Neal S. Parikh

A Simplified Mechanistic Algorithm for Treating Resistant Hypertension: Efficacy in a Retrospective Study

J Clin Hypertens (Greenwich). 2012;14:191–197. ©2012 Wiley Periodicals, Inc.

Stroke Risk and Mortality in Patients With Ventricular Assist Devices

Background and Purpose— Ventricular assist devices (VADs) have advanced the management of end-stage heart failure. However, these devices are associated with hemorrhagic and thrombotic complications, including stroke. We assessed the incidence, risk factors, and outcomes of ischemic and hemorrhagic stroke after VAD placement. Methods— Using administrative claims data from acute care hospitals in California, Florida, and New York from 2005 to 2013, we identified patients who underwent VAD placement, defined by the International Classification of Diseases, Ninth Revision, Clinical Modification code 37.66. Ischemic and hemorrhagic strokes were identified by previously validated coding algorithms. We used survival statistics to determine the incidence rates and Cox proportional hazard analyses to examine the associations. Results— Among 1813 patients, we identified 201 ischemic strokes and 116 hemorrhagic strokes during 3.4 (±2.0) years of follow-up after implantation of a VAD. The incidence of stroke was 8.7% per year (95% confidence interval [CI], 7.7–9.7). The annual incidence of ischemic stroke (5.5%; 95% CI, 4.8–6.4) was nearly double that of hemorrhagic stroke (3.1%; 95% CI, 2.6–3.8). Women faced a higher hazard of stroke than men (hazard ratio, 1.6; 95% CI, 1.2–2.1), particularly hemorrhagic stroke (hazard ratio, 2.2; 95% CI, 1.4–3.4). Stroke was strongly associated with subsequent in-hospital mortality (hazard ratio, 6.1; 95% CI, 4.6–7.9). Conclusions— The incidence of stroke after VAD implantation was 8.7% per year, and incident stroke was strongly associated with subsequent in-hospital mortality. Notably, ischemic stroke occurred at nearly twice the rate of hemorrhagic stroke. Women seemed to face a higher risk for hemorrhagic stroke than men.

Association between Liver Disease and Intracranial Hemorrhage.

BACKGROUND Liver disease is common and associated with clinical and laboratory evidence of coagulopathy. The association between liver disease and intracranial hemorrhage (ICH) remains unclear. Our aim was to assess whether liver disease increases the risk of ICH. METHODS We performed a retrospective cohort study based on administrative claims data from California, Florida, and New York acute care hospitals from 2005 through 2011. Of a random 5% sample, we included patients discharged from the emergency department or hospital after a diagnosis of liver disease and compared them to patients without liver disease. Patients with cirrhotic liver disease were additionally analyzed separately. Kaplan-Meier survival statistics were used to calculate cumulative rates of incident ICH, and Cox proportional hazard analysis was used to adjust for demographic characteristics, vascular disease, and Elixhauser comorbidities. Multiple models tested the robustness of our results. RESULTS Among 1,909,816 patients with a mean follow-up period of 4.1 (±1.8) years, the cumulative rate of ICH after a diagnosis of liver disease was 1.70% (95% confidence interval [CI], 1.55%-1.87%) compared to .40% (95% CI, .39%-.41%) in patients without liver disease (P <.001 by the log-rank test). Liver disease remained associated with an increased hazard of ICH after adjustment for demographic characteristics and vascular risk factors (hazard ratio [HR], 1.8; 95% CI, 1.6-2.0). This was attenuated in models additionally adjusted for general comorbidities (HR, 1.3; 95% CI, 1.2-1.5). CONCLUSIONS There is a modest, independent association between liver disease and the risk of ICH.

Association Between Cirrhosis and Stroke in a Nationally Representative Cohort

Importance Cirrhosis is associated with hemorrhagic and thrombotic extrahepatic complications. The risk of cerebrovascular complications is less well understood. Objective To investigate the association between cirrhosis and various stroke types. Design, Setting, and Participants We performed a retrospective cohort study using inpatient and outpatient Medicare claims data from January 1, 2008, through December 31, 2014, for a random 5% sample of 1 618 059 Medicare beneficiaries older than 66 years. Exposures Cirrhosis, as defined by a validated diagnosis code algorithm. Main Outcomes and Measures The primary outcome was stroke, and secondary outcomes were ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage as defined by validated diagnosis code algorithms. Results Among 1 618 059 beneficiaries, 15 586 patients (1.0%) had cirrhosis (mean [SD] age, 74.1 [6.9] years; 7263 [46.6%] female). During a mean (SD) of 4.3 (1.9) years of follow-up, 77 268 patients were hospitalized with a stroke. The incidence of stroke was 2.17% (95% CI, 1.99%-2.36%) per year in patients with cirrhosis and 1.11% (95% CI, 1.10%-1.11%) per year in patients without cirrhosis. After adjustment for demographic characteristics and stroke risk factors, patients with cirrhosis had a higher risk of stroke (hazard ratio [HR], 1.4; 95% CI, 1.3-1.5). The magnitude of association appeared to be higher for intracerebral hemorrhage (HR, 1.9; 95% CI, 1.5-2.4) and subarachnoid hemorrhage (HR, 2.4; 95% CI, 1.7-3.5) than for ischemic stroke (HR, 1.3; 95% CI, 1.2-1.5). Conclusions and Relevance In a nationally representative sample of Medicare beneficiaries, cirrhosis was associated with an increased risk of stroke, particularly hemorrhagic stroke. A potential explanation of these findings implicates the mixed coagulopathy observed in cirrhosis.

