory? 60 1.72 0–3  0.51 **  0.33 ** 0.85 (0.12) 
Q3† How satisfied are you with your concentration? 59 2.25 1–4 0.15 0.11 0.52 (0.13) 
Q4 How satisfied are you with your thinking processes? 60 2.00 0–4  0.30 *  0.27 * 0.61 (0.11) 
Q5 How satisfied are you with your ability to look after yourself? 60 2.50 0–4  0.50 **  0.29 * 0.73 (0.11) 
Q6† How satisfied are you with your ability to carry out daily activities in the home? 60 2.45  0–4 a  0.45 ** 0.12 0.71 (0.13) 
Q7 How satisfied are you with your level of energy? 60 2.73  0–4 a  0.67 **  0.40 ** 0.41 (0.13) 
Q8 How satisfied are you with your enthusiasm for doing things? 60 2.45  0–4 a  0.54 **  0.48 ** 0.55 (0.11) 
Q9† How satisfied are you with your sleep? 60 3.02  0–4 a  0.31 * 0.05 0.66 (0.13) 
Q10† How satisfied are you with your ability to move around all areas of your home? 60 3.18 0–4a  0.60 **  0.50 ** 0.58 (0.14) 
Q11 How satisfied are you with your ability to get out of your home? 59 2.91 0–4  0.74 **  0.41 * 0.47 (0.12) 
Q12 How satisfied are you with your ability to move around your local community? 59 3.11  0–4 a  0.66 **  0.27 * 0.52 (0.13) 
Q13† How satisfied are you with your ability to travel to places outside of your local community? 59 2.58 0–4  0.39 ** −0.02 0.45 (0.12) 
Q14 How satisfied are you with the way you usually spend your day? 59 2.76  1–4 a  0.58 **  0.48 ** 0.72 (0.12) 
Q15 How satisfied are you with your level of independence? 59 2.39 0–4  0.67 **  0.35 ** 0.47 (0.11) 
Q16 How satisfied are you with your relationships with people who are close to you? 59 3.27  2–4 a  0.33 *  0.28 * 0.61 (0.18) 
Q17 How satisfied are you with your ability to talk to other people? 59 2.93 0–4  0.57 **  0.27 * 0.57 (0.11) 
Q18† How satisfied are you with the way other people treat you? 59 3.10 1–4a  0.48 **  0.36 ** 0.50 (0.13) 
Q19† How satisfied are you with the support you receive from other people? 58 3.2 2–4a −0.11 –0.20 0.59 (0.15) 
Q20† How satisfied are you with the support you receive from medical and social services? 56 3.21 2–4a  0.28 * 0.03 0.42 (0.13) 
Q21† How satisfied are you with the place where you live? 59 3.49  2–4 a  0.27 * 0.03 0.71 (0.15) 
Q22† How satisfied are you with your financial situation? 59 3.08  1–4 a  0.47 ** 0.19 0.70 (0.15) 
Q23 To what extent do you suffer from physical discomfort? 59 3.02  0–4 a  0.32 *  0.31 * 0.64 (0.12) 
Q24 To what extent do you feel unwell? 59 3.39  1–4 a  0.44 **  0.33 ** 0.71 (0.12) 
Q25 To what extent are you able to do all the activities that you want to? 57 2.67 0–4  0.55 **  0.52 ** 0.50 (0.11) 
Q26† To what extent do you have confidence in your ability to do things? 59 3.08 1–4a  0.44 **  0.31 * 0.53 (0.13) 
Q27 To what extent do you feel frustrated with your ability to do things? 59 2.88 0–4  0.43 **  0.29 * 0.61 (0.12) 
Q28† To what extent do you feel anxious about your ability to do things? 59 3.05 0–4a  0.49 ** 0.37 0.51 (0.13) 
Q29 To what extent are you bothered by feelings of tiredness and fatigue? 59 2.98 1–4  0.42 **  0.32 * 0.71 (0.12) 
Q30† To what extent are you able to go to the places that you want to? 58 2.53 0–4  0.35 * 0.10 0.64 (0.11) 
