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. 2013 Apr 12:13:35.
doi: 10.1186/1471-2377-13-35.

A systematic review of biomarkers for disease progression in Parkinson's disease

David J M McGhee  1 , Pamela L Royle, Paul A Thompson, David E Wright, John P Zajicek, Carl E Counsell
Affiliations

A systematic review of biomarkers for disease progression in Parkinson's disease

David J M McGhee et al. BMC Neurol. .

Abstract

Background: Using surrogate biomarkers for disease progression as endpoints in neuroprotective clinical trials may help differentiate symptomatic effects of potential neuroprotective agents from true disease-modifying effects. A systematic review was undertaken to determine what biomarkers for disease progression in Parkinson's disease (PD) exist.

Methods: MEDLINE and EMBASE (1950-2010) were searched using five search strategies. Abstracts were assessed to identify papers meriting review in full. Studies of participants with idiopathic PD diagnosed by formal criteria or clearly described clinical means were included. We made no restriction on age, disease duration, drug treatment, or study design. We included studies which attempted to draw associations between any tests used to investigate disease progression and any clinical measures of disease progression. The electronic search was validated by hand-searching the two journals from which most included articles came.

Results: 183 studies were included: 163 (89%) cross-sectional, 20 (11%) longitudinal. The electronic search strategy had a sensitivity of 71.4% (95% CI 51.1-86.0) and a specificity of 97.1% (95% CI 96.5-97.7). In longitudinal studies median follow-up was 2.0 years (IQR 1.1-3.5). Included studies were generally poor quality--cross-sectional with small numbers of participants, applying excessive inclusion/exclusion criteria, with flawed methodologies and simplistic statistical analyses.

Conclusion: We found insufficient evidence to recommend the use of any biomarker for disease progression in PD clinical trials, which may simply reflect the poor quality of research in this area. We therefore present a provisional 'roadmap' for conducting future disease progression biomarker studies, and recommend new quality criteria by which future studies may be judged.

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Figures

Figure 1
Figure 1
Flow diagram outlying the selection procedure to identify 183 articles included in the systematic review of biomarkers for disease progression in PD. Note that of the 58 articles identified by reviewing reference lists, 41 were excluded, one article could not be located and 16 were included in the final qualitative synthesis. All eight articles identified by hand searching (all cross-sectional) were included in the final qualitative synthesis.
Figure 2
Figure 2
Flow diagram outlying a provisional ‘roadmap’ for conducting a study to determine whether a given biomarker is a suitable surrogate for a clinical measure of disease progression.
See this image and copyright information in PMC

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