Rates of Spinal Cord Infarction After Repair of Aortic Aneurysm or Dissection

Background and Purpose— The rate of spinal cord infarction (SCI) after surgical or endovascular repair of an aortic aneurysm or dissection is unclear. Methods— Using administrative claims data, we identified adult patients discharged from nonfederal acute care hospitals in California, New York, and Florida who underwent surgical or endovascular repair of an aortic aneurysm or dissection between 2005 and 2013. Patients with SCI diagnosed before the aortic repair were excluded. Our primary outcome was an SCI during the index hospitalization for aortic repair. Descriptive statistics were used to estimate crude rates of SCI. Analyses were stratified by whether the aneurysm or dissection had ruptured and by type of repair (surgical versus endovascular). Results— We identified 91 212 patients who had repair of an aortic aneurysm or dissection. SCI occurred in 235 cases (0.26%; 95% confidence interval [CI], 0.22%–0.29%). In patients with ruptured aneurysm or dissection, the rate of SCI was 0.74% (95% CI, 0.60%–0.88%) compared with 0.16% (95% CI, 0.13%–0.19%) with unruptured aneurysm. In secondary analyses, rates of SCI were similar after endovascular repair (0.91%; 95% CI, 0.62%–1.19%) compared with surgical repair (0.68%; 95% CI, 0.53%–0.83%; P=0.147) of ruptured aortic aneurysm or dissection; however, rates of SCI were higher after surgical repair (0.20%; 95% CI, 0.15%–0.25%) versus endovascular repair (0.11%; 95% CI, 0.08%–0.14%; P<0.001) of unruptured aneurysm. Conclusions— SCI occurs in ≈1 in 130 patients undergoing aortic dissection or ruptured aortic aneurysm repair and in 1 in 600 patients undergoing unruptured aortic aneurysm repair.

The imaging spectrum of posterior reversible encephalopathy syndrome: A pictorial review

Posterior reversible encephalopathy syndrome (PRES) is characterized by the acute onset of neurologic symptoms (headache, altered mental status, visual changes, seizures) with accompanying vasogenic edema on brain imaging. Risk factors for PRES include infection, uremia, malignancy, autoimmune disorders, the peripartum state and hypertension. PRES is classically described as being posterior (i.e. parieto-occipital) but radiologic variants are increasingly recognized. This pictorial review demonstrates the heterogeneity of the different radiologic presentations of PRES in reference to lesion distribution, hemorrhage, diffusion restriction, contrast enhancement, and other associated findings.

Discharge Disposition After Stroke in Patients With Liver Disease

Background and Purpose— Liver disease is associated with both hemorrhagic and thrombotic processes, including an elevated risk of intracranial hemorrhage. We sought to assess the relationship between liver disease and outcomes after stroke, as measured by discharge disposition. Methods— Using administrative claims data, we identified a cohort of patients hospitalized with stroke in California, Florida, and New York from 2005 to 2013. The predictor variable was liver disease. All diagnoses were defined using validated diagnosis codes. Ordinal logistic regression was used to analyze the association between liver disease and worsening discharge disposition: home, nursing/rehabilitation facility, or death. Secondarily, multiple logistic regression was used to analyze the association between liver disease and in-hospital mortality. Models were adjusted for demographics, vascular risk factors, and comorbidities. Results— We identified 121 428 patients with intracerebral hemorrhage and 703 918 with ischemic stroke. Liver disease was documented in 13 584 patients (1.7%). Liver disease was associated with worse discharge disposition after both intracerebral hemorrhage (global odds ratio, 1.28; 95% confidence interval, 1.19–1.38) and ischemic stroke (odds ratio, 1.23; 95% confidence interval, 1.17–1.29). Similarly, liver disease was associated with in-hospital death after both intracerebral hemorrhage (odds ratio, 1.33; 95% confidence interval, 1.23–1.44) and ischemic stroke (odds ratio, 1.60; 95% confidence interval, 1.51–1.71). Conclusions— Liver disease was associated with worse hospital discharge disposition and in-hospital mortality after stroke, suggesting worse functional outcomes.

Risk of Intracerebral Hemorrhage after Emergency Department Discharges for Hypertension

BACKGROUND Recent literature suggests that acute rises in blood pressure may precede intracerebral hemorrhage. We therefore hypothesized that patients discharged from the emergency department with hypertension face an increased risk of intracerebral hemorrhage in subsequent weeks. METHODS Using administrative claims data from California, New York, and Florida, we identified all patients discharged from the emergency department from 2005 to 2011 with a primary diagnosis of hypertension (ICD-9-CM codes 401-405). We excluded patients if they were hospitalized from the emergency department or had prior histories of cerebrovascular disease at the index visit with hypertension. We used the Mantel-Haenszel estimator for matched data to compare each patients odds of intracerebral hemorrhage during days 8-38 after emergency department discharge to the same patients odds during days 373-403 after discharge. This cohort-crossover design with a 1-week washout period enabled individual patients to serve as their own controls, thereby minimizing confounding bias. RESULTS Among the 552,569 patients discharged from the emergency department with a primary diagnosis of hypertension, 93 (.017%) were diagnosed with intracerebral hemorrhage during days 8-38 after discharge compared to 70 (.013%) during days 373-403 (odds ratio 1.33, 95% confidence interval .96-1.84). The odds of intracerebral hemorrhage were increased in certain subgroups of patients (≥60 years of age and those with secondary discharge diagnoses besides hypertension), but absolute risks were low in all subgroups. CONCLUSIONS Patients with emergency department discharges for hypertension do not face a substantially increased short-term risk of intracerebral hemorrhage after discharge.

Hospital revisit rate after a diagnosis of conversion disorder

Objective To estimate the hospital revisit rate of patients diagnosed with conversion disorder (CD). Methods Using administrative data, we identified all patients discharged from California, Florida and New York emergency departments (EDs) and acute care hospitals between 2005 and 2011 with a primary discharge diagnosis of CD. Patients discharged with a primary diagnosis of seizure or transient global amnesia (TGA) served as control groups. Our primary outcome was the rate of repeat ED visits and hospital admissions after initial presentation. Poisson regression was used to compare rates between diagnosis groups while adjusting for demographic characteristics. Results We identified 7946 patients discharged with a primary diagnosis of CD. During a mean follow-up of 3.0 (±1.6) years, patients with CD had a median of three (IQR, 1–9) ED or inpatient revisits, compared with 0 (IQR, 0–2) in patients with TGA and 3 (IQR, 1–7) in those with seizures. Revisit rates were 18.25 (95% CI, 18.10 to 18.40) visits per 100 patients per month in those with CD, 3.90 (95% CI, 3.84 to 3.95) in those with TGA and 17.78 (95% CI, 17.75 to 17.81) in those with seizures. As compared to CD, the incidence rate ratio for repeat ED visits or hospitalisations was 0.89 (95% CI, 0.86 to 0.93) for seizure disorder and 0.32 (95% CI 0.31 to 0.34) for TGA. Conclusions CD is associated with a substantial hospital revisit rate. Our findings suggest that CD is not an acute, time-limited response to stress, but rather that CD is a manifestation of a broader pattern of chronic neuropsychiatric disease.

Modeling the Impact of Interhospital Transfer Network Design on Stroke Outcomes in a Large City

Background and Purpose— We sought to model the effects of interhospital transfer network design on endovascular therapy eligibility and clinical outcomes of stroke because of large-vessel occlusion for the residents of a large city. Methods— We modeled 3 transfer network designs for New York City. In model A, patients were transferred from spoke hospitals to the closest hub hospitals with endovascular capabilities irrespective of hospital affiliation. In model B, which was considered the base case, patients were transferred to the closest affiliated hub hospitals. In model C, patients were transferred to the closest affiliated hospitals, and transfer times were adjusted to reflect full implementation of streamlined transfer protocols. Using Monte Carlo methods, we simulated the distributions of endovascular therapy eligibility and good functional outcomes (modified Rankin Scale score, 0–2) in these models. Results— In our models, 200 patients (interquartile range [IQR], 168–227) with a stroke amenable to endovascular therapy present to New York City spoke hospitals each year. Transferring patients to the closest hub hospital irrespective of affiliation (model A) resulted in 4 (IQR, 1–9) additional patients being eligible for endovascular therapy and an additional 1 (IQR, 0–2) patient achieving functional independence. Transferring patients only to affiliated hospitals while simulating full implementation of streamlined transfer protocols (model C) resulted in 17 (IQR, 3–41) additional patients being eligible for endovascular therapy and 3 (IQR, 1–8) additional patients achieving functional independence. Conclusions— Optimizing acute stroke transfer networks resulted in clinically small changes in population-level stroke outcomes in a dense, urban area.