Time-to-event outcomes are common in medical research as they offer more information than simply whether or not an event occurred. To handle these outcomes, as well as censored observations where the event was not observed during follow-up, survival analysis methods should be used. Kaplan-Meier estimation can be used to create graphs of the observed survival curves, while the log-rank test can be used to compare curves from different groups. If it is desired to test continuous predictors or to test multiple covariates at once, survival regression models such as the Cox model or the accelerated failure time model (AFT) should be used. The choice of model should depend on whether or not the assumption of the model (proportional hazards for the Cox model, a parametric distribution of the event times for the AFT model) is met. The goal of this paper is to review basic concepts of survival analysis. Discussions relating the Cox model and the AFT model will be provided. The use and interpretation of the survival methods model are illustrated using an artificially simulated dataset.

Objective To identify risk factors for uterine atony or hemorrhage. Study Design Secondary analysis of a 3-arm double-blind randomized trial of different dose-regimens of oxytocin to prevent uterine atony after vaginal delivery. The primary outcome was uterine atony or hemorrhage requiring treatment. Twenty-one potential risk factors were evaluated. Logistic regression was used to identify independent risk factors using 2 complementary pre-defined model selection strategies. Results Among 1798 women randomized to 10, 40 or 80U prophylactic oxytocin after vaginal delivery, treated uterine atony occurred in 7%. Hispanic (OR 2.1; 95% CI 1.3–3.4) and non-Hispanic whites (OR 1.6; 95% CI 1.0–2.5), preeclampsia (OR 3.2; 95% CI 2.0–4.9) and chorioamnionitis (OR 2.8; 95% CI 1.6–5.0) were consistent independent risk factors. Other risk factors based on the specified selection strategies were obesity, induction/augmentation of labor, twins, hydramnios, anemia, and arrest of descent. Amnioinfusion appeared to be protective against uterine atony (OR 0.53; 95% CI 0.29–0.98). Conclusion Independent risk factors for uterine atony requiring treatment include Hispanic and non-Hispanic white ethnicity, preeclampsia and chorioamnionitis.

Masked hypertension, defined as non-elevated clinic blood pressure (BP) with elevated out-of-clinic BP, has been associated with increased cardiovascular disease (CVD) risk in Europeans and Asians. Few data are available on masked hypertension and CVD and mortality risk among African Americans (AAs). We analyzed data from the Jackson Heart Study, a prospective cohort study of AAs. Analyses included participants with clinic-measured systolic/diastolic BP (SBP/DBP)<140/90mmHg who completed ambulatory BP monitoring (ABPM) following the baseline exam in 2000–2004 (n=738). Masked daytime (10:00am–8:00pm) hypertension was defined as mean ambulatory SBP/DBP≥135/85mmHg. Masked nighttime (midnight-6:00am) hypertension was defined as mean ambulatory SBP/DBP≥120/70mmHg. Masked 24-hour hypertension was defined as mean SBP/DBP≥130/80mmHg. CVD events (nonfatal/fatal stroke, nonfatal myocardial infarction or fatal coronary heart disease) and deaths identified through December 2010 were adjudicated. Any masked hypertension (masked daytime, nighttime or 24-hour hypertension) was present in 52.2% of participants; 28.2%, 48.2% and 31.7% had masked daytime, nighttime and 24-hour hypertension, respectively. There were 51 CVD events and 44 deaths over a median follow-up of 8.2 and 8.5 years, respectively. CVD rates per 1,000 person-years (95% CI) in participants with and without any masked hypertension were 13.5 (9.9–18.4) and 3.9 (2.2–7.1), respectively. The multivariable adjusted hazard ratio (95% CI) for CVD was 2.49 (1.26–4.93) for any masked hypertension and 2.86 (1.59–5.13), 2.35 (1.23–4.50) and 2.52 (1.39–4.58) for masked daytime, nighttime and 24-hour hypertension, respectively. Masked hypertension was not associated with all-cause mortality. Masked hypertension is common and associated with increased risk for CVD events in AAs.

There is limited empirical evidence to support the protective effects of physical activity in the prevention of hypertension among African Americans. The purpose of this study was to examine the association of physical activity with incident hypertension among African Americans. We studied 1,311 participants without hypertension at baseline enrolled in the Jackson Heart Study, a community-based study of African Americans residing in Jackson, MS. Overall physical activity, moderate-vigorous physical activity (MVPA), and domain-specific physical activity (work, active living, household, and sport/exercise) were assessed by self-report during the baseline exam (2000–2004). Incident hypertension, assessed at exam 2 (2005–2008) and exam 3 (2009–2013), was defined as the first visit with systolic/diastolic blood pressure ≥140/90mmHg or self-reported antihypertensive medication use. Over a median follow-up of 8.0 years, there were 650 (49.6%) incident hypertension cases. The multivariable-adjusted hazard ratios (95% CI) for incident hypertension comparing participants with intermediate and ideal versus poor levels of MVPA were 0.84 (0.67–1.05) and 0.76 (0.58–0.99), respectively (P-trend=0.038). A graded, dose-response association was also present for sport/exercise-related physical activity (Quartiles 2, 3, and 4 vs. Quartile 1: 0.92 [0.68–1.25], 0.87 [0.67–1.13], 0.75 [0.58–0.97], respectively; P-trend=0.032). There were no statistically significant associations observed for overall physical activity, or work, active living, and household-related physical activities. In conclusion, the results of the current study suggest that regular MVPA or sport/exercise-related physical activity may reduce the risk of developing hypertension in African Americans.

Background Data from before the 2000s indicate the majority of incident cardiovascular disease (CVD) events occur among US adults with systolic and diastolic blood pressure (SBP/DBP)≥140/90 mmHg. Over the past several decades, BP declined and hypertension control has improved. Methods We estimated the percentage of incident CVD events that occur at SBP/DBP<140/90 mmHg in a pooled analysis of three contemporary US cohorts: the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, the Multi-Ethnic Study of Atherosclerosis (MESA), and the Jackson Heart Study (JHS) (n=31,856; REGARDS=21,208; MESA=6,779; JHS=3,869). Baseline study visits were conducted in 2003–2007 for REGARDS, 2000–2002 for MESA, and 2000–2004 for JHS. BP was measured by trained staff using standardized methods. Antihypertensive medication use was self-reported. The primary outcome was incident CVD, defined by the first occurrence of fatal or non-fatal stroke, non-fatal myocardial infarction, fatal coronary heart disease, or heart failure. Events were adjudicated in each study. Results Over a mean follow-up of 7.7 years, 2,584 participants had incident CVD events. Overall, 63.0% (95%CI: 54.9%–71.1%) of events occurred in participants with SBP/DBP<140/90 mmHg; 58.4% (95%CI: 47.7%–69.2%) and 68.1% (95%CI: 60.1%–76.0%) among those taking and not taking antihypertensive medication, respectively. The majority of events occurred in participants with SBP/DBP<140/90 mmHg among those <65 years (66.7% 95%CI: 60.5%–73.0%) and ≥65 years (60.3% 95%CI: 51.0%–69.5%), women (61.4%; 95%CI: 49.9%–72.9%) and men (63.8%; 95%CI: 58.4%–69.1%), and for whites (68.7%; 95%CI: 66.1%–71.3%), blacks (59.0%; 95%CI: 49.5%-68.6%), Hispanics (52.7% 95%CI: 45.1%–60.4%) and Chinese-Americans (58.5%; 95%CI: 45.2%–71.8%). Among participants taking antihypertensive medication with SBP/DBP<140/90 mmHg, 76.6% (95% CI: 75.8%–77.5%) were eligible for statin treatment but only 33.2% (95%CI: 32.1%–34.3%) were taking one and 19.5% (95%CI: 18.5%–20.5%) met the Systolic Blood Pressure Intervention Trial eligibility criteria and may benefit from a SBP target goal of 120 mmHg. Conclusions While higher BP levels are associated with increased CVD risk, in the modern era, the majority of incident CVD events occur in US adults with SBP/DBP<140/90 mmHg. Although absolute risk and cost-effectiveness should be considered, additional CVD risk reduction measures for adults with SBP/DBP<140/90 mmHg at high risk for CVD may be warranted.

Introduction Timely, appropriate intervention is key to improving outcomes in many emergent conditions. In rural areas, it is particularly challenging to assure quality, timely emergency care. The TelEmergency (TE) program, which utilizes a dual nurse practitioner and emergency medicine-trained, board-certified physician model, has the potential to improve access to quality emergency care in rural areas. The objective of this study was to examine how the implementation of the TE program impacts rural hospital Emergency Department (ED) operations. Methods Methods included a before and after study of the effect of the TE program on participating rural hospitals between January 2007 and December 2008. Data on ED and hospital operations were collected one year prior to and one year following the implementation of TE. Data from participating hospitals were combined and compared for the two time periods. Results Nine hospitals met criteria for inclusion and participated in the study. Total ED volumes did not significantly change with TE implementation, but ED admissions to the same rural hospital significantly increased following TE implementation (6.7% to 8.1%, p-value = 0.02). Likewise, discharge rates from the ED declined post-initiation (87.1% to 80.0%, p-value = 0.003). ED deaths and transfer rates showed no significant change, while the rate of patient discharge against medical advice significantly increased with TE use. Discussion In this analysis, we found a significant increase in the rate of ED admissions to rural hospitals with TE use. These findings may have important implications for the quality of emergency care in rural areas and the sustainability of rural hospitals' EDs.

IMPORTANCE African Americans and individuals of African ancestry have a higher risk of stroke compared with non-Hispanic white individuals. Identifying the source of this disparity could provide an opportunity for clinical stroke risk stratification and more targeted therapy. Whether sickle cell trait (SCT) is an indicator of increased risk of ischemic stroke among African Americans is still unclear.OBJECTIVE To examine whether SCT is associated with a higher risk of incident ischemic stroke among African Americans. DESIGN, SETTING, AND PARTICIPANTSThis meta-analysis assessed the association of SCT with the risk of incident ischemic stroke. Four large, prospective, population-based studies with African American cohorts were assessed:

IMPORTANCELittle is known regarding health outcomes associated with higher blood pressure (BP) levels measured outside the clinic among African American individuals.OBJECTIVE To examine whether daytime and nighttime BP levels measured outside the clinic among African American individuals are associated with cardiovascular disease (CVD) and all-cause mortality independent of BP levels measured inside the clinic. DESIGN, SETTING, AND PARTICIPANTSThis prospective cohort study analyzed data from 1034 African American participants in the Jackson Heart Study who completed ambulatory BP monitoring at baseline (September 26, 2000, to March 31, 2004. Mean daytime and nighttime BPs were calculated based on measurements taken while participants were awake and asleep, respectively. Data were analyzed from July 1, 2017, to April 30, 2019.MAIN OUTCOMES AND MEASURES Cardiovascular disease events, including coronary heart disease and stroke, experienced through December 31, 2014, and all-cause mortality experienced through December 31, 2016, were adjudicated. The associations of daytime BP and nighttime BP, separately, with CVD events and all-cause mortality were determined using Cox proportional hazards regression models.RESULTS A total of 1034 participants (mean [SD] age, 58.9 [10.9] years; 337 [32.6%] male; and 583 [56.4%] taking antihypertensive medication) were included in the study. The mean daytime systolic BP (SBP)/diastolic BP (DBP) was 129.4/77.6 mm Hg, and the mean nighttime SBP/DBP was 121.3/68.4 mm Hg. During follow-up (median [interquartile range], 12.5 [11.1-13.6] years for ] years for all-cause mortality), 113 CVD events and 194 deaths occurred. After multivariable adjustment, including in-clinic SBP and DBP, the hazard ratios (HRs) for CVD events for each SD higher level were 1.53 (95% CI, 1.24-1.88) for daytime SBP (per 13.5 mm Hg), 1.48 (95% CI, 1.22-1.80) for nighttime SBP (per 15.5 mm Hg), 1.25 (95% CI, 1.02-1.51) for daytime DBP (per 9.3 mm Hg), and 1.30 (95% CI, 1.06-1.59) for nighttime DBP (per 9.5 mm Hg). Nighttime SBP was associated with all-cause mortality (HR per 1-SD higher level, 1.24; 95% CI, 1.06-1.45), but no association was present for daytime SBP (HR, 1.13; 95% CI, 0.97-1.33) and daytime (HR, 0.95; 95% CI, 0.81-1.10) and nighttime (HR, 1.06; 95% CI, 0.90-1.24) DBP.CONCLUSIONS AND RELEVANCE Among African American individuals, higher daytime and nighttime SBPs were associated with an increased risk for CVD events and all-cause mortality independent of BP levels measured in the clinic. Measurement of daytime and nighttime BP using ambulatory monitoring during a 24-hour period may help identify African American individuals who have an increased cardiovascular disease risk.