Q31 To what extent are you able to do things that you enjoy? 59 2.76  0–4 a  0.64 **  0.60 ** 0.75 (0.12) 
Q32† To what extent do you enjoy life? 59 3.39 0–4a  0.60 ** 0.51 0.59 (0.15) 
Q33 To what extent do you feel bored? 59 3.05 0–4  0.53 **  .35 ** .72 (.12) 
Q34 To what extent do you feel you are in control of your life? 58 2.62  0–4 a  0.60 **  0.38 ** 0.59 (0.13) 
Q35 To what extent do you feel you have the choice to do the things that you want to do? 58 2.60 0–4  0.53 **  0.51 ** 0.45 (0.12) 
Q36† To what extent do you have the opportunity to meet other people? 58 2.57 1–4 0.23 0.18 .68 (.12) 
Q37† To what extent do you have confidence when meeting other people? 59 2.86  0–4 a  0.44 ** 0.19 .49 (.12) 
Q38 To what extent do you feel useful? 59 2.46 0–4  0.55 **  0.38 ** 0.54 (0.12) 
Q39† To what extent do you feel that other people take notice of your opinions? 57 2.18 0–4  0.44 ** 0.16 0.53 (0.12) 
Q40† To what extent do you feel there are people you can call on if you need help with anything? 58 2.91  1–4 a  0.43 ** 0.10 0.33 (.11) 
Q41 To what extent do you feel happy? 58 2.87  2–4 a  0.49 **  0.52 ** 0.54 (.13) 
Q42† To what extent do you feel unhappy? 58 3.26 1–4a  0.42 **  0.43 ** 0.58 (.12) 
Q43 To what extent do you feel anxious? 59 2.88 1–4  0.35 *  0.51 ** 0.78 (.13) 
Q44† To what extent do you have the goods and possessions to meet your needs? 58 3.21 2–4a  0.64 **  0.36 ** 0.57 (0.13) 
No. Item  Valid
n  
Facility index Range  Item-total r
n  = 53  
Item-global r  Weighted Kappa (S.E.)
n  = 29  
Q1 How satisfied are you with your health? 60 2.83  1–4 a  0.71 **  0.46 ** 0.72 (0.13) 
Q2 How satisfied are you with your memory? 60 1.72 0–3  0.51 **  0.33 ** 0.85 (0.12) 
Q3† How satisfied are you with your concentration? 59 2.25 1–4 0.15 0.11 0.52 (0.13) 
Q4 How satisfied are you with your thinking processes? 60 2.00 0–4  0.30 *  0.27 * 0.61 (0.11) 
Q5 How satisfied are you with your ability to look after yourself? 60 2.50 0–4  0.50 **  0.29 * 0.73 (0.11) 
Q6† How satisfied are you with your ability to carry out daily activities in the home? 60 2.45  0–4 a  0.45 ** 0.12 0.71 (0.13) 
Q7 How satisfied are you with your level of energy? 60 2.73  0–4 a  0.67 **  0.40 ** 0.41 (0.13) 
Q8 How satisfied are you with your enthusiasm for doing things? 60 2.45  0–4 a  0.54 **  0.48 ** 0.55 (0.11) 
Q9† How satisfied are you with your sleep? 60 3.02  0–4 a  0.31 * 0.05 0.66 (0.13) 
Q10† How satisfied are you with your ability to move around all areas of your home? 60 3.18 0–4a  0.60 **  0.50 ** 0.58 (0.14) 
Q11 How satisfied are you with your ability to get out of your home? 59 2.91 0–4  0.74 **  0.41 * 0.47 (0.12) 
Q12 How satisfied are you with your ability to move around your local community? 59 3.11  0–4 a  0.66 **  0.27 * 0.52 (0.13) 
Q13† How satisfied are you with your ability to travel to places outside of your local community? 59 2.58 0–4  0.39 ** −0.02 0.45 (0.12) 
Q14 How satisfied are you with the way you usually spend your day? 59 2.76  1–4 a  0.58 **  0.48 ** 0.72 (0.12) 
Q15 How satisfied are you with your level of independence? 59 2.39 0–4  0.67 **  0.35 ** 0.47 (0.11) 
