Projected number of people with Parkinson disease in the most populous nations, 2005 through 2030
Vincent P.Calabrese, MD, FAAN (senior), retired, Midlothian, VA 23113linvincal@verizon.net
Submitted April 01, 2007
The article by Dorsey et al is an important update of a lingering
question about the worldwide incidence of Parkinson’s disease (PD). [1] While they
report an increasing prevalence, there are questions about
their study design. They state the study examines the incidence and
prevalence in the ten most populous countries of the world, yet the data
from four of the ten are manipulated.
In the absence of data, the authors should have stated that
fact and then proceed to use the data from neighboring countries. It would have been more effective if the authors used data from the ten most populous countries
where data is available and then point out that specific countries should have been included but there were no data.
Neighboring countries
can have markedly different populations, environment and geography so data extrapolated from one country to another may not be accurate. Estonia is ethnically, environmentally and geographically
different from Russia as is Singapore from Indonesia. It appears that
there is data from India, Pakistan and Bangladesh when it is actually one
set of data for all three.
For example, people in
India, Pakistan and Bangladesh have a curiously flat prevalence from age
60 to 80+ when actually it is only India which reflects this incidence. The way the
data is presented it initially appears that the prevalence remains
flat in this vast area of the world. Russia and Indonesia have a very
high prevalence in the 80+ group, when it is Estonia and
Singapore that show this trend.
Presenting the data more clearly would have enhanced the article. Their conclusions are perhaps valid but their extrapolation
of data from one country to another may not be.
References
1. Dorsey ER, Constantinescu R, Thompson JP, et al. Projected number of people with Parkinson disease in the most populous nations, 2005 through 2030. Neurology 2007; 68: 384-386.
Disclosure: The author is an investigator for Schwarz
Pharma and Kyowa Pharma.
The article by Dorsey et al is an important update of a lingering question about the worldwide incidence of Parkinson’s disease (PD). [1] While they report an increasing prevalence, there are questions about their study design. They state the study examines the incidence and prevalence in the ten most populous countries of the world, yet the data from four of the ten are manipulated.
In the absence of data, the authors should have stated that fact and then proceed to use the data from neighboring countries. It would have been more effective if the authors used data from the ten most populous countries where data is available and then point out that specific countries should have been included but there were no data.
Neighboring countries can have markedly different populations, environment and geography so data extrapolated from one country to another may not be accurate. Estonia is ethnically, environmentally and geographically different from Russia as is Singapore from Indonesia. It appears that there is data from India, Pakistan and Bangladesh when it is actually one set of data for all three.
For example, people in India, Pakistan and Bangladesh have a curiously flat prevalence from age 60 to 80+ when actually it is only India which reflects this incidence. The way the data is presented it initially appears that the prevalence remains flat in this vast area of the world. Russia and Indonesia have a very high prevalence in the 80+ group, when it is Estonia and Singapore that show this trend.
Presenting the data more clearly would have enhanced the article. Their conclusions are perhaps valid but their extrapolation of data from one country to another may not be.
References
1. Dorsey ER, Constantinescu R, Thompson JP, et al. Projected number of people with Parkinson disease in the most populous nations, 2005 through 2030. Neurology 2007; 68: 384-386.
Disclosure: The author is an investigator for Schwarz Pharma and Kyowa Pharma.