Neurology -- Correspondence for Becker et al., 70 (16_Part

Correspondence published:

Use of antihypertensives and the risk of Parkinson disease: Alberto Ascherio, Caroline M. Tanner (29 August 2008)

Use of antihypertensives and the risk of Parkinson disease 29 August 2008

Alberto Ascherio,
Harvard School of Public Health
677 Huntington Avenue, Boston, MA 02115,
Caroline M. Tanner
Send Correspondence to journal:
Re: Use of antihypertensives and the risk of Parkinson disease

aascheri{at}hsph.harvard.edu Alberto Ascherio, et al.

The objective of Becker et al.’s article was “to explore the association between antihypertensive drug use and the risk of developing a first-time diagnosis of Parkinson’s disease (PD).” [1] However, the authors mention the possible neuroprotective effects of angiotensin converting enzyme inhibitors and calcium channel blockers.
If addressing possible neuroprotective effects is the primary purpose of the investigation, the logical analysis would be to examine whether use of different classes of antihypertensive among individuals who do not have PD is associated with future risk of developing PD. The results of such analysis were not included.
The authors focused their main analyses on current use of antihypertensives, defined as at least one prescription during the 90 days preceding the date of the first recording of a diagnosis of PD in the electronic medical record. Because all patients with a diagnosis of PD will have had symptoms for at least a few months before the diagnosis, “current use” may not accurately reflect use during the relevant period of exposure, which is before the onset of PD symptoms.

As the authors mention, tremor may lead to a new prescription of beta-blockers. Furthermore, a decline in blood pressure, which is frequent in individuals with PD, may lead to termination or change in antihypertensive medications. To overcome this potential source of bias, previous investigations using the same database--for example, to address the association between non-steroidal anti-inflammatory drugs and PD risk [2]— considered only exposures during a period of at least two years before the recording in the medical record of the first symptoms of PD. This is because the disease onset is insidious and often preceded by several months of neurological symptoms.
We encourage Dr. Becker et al. to complement their interesting paper by reporting whether use of antihypertensives up to two years before the onset of PD symptoms was related to risk of PD.
References
1. Becker C, Jick S and Meier C. Use of antihypertensives and the risk of Parkinson disease. Neurology 2998;70:1438-1444.
2. Hernan MA, Logroscino G, Garcia Rodriguez LA. Nonsteroidal anti- inflammatory drugs and the incidence of Parkinson disease. Neurology 2006;66:1097-1099.
Disclosures: The authors report no disclosures.
Editor's Note: The authors of the article were offered the opportunity to respond but declined.