Q16 How satisfied are you with your relationships with people who are close to you? 59 3.27  2–4 a  0.33 *  0.28 * 0.61 (0.18) 
Q17 How satisfied are you with your ability to talk to other people? 59 2.93 0–4  0.57 **  0.27 * 0.57 (0.11) 
Q18† How satisfied are you with the way other people treat you? 59 3.10 1–4a  0.48 **  0.36 ** 0.50 (0.13) 
Q19† How satisfied are you with the support you receive from other people? 58 3.2 2–4a −0.11 –0.20 0.59 (0.15) 
Q20† How satisfied are you with the support you receive from medical and social services? 56 3.21 2–4a  0.28 * 0.03 0.42 (0.13) 
Q21† How satisfied are you with the place where you live? 59 3.49  2–4 a  0.27 * 0.03 0.71 (0.15) 
Q22† How satisfied are you with your financial situation? 59 3.08  1–4 a  0.47 ** 0.19 0.70 (0.15) 
Q23 To what extent do you suffer from physical discomfort? 59 3.02  0–4 a  0.32 *  0.31 * 0.64 (0.12) 
Q24 To what extent do you feel unwell? 59 3.39  1–4 a  0.44 **  0.33 ** 0.71 (0.12) 
Q25 To what extent are you able to do all the activities that you want to? 57 2.67 0–4  0.55 **  0.52 ** 0.50 (0.11) 
Q26† To what extent do you have confidence in your ability to do things? 59 3.08 1–4a  0.44 **  0.31 * 0.53 (0.13) 
Q27 To what extent do you feel frustrated with your ability to do things? 59 2.88 0–4  0.43 **  0.29 * 0.61 (0.12) 
Q28† To what extent do you feel anxious about your ability to do things? 59 3.05 0–4a  0.49 ** 0.37 0.51 (0.13) 
Q29 To what extent are you bothered by feelings of tiredness and fatigue? 59 2.98 1–4  0.42 **  0.32 * 0.71 (0.12) 
Q30† To what extent are you able to go to the places that you want to? 58 2.53 0–4  0.35 * 0.10 0.64 (0.11) 
Q31 To what extent are you able to do things that you enjoy? 59 2.76  0–4 a  0.64 **  0.60 ** 0.75 (0.12) 
Q32† To what extent do you enjoy life? 59 3.39 0–4a  0.60 ** 0.51 0.59 (0.15) 
Q33 To what extent do you feel bored? 59 3.05 0–4  0.53 **  .35 ** .72 (.12) 
Q34 To what extent do you feel you are in control of your life? 58 2.62  0–4 a  0.60 **  0.38 ** 0.59 (0.13) 
Q35 To what extent do you feel you have the choice to do the things that you want to do? 58 2.60 0–4  0.53 **  0.51 ** 0.45 (0.12) 
Q36† To what extent do you have the opportunity to meet other people? 58 2.57 1–4 0.23 0.18 .68 (.12) 
Q37† To what extent do you have confidence when meeting other people? 59 2.86  0–4 a  0.44 ** 0.19 .49 (.12) 
Q38 To what extent do you feel useful? 59 2.46 0–4  0.55 **  0.38 ** 0.54 (0.12) 
Q39† To what extent do you feel that other people take notice of your opinions? 57 2.18 0–4  0.44 ** 0.16 0.53 (0.12) 
Q40† To what extent do you feel there are people you can call on if you need help with anything? 58 2.91  1–4 a  0.43 ** 0.10 0.33 (.11) 
Q41 To what extent do you feel happy? 58 2.87  2–4 a  0.49 **  0.52 ** 0.54 (.13) 
Q42† To what extent do you feel unhappy? 58 3.26 1–4a  0.42 **  0.43 ** 0.58 (.12) 
Q43 To what extent do you feel anxious? 59 2.88 1–4  0.35 *  0.51 ** 0.78 (.13) 
Q44† To what extent do you have the goods and possessions to meet your needs? 58 3.21 2–4a  0.64 **  0.36 ** 0.57 (0.13) 
*

