Preparing to take the USMLE Step 1: a survey on medical students' self-reported study habits.

BACKGROUND: The USA Medical Licensing Examination Step 1 is a computerised multiple-choice examination that tests the basic biomedical sciences. It is administered after the second year in a traditional four-year MD programme. Most Step 1 scores fall between 140 and 260, with a mean (SD) of 227 (22). Step 1 scores are an important selection criterion for residency choice. Little is known about which study habits are associated with a higher score. OBJECTIVE: To identify which self-reported study habits correlate with a higher Step 1 score. METHODS: A survey regarding Step 1 study habits was sent to third year medical students at Tulane University School of Medicine every year between 2009 and 2011. The survey was sent approximately 3 months after the examination. RESULTS: 256 out of 475 students (54%) responded. The mean (SD) Step 1 score was 229.5 (22.1). Students who estimated studying more than 8-11 h per day had higher scores (p<0.05), but there was no added benefit with additional study time. Those who reported studying <40 days achieved higher scores (p<0.05). Those who estimated completing >2000 practice questions also obtained higher scores (p<0.01). Students who reported studying in a group, spending the majority of study time on practice questions or taking >40 preparation days did not achieve higher scores. CONCLUSIONS: Certain self-reported study habits may correlate with a higher Step 1 score compared with others. Given the importance of achieving a high Step 1 score on residency choice, it is important to further identify which characteristics may lead to a higher score.

Persistent leukocytosis-is this a persistent problem for patients with acute ischemic stroke?

BACKGROUND: In the setting of acute ischemic stroke (AIS), leukocytosis has been shown to be an indicator of inflammatory response. Although leukocytosis on admission has been shown to correlate with initial stroke severity in AIS patients, no work has been done to assess if there are differences in transient or persistent leukocytosis in patients without infection. The objective of this study is to determine the clinical significance of persistent versus transient leukocytosis during the early phase of AIS. METHODS: Patients who presented with AIS to our center within 48 hours of symptom onset between July 2008 and June 2010 were retrospectively identified by chart review. Patients were included if they had leukocytosis on admission (defined as white blood cell count >11,000/µL based on laboratory reference range values). A logistic regression model was used to evaluate persistent leukocytosis (leukocytosis 48 hours after admission) as a predictor of several outcome measures, including good functional outcome (discharge modified Rankin Scale score of 0-2). Marginal effects were used to estimate the probability of poor functional outcome. RESULTS: Of the 438 patients screened, 49 had leukocytosis on admission and of those 24 (49%) had persistent leukocytosis. NIHSS score correlated significantly with persistence of leukocytosis (r = .306; P = .0044). More people with transient leukocytosis (leukocytosis lasting <48 hours) had a good functional outcome (44% versus 16%; P = .006). After adjusting for baseline NIHSS score, persistent leukocytosis was not a significant independent predictor of good functional outcome, but showed an association (OR, 2.5; 95% CI, .562-10.7; P = .2322). Persistent leukocytosis after adjusting for age and NIHSS score at admission is associated with a poor functional outcome, but it is not statistically significant (OR, 2.43; 95% CI, .59-9.87; P = .2151). After controlling for age and NIHSS score on admission, for patients with persistent leukocytosis, the probability of having poor functional outcome at discharge was increased by 16 percentage points. CONCLUSIONS: Persistent leukocytosis is associated with higher baseline NIHSS scores. Persistent leukocytosis is tightly linked with baseline stroke severity and is associated with poor patient outcomes. Our study found that patients with persistent leukocytosis are more likely to present with severe strokes and maintain a high NIHSS score at 24 hours after admission, unlike patients without leukocytosis or patients with transient leukocytosis. Furthermore, it appears that persistent leukocytosis outside the setting of an infection negatively impacts the short-term functional outcome of AIS patients. Identifying patients with persistent leukocytosis could help to prognosticate and target patients that may benefit from future anti-inflammatory interventions.

Identification of modifiable and nonmodifiable risk factors for neurologic deterioration after acute ischemic stroke.

BACKGROUND: Neurologic deterioration (ND) after ischemic stroke has been shown to impact short-term functional outcome and is associated with in-hospital mortality. METHODS: Patients with acute ischemic stroke who presented between July 2008 and December 2010 were identified and excluded for in-hospital stroke, presentation >48 hours since last seen normal, or unknown time of last seen normal. Clinical and laboratory data, National Institutes of Health Stroke Scale (NIHSS) scores, and episodes of ND (increase in NIHSS score ≥ 2 within a 24-hour period) were investigated. RESULTS: Of the 596 patients screened, 366 were included (median age 65 years; 42.1% female; 65.3% black). Of these, 35.0% experienced ND. Patients with ND were older (69 v 62 years; P < .0001), had more severe strokes (median admission NIHSS score 12 v 5; P < .0001), carotid artery stenosis (27.0% v 16.8%; P = .0275), and coronary artery disease (26.0% v 16.4%; P = .0282) compared to patients without ND. Patients with ND had higher serum glucose on admission than patients without ND (125.5 v 114 mg/dL; P = .0036). After adjusting for crude variables associated with ND, age >65 years, and baseline NIHSS score >14 remained significant independent predictors of ND. In a logistic regression analysis adjusting for age and serum glucose, each 1-point increase in admission NIHSS score was associated with a 7% increase in the odds of ND (odds ratio 1.07; 95% confidence interval 1.04-1.10; P < .0001). CONCLUSIONS: Older patients and patients with more severe strokes are more likely to experience ND. Initial stroke severity was the only significant, independent, and modifiable risk factor for ND, amenable to recanalization and reperfusion.

What change in the National Institutes of Health Stroke Scale should define neurologic deterioration in acute ischemic stroke?

BACKGROUND: Neurologic deterioration (ND) occurs in one-third of patients with stroke. However, the true incidence of ND and risk for adverse outcomes remains unknown because no standardized definition of ND exists. Our study compared the prognostic value of a range of definitions for ND in patients with acute ischemic stroke (AIS). METHODS: All patients who presented to our center with AIS within 48 hours of symptom onset between July 2008 and June 2010 were retrospectively identified. Patient demographics, National Institutes of Health Stroke Scale (NIHSS) scores, etiologies of ND, and outcome measures were compared between patients according to a range of ND definitions using receiver operating characteristic analyses. RESULTS: Three hundred forty-seven patients were included. The 2 definitions of ND with the highest sensitivity and specificity for several outcome measures were tested against each other: an increase in the NIHSS score by ≥2 or ≥4 points in a 24-hour period. More than one third (36.9%) of patients experienced ≥2-point ND versus 17.3% with ≥4-point ND. Patients who experienced ND by either definition had prolonged hospitalization (P < .001), poorer functional outcome (discharge modified Rankin Scale score >2; P < .001), and higher discharge NIHSS score (P < .001) compared to patients without ND. Compared to patients without ND, a ≥2-point ND was associated with a 3-fold risk of death (odds ratio 3.120; 95% confidence interval 1.231-7.905; P < .0165) after adjusting for admission NIHSS score, serum glucose, and age. CONCLUSIONS: A ≥2-point ND is a sensitive indicator of poor outcome and in-hospital mortality. An accepted definition of ND is needed to systematically study and compare results across trials for ND in patients with stroke.

Leukocytosis in patients with neurologic deterioration after acute ischemic stroke is associated with poor outcomes.

BACKGROUND: Neurologic deterioration (ND) after acute ischemic stroke (AIS) has been shown to result in poor outcomes. ND is thought to arise from penumbral excitotoxic cell death caused in part by leukocytic infiltration. Elevated admission peripheral leukocyte levels are associated with poor outcomes in stroke patients who suffer ND, but little is known about the dynamic changes that occur in leukocyte counts around the time of ND. We sought to determine if peripheral leukocyte levels in the days surrounding ND are correlated with poor outcomes. METHODS: Patients with AIS who presented to our center within 48 hours of symptom onset between July 2008 and June 2010 were retrospectively identified by chart review and screened for ND (defined as an increase in National Institutes of Health Stroke Scale score ≥ 2 within a 24-hour period). Patients were excluded for steroid use during hospitalization or in the month before admission and infection within the 48 hours before or after ND. Demographics, daily leukocyte counts, and poor functional outcome (modified Rankin Scale score 3-6) were investigated. RESULTS: Ninety-six of the 292 (33%) patients screened had ND. The mean age was 69.5 years; 62.5% were male and 65.6% were black. Patients with a poor functional outcome had significantly higher leukocyte and neutrophil levels 1 day before ND (P = .048 and P = .026, respectively), and on the day of ND (P = .013 and P = .007, respectively), compared to patients with good functional outcome. CONCLUSIONS: Leukocytosis at the time of ND correlates with poor functional outcomes and may represent a marker of greater cerebral damage through increased parenchymal inflammation.

Infections present on admission compared with hospital-acquired infections in acute ischemic stroke patients.

BACKGROUND: To date, few studies have assessed the influence of infections present on admission (POA) compared with hospital-acquired infections (HAIs) on neurologic deterioration (ND) and other outcome measures in acute ischemic stroke (AIS). METHODS: Patients admitted with AIS to our stroke center (July 2010 to December 2010) were retrospectively assessed. The following infections were assessed: urinary tract infection, pneumonia, and bacteremia. Additional chart review was performed to determine whether the infection was POA or HAI. We assessed the relationship between infections in ischemic stroke patients and several outcome measures including ND and poor functional outcome. A mediation analysis was performed to assess the indirect effects of HAI, ND, and poor functional outcome. RESULTS: Of the 334 patients included in this study, 77 had any type of infection (23 POA). After adjusting for age, National Institutes of Health Stroke Scale at baseline, glucose on admission, and intravenous tissue plasminogen activator, HAI remained a significant predictor of ND (odds ratio [OR]=8.8, 95% confidence interval [CI]: 4.2-18.7, P<.0001) and poor functional outcome (OR=41.7, 95% CI: 5.2-337.9, P=.005), whereas infections POA were no longer associated with ND or poor functional outcome. In an adjusted analysis, we found that 57% of the effect from HAI infections on poor functional outcome is because of mediation through ND (P<.0001). CONCLUSIONS: Our data suggests that HAI in AIS patients increases the odds of experiencing ND and subsequently increases the odds of being discharged with significant disability. This mediated effect suggests a preventable cause of ND that can thereby decrease the odds of poor functional outcomes after an AIS.

Time to Neurological Deterioration in Ischemic Stroke.

BACKGROUND: Neurological deterioration (ND) is common, with nearly one-half of ND patients deteriorating within the first 24 to 48 hours of stroke. The timing of ND with respect to ND etiology and reversibility has not been investigated. METHODS: At our center, we define ND as an increase of 2 or more points in the National Institutes of Health Stroke Scale (NIHSS) score within 24 hours and categorize etiologies of ND according to clinical reversibility. ND etiologies were considered non-reversible if such causes may have produced or extended any areas of ischemic neurologic injury due to temporary or permanent impairment in cerebral perfusion. RESULTS: Seventy-one of 350 ischemic stroke patients experienced ND. Over half (54.9%) of the patients who experienced ND did so within the 48 hours of last seen normal. The median time to ND for non-reversible causes was 1.5 days (IQR 0.9, 2.4 days) versus 2.6 days for reversible causes (IQR 1.4, 5.5 days, p=0.011). After adjusting for NIHSS and hematocrit on admission, the log-normal survival model demonstrated that for each 1-year increase in a patient's age, we expect a 3.9% shorter time to ND (p=0.0257). In addition, adjusting for age and hematocrit on admission, we found that that for each 1-point increase in the admission NIHSS, we expect a 3.1% shorter time to ND (p=0.0034). CONCLUSIONS: We found that despite having similar stroke severity and age, patients with nonreversible causes of ND had significantly shorter median time to ND when compared to patients with reversible causes of ND.