In the JournalsPerspective

Smoking prior to stroke may increase risk for functional dependence

Within 3 months after acute ischemic stroke, current smokers are at greater risk for unfavorable functional outcomes than patients who quit smoking or never started, according to research published in Stroke.

After adjusting for confounders, researchers in Japan determined that the likelihood for worse functional outcome 3 months after ischemic stroke were elevated in current smokers compared with nonsmokers (OR = 1.29; 95% CI, 1.11-1.49). However, worse functional outcome 3 months after ischemic stroke did not differ between former smokers and nonsmokers (OR = 1.05; 95% CI, 0.92-1.21).

Moreover, among former smokers who experienced ischemic stroke, the likelihood of poor functional outcome was higher in patients who quit smoking within 2 years of stroke compared with nonsmokers (OR = 1.75; 95% CI, 1.15-2.66).

“The present study suggests that neurological functions were significantly less improved during hospitalization in current smokers and in former smokers who had abstained for less than 2 years before stroke than in nonsmokers,” Ryu Matsuo, MD, PhD, of the department of medicine and clinical science and department of health care administration and management at Kyushu University, Fukuoka, Japan, and colleagues wrote. “Attenuated functional outcome at 3 months may be attributable at least in part to reduced poststroke neurological recovery.”

In other findings, the risk for worse functional outcome after ischemic stroke increased as the number of daily cigarettes increased in current smokers (P for trend = .002).

“The concept of dose-dependent detrimental effects of smoking is also relevant to poststroke short-term outcomes,” the researchers wrote. “Furthermore, it is interesting to note that detrimental effects on poststroke functional outcomes may also be avoided by those who have abstained from smoking for at least 2 years before the stroke. Thus, even from the standpoint of poststroke functional outcomes, smoking cessation or reduction is strongly recommended, particularly in people at high risk of ischemic stroke.”

Researchers used a multicenter hospital-based stroke registry in Japan to assess 10,825 patients (mean age 70 years; 37% women; 43% nonsmokers; 32% former smokers; 25% current smokers) hospitalized with acute ischemic stroke between July 2007 and December 2017. Clinical outcomes included poor functional outcome and functional dependence at 3 months after stroke onset in patients who were independent prior to stroke.

“The idea still remains that smoking may play neuroprotective roles in some central nervous system diseases (Quik M, et al. Mov Disord. 2012;doi:10.1002/mds.2502811; Piao WH, et al. Acta Pharmacol Sin. 2009;doi:10.1038/aps.2009.6712; Chang RC, et al. Acta Neuropathol. 2014;doi:10.1007/s00401-013-1210-x), which may arise because nicotine stimulates nicotinic acetylcholine receptors in memory-related neurons or because it induces dopamine secretion in dopaminergic cells,” the researchers wrote. “However, the present study does not corroborate the idea that smoking exerts beneficial neuroprotective effects in patients with acute ischemic stroke.” – by Scott Buzby

Disclosures: One author reports he received grants from the Smoking Research Foundation. The other authors report no relevant financial disclosures.

Within 3 months after acute ischemic stroke, current smokers are at greater risk for unfavorable functional outcomes than patients who quit smoking or never started, according to research published in Stroke.

After adjusting for confounders, researchers in Japan determined that the likelihood for worse functional outcome 3 months after ischemic stroke were elevated in current smokers compared with nonsmokers (OR = 1.29; 95% CI, 1.11-1.49). However, worse functional outcome 3 months after ischemic stroke did not differ between former smokers and nonsmokers (OR = 1.05; 95% CI, 0.92-1.21).

Moreover, among former smokers who experienced ischemic stroke, the likelihood of poor functional outcome was higher in patients who quit smoking within 2 years of stroke compared with nonsmokers (OR = 1.75; 95% CI, 1.15-2.66).

“The present study suggests that neurological functions were significantly less improved during hospitalization in current smokers and in former smokers who had abstained for less than 2 years before stroke than in nonsmokers,” Ryu Matsuo, MD, PhD, of the department of medicine and clinical science and department of health care administration and management at Kyushu University, Fukuoka, Japan, and colleagues wrote. “Attenuated functional outcome at 3 months may be attributable at least in part to reduced poststroke neurological recovery.”

In other findings, the risk for worse functional outcome after ischemic stroke increased as the number of daily cigarettes increased in current smokers (P for trend = .002).

“The concept of dose-dependent detrimental effects of smoking is also relevant to poststroke short-term outcomes,” the researchers wrote. “Furthermore, it is interesting to note that detrimental effects on poststroke functional outcomes may also be avoided by those who have abstained from smoking for at least 2 years before the stroke. Thus, even from the standpoint of poststroke functional outcomes, smoking cessation or reduction is strongly recommended, particularly in people at high risk of ischemic stroke.”

Researchers used a multicenter hospital-based stroke registry in Japan to assess 10,825 patients (mean age 70 years; 37% women; 43% nonsmokers; 32% former smokers; 25% current smokers) hospitalized with acute ischemic stroke between July 2007 and December 2017. Clinical outcomes included poor functional outcome and functional dependence at 3 months after stroke onset in patients who were independent prior to stroke.

“The idea still remains that smoking may play neuroprotective roles in some central nervous system diseases (Quik M, et al. Mov Disord. 2012;doi:10.1002/mds.2502811; Piao WH, et al. Acta Pharmacol Sin. 2009;doi:10.1038/aps.2009.6712; Chang RC, et al. Acta Neuropathol. 2014;doi:10.1007/s00401-013-1210-x), which may arise because nicotine stimulates nicotinic acetylcholine receptors in memory-related neurons or because it induces dopamine secretion in dopaminergic cells,” the researchers wrote. “However, the present study does not corroborate the idea that smoking exerts beneficial neuroprotective effects in patients with acute ischemic stroke.” – by Scott Buzby

Disclosures: One author reports he received grants from the Smoking Research Foundation. The other authors report no relevant financial disclosures.

    Perspective
    Larry B. Goldstein

    Larry B. Goldstein

    Cigarette smoking (and exposure to environmental tobacco smoke) are important risk factors for stroke. This study indicates that current or recent (within 2 years) smoking is also associated with poorer outcomes among those who have a stroke.

    As with other retrospective studies of this type, there remains the possibility of residual confounding (the possibility that an observed effect is due to an unmeasured factor associated with the measured factor).

    This study adds yet another reason not to smoke. 

    • Larry B. Goldstein, MD, FAAN, FANA, FAHA
    • Cardiology Today Editorial Board Member
      University of Kentucky

    Disclosures: Goldstein reports no relevant financial disclosures.