Significant at P < 0.05.

**

Significant at P <0.01.

a

Two or more adjacent scale points showing <10% of the responses.† items flagged for deletion from item pool. Figures in bold indicate main reasons for item deletion.

The internal consistency of the reduced item pool (24 items) was excellent, with a Cronbach's coefficient alpha of 0.91 ( n  = 55). All corrected item-total correlations were >0.3, and alpha could not be improved by omitting any single item. A total score for the scale (0–96) was calculated by summing the scores on individual items. The mean for the total score was 66.52 (SD = 12.91, range = 35–91, n  = 55). Values for 25 and 75% quartiles were 58 and 76 respectively. Analysis of the test-retest reliability of the 24-item scale produced an intraclass correlation coefficient of 0.82 ( n  = 29; 95% CI = 0.66–0.91), indicating good agreement between responses over 2 weeks. The mean score for Time 1 assessments was 67.75 (SD = 11.36, n  = 29), and Time 2 was 69.35 (SD = 8.80, n  = 29). The mean difference in scores over 2 weeks (Time 1–Time 2) was 1.60 (SD = 5.97) with values ranging from −18 to 7. Eight participants obtained the same score on both occasions.

Discussion

The initial BASQID item pool contained items drawn from nine different domains of QoL incorporating questions on health, social interaction, function, being occupied, energy, sleep, psychological well-being and environment. Questions not only included assessment of ‘feelings’, as in the DQoL [ 9 ], but also included an appraisal of different QoL areas. Framing appraisal items in terms of respondent satisfaction gives an indication as to how changes in function are cognitively processed by individuals [ 2 ]. This allows for the possibility that respondents may report higher levels of satisfaction in areas of poor performance, due to a low perceived importance of a QoL domain or the successful use of coping and adaptation [ 22 ]. In this way, the BASQID differs from measures such as the QoL-AD [ 16 ] which typically ask the respondent to rate actual performance. That respondents were able to complete the item pool with minimal missing data supports previous research that suggests people with mild to moderate dementia are able to respond appropriately to QoL questions [ 14 ], and express these responses using a standardised response scale [ 9 , 16 , 29 ]. Moreover, the level of test-retest reliability at both item and scale levels over a 2-week period supports the view that people in the earlier stages of dementia are able to respond consistently to such items [ 15 ].

Item analysis of the BASQID item pool reduced the number of items from 44 to 24. Items were rejected from the pool according to several criteria including item facility, item discrimination, response distribution, construct validity, and repeatability. The remaining 24 items form an internally consistent scale with good test-retest reliability over 2 weeks. All items within the final item pool display moderate to very good test-retest reliability, with 13 items displaying weighted kappa coefficients over 0.6.

Although the group data suggests that standardised QoL assessments can be used in this population, care must be taken when evaluating responses at an individual level. The Scientific Advisory Committee of the Medical Outcomes Trust [ 24 ] suggests that for group comparisons a minimum reliability coefficient (reproducibility and internal consistency) of 0.7 is required. As with existing self-reporting measures of QoL in dementia [ 9 , 16 , 29 ] the BASQID items when taken together fulfill this criterion. However, to use a measure for individual comparisons, a higher reliability coefficient of 0.9–0.95 is ideal. Reliability coefficients less than 0.9 lead to the potential for wide confidence intervals in relation to an individual's score. Therefore, care must be taken with the interpretation and use of individual scores, until more is known about those factors that predict the ability of individuals to reliably complete such measures. Further work is needed to determine the minimum cognitive requirements needed to complete self-reported QoL assessments.

However, the inevitability of unreliability in certain individual cases should not be used as an argument against self-reporting in dementia. The data presented here illustrates that self-reporting measures of QoL such as the BASQID, can provide valid, reliable and useful information at the group level, which allows exploration of the subjective experiences of people with dementia. Measurement in all fields is an imprecise science, and error may be introduced through a wide variety of sources, such as position effects, and satisfying strategies [ 3 , 30 ], and yet none prohibit measurement in other conditions or situations. As long as developers seek ways of reducing these potential sources of measurement error through careful attention to the wording and format of questionnaires, the cognitive limitations and reduced insight of respondents should not be used as justification for ignoring the perspective of the person with dementia on QoL issues.

Key points

  • Subjective accounts of quality of life (QoL) are necessary to better understand the experience of people with dementia.

  • Cognitive impairment and reduced insight have previously been viewed as barriers to completion of self-reported QoL assessments in dementia.

  • Data presented here adds to a growing body of evidence suggesting that people with mild to moderate dementia can complete standardised self-reported QoL assessments.

  • Reliability coefficients indicate that it is feasible and appropriate to obtain QoL ratings across a range of domains, from people with MMSE scores of >11.

  • Further work is needed to determine the minimum cognitive requirements needed to complete self-reported QoL assessments.

Conflicts of Interest

None

Sources of Research Funding

Alzheimer's Society, UK

Ethical Approval

The study was approved by the Bath Local Research Ethics Committee (ref. BA147/00-01)

References

1.
Albrecht
GL
Devleiger
PJ
The disability paradox: high quality of life against all the odds
Soc Sci Med
 , 
1999
, vol. 
48
 (pg. 
977
-
88
)
2.
Woods
RT
Promoting wellbeing and independence for people with dementia
Int J Geriatr Psychiatry
 , 
1999
, vol. 
14
 (pg. 
97
-
109
)
3.
Tourangeau
R
Rips
LJ
Rasinski
K
The Psychology of Survey Response
 , 
2000
Cambridge
Cambridge University Press
4.
Katschnig
H
Freeman
H
Sartorius
N
Quality of Life in Mental Disorders
 , 
1997
Chichester
John Wiley
5.
Agnew
SK
Morris
RG
The heterogeneity of anosognosia for memory impairment in Alzheimer's disease: a review of the literature and a proposed model
Aging Ment Health
 , 
1998
, vol. 
2
 (pg. 
7
-
19
)
6.
Zanetti
O
Vallotti
B
Frisoni
GB
, et al.  . 
Insight in dementia: When does it occur? Evdence for a nonlinear relationship between insight and cognitive status
J Gerontol
 , 
1999
, vol. 
54B
 (pg. 
100
-
6
)
7.
Green
J
Goldstein
FC
Sirockman
BE
Green
RC
Variable awareness of deficits in Alzheimer's disease
Neuropsychiatry, Neuropsychology and Behavioural Neurology
 , 
1993
, vol. 
6
 (pg. 
159
-
65
)
8.
Vasterling
JJ
Seltzer
B
Foss
JW
Vanderbrook
V
Unawareness of deficit in Alzheimer's disease: domain specific differences and disease correlates
Neuropsychiatry, Neuropsychol Behav Neurol
 , 
1995
, vol. 
8
 (pg. 
26
-
32
)
9.
Brod
M
Stewart
AL
Sands
L
Walton
P
Conceptualisation and measurement of quality of life in dementia: The dementia quality of life instrument (DQoL)
Gerontologist
 , 
1999
, vol. 
39
 (pg. 
25
-
35
)
10.
Seltzer
B
Vasterling
JJ
Hale
MA
Khurana
R
Unawareness of memory defecit in Alzheimer's disease: relation to mood and other disease variables
Neuropsychiatry, Neurophysiology and Behavioural Neurology
 , 
1995
, vol. 
8
 (pg. 
176
-
81
)
11.
Cohen
D
Eisdorfer
C
The Loss of Self
 , 
1986
New York
WW Norton
12.
Parmelee
PA
Lawton
MP
Katz
IR
Psychometric properties of the Geriatric Depression Scale among the institutionalised aged
Psychol Assess
 , 
1989
, vol. 
1
 pg. 
338
 
13.
McHorney
CA
Measuring and monitoring general health status in elderly persons. Practical and methodological issues using the SF-36 Health Survey
Gerontologist
 , 
1996
, vol. 
36
 (pg. 
571
-
83
)
14.
Mozley
CG
Huxley
P
Sutcliffe
C
, et al.  . 
Not knowing Where I am doesn't mean I don't know What I Like: Cognitive impairment and quality of life responses in elderly people
Int J Geriatr Psychiatry
 , 
1999
, vol. 
14
 (pg. 
776
-
83
)
15.
Feinburg
LF
Whitlatch
CJ
Are persons with cognitive impairment able to state consistent choices?
Gerontologist
 , 
2001
, vol. 
41
 (pg. 
374
-
82
)
16.
Logsdon
R
Gibbons
LE
McCurry
SM
Teri
L
Assessing quality of life in older adults with cognitive impairment
Psychosom Med
 , 
2002
, vol. 
64
 (pg. 
510
-
9
)
17.
Logsdon
R
Gibbons
LE
McCurry
SM
Teri
L
Quality of life in Alzheimer's disease: Patient and caregiver reports
J Ment Health Aging
 , 
1999
, vol. 
5
 (pg. 
21
-
31
)
18.
Sanifort
F
Becker
M
Diamond
R
Judgements of quality of life of individuals with severe mental disorders: Patient self-report versus provider perspectives
Am J Psychiatry
 , 
1996
, vol. 
153
 (pg. 
497
-
502
)
19.
Teri
L
Wagner
A
Assessment of depression in patients with Alzheimer's disease: Concordance among informants
Psychl Aging
 , 
1991
, vol. 
6
 (pg. 
280
-
5
)
20.
Lukovits
T
McDaniel
K
Behavioral disturbance in severe Alzheimer's disease: A comparison of family member and nursing staff reporting
J Am Geriat Soc
 , 
1992
, vol. 
40
 (pg. 
891
-
5
)
21.
Folstein
MF
Folstein
SE
McHugh
PR
Mini-Mental state: a practical guide for grading the cognitive state of patients for the clinician
J Psychiatr Res
 , 
1975
, vol. 
12
 (pg. 
189
-
98
)
22.
Trigg
R
Skevington
SM
Jones
RW
How can we best assess the quality of life of people with dementia?
The Bath Assessment of Subjective Quality of Life in Dementia (BASQID)
 , 
2007
 
in press
23.
Landis
JR
Koch
G
The measurement of observer agreement for categorical data
Biometrics
 , 
1977
, vol. 
33
 (pg. 
159
-
74
)
24.
Assessing health status and quality of life instruments: Attributes and review criteria
Qual Life Res
 , 
2002
, vol. 
11
 (pg. 
193
-
205
Scientific Advisory Committee of the Medical Outcomes Trust
25.
The World Health Organisation Quality of Life Assessment (WHOQOL): Development and general psychometric properties
Soc Sci Med
 , 
1998
, vol. 
46
 (pg. 
1569
-
85
The WHOQOL Group
26.
Kline
P
Handbook of Test Construction: Introduction to Psychometric Design
 , 
1986
London
Methuen
27.
Diagnostic and Statistical Manual of Mental Disorders
 , 
1994
4th
Washington, DC
APA
 
American Psychiatric Association (DSM-IV).
28.
Sprangers
MAG
Cull
A
Groenveld
M
EORTC Quality of Life Study Group Guidelines for Developing Questionnaire Modules
 , 
1998
Brussels
EORTC
 
EORTC Quality of Life Study Group
29.
Smith
SC
Lamping
DL
Banerjee
S
, et al.  . 
Measurement of health-related quality of life for people with dementia: development of a new instrument (DEMQOL) and an evaluation of current methodology
Health Technol Assess
 , 
2005
, vol. 
9
 
10
30.
Streiner
DL
Norman
GR
Health Measurement Scales: a Practical Guide to their Development and Use
 , 
1995
2nd
Oxford
Oxford University Press

Comments

0 Comments