Cigarette smoking and outcomes after aneurysmal subarachnoid hemorrhage: a nationwide analysis

Abstract

OBJECTIVE Although cigarette smoking is one of the strongest risk factors for cerebral aneurysm development and rupture, there are limited data evaluating the impact of smoking on outcomes after aneurysmal subarachnoid hemorrhage (SAH). Additionally, two recent studies suggested that nicotine replacement therapy was associated with improved neurological outcomes among smokers who had sustained an SAH compared with smokers who did not receive nicotine. METHODS Patients who underwent endovascular or microsurgical repair of a ruptured cerebral aneurysm were extracted from the Nationwide Inpatient Sample (NIS, 2009-2011) and stratified by cigarette smoking. Multivariable logistic regression analyzed in-hospital mortality, complications, tracheostomy or gastrostomy placement, and discharge to institutional care (a nursing or an extended care facility). Additionally, the composite NIS-SAH outcome measure (based on mortality, tracheostomy or gastrostomy, and discharge disposition) was evaluated, which has been shown to have excellent agreement with a modified Rankin Scale score greater than 3. Covariates included in regression constructs were patient age, sex, race/ethnicity, insurance status, socioeconomic status, comorbidities (including hypertension, drug and alcohol abuse), the NIS-SAH severity scale (previously validated against the Hunt and Hess grade), treatment modality used for aneurysm repair, and hospital characteristics. A sensitivity analysis was performed matching smokers to nonsmokers on age, sex, number of comorbidities, and NIS-SAH severity scale score. RESULTS Among the 5784 admissions evaluated, 37.1% (n = 2148) had a diagnosis of tobacco use, of which 31.1% (n = 1800) were current and 6.0% (n = 348) prior tobacco users. Smokers were significantly younger (mean age 51.4 vs 56.2 years) and had more comorbidities compared with nonsmokers (p < 0.001). There were no significant differences in mortality, total complications, or neurological complications by smoking status. However, compared with nonsmokers, smokers had significantly decreased adjusted odds of tracheostomy or gastrostomy placement (11.9% vs 22.7%, odds ratio [OR] 0.63, 95% confidence interval [CI] 0.51-0.78, p < 0.001), discharge to institutional care (OR 0.71, 95% CI 0.57-0.89, p = 0.002), and a poor outcome (OR 0.65, 95% CI 0.55-0.77, p < 0.001). Similar statistical associations were noted in the matched-pairs sensitivity analysis and in a subgroup of poor-grade patients (the upper quartile of the NIS-SAH severity scale). CONCLUSIONS In this nationwide study, smokers experienced SAH at a younger age and had a greater number of comorbidities compared with nonsmokers, highlighting the negative ramifications of cigarette smoking among patients with cerebral aneurysms. However, smoking was also associated with paradoxical superior outcomes on some measures, and future research to confirm and further understand the basis of this relationship is needed.

Impact of smoking on course and outcome of aneurysmal subarachnoid hemorrhage

“…Presently, smokers were younger than nonsmokers. The difference was though less than in earlier studies reporting smokers to be 5-10 years younger than nonsmokers at the onset of their hemorrhage [7,44,59]. Aneurysm location was very similar in smokers and nonsmokers, and overall, our material shows the same distribution as that found in recent series [11,50], but ruptured aneurysm in the vertebrobasilar circulation was more common in our cohort than in that reported by Hammer at al.…”

“…With such long-lasting impact of smoking on the natural history of intracranial aneurysms, one cannot exclude that also the protective effects persist over some time. This is partly supported by former smokers faring slightly better on some measures than never-smokers in the study of Dasenbrock et al [7].…”

“…Several authors have found similar or lower mortality in smokers than nonsmokers after aSAH [7,14,44,51], and also functional outcome has been reported to be similar or superior in smokers [7,14,26,62]. Smokers are younger when experiencing aSAH [7,44,59], a factor that could contribute to this paradoxal outcome in smokers.…”

“…Moreover, in the paired analysis matched for age, the lower mortality in smokers persisted and even became significantly lower at 30 days. Several authors have found better outcomes in smokers compared with nonsmokers in different settings, including aSAH [1,7,14,35,44] an effect that could not be explained by younger age alone. "Paradoxically superior outcomes" in smokers have also been reported after myocardial infarction and after acute ischemic stroke, but may be due to residual confounding or lower baseline risks [1,35].…”

Survival bias explains improved survival in smokers and hypertensive individuals after aSAH

“…Two recent hospital-based studies reported that smokers and those with history of hypertension have better survival after aneurysmal subarachnoid hemorrhage (aSAH), 2,3 even though these two factors are considered the main risk factors for aSAH. 1 It is important to recognize that these studies included only hospital-admitted early aSAH survivors and excluded the sudden-death aSAH individuals that, among all aSAH cases, account for approximately 25%.…”