Publications

Hepatitis B virus (HBV) is a major human pathogen that causes immune-mediated hepatitis. Successful immunity to HBV is age dependent: viral clearance occurs in most adults, whereas neonates and young children usually develop chronic infection. Using a mouse model of HBV infection, we sought mechanisms underpinning the age-dependent outcome of HBV and demonstrated that hepatic macrophages facilitate lymphoid organization and immune priming within the adult liver and promote successful immunity. In contrast, lymphoid organization and immune priming was greatly diminished in the livers of young mice, and of macrophage-depleted adult mice, leading to abrogated HBV immunity. Furthermore, we found that CXCL13, which is involved in B lymphocyte trafficking and lymphoid architecture and development, is expressed in an age-dependent manner in both adult mouse and human hepatic macrophages and plays an integral role in facilitating an effective immune response against HBV. Taken together, these results identify some of the immunological mechanisms necessary for effective control of HBV.

OBJECTIVES

To determine whether 30-day postoperative mortality, complications, failure-to-rescue (FTR) rates, and postoperative length of stay increase with advancing age.

DESIGN

Retrospective cohort study.

SETTING

Hospitals participating in the American College of Surgeons National Surgical Quality Improvement Program.

PARTICIPANTS

Individuals undergoing nonemergent major general surgeries between 2005 and 2008 were studied (N = 165,600).

MEASUREMENTS

Postoperative outcomes of interest were complications occurring within 30 days of the index operation, return to the operating room within 30 days, FTR after a postoperative complication, postsurgical length of stay, and 30-day mortality.

RESULTS

Postoperative mortality, overall morbidity, and each type of postoperative complication increased with increasing age. Rates of FTR after each type of postoperative complication also increased with age. Mortality in individuals aged 80 and older after renal insufficiency (43.3%), stroke (36.5%), myocardial infarction (MI) (35.6%), and pulmonary complications (25-39%) were particularly high. Median postoperative length of stay increased with age after surgical site infection, urinary tract infection, pneumonia, return to the operating room, and overall morbidity but not after venous thromboembolism, stroke, MI, renal insufficiency, failure to wean from the ventilator, or reintubation.

CONCLUSION

Thirty-day mortality and complication and FTR rates increase with age after nonemergent general surgeries. Individuals aged 80 and older have especially high mortality after renal, cardiovascular, and pulmonary complications. Surgeons need to be more selective with advancing age regarding who will benefit from the surgical intervention.

BACKGROUND AND OBJECTIVES

Little is known about geographic differences in the incidence of AKI. The objective of this study was to determine if regional variation exists in the population incidence of dialysis-requiring AKI in the United States.

DESIGN, SETTING, PARTICIPANTS, & METHODS

Data from the Nationwide Inpatient Sample, a US nationally representative sample of hospitalizations, were used to determine the incidence rates of dialysis-requiring AKI between 2007 and 2009 among the four US Census-designated regions. Cases were identified using validated discharge codes. Poisson regression models were used to estimate overall regional rates, accounting for the data's sampling scheme.

RESULTS

In 2007-2009, the population incidence rates of dialysis-requiring AKI differed across the four Census-designated regions (P=0.04). Incidence was highest in the Midwest (523 cases/million person-yr, 95% confidence interval=483 to 568) and lowest in the Northeast (457 cases/million person-yr, 95% confidence interval=426 to 492). The pattern of regional variation in the incidence of dialysis-requiring AKI was not the same as the pattern of regional variation in the incidence of renal replacement therapy-requiring ESRD (obtained from the US Renal Data System). In-hospital mortality associated with dialysis-requiring AKI differed across the four regions, with the highest case fatality in the Northeast (25.9%) and the lowest case fatality in the Midwest (19.4%).

CONCLUSIONS

Significant regional variation exists in the population incidence of dialysis-requiring AKI in the United States, and additional investigation is warranted to uncover potential causes behind these geographic differences.