Reports of trends in mortality from neurodegenerative disease have long relied on death
certificates registries and other nationally-administered databanks to determine the state and
direction of public health regarding these conditions. In this article, Mylne et. al. turned to the
Office of National Statistics, England to ascertain the death statistics for patients with
Parkinson's disease (PD) for the most recent time period available. Their findings are both
intriguing and encouraging, and deserve further comment

Haberfeld, Elizabeth

Louis, Elan D.

English

PubMed

Columbia University Academic Commons

Is Parkinson's disease-related Mortality Declining?Elizabeth Haberfeld, MD1,2 and Elan Louis, MD, MS1,2,3,41G.H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NYUSA.2Department of Neurology, College of Physicians and Surgeons, Columbia University, New York,NY USA.3Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physiciansand Surgeons, Columbia University, New York, NY, USA4Department of Epidemiology, Mailman School of Public Health, Columbia University, New York,NY 10032, USA.Reports of trends in mortality from neurodegenerative disease have long relied on deathcertificates registries and other nationally-administered databanks to determine the state anddirection of public health regarding these conditions. In this article, Mylne et. al. turned to theOffice of National Statistics, England to ascertain the death statistics for patients withParkinson's disease (PD) for the most recent time period available. Their findings are bothintriguing and encouraging, and deserve further comment.Previous reports of PD mortality trends typically used cause of death data extracted from deathcertificates. This approach can under-ascertain such deaths, because there is a tendency torecord on these certificates the proximal cause of death (i.e., pneumonia) rather than anunderlying chronic illness (PD) as the main cause of death1,2, 3.To address this issue, the researchers used a different methodology. Instead of using only thosethat listed PD as the cause of death, they analyzed all the death certificates that mentioned PDas present, even if it was not the proximal cause of death. Because data on such “mentions” ofPD were only available beginning in 1993, they analyzed the data from that year onwards.Because there was no exactly comparable data on mortality for preceding years, they comparedthe trend observed not against an earlier era but against itself, mapping out the contour of theperiod under observation.Several trends emerged. Principally, there was a nearly one-fifth decline in age-standardizedmortality rates over the years 1993!2006. This decline was more pronounced in men, and inolder age groups, specifically those "85 years old.Several issues deserve further discussion.First is the data acquisition itself. Death certificates are a convenient and well-established, butoften limited, data source. Inclusion of neurodegenerative disease on the death certificate isinconsistent and under-represented4, and can be influenced by factors such as socioeconomonicstatus5 the latter being perhaps a proxy for place of death, or for who completed the deathcertificate (personal physician with thorough knowledge of the patient vs. another physician).Correspondence: Dr. Elan Louis, Unit 198, Neurological Institute, 710 West 168th Street, New York, NY, 10032, USA. Tel: (212) 305! 9194, FAX: (212) 305 !1304, Email: edl2@columbia.edu.Conflict of Interest: None.NIH Public AccessAuthor ManuscriptEur J Neurol. Author manuscript; available in PMC 2009 September 1.Published in final edited form as:Eur J Neurol. 2009 September ; 16(9): 964–965. doi:10.1111/j.1468-1331.2009.02711.x.NIH-PA Author ManuscriptNIH-PA Author ManuscriptNIH-PA Author ManuscriptUnder- or inaccurate reporting stands to hamper true estimates of disease-specific mortality.The authors sought to overcome this by using “mentions” instead of “cause of death” data.Mentions, however, may also be subject to some extent to such biases.Second, examining the data, one observes a substantial decrease in standardized mortality ratesin the early years under study (Appendix 1). There is disproportionate weight of these earlyyears in determining the overall size of the downward trend. Among both men and women,approximately 50% of the overall decline seen in the 14-year interval studied occurred duringthe first 4 years of that period (1993!1996). Why this early decline occurred is not clear; a1993 change in coding practice resulted in a decreasein reporting of PD as the principal causeof death, but the use of mentions, and the starting point of 1993, are meant to overcome exactlythat artifact. This early downtick is particularly evident in older age groups. Explanation ofthis phenomenon may be beyond the scope of the study, but deserves further analysis. Had theanalysis period started in 1996, the overall declining trend would have been a more modestone.Third, if the mortality rate among people with PD is truly declining to a significant degree, onewould expect a corresponding increase in prevalence during the same period. However, as theauthors note, prevalence of PD in this population in the past 30 years has been constant6. Thissuggests a decrease in incidence, but incidence data have proved difficult to obtain.If there is truly a decrease in mortality of even a moderate degree for patients with PD, whatis the reason? The authors cite several possibilities, noting that the trend observed could becaused by either a true decrease in incidence, or an increase in survival, which in turn may bedue to better medical care. If the latter is the explanation, this would indeed be noteworthy.The data seen here are a promising beginning. Perhaps most positive for PD patients is thesuggestion that the decline has not yet reached a plateau. Repeated measures of these figuresat future intervals will provide the clearest picture of how far this trend has come, and whetherit continues.AcknowledgmentsSupport: RO1 NS039422 from the National Institutes of Health (Bethesda, MD, USA).REFERENCES1. Smith Sehdev AE, Hutchins GM. Problems with proper completion and accuracy of the cause-of-deathstatement. Arch Intern Med Jan 22;2001 161(2):277–84. [PubMed: 11176744]2. Johansson LA, Björkenstam C, Westerling R. Unexplained differences between hospital and mortalitydata indicated mistakes in death certification: an investigation of 1,094 deaths in Sweden during 1995.J Clin Epidemiol. Apr 11;20093. Stalioraityte E, Pangonyte D, Kazlauskaite D. Reliability of cause-specific mortality rate statistics:case of Lithuania. Public Health Sep;2005 119(9):799–807. [PubMed: 15990128]4. Nath U, Thomson R, Wood R, Ben-Shlomo Y, Lees A, Rooney C, Burn D. Population based mortalityand quality of death certification in progressive supranuclear palsy (Steele-Richardson-Olszewskisyndrome). J Neurol Neurosurg Psychiatry Apr;2005 76(4):498–502. [PubMed: 15774434]5. Pressley JC, Tang MX, Marder K, Cote LJ, Mayeux R. Disparities in the recording of Parkinson'sdisease on death certificates. Mov Disord Mar;2005 20(3):315–21. [PubMed: 15580618]6. Porter B, Macfarlane R, Unwin N, Walker R. The prevalence of Parkinson's disease in an area of NorthTynesdale in the North-East Corner of England. Neuroepidemiology 2006;26(3):156–61. [PubMed:16493203]Haberfeld and Louis Page 2Eur J Neurol. Author manuscript; available in PMC 2009 September 1.NIH-PA Author ManuscriptNIH-PA Author ManuscriptNIH-PA Author Manuscript

Is Parkinson's disease-related mortality declining?

http://dx.doi.org/10.1111/j.1468-1331.2009.02711.x

Is Parkinson's disease-related mortality declining?

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