Is the effectiveness of memory assessment services associated with their structural and process characteristics?

Estimating the minimum important difference in the DEMQOL instrument in people with dementia

PURPOSE

The Dementia-Related Quality of Life (DEMQOL) measure and the DEMQOL-Utility Score (DEMQOL-U) are validated tools for measuring quality of life (QOL) in people with dementia. What score changes translate to a clinically significant impact on patients' lives was unknown. This study establishes the minimal important differences (MID) for these two instruments.

METHODS

Anchor-based and distribution-based methods were used to estimate the MID scores from patients enrolled in a randomised controlled trial. For the anchor-based method, the global QOL (Q29) item from the DEMQOL was chosen as the anchor for DEMQOL and both Q29 and EQ-5D for DEMQOL-U. A one category difference in Q29, and a 0.07 point difference in EQ-5D score, were used to classify improvement and deterioration, and the MID scores were calculated for each category. These results were compared with scores obtained by the distribution-based methods.

RESULTS

A total of 490 people with dementia had baseline DEMQOL data, of these 386 had 8-month data, and 344 had 12-month DEMQOL data. The absolute change in DEMQOL for a combined 1-point increase or decrease in the Q29 anchor was 5.2 at 8 months and 6.0 at 12 months. For the DEMQOL-U, the average absolute change at 8 and 12 months was 0.032 and 0.046 for the Q29 anchor and 0.020 and 0.024 for EQ-5D anchor.

CONCLUSION

We present MID scores for the DEMQOL and DEMQOL-U instruments obtained from a large cohort of patients with dementia. An anchored-based estimate of the MID for the DEMQOL is around 5 to 6 points; and 0.02 to 0.05 points for the DEMQOL-U. The results of this study can guide clinicians and researchers in the interpretation of these instruments comparisons between groups or within groups of people with dementia.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

ISRCTN17993825 on 11th October 2016.

Memory assessment services and health-related quality of life: 1-year follow-up

OBJECTIVES

Our group has already demonstrated that patients' health-related quality of life (HRQL) improves in the first 6 months after their first appointment at memory assessment services (MASs), but the sustainability of such gains is unknown. We aimed to describe changes in patients' HRQL at 12 months after their first MAS appointment and to examine associations with patient and MAS characteristics.

METHODS

We collected data from 702 patients and 452 lay caregivers at the first appointment and 12 months later. Multivariable linear regression was used to examine the relationships of change in HRQL (self-reported and proxy-reported) with patients' characteristics and use of post-diagnostic interventions, and multilevel models were used to analyse the relationships of HRQL with MAS characteristics.

RESULTS

In the whole group, self-reported HRQL improved over 12 months (+3.5 points, 95% CI 2.7 to 4.2). Among people diagnosed with dementia, improvement in HRQL was more than double that among those with mild cognitive impairment or no diagnosis. Proxy-reported HRQL improved only in those diagnosed with dementia (+1.2 points, 95% CI 0.2 to 2.2). Changes in HRQL were not associated with any patient characteristics. The only feature of MASs associated with larger improvements in HRQL was the presence of advisory and support staff.

CONCLUSIONS

Improvements in HRQL observed at 6 months are maintained up to 1 year after the first MAS appointment, more so among those who receive a diagnosis of dementia. Continued follow-up will determine if the improvement is even longer lasting.