Secular Change in Prevalence of Dementia in Western Australia
Aims: Increasingly we are reliant on administrative datasets to estimate population incidence and prevalence of dementia. It is unknown whether these estimates are stable over time.
Methods: . We obtained linked data from all people in Western Australia over the age of 50 years. The administrative datasets including hospital admitted patient data, emergency department attendance, cause-of-death data, Aged Care Assessment Program, cancer registry and mental health services data. Data were complete from 1980 until 2016. Incidence and prevalence rates of dementia were calculated based on the observed rates in the linked data from all available sources (prevalence data only described). Prevalence rates were calculated based on the number of persons living with dementia divided by the total number of persons alive at any point during each 5-year age period.
Results: There were 1,298,213 included in this study of which 49.7% were females. There was a marked increase in prevalence and incidence over the time period. Secular change in prevalence (%) over time for 5 year age groups is indicated in the table.
|
Time period |
60-64 years |
65-69 years |
70-74 years |
75-79 Year |
80-84 years |
|
1980-84 |
0.42 |
0.79 |
1.90 |
4.08 |
7.64 |
|
1985-89 |
0.48 |
0.93 |
2.17 |
5.21 |
10.59 |
|
1990-94 |
0.46 |
1.00 |
2.23 |
5.40 |
11.88 |
|
1995-99 |
0.50 |
1.09 |
2.48 |
6.24 |
13.47 |
|
2000-04 |
0.72 |
1.55 |
3.46 |
8.23 |
17.60 |
|
2005-09 |
1.07 |
2.22 |
4.95 |
10.84 |
22.13 |
Conclusions: There has been a doubling of prevalence of dementia as determined by administrative datasets between 1980-2010. This most likely represents an increased propensity to diagnose dementia over this period.