Differential associations between body mass index and outcomes after elective adult cardiac surgery: a linked data cohort study.

This study assessed the relationships between body mass index (BMI) and different outcomes after adult cardiac surgery by linking detailed preoperative comorbidity data with the long-term mortality and morbidity outcomes of 2131 consecutive patients who had elective cardiac surgery at a major cardiac surgical hospital in Western Australia. Patients with a high BMI had more comorbidities and were more likely to have had coronary artery bypass grafting than valve surgery. A total of 143 patients (6.7%) died during a median follow-up period of 30 months. The major causes of death were congestive heart failure (25.9%), myocardial infarction (14.7%), infection (23.8%) and cancer (13.9%). BMI had no association with long-term mortality, after adjusting for important confounders including the Charlson Comorbidity Index. BMI had a relatively linear relationship with the risk of new-onset atrial fibrillation (odds ratio 1.05 per point increment, 95% confidence interval 1.03 to 1.05) and venous thromboembolism (odds ratio 1.20, 95% confidence interval 1.14 to 1.26). BMI was the second most important predictor after age and accounted for 22% of the variability in the risk of atrial fibrillation. BMI had an inverse relationship with the risk of requiring allogeneic blood transfusion, postoperative intra-aortic balloon pump, or surgical re-exploration. In summary, BMI had differential associations with different short- and long-term outcomes after elective adult cardiac surgery. After adjusting for important confounders including the presence of cancers, we did not observe any 'obesity paradox' and patients with a high BMI were not associated with an increased probability of long-term survival.

Results of antibiotic susceptibility testing do not influence clinical outcome in children with cystic fibrosis.

INTRODUCTION: Patients with CF experience pulmonary exacerbations. These are often initially empirically treated with intravenous antibiotics, with antibiotic choice refined after susceptibility testing. METHODS: We completed a 5-year retrospective review of children attending the Paediatric CF Unit, Nottingham. The respiratory sampling, antibiotic prescribing and susceptibility testing guidance were audited. Episodes were classified according to the concordance between the antibiotics prescribed and antibiotic susceptibility testing. RESULTS: Of 52 patients who had previously isolated Pseudomonas aeruginosa, 103 antibiotic courses were commenced that coincided with an isolation of P. aeruginosa. P. aeruginosa was fully susceptible, partially susceptible or fully resistant on 33%, 44.7% or 16.5% of occasions respectively. The antibiotic prescriptions were never changed following antibiotic susceptibility testing. We found no association between change in FEV(1) (p=0.54), change in BMI (p=0.12) or time to next exacerbation (p=0.66) and concordance between antibiotic susceptibility and the antibiotics administered. CONCLUSION: This study contributes to mounting evidence questioning the utility of routine antibiotic susceptibility testing.

Case-control study of acute renal failure in patients with cystic fibrosis in the UK.

BACKGROUND: There has been a recent increase in the number of reported cases of acute renal failure (ARF) in cystic fibrosis (CF). A case-control study was conducted to determine the factors which are associated with an increased risk of ARF. METHODS: 24 cases of confirmed ARF were identified in patients with CF from 20 UK CF centres presenting between 1997 and 2004. Using the UK CF database, sex- and age-matched controls were identified. Risk factors were analysed by conditional logistic regression and Mantel-Haenszel analysis. RESULTS: 21 of the 24 patients with ARF had received an aminoglycoside at the time of their episode of ARF or in the preceding week compared with only 3 of 42 controls during the same time period (OR 81.8, 95% CI 4.7 to 1427, p<0.001). In the year before the episode of ARF, significantly more cases than controls had received gentamicin (19/24 cases vs 1/42 controls, p<0.001). The numbers receiving tobramycin were similar (9/24 cases vs 16/42 controls, p = 0.9). A known risk factor for renal impairment (prior renal disease, acute dehydration or long-term treatment with a nephrotoxic drug) was present in 18/24 cases and 7/42 controls (OR 24.0, 95% CI 3.1 to 186.6, p = 0.002). CONCLUSIONS: In patients with CF the use of an intravenous aminoglycoside is a risk factor for ARF; gentamicin is more nephrotoxic than tobramycin. Most patients who develop ARF have a risk factor which necessitates withholding aminoglycosides or more closely monitoring their use.