Friday, 30 June 2017

Association of Autonomic Dysfunction With Disease Progression and Survival in Parkinson Disease

These post mortem studies have high value given the certainty in diagnosis and there still being an appreciable misdiagnosis rate in patients still living... for example, Multiple System Atrophy is a parkinsonian disorder associated with autonomic dysfunction and reduced survival. If there were a few MSA patients in amongst people with Parkinson's in a living cohort, then their presence could induce an association between autonomic dysfunction and reduced survival, and be attributed to an effect of AutD and survival in people Parkinson's... this would be an example of bias. By using post mortem diagnosis as the standard, the authors navigate around that potential source of misclassification.

People have intuitively associated AutD with more severe forms of Parkinson's or being at a more advanced stage clinically. This study reaffirms this suspicions. It is interesting however to see that pathological staging was not associated...

 2017 Jun 26. doi: 10.1001/jamaneurol.2017.1125. [Epub ahead of print]

IMPORTANCE: 

Evidence suggests that development of autonomic dysfunction (AutD) may negatively affect disease course and survival in patients with synucleinopathies. However, the few available studies on Parkinson disease (PD) have conflicting results, comprise a small number of patients, have short follow-up periods, and lack pathologic confirmation of the diagnosis.

OBJECTIVE: 

To examine the association of time of onset of AutD with disease progression and survival in PD.

DESIGN, SETTING, AND PARTICIPANTS: 

This retrospective review of clinical data from 100 consecutive patients with an autopsy-confirmed diagnosis of PD from the archives of the Queen Square Brain Bank in London, United Kingdom, from January 1, 2006, to June 3, 2016, included patients with PD regularly seen by hospital specialists (neurologists or geriatricians) in the United Kingdom throughout their disease until death. Patients with dementia before or within 1 year after onset of motor symptoms, monogenic forms of PD, comorbidities that affect autonomic function, a coexisting neuropathologic diagnosis, or insufficient clinical information were excluded.

MAIN OUTCOMES AND MEASURES: 

Survival and time from diagnosis to specific disease milestones were calculated to assess disease progression. Autonomic dysfunction was defined as autonomic failure at autonomic function testing or 2 of the following symptoms: urinary symptoms, constipation, upper gastrointestinal tract dysfunction, orthostatic hypotension, sweating abnormalities, or erectile dysfunction. Multivariable Cox proportional hazards regression models on the risk of a disease milestone and death were used.

RESULTS: 

A total of 100 patients (60 [60.0%] male; mean [SD] age at diagnosis, 63.9 [10.3] years; mean [SD] disease duration, 14.6 [7.7] years) were studied. Autonomic dysfunction developed in 85 patients (mean [SD] time from diagnosis, 6.7 [7.7] years) and was associated with older age at diagnosis, male sex, poor initial levodopa treatment response, and postural instability and gait difficulty motor PD subtype in linear regression analysis, but staging of α-synuclein pathologic changes was unrelated. Earlier AutD increased the risk of reaching the first milestone (hazard ratio, 0.86; 95% CI, 0.83-0.89; P < .001) and shortened survival (hazard ratio, 0.92; 95% CI, 0.88-0.96; P < .001). Older age at diagnosis and poorer levodopa treatment response were the other factors associated with shorter survival in adjusted multivariate analysis.

CONCLUSIONS AND RELEVANCE: 

Earlier AutD is associated with a more rapid development of disease milestones and shorter survival in patients with PD.

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