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From a news article titled Having OCD May Triple a Person's Odds for a Stroke:

Dr. Larry Goldstein, chairman of the University of Kentucky department of neurology in Lexington, reviewed the study findings. Goldstein pointed out that the actual risk of stroke among OCD patients is quite low. "Although the relative risk of ischemic stroke is approximately three times higher in those with a history of OCD, the absolute risk is small, less than 1% over the course of the follow-up period," he said. That translates to one additional stroke over the follow-up period among those with OCD. Goldstein also said that the findings may be affected by factors that the researchers could not control for, which could weaken the link they identified. He pointed out that there was no assessment of the types or effectiveness of risk factor controls over time in reducing stroke odds. The study was conducted in Taiwan, and more research would be needed to learn if the results would be similar in other populations, Goldstein added. "Nonetheless, the results should prompt further study of the relationship between OCD and stroke risk," he said.

I cannot understand the meaning of the sentence in bold, and would be very grateful for a simple-language explanation.

There was no "assessment of the types of risk factor controls" or "assessment of the effectiveness of risk factor controls". Am I right in reading it thus? But what does it mean?

And what part of the sentence does "over time in reducing stroke odds" refer to? I cannot parse the whole sentence, it's breaking up for me. I'm not a native speaker of English so maybe I'm missing something.

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Full Background

The full-text of the study that Dr. Goldstein discusses is available online at: https://www.ahajournals.org/doi/10.1161/STROKEAHA.120.032995

Chen MH, Tsai SJ, Su TP, Li CT, Lin WC, Chen TJ, Pan TL, Bai YM. Increased Risk of Stroke in Patients With Obsessive-Compulsive Disorder: A Nationwide Longitudinal Study. Stroke. 2021 May 27:STROKEAHA120032995. doi: 10.1161/STROKEAHA.120.032995. Epub ahead of print. PMID: 34039028.

The study used computer-stored data from the Taiwan Health Insurance Research Database. People with a diagnosis of obsessive compulsive disorder (OCD) were identified along with a matched group of people without (OCD) of equal size. The factors used to match the people without OCD to those with OCD included age, sex, income, and, among others, several factors that are known to be important risk factors for ischemic stroke—smoking, ischemic heart disease, dyslipidemia, hypertension, diabetes, and obesity. As the authors point out, prior research has shown an association between OCD and risk factors for stroke including diabetes and obesity.

The people were “followed” (in the database) through 2010 to identify cases of ischemic and hemorrhagic stroke in the two groups.

The number of people in the OCD and non-OCD groups were equal (28,064) and the two groups had identical percentages with the stroke related risk factors (smoking, ischemic heart disease, dyslipidemia, hypertension, diabetes, obesity) in the two groups (OCD and non-OCD). At the end of “follow-up,” there were 82 ischemic strokes in the OCD group (0.29%) and 24 in the non-OCD group (0.09%).

Dr. Goldstein’s Comment

Dr. Goldstein’s refers to factors that “the researchers could not control for” as a possible explanation for the study findings. His difficult to follow sentence follows:

“He pointed out that there was no assessment of the types or effectiveness of risk factor controls over time in reducing stroke odds.”

Effect of Risk Factor Management on the Risk of Ischemic Stroke

A recent review of stroke prevention discusses interventions to prevent ischemic stroke. https://www.ncbi.nlm.nih.gov/books/NBK470234/

Reduction in blood pressure using anti-hypertensive drugs, statin treatment in people with hyperlipidemia, aspirin treatment in people with ischemic heart disease, and careful management of elevated blood glucose in people with diabetes prevent ischemic stroke and/or cerebral atherosclerosis.

What the Study Did and Did Not Do

The people with OCD and without OCD were well-matched for the main risk factors for ischemic stroke.

No attempt was made to account for possible differences in the management/treatment of these risk factors comparing the people with OCD and without OCD.

Answer to the Question Posed

Differences in the management of risk factors for ischemic stroke during follow-up comparing people with OCD and those without OCD is a possible explanation for the higher risk of ischemic stroke in people with OCD that was observed in this study.

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  • Very nicely done!
    – Armand
    May 31 at 0:13
  • Thank you! It turns out that I misunderstood the meaning of controls here. It stands for "measures to curb the risk". Whew! Now it all dovetails into a meaningful sentence. May 31 at 3:53
  • 2
    @CopperKettle I also found the sentence very confusing! May 31 at 22:29

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