Smoking Paradox in Patients Hospitalized With Coronary Artery Disease or Acute Ischemic Stroke

Abstract

Despite the plethora of data exploring smokers' post-MI survival advantage, the role of cigarette smoking in the shortterm prognosis after AIS remains to be clarified, and analyses Background-Smoking is a potent risk factor for coronary artery disease (CAD) and acute ischemic stroke (AIS), but there are numerous reports of lower in-hospital mortality among smokers versus nonsmokers hospitalized for these events. Methods and Results-We analyzed all consecutive patients hospitalized with a first index CAD (n=158 054) or AIS (n=899 295) event in Get With The Guidelines from 2002 to 2012; 20.4% of AIS and 30.4% of patients with CAD were past-year smokers. Multivariable models and age-stratified analyses were used to estimate the adjusted odds ratio of in-hospital mortality in smokers versus nonsmokers. Smokers were younger, more often male, with fewer vascular risk factors, and were more likely to be admitted to hospitals that were large, academic, or in the South. In-hospital mortality was significantly lower among smokers in both CAD (2.7% versus 5.2%; P<0.0001) and AIS (3.5% versus 5.8%; P<0.0001). The difference between unadjusted and adjusted odds ratios for smoking (0.57 versus 0.86 in CAD; 0.56 versus 0.86 in AIS) indicates the presence of substantial confounding by age and other covariates, but a significant association of past-year smoking remained. Conclusions-Among patients hospitalized with CAD and AIS, smoking is a risk factor for early age of onset, even among those with few vascular risk factors. The persistent association with lower in-hospital mortality after adjusted and stratified analyses probably represents residual unmeasured confounding, although a biological effect of smoking cannot be excluded.Further clinical and prospective population-based studies are needed to explore variables that contribute to outcomes in these patients. (Circ Cardiovasc Qual Outcomes. 2015;8:S73-S80.

Electroencephalography Patterns and Prognosis in Acute Ischemic Stroke

“…The association of age with the occurrence of seizures after stroke is controversial with younger age shown as a risk factor for early seizures, while others have not shown such association [7,8]. The association of smoking with better functional outcome might be explained by the effect of confounding (as smokers tend to have strokes at younger ages and also fewer vascular risk factors) or a possible true association (“the smoking paradox”) [16]. However, this was not statistically significant (OR 0.55, 95% CI 0.27-1.12; p = 0.11).…”

Smoker's Paradox in Patients With ST‐Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention

“…Some prior studies, however, have suggested the existence of a “smoker's paradox,” implying that the outcomes of acute myocardial infarction (MI) may be more favorable in smokers than in nonsmokers 2, 3, 4, 5, 6. More recently, smoking has also been shown to be associated with lower in‐hospital mortality in patients with acute ischemic stroke, acute heart failure, and cardiac arrest 7, 8, 9, 10…”

“…[2][3][4][5][6] More recently, smoking has also been shown to be associated with lower in-hospital mortality in patients with acute ischemic stroke, acute heart failure, and cardiac arrest. [7][8][9][10] This phenomenon of smoker's paradox was first introduced into scientific discourse >25 years ago, when studies in the prethrombolytic era showed that smokers with acute MI experienced lower mortality compared with nonsmokers. [3][4][5]11 Similar findings of paradoxical associations with smoking were also seen subsequently in randomized clinical trials investigating thrombolytic therapy for ST-segment elevation MI (STEMI).…”

A score using left ventricular diastolic dysfunction to predict 90-day mortality in acute ischemic stroke: The DONE score

“…However, previous studies have shown that they seem to be associated with lower mortality after coronary artery disease or acute ischemic stroke. [25,26] Mechanisms of these paradoxes remain unclear.…”