2 Minute Medicine Rewind August 11 – August 18, 2014

In this section, we highlight the key high-impact studies, updates, and analyses published in medicine during the past week.

Urinary Sodium and Potassium Excretion, Mortality, and Cardiovascular Events

Decreased sodium intake is associated with a modest decrease in blood pressure, but it is unclear whether this translates to a decrease in cardiovascular events, and the optimal range for sodium intake is controversial. In this prospective cohort study, investigators followed 101,945 middle-aged adults from 14 countries for an average of 3.7 years to determine the association between estimated excretion of sodium and potassium and a primary composite outcome of death and major cardiovascular events. Participants had estimated sodium and potassium excretion of 4.93g and 2.12g per day on average, with higher sodium excretion associated with higher blood pressures (p<.001). People with both high (>7g) and low (<3g) estimated sodium excretion were associated with greater odds of the primary outcome compared to the reference group of 4-6g/day (OR 1.15, 95%CI 1.02-1.30 and OR 1.27, 95%CI 1.12-1.44, respectively). Only 10% of patients in the study has estimated sodium excretion of <3g/day. Potassium excretion greater than the reference group of <1.5g/day was associated with lower risk of death and cardiovascular events, and no interaction effect was found between sodium and potassium excretion on the primary outcome (p=.55). This study brings into question whether current recommendations for maximum daily sodium intake of less than 2.4g may suboptimal.

Efficacy of High-Dose versus Standard-Dose Influenza Vaccine in Older Adults

It has been documented that high-dose influenza vaccine generates a more robust antibody response in older adults compared to a standard-dose vaccine, however the clinical benefit of this improved antibody response is not well studied. In this phase IIIb-IV, multicenter, randomized, double-blind trial, investigators randomized adults older than 65 to receive a high-dose (HD) or standard-dose (SD) trivalent inactivated influenza vaccine to determine the efficacy of HD compared to SD vaccination in preventing laboratory-confirmed influenza infection. Individuals enrolled in both years of the study were re-randomized in the second year, yielding 31,989 randomizations. Lab-confirmed influenza illness occurred in 1.4% of participants receiving the HD vaccine, compared to 1.9% of those who received the SD vaccine (relative efficacy 24.2%, 95%CI 9.7-36.5). Antibody titers, a secondary outcome, were at seroprotective levels in 91.6-99.2% of HD vaccine recipients compared to 83.9-94.2% of SD vaccine recipients, depending on the targeted influenza strain.

Effect of a Long-Term Behavioural Weight Loss Intervention on Nephropathy in Overweight or Obese Adults with Type 2 Diabetes: A Secondary Analysis of the Look AHEAD Randomised Clinical Trial

Lifestyle interventions, particularly weight loss, are recommended in Type 2 Diabetes, but the effects of lifestyle changes on progression of diabetic nephropathy is not well characterized. In this secondary post-hoc analysis of a randomized trial, researchers analyzed the effect of randomization to intensive lifestyle intervention (ILI) or diabetes support and education on progression to very-high-risk chronic kidney disease (CKD) among 4,831 adults with Type 2 Diabetes. Over a median follow up of 8 years, very-high-risk CKD developed less frequently in the ILI group than in the control group (0.63% vs 0.91% of participants, respectively; HR 0.69, 95%CI 0.55-0.87, p=.0016). Fewer individuals in the ILI group progressed to need dialysis compared to the control group, but this difference was not significant, possibly due to insufficient numbers at that time point (0.13% vs 0.16% respectively; HR 0.80, 95%CI 0.49-1.30). The significant decrease in progression to very-high-risk CKD among ILI group participants supports the study’s initial finding of a non-significant reduction in mortality compared to diabetes support and education (HR 0.85, 95%CI 0.69-1.04.

Perioperative Atrial Fibrillation and the Long-term Risk of Ischemic Stroke

Perioperative atrial fibrillation (AF) is traditionally believed to be a transient phenomenon, though little data exists demonstrating long-term stroke risk in patients with perioperative AF. In this retrospective cohort study of discharge claims data from nonfederal acute care hospitals in California, investigators analyzed records of over 1.7 million surgical patients to determine the incidence and associated stroke risk of documented perioperative AF over a median of 2.1 years. Perioperative AF was much more common in patients after cardiac surgery than non-cardiac surgery (16.1% vs 0.78%, p<.001). After non-cardiac surgery, patients with perioperative AF were more likely to have a stroke by 1-year postoperatively (HR 2.0, 95% CI 1.7-2.3, cumulative incidence 1.47% vs 0.36% among patients who did not have perioperative AF). The difference in stroke risk in cardiac surgery patients with perioperative AF and those without AF was smaller (HR 1.3, 95%CI 1.1-1.6, cumulative incidence 0.99% vs 0.83%). Though these findings suggest that perioperative AF outside the setting of direct heart manipulation may reflect an increased predisposition for stroke, significant limitations of this study include lack of information on duration of perioperative AF and outpatient management.

Patterns of Injury, Outcomes, and Predictors of In-Hospital and 1-Year Mortality in Nonagenerian and Centenarian Trauma Patients

As the US population continue to age, it is important to understand the outcomes and predictive factors in treating older trauma patients. In this retrospective analysis, researchers reviewed records of 474 consecutive trauma patients aged 90+ years at a single trauma center to determine in-hospital and one-year mortality. In-hospital mortality in the study population was 9.5%, on the low end of previously reported mortality rates. However, cumulative mortality was 26% at 3 months after discharge, and 40% at 1 year. Independent predictors of in-hospital mortality included mechanical ventilation (OR 6.23, 95%CI 1.42-27.27), cervical spine injury (OR 4.37, 95%CI 1.41-13.50), and initial injury severity (OR 1.09, 95%CI 1.02-1.16). Presence of head injury (OR 2.65, 95%CI 1.24-5.67) and length of hospital stay (OR 1.06, 95%CI 1.02-1.11) predicted 1-year mortality. As other literature has suggested, presence of comorbidities were not associated with increased mortality after trauma.

Image: PD

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