Complications associated with influenza infection

Outcomes after surgery in patients with and without recent influenza: a nationwide population-based study

Background

The influence of recent influenza infection on perioperative outcomes is not completely understood.

Method

Using Taiwan's National Health Insurance Research Data from 2008 to 2013, we conducted a surgical cohort study, which included 20,544 matched patients with a recent history of influenza and 10,272 matched patients without. The main outcomes were postoperative complications and mortality. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) for the complications and for mortality in patients with a history of influenza within 1-14 days or 15-30 days compared with non-influenza controls.

Results

Compared with patients who had no influenza, patients with influenza within preoperative days 1-7 had increased risks of postoperative pneumonia (OR 2.22, 95% CI 1.81-2.73), septicemia (OR 1.98, 95% CI 1.70-2.31), acute renal failure (OR 2.10, 95% CI 1.47-3.00), and urinary tract infection (OR 1.45, 95% CI 1.23-1.70). An increased risk of intensive care admission, prolonged length of stay, and higher medical expenditure was noted in patients with history of influenza within 1-14 days.

Conclusion

We found that there was an association between influenza within 14 days preoperatively and the increased risk of postoperative complications, particularly with the occurrence of influenza within 7 days prior to surgery.

Renal complications of seasonal and pandemic influenza A virus infections

Renal complications of influenza A virus infections are uncommon but can contribute to a deterioration in the patient's condition, which include acute kidney injury (AKI) in critically ill patients, rhabdomyolysis, hemolytic uremic syndrome (HUS), acute glomerulonephritis (AGN), disseminated intravascular coagulation (DIC), Goodpasture's syndrome, and acute tubulointerstitial nephritis (TIN). The clinical characteristics of AKI in critically ill patients with pandemic influenza A(H1N1) 2009 virus (A(H1N1)pdm09) infection are similar to uninfected patients. Underlying conditions associated with AKI include older age, diabetes mellitus, obesity, pregnancy, history of asthma, and chronic kidney disease. Histologic examination of the kidneys from patients with A(H1N1)pdm09 infection who died include acute tubular necrosis (ATN), myoglobin pigment, and DIC. A(H1N1)pdm09 is present in the kidneys of some patients. The clinical characteristics of patients with rhabdomyolysis associated with influenza A include younger age and the frequent occurrence of muscle symptoms. AKI occurs in approximately one third of patients with rhabdomyolysis due to influenza A. HUS is associated with A(H1N1)pdm09 as follows: Streptococcus pneumoniae-associated HUS following A(H1N1)pdm09 infection, HUS triggered by A(H1N1)pdm09 in patients with genetic complement dysregulation, and HUS associated with A(H1N1)pdm09 without known underlying disorder. AGN, Goodpasture's syndrome, and acute TIN are extremely rare complications of influenza A virus infection. Although the pathogenesis underlying renal injuries due to influenza A virus has not been delineated, some hypotheses have been advanced, including ATN due to renal hypoperfusion or rhabdomyolysis, glomerular microthrombosis due to DIC, direct viral injury to the kidney, and an altered immune system with systemic mononuclear cell activation following influenza A virus infections.

Influenza B-associated rhabdomyolysis in Taiwanese children

AIM

Influenza B-associated rhabdomyolysis (IBAR) is an infrequent and little-known complication of influenza B virus infection in children. Diagnosis is usually made based on clinical history, the presence of influenza in the community and detection of virus in nasopharyngeal specimens. The aim of this study was to describe the clinical and laboratory manifestations, complications and outcomes of IBAR in Taiwanese children.

METHODS

A retrospective analysis was conducted in patients aged < 17 years who had been diagnosed with IBAR at a university children's hospital in North Taiwan during 2000-2007. All children enrolled in the study had presented with rhabdomyolysis associated with laboratory-confirmed influenza B infections. Demographic data, clinical manifestations, complications and outcomes were included in the analysis.

RESULTS

Overall, 24 IBAR cases were analysed. IBAR typically occurred in school-aged children with a 7:3 male:female ratio. The mean age was 7.2 ± 1.9 years. Nearly 63% of cases occurred between the ages of 6 and 9 years. The median interval between the onset of influenza and onset of IBAR was 3.4 days (range, 1-14). The calf muscles were involved in all cases. Laboratory tests indicated a mean initial blood creatine kinase of 4212 U/L. The median time to clinical recovery was 5 days (range 1-24). No patient had renal failure. IBAR tends to occur mainly in winter and spring during influenza B outbreaks. IBAR sometimes induces some complications, and early detection and careful medical treatment are necessary.

CONCLUSION

The results of this study indicate that outcomes of IBAR are good with proper